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Author SHA1 Message Date
yhirose
2e925abacc Release v0.36.0 2026-03-02 21:53:42 -05:00
234 changed files with 14027 additions and 21572 deletions

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@@ -1,34 +0,0 @@
name: docs
on:
push:
branches: [master]
paths:
- 'docs-src/**'
workflow_dispatch:
permissions:
contents: read
pages: write
id-token: write
concurrency:
group: ${{ github.workflow }}-${{ github.ref }}
cancel-in-progress: true
jobs:
deploy:
runs-on: ubuntu-latest
environment:
name: github-pages
url: ${{ steps.deployment.outputs.page_url }}
steps:
- uses: actions/checkout@v4
- uses: dtolnay/rust-toolchain@stable
- uses: Swatinem/rust-cache@v2
- name: Install docs-gen
run: cargo install docs-gen
- name: Build
run: docs-gen build docs-src docs
- uses: actions/configure-pages@v5
- uses: actions/upload-pages-artifact@v3
with:
path: docs
- id: deployment
uses: actions/deploy-pages@v4

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@@ -1,37 +0,0 @@
name: 32-bit Build Test
on:
push:
branches: [master]
pull_request:
branches: [master]
workflow_dispatch:
concurrency:
group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
cancel-in-progress: true
jobs:
test-win32:
name: Windows 32-bit (MSVC x86)
runs-on: windows-latest
timeout-minutes: 10
steps:
- uses: actions/checkout@v4
- name: Build (Win32)
shell: cmd
run: |
for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -property installationPath`) do set VSDIR=%%i
call "%VSDIR%\VC\Auxiliary\Build\vcvarsall.bat" x86 || exit /b 1
cl /std:c++14 /EHsc /W4 /WX /c /Fo:NUL test\test_32bit_build.cpp
test-arm32:
name: ARM 32-bit (cross-compile)
runs-on: ubuntu-latest
timeout-minutes: 10
steps:
- uses: actions/checkout@v4
- name: Install cross compiler
run: sudo apt-get update && sudo apt-get install -y g++-arm-linux-gnueabihf
- name: Build (ARM 32-bit)
run: arm-linux-gnueabihf-g++ -std=c++11 -Wall -Wextra -Wno-psabi -Werror -c -o /dev/null test/test_32bit_build.cpp

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@@ -25,9 +25,7 @@ concurrency:
cancel-in-progress: true
env:
# Exclude *_Online tests by default — they hit external services and flake on
# CI runners. Run with workflow_dispatch + a custom filter to include them.
GTEST_FILTER: ${{ github.event.inputs.gtest_filter || '-*_Online' }}
GTEST_FILTER: ${{ github.event.inputs.gtest_filter || '*' }}
jobs:
style-check:
@@ -42,7 +40,7 @@ jobs:
clang-format --version
cd test && make style_check
build-and-test-on-32bit:
build-error-check-on-32bit:
runs-on: ubuntu-latest
if: >
(github.event_name == 'push') ||
@@ -66,8 +64,9 @@ jobs:
libssl-dev${{ matrix.config.arch_suffix }} libcurl4-openssl-dev${{ matrix.config.arch_suffix }} \
zlib1g-dev${{ matrix.config.arch_suffix }} libbrotli-dev${{ matrix.config.arch_suffix }} \
libzstd-dev${{ matrix.config.arch_suffix }}
- name: build and run tests
- name: build and run tests (expect failure)
run: cd test && make test EXTRA_CXXFLAGS="${{ matrix.config.arch_flags }}"
continue-on-error: true
ubuntu:
runs-on: ubuntu-latest
@@ -77,7 +76,6 @@ jobs:
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_linux == 'true')
strategy:
fail-fast: false
matrix:
tls_backend: [openssl, mbedtls, wolfssl]
name: ubuntu (${{ matrix.tls_backend }})
@@ -104,10 +102,7 @@ jobs:
LSAN_OPTIONS: suppressions=lsan_suppressions.txt
- name: build and run tests (Mbed TLS)
if: matrix.tls_backend == 'mbedtls'
# Run mbedTLS shards with reduced parallelism — under ASAN+mbedTLS the
# default 4 shards overload CI runners enough that timing-sensitive
# ServerTest cases flake on first-request keep-alive reuse.
run: cd test && make test_split_mbedtls && SHARDS=2 make test_mbedtls_parallel
run: cd test && make test_split_mbedtls && make test_mbedtls_parallel
- name: build and run tests (wolfSSL)
if: matrix.tls_backend == 'wolfssl'
run: cd test && make test_split_wolfssl && make test_wolfssl_parallel
@@ -120,241 +115,6 @@ jobs:
- name: build and run ThreadPool test
run: cd test && make test_thread_pool && ./test_thread_pool
# BoringSSL is Google's fork of OpenSSL. It has no API stability guarantee
# and is not packaged by distros, so we build it from source. cpp-httplib
# treats it as an OpenSSL backend variant via the OPENSSL_IS_BORINGSSL
# macro (see httplib.h). This job is best-effort: continue-on-error keeps
# upstream API drift from blocking PRs while still surfacing breakage.
ubuntu-boringssl:
runs-on: ubuntu-latest
if: >
(github.event_name == 'push') ||
(github.event_name == 'pull_request' &&
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_linux == 'true')
continue-on-error: true
name: ubuntu (boringssl, best-effort)
env:
# Tracking HEAD keeps us honest about upstream churn. If breakage
# becomes routine, replace HEAD with a 40-char commit SHA; the
# resolve step uses the SHA directly when it matches that shape.
BORINGSSL_REF: HEAD
BORINGSSL_PREFIX: ${{ github.workspace }}/boringssl-install
steps:
- name: checkout
uses: actions/checkout@v4
- name: install common libraries
run: |
sudo apt-get update
sudo apt-get install -y libcurl4-openssl-dev zlib1g-dev libbrotli-dev libzstd-dev
- name: resolve BoringSSL commit
id: boringssl-rev
# Accept either a ref name (resolved via git ls-remote) or a full
# 40-char SHA used directly. ls-remote does not list arbitrary
# commit SHAs, so pinning requires the second path.
run: |
if [[ "${BORINGSSL_REF}" =~ ^[0-9a-f]{40}$ ]]; then
sha="${BORINGSSL_REF}"
echo "Using pinned BoringSSL SHA: ${sha}"
else
sha=$(git ls-remote https://boringssl.googlesource.com/boringssl "${BORINGSSL_REF}" | awk '{print $1}')
if [ -z "$sha" ]; then
echo "Failed to resolve BoringSSL ref ${BORINGSSL_REF}" >&2
exit 1
fi
echo "Resolved ${BORINGSSL_REF} -> ${sha}"
fi
echo "sha=${sha}" >> "$GITHUB_OUTPUT"
- name: cache BoringSSL build
id: boringssl-cache
uses: actions/cache@v4
with:
path: ${{ env.BORINGSSL_PREFIX }}
key: boringssl-${{ runner.os }}-${{ steps.boringssl-rev.outputs.sha }}
- name: build BoringSSL
if: steps.boringssl-cache.outputs.cache-hit != 'true'
run: |
set -e
git clone https://boringssl.googlesource.com/boringssl boringssl
cd boringssl
git checkout "${{ steps.boringssl-rev.outputs.sha }}"
cmake -S . -B build \
-DCMAKE_BUILD_TYPE=Release \
-DBUILD_SHARED_LIBS=OFF \
-DCMAKE_POSITION_INDEPENDENT_CODE=ON \
-DCMAKE_INSTALL_PREFIX="${BORINGSSL_PREFIX}"
cmake --build build -j"$(nproc)" --target install
- name: build and run tests (BoringSSL)
# Override OPENSSL_SUPPORT to point the existing OpenSSL Makefile path
# at BoringSSL's prefix. BoringSSL defines OPENSSL_IS_BORINGSSL in
# <openssl/base.h>, which httplib.h and test.cc use to switch on API
# differences (e.g. SAN-only hostname verification, no CN fallback).
#
# BoringSSL's public headers (<openssl/stack.h>) use std::enable_if_t,
# so consumers must compile with C++14 or later. cpp-httplib itself
# supports C++11, but anyone pairing it with BoringSSL inherits this
# constraint. EXTRA_CXXFLAGS appends after the Makefile's -std=c++11
# and the later flag wins.
run: |
cd test
BORINGSSL_FLAGS="-DCPPHTTPLIB_OPENSSL_SUPPORT -I${BORINGSSL_PREFIX}/include -L${BORINGSSL_PREFIX}/lib -lssl -lcrypto -lpthread"
make test_split OPENSSL_SUPPORT="${BORINGSSL_FLAGS}" EXTRA_CXXFLAGS="-std=c++17"
make test_openssl_parallel OPENSSL_SUPPORT="${BORINGSSL_FLAGS}" EXTRA_CXXFLAGS="-std=c++17"
env:
LSAN_OPTIONS: suppressions=lsan_suppressions.txt
# macOS counterpart of the BoringSSL job. Same best-effort posture; the
# extra framework links cover the macOS Keychain integration that
# httplib.h auto-enables for any TLS backend on macOS.
macos-boringssl:
runs-on: macos-latest
if: >
(github.event_name == 'push') ||
(github.event_name == 'pull_request' &&
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_macos == 'true')
continue-on-error: true
name: macos (boringssl, best-effort)
env:
BORINGSSL_REF: HEAD
BORINGSSL_PREFIX: ${{ github.workspace }}/boringssl-install
steps:
- name: checkout
uses: actions/checkout@v4
- name: resolve BoringSSL commit
id: boringssl-rev
# Accept either a ref name (resolved via git ls-remote) or a full
# 40-char SHA used directly. ls-remote does not list arbitrary
# commit SHAs, so pinning requires the second path.
run: |
if [[ "${BORINGSSL_REF}" =~ ^[0-9a-f]{40}$ ]]; then
sha="${BORINGSSL_REF}"
echo "Using pinned BoringSSL SHA: ${sha}"
else
sha=$(git ls-remote https://boringssl.googlesource.com/boringssl "${BORINGSSL_REF}" | awk '{print $1}')
if [ -z "$sha" ]; then
echo "Failed to resolve BoringSSL ref ${BORINGSSL_REF}" >&2
exit 1
fi
echo "Resolved ${BORINGSSL_REF} -> ${sha}"
fi
echo "sha=${sha}" >> "$GITHUB_OUTPUT"
- name: cache BoringSSL build
id: boringssl-cache
uses: actions/cache@v4
with:
path: ${{ env.BORINGSSL_PREFIX }}
key: boringssl-${{ runner.os }}-${{ steps.boringssl-rev.outputs.sha }}
- name: build BoringSSL
if: steps.boringssl-cache.outputs.cache-hit != 'true'
run: |
set -e
git clone https://boringssl.googlesource.com/boringssl boringssl
cd boringssl
git checkout "${{ steps.boringssl-rev.outputs.sha }}"
cmake -S . -B build \
-DCMAKE_BUILD_TYPE=Release \
-DBUILD_SHARED_LIBS=OFF \
-DCMAKE_POSITION_INDEPENDENT_CODE=ON \
-DCMAKE_INSTALL_PREFIX="${BORINGSSL_PREFIX}"
cmake --build build -j"$(sysctl -n hw.ncpu)" --target install
- name: build and run tests (BoringSSL)
run: |
cd test
# CoreFoundation/Security frameworks satisfy the Keychain integration
# auto-enabled in httplib.h for macOS TLS builds.
BORINGSSL_FLAGS="-DCPPHTTPLIB_OPENSSL_SUPPORT -I${BORINGSSL_PREFIX}/include -L${BORINGSSL_PREFIX}/lib -lssl -lcrypto -framework CoreFoundation -framework Security"
make test_split OPENSSL_SUPPORT="${BORINGSSL_FLAGS}" EXTRA_CXXFLAGS="-std=c++17"
make test_openssl_parallel OPENSSL_SUPPORT="${BORINGSSL_FLAGS}" EXTRA_CXXFLAGS="-std=c++17"
env:
LSAN_OPTIONS: suppressions=lsan_suppressions.txt
# Reproducer for https://github.com/yhirose/cpp-httplib/issues/2431.
# On Linux/glibc, getaddrinfo_with_timeout() schedules an asynchronous
# DNS lookup with getaddrinfo_a(GAI_NOWAIT) using a stack-local gaicb.
# When gai_suspend() hits the connection timeout, gai_cancel() is called
# but does not block; the resolver worker can later write back into the
# destroyed stack frame. To make the worker actually reach that write,
# the test job runs a loopback UDP responder (test/dns_test_fixture.py)
# that delays its reply past the test's 1s timeout, and uses an iptables
# NAT rule so glibc's lookups land on that fixture instead of a real
# nameserver. With ASAN's detect_stack_use_after_return enabled, the
# late write-back is reported as a stack-use-after-return.
issue-2431-repro:
runs-on: ubuntu-latest
if: >
(github.event_name == 'push') ||
(github.event_name == 'pull_request' &&
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_linux == 'true')
name: issue-2431 repro (Linux + ASAN)
# Bound the whole job in case anything in the test harness hangs
# unexpectedly. With the fixture in place a normal run is well under
# a minute either way (ASAN abort on broken HEAD, clean pass on fix).
timeout-minutes: 5
env:
DNS_FIXTURE_PORT: "15353"
DNS_FIXTURE_DELAY: "3"
steps:
- name: checkout
uses: actions/checkout@v4
- name: install libraries
run: |
sudo apt-get update
sudo apt-get install -y libssl-dev zlib1g-dev libbrotli-dev \
libzstd-dev libcurl4-openssl-dev iptables util-linux iproute2
- name: start loopback DNS test fixture
run: |
# Force glibc through its DNS code path: Ubuntu's default
# nsswitch short-circuits to NOTFOUND through mdns4_minimal,
# which would skip the buggy code entirely.
sudo sed -i 's/^hosts:.*/hosts: dns/' /etc/nsswitch.conf
# Run the loopback fixture (delayed UDP responder).
python3 test/dns_test_fixture.py "$DNS_FIXTURE_PORT" "$DNS_FIXTURE_DELAY" \
>/tmp/dns_fixture.log 2>&1 &
echo $! | sudo tee /tmp/dns_fixture.pid >/dev/null
# Wait for the fixture to start listening.
for _ in $(seq 1 50); do
if ss -lun "( sport = :$DNS_FIXTURE_PORT )" | grep -q ":$DNS_FIXTURE_PORT"; then
break
fi
sleep 0.1
done
ss -lun "( sport = :$DNS_FIXTURE_PORT )" | grep -q ":$DNS_FIXTURE_PORT" \
|| { echo "fixture failed to start"; cat /tmp/dns_fixture.log; exit 1; }
# Send the test process's DNS lookups to the loopback fixture.
# NAT only the local OUTPUT chain; conntrack handles the reply path.
sudo iptables -t nat -I OUTPUT -p udp --dport 53 \
-j REDIRECT --to-port "$DNS_FIXTURE_PORT"
# Sanity check: a query must take at least the fixture delay
# and resolve to NXDOMAIN (proving traffic reaches the fixture).
start=$(date +%s)
getent hosts unresolvable-host.invalid >/dev/null 2>&1 || true
elapsed=$(( $(date +%s) - start ))
if [ "$elapsed" -lt 2 ]; then
echo "ERROR: lookup returned in ${elapsed}s; fixture not in path" >&2
exit 1
fi
echo "[ok] DNS lookups are routed to the test fixture (took ${elapsed}s)"
- name: build test binary
run: cd test && make test
- name: run GetAddrInfoAsyncCancelTest
run: |
cd test
ARCH=$(uname -m)
CPPHTTPLIB_TEST_ISSUE_2431=1 \
ASAN_OPTIONS=detect_stack_use_after_return=1 \
LSAN_OPTIONS=suppressions=lsan_suppressions.txt \
setarch "$ARCH" -R \
./test --gtest_filter='GetAddrInfoAsyncCancelTest.*'
- name: tear down test fixture
if: always()
run: |
sudo iptables -t nat -F OUTPUT || true
if [ -f /tmp/dns_fixture.pid ]; then
sudo kill "$(cat /tmp/dns_fixture.pid)" 2>/dev/null || true
fi
macos:
runs-on: macos-latest
if: >
@@ -363,7 +123,6 @@ jobs:
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_macos == 'true')
strategy:
fail-fast: false
matrix:
tls_backend: [openssl, mbedtls, wolfssl]
name: macos (${{ matrix.tls_backend }})
@@ -383,10 +142,7 @@ jobs:
LSAN_OPTIONS: suppressions=lsan_suppressions.txt
- name: build and run tests (Mbed TLS)
if: matrix.tls_backend == 'mbedtls'
# macOS runners under ASAN+mbedTLS still flake at SHARDS=2 (rapid
# bind/connect on the fixture's fixed port races on the slower
# macos-latest runner). Serialize fully here; ubuntu stays at 2.
run: cd test && make test_split_mbedtls && SHARDS=1 make test_mbedtls_parallel
run: cd test && make test_split_mbedtls && make test_mbedtls_parallel
- name: build and run tests (wolfSSL)
if: matrix.tls_backend == 'wolfssl'
run: cd test && make test_split_wolfssl && make test_wolfssl_parallel
@@ -399,54 +155,6 @@ jobs:
- name: build and run ThreadPool test
run: cd test && make test_thread_pool && ./test_thread_pool
ios-parse-check:
runs-on: macos-latest
if: >
(github.event_name == 'push') ||
(github.event_name == 'pull_request' &&
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_macos == 'true')
name: ios header parse check (not officially supported)
steps:
- name: checkout
uses: actions/checkout@v4
- name: install OpenSSL headers
run: brew install openssl@3
- name: verify header parses on iOS target
run: |
IOS_SDK=$(xcrun --sdk iphoneos --show-sdk-path)
OPENSSL_INC=$(brew --prefix openssl@3)/include
echo "Using iOS SDK: $IOS_SDK"
echo '#include "httplib.h"' | clang++ \
-isysroot "$IOS_SDK" \
-target arm64-apple-ios16.0 \
-std=c++11 \
-DCPPHTTPLIB_OPENSSL_SUPPORT \
-I"$OPENSSL_INC" \
-I. -Wall -Wextra \
-fsyntax-only -x c++ -
- name: verify CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN is rejected on iOS
run: |
IOS_SDK=$(xcrun --sdk iphoneos --show-sdk-path)
OPENSSL_INC=$(brew --prefix openssl@3)/include
out=$(echo '#include "httplib.h"' | clang++ \
-isysroot "$IOS_SDK" \
-target arm64-apple-ios16.0 \
-std=c++11 \
-DCPPHTTPLIB_OPENSSL_SUPPORT \
-DCPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN \
-I"$OPENSSL_INC" \
-I. \
-fsyntax-only -x c++ - 2>&1 || true)
if echo "$out" | grep -q "only supported on macOS"; then
echo "OK: #error fired as expected"
else
echo "FAIL: expected #error did not fire"
echo "--- compiler output ---"
echo "$out"
exit 1
fi
windows:
runs-on: windows-latest
if: >
@@ -455,7 +163,6 @@ jobs:
github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name) ||
(github.event_name == 'workflow_dispatch' && github.event.inputs.test_windows == 'true')
strategy:
fail-fast: false
matrix:
config:
- with_ssl: false
@@ -522,7 +229,7 @@ jobs:
for ($i = 0; $i -lt $shards; $i++) {
$log = "shard_${i}.log"
$procs += Start-Process -FilePath ./Release/httplib-test.exe `
-ArgumentList "--gtest_color=yes","--gtest_filter=${{ github.event.inputs.gtest_filter || '-*_Online' }}" `
-ArgumentList "--gtest_color=yes","--gtest_filter=${{ github.event.inputs.gtest_filter || '*' }}-*BenchmarkTest*" `
-NoNewWindow -PassThru -RedirectStandardOutput $log -RedirectStandardError "${log}.err" `
-Environment @{ GTEST_TOTAL_SHARDS="$shards"; GTEST_SHARD_INDEX="$i" }
}
@@ -530,14 +237,11 @@ jobs:
$failed = $false
for ($i = 0; $i -lt $shards; $i++) {
$log = "shard_${i}.log"
$proc = $procs[$i]
$hasPassed = Select-String -Path $log -Pattern "\[ PASSED \]" -Quiet
$hasFailed = Select-String -Path $log -Pattern "\[ FAILED \]" -Quiet
if ($hasPassed -and -not $hasFailed -and $proc.ExitCode -eq 0) {
if (Select-String -Path $log -Pattern "\[ PASSED \]" -Quiet) {
$passed = (Select-String -Path $log -Pattern "\[ PASSED \]").Line
Write-Host "Shard ${i}: $passed"
} else {
Write-Host "=== Shard $i FAILED (exit=$($proc.ExitCode)) ==="
Write-Host "=== Shard $i FAILED ==="
Get-Content $log
if (Test-Path "${log}.err") { Get-Content "${log}.err" }
$failed = $true
@@ -545,6 +249,9 @@ jobs:
}
if ($failed) { exit 1 }
Write-Host "All shards passed."
- name: Run benchmark tests with retry ${{ matrix.config.name }}
if: ${{ matrix.config.run_tests }}
run: ctest --output-on-failure --test-dir build -C Release -R "BenchmarkTest" --repeat until-pass:5
env:
VCPKG_ROOT: "C:/vcpkg"

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@@ -1,79 +0,0 @@
name: benchmark
on:
push:
pull_request:
workflow_dispatch:
concurrency:
group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
cancel-in-progress: true
jobs:
ubuntu:
runs-on: ubuntu-latest
if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
steps:
- name: checkout
uses: actions/checkout@v4
- name: build and run
run: cd test && make test_benchmark && ./test_benchmark
macos:
runs-on: macos-latest
if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
steps:
- name: checkout
uses: actions/checkout@v4
- name: build and run
run: cd test && make test_benchmark && ./test_benchmark
windows:
runs-on: windows-latest
if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
steps:
- name: Prepare Git for Checkout on Windows
run: |
git config --global core.autocrlf false
git config --global core.eol lf
- name: checkout
uses: actions/checkout@v4
- name: Export GitHub Actions cache environment variables
uses: actions/github-script@v7
with:
script: |
core.exportVariable('ACTIONS_CACHE_URL', process.env.ACTIONS_CACHE_URL || '');
core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
- name: Cache vcpkg packages
id: vcpkg-cache
uses: actions/cache@v4
with:
path: C:/vcpkg/installed
key: vcpkg-installed-windows-gtest
- name: Install vcpkg dependencies
if: steps.vcpkg-cache.outputs.cache-hit != 'true'
run: vcpkg install gtest
- name: Configure and build
shell: pwsh
run: |
$cmake_content = @"
cmake_minimum_required(VERSION 3.14)
project(httplib-benchmark CXX)
find_package(GTest REQUIRED)
add_executable(httplib-benchmark test/test_benchmark.cc)
target_include_directories(httplib-benchmark PRIVATE .)
target_link_libraries(httplib-benchmark PRIVATE GTest::gtest_main)
target_compile_options(httplib-benchmark PRIVATE "$<$<CXX_COMPILER_ID:MSVC>:/utf-8>")
"@
New-Item -ItemType Directory -Force -Path build_bench/test | Out-Null
Set-Content -Path build_bench/CMakeLists.txt -Value $cmake_content
Copy-Item -Path httplib.h -Destination build_bench/
Copy-Item -Path test/test_benchmark.cc -Destination build_bench/test/
cmake -B build_bench/build -S build_bench `
-DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_ROOT/scripts/buildsystems/vcpkg.cmake"
cmake --build build_bench/build --config Release
- name: Run with retry
run: ctest --output-on-failure --test-dir build_bench/build -C Release --repeat until-pass:5
env:
VCPKG_ROOT: "C:/vcpkg"
VCPKG_BINARY_SOURCES: "clear;x-gha,readwrite"

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@@ -28,10 +28,6 @@ jobs:
- name: Run proxy tests (OpenSSL)
if: matrix.tls_backend == 'openssl'
run: cd test && make proxy
env:
COMPOSE_FILE: docker-compose.yml:docker-compose.ci.yml
- name: Run proxy tests (Mbed TLS)
if: matrix.tls_backend == 'mbedtls'
run: cd test && make proxy_mbedtls
env:
COMPOSE_FILE: docker-compose.yml:docker-compose.ci.yml
run: cd test && make proxy_mbedtls

10
.gitignore vendored
View File

@@ -1,8 +1,4 @@
tags
AGENTS.md
docs-src/pages/AGENTS.md
plans/
work/
# Ignore executables (no extension) but not source files
example/server
@@ -43,9 +39,6 @@ test/test_mbedtls
test/test_wolfssl
test/test_no_tls
test/server_fuzzer
test/client_fuzzer
test/header_parser_fuzzer
test/url_parser_fuzzer
test/test_proxy
test/test_proxy_mbedtls
test/test_proxy_wolfssl
@@ -55,7 +48,6 @@ test/test_split_wolfssl
test/test_split_no_tls
test/test_websocket_heartbeat
test/test_thread_pool
test/test_benchmark
test/test.xcodeproj/xcuser*
test/test.xcodeproj/*/xcuser*
test/*.o
@@ -63,7 +55,9 @@ test/*.pem
test/*.srl
test/*.log
test/_build_*
work/
benchmark/server*
docs-gen/target/
*.swp

View File

@@ -173,6 +173,9 @@ if(CMAKE_SYSTEM_NAME MATCHES "Windows")
message(WARNING "The target is Windows but CMAKE_SYSTEM_VERSION is not set, the default system version is set to Windows 10.")
endif()
endif()
if(CMAKE_SIZEOF_VOID_P LESS 8)
message(WARNING "Pointer size ${CMAKE_SIZEOF_VOID_P} is not supported. Please use a 64-bit compiler.")
endif()
# Set some variables that are used in-tree and while building based on our options
set(HTTPLIB_IS_COMPILED ${HTTPLIB_COMPILE})
@@ -242,33 +245,27 @@ endif()
# zstd < 1.5.6 does not provide the CMake imported target `zstd::libzstd`.
# Older versions must be consumed via their pkg-config file.
if(HTTPLIB_REQUIRE_ZSTD)
if (NOT TARGET zstd::libzstd)
find_package(zstd 1.5.6 CONFIG)
if(NOT zstd_FOUND)
find_package(PkgConfig REQUIRED)
pkg_check_modules(zstd REQUIRED IMPORTED_TARGET libzstd)
add_library(zstd::libzstd ALIAS PkgConfig::zstd)
endif()
find_package(zstd 1.5.6 CONFIG)
if(NOT zstd_FOUND)
find_package(PkgConfig REQUIRED)
pkg_check_modules(zstd REQUIRED IMPORTED_TARGET libzstd)
add_library(zstd::libzstd ALIAS PkgConfig::zstd)
endif()
set(HTTPLIB_IS_USING_ZSTD TRUE)
elseif(HTTPLIB_USE_ZSTD_IF_AVAILABLE)
if (TARGET zstd::libzstd)
set(HTTPLIB_IS_USING_ZSTD TRUE)
else()
find_package(zstd 1.5.6 CONFIG QUIET)
if(NOT zstd_FOUND)
find_package(PkgConfig QUIET)
if(PKG_CONFIG_FOUND)
pkg_check_modules(zstd QUIET IMPORTED_TARGET libzstd)
find_package(zstd 1.5.6 CONFIG QUIET)
if(NOT zstd_FOUND)
find_package(PkgConfig QUIET)
if(PKG_CONFIG_FOUND)
pkg_check_modules(zstd QUIET IMPORTED_TARGET libzstd)
if(TARGET PkgConfig::zstd)
add_library(zstd::libzstd ALIAS PkgConfig::zstd)
endif()
if(TARGET PkgConfig::zstd)
add_library(zstd::libzstd ALIAS PkgConfig::zstd)
endif()
endif()
# Both find_package and PkgConf set a XXX_FOUND var
set(HTTPLIB_IS_USING_ZSTD ${zstd_FOUND})
endif()
# Both find_package and PkgConf set a XXX_FOUND var
set(HTTPLIB_IS_USING_ZSTD ${zstd_FOUND})
endif()
# Used for default, common dirs that the end-user can change (if needed)
@@ -323,13 +320,13 @@ if(HTTPLIB_COMPILE)
$<BUILD_INTERFACE:${_httplib_build_includedir}/httplib.h>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/httplib.h>
)
# Add C++20 module support if requested
# Include from separate file to prevent parse errors on older CMake versions
if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.28")
include(cmake/modules.cmake)
endif()
set_target_properties(${PROJECT_NAME}
PROPERTIES
VERSION ${${PROJECT_NAME}_VERSION}

View File

@@ -74,9 +74,6 @@ sse.set_reconnect_interval(5000);
// Set max reconnect attempts (default: 0 = unlimited)
sse.set_max_reconnect_attempts(10);
// Update headers at any time (thread-safe)
sse.set_headers({{"Authorization", "Bearer new_token"}});
```
#### Control
@@ -157,25 +154,6 @@ httplib::sse::SSEClient sse(cli, "/events", headers);
sse.start();
```
### Refreshing Auth Token on Reconnect
```cpp
httplib::sse::SSEClient sse(cli, "/events",
{{"Authorization", "Bearer " + get_token()}});
// Preemptively refresh token on each successful connection
sse.on_open([&sse]() {
sse.set_headers({{"Authorization", "Bearer " + get_token()}});
});
// Or reactively refresh on auth failure (401 triggers reconnect)
sse.on_error([&sse](httplib::Error) {
sse.set_headers({{"Authorization", "Bearer " + refresh_token()}});
});
sse.start();
```
### Error Handling
```cpp

View File

@@ -45,7 +45,7 @@ cpp-httplib provides multiple API layers for different use cases:
```text
┌─────────────────────────────────────────────┐
│ SSEClient │ ← SSE-specific, parsed events
│ SSEClient (planned) │ ← SSE-specific, parsed events
│ - on_message(), on_event() │
│ - Auto-reconnect, Last-Event-ID │
├─────────────────────────────────────────────┤
@@ -61,7 +61,7 @@ cpp-httplib provides multiple API layers for different use cases:
| Use Case | Recommended API |
|----------|----------------|
| SSE with auto-reconnect | `SSEClient` (see [README-sse.md](README-sse.md)) |
| SSE with auto-reconnect | SSEClient (planned) or `ssecli-stream.cc` example |
| LLM streaming (JSON Lines) | `stream::Get()` |
| Large file download | `stream::Get()` or `open_stream()` |
| Reverse proxy | `open_stream()` |

View File

@@ -3,19 +3,15 @@
A simple, blocking WebSocket implementation for C++11.
> [!IMPORTANT]
> This is a blocking I/O WebSocket implementation using a thread-per-connection model (plus one heartbeat thread per connection). It is intended for small- to mid-scale workloads; handling large numbers of simultaneous WebSocket connections is outside the design target of this library. If you need high-concurrency WebSocket support with non-blocking/async I/O (e.g., thousands of simultaneous connections), this is not the one that you want.
> [!NOTE]
> WebSocket extensions (`permessage-deflate` and others defined by RFC 6455) are **not supported**. If a client proposes an extension via `Sec-WebSocket-Extensions`, the server silently declines it — the negotiated connection always runs without extensions.
> This is a blocking I/O WebSocket implementation using a thread-per-connection model. If you need high-concurrency WebSocket support with non-blocking/async I/O (e.g., thousands of simultaneous connections), this is not the one that you want.
## Features
- **RFC 6455 compliant**: Full WebSocket protocol support (extensions are not implemented)
- **RFC 6455 compliant**: Full WebSocket protocol support
- **Server and Client**: Both sides included
- **SSL/TLS support**: `wss://` scheme for secure connections
- **Text and Binary**: Both message types supported
- **Automatic heartbeat**: Periodic Ping/Pong keeps connections alive
- **Unresponsive-peer detection**: Opt-in liveness check via `set_websocket_max_missed_pongs()`
- **Subprotocol negotiation**: `Sec-WebSocket-Protocol` support for GraphQL, MQTT, etc.
## Quick Start
@@ -356,41 +352,6 @@ if (ws.connect()) {
| `CPPHTTPLIB_WEBSOCKET_READ_TIMEOUT_SECOND` | `300` | Read timeout for WebSocket connections (seconds) |
| `CPPHTTPLIB_WEBSOCKET_CLOSE_TIMEOUT_SECOND` | `5` | Timeout for waiting peer's Close response (seconds) |
| `CPPHTTPLIB_WEBSOCKET_PING_INTERVAL_SECOND` | `30` | Automatic Ping interval for heartbeat (seconds) |
| `CPPHTTPLIB_WEBSOCKET_MAX_MISSED_PONGS` | `0` (disabled) | Close the connection after N consecutive unacked pings |
### Runtime Ping Interval
You can override the ping interval at runtime instead of changing the compile-time macro. Set it to `0` to disable automatic pings entirely.
```cpp
// Server side
httplib::Server svr;
svr.set_websocket_ping_interval(10); // 10 seconds
// Or using std::chrono
svr.set_websocket_ping_interval(std::chrono::seconds(10));
// Client side
httplib::ws::WebSocketClient ws("ws://localhost:8080/ws");
ws.set_websocket_ping_interval(10); // 10 seconds
// Disable automatic pings
ws.set_websocket_ping_interval(0);
```
### Unresponsive-Peer Detection (Pong Timeout)
By default the heartbeat only sends pings — it does not enforce that pongs come back. To detect a silently dropped connection faster, enable the max-missed-pongs check. Once `max_missed_pongs` consecutive pings go unanswered, the heartbeat thread closes the connection with `CloseStatus::GoingAway` and the reason `"pong timeout"`.
```cpp
ws.set_websocket_max_missed_pongs(2); // close after 2 consecutive unacked pings
```
The server side has the same `set_websocket_max_missed_pongs()`.
With the default ping interval of 30 seconds, `max_missed_pongs = 2` detects a dead peer within ~60 seconds. The counter is reset every time a Pong frame is received, so the mechanism only works when your code is actively calling `read()` — exactly the pattern a normal WebSocket client already uses.
**The default is `0`**, which means "never close the connection because of missing pongs." Pings are still sent on the heartbeat interval, but their responses are not checked. Even so, a dead connection does not linger forever: while your code is inside `read()`, `CPPHTTPLIB_WEBSOCKET_READ_TIMEOUT_SECOND` (default **300 seconds = 5 minutes**) acts as a backstop and `read()` fails if no frame arrives in time. `max_missed_pongs` is the knob for detecting an unresponsive peer faster than that 5-minute fallback.
## Threading Model

122
README.md
View File

@@ -5,13 +5,10 @@
A C++11 single-file header-only cross platform HTTP/HTTPS library.<br>
It's extremely easy to set up. Just include the **[httplib.h](https://raw.githubusercontent.com/yhirose/cpp-httplib/refs/heads/master/httplib.h)** file in your code!
Learn more in the [official documentation](https://yhirose.github.io/cpp-httplib/) (built with [docs-gen](https://github.com/yhirose/docs-gen)).
**Learn more in the [official documentation](https://yhirose.github.io/cpp-httplib/)**.
> [!IMPORTANT]
> This library uses 'blocking' socket I/O. If you are looking for a library with 'non-blocking' socket I/O, this is not the one that you want. Only **HTTP/1.1** is supported — HTTP/2 and HTTP/3 are not implemented.
> [!WARNING]
> 32-bit platforms are **NOT supported**. Use at your own risk. The library may compile on 32-bit targets, but no security review has been conducted for 32-bit environments. Integer truncation and other 32-bit-specific issues may exist. **Security reports that only affect 32-bit platforms will be closed without action.** The maintainer does not have access to 32-bit environments for testing or fixing issues. CI includes basic compile checks only, not functional or security testing.
> This library uses 'blocking' socket I/O. If you are looking for a library with 'non-blocking' socket I/O, this is not the one that you want.
## Main Features
@@ -64,17 +61,26 @@ if (auto res = cli.Get("/hi")) {
cpp-httplib supports multiple TLS backends through an abstraction layer:
| Backend | Define | Libraries | Notes |
| :------ | :----- | :-------- | :---- |
| OpenSSL | `CPPHTTPLIB_OPENSSL_SUPPORT` | `libssl`, `libcrypto` | [3.0 or later](https://www.openssl.org/policies/releasestrat.html) required |
| Mbed TLS | `CPPHTTPLIB_MBEDTLS_SUPPORT` | `libmbedtls`, `libmbedx509`, `libmbedcrypto` | 2.x and 3.x supported (auto-detected) |
| wolfSSL | `CPPHTTPLIB_WOLFSSL_SUPPORT` | `libwolfssl` | 5.x supported; must build with `--enable-opensslall` |
| Backend | Define | Libraries |
| :------ | :----- | :-------- |
| OpenSSL | `CPPHTTPLIB_OPENSSL_SUPPORT` | `libssl`, `libcrypto` |
| Mbed TLS | `CPPHTTPLIB_MBEDTLS_SUPPORT` | `libmbedtls`, `libmbedx509`, `libmbedcrypto` |
| wolfSSL | `CPPHTTPLIB_WOLFSSL_SUPPORT` | `libwolfssl` |
> [!NOTE]
> **Mbed TLS / wolfSSL limitation:** `get_ca_certs()` and `get_ca_names()` only reflect CA certificates loaded via `load_ca_cert_store()`. Certificates loaded through `set_ca_cert_path()` or system certificates (`load_system_certs`) are not enumerable.
> OpenSSL 3.0 or later is required. Please see [this page](https://www.openssl.org/policies/releasestrat.html) for more information.
> [!NOTE]
> **BoringSSL (best-effort):** BoringSSL builds under `CPPHTTPLIB_OPENSSL_SUPPORT` and is exercised by CI against current upstream. Because BoringSSL does not guarantee API stability, support is best-effort — breakage may occasionally land. Two known behavioral differences vs OpenSSL: (1) BoringSSL's public headers require C++14 or later, so consumers must compile accordingly; (2) hostname verification is SAN-only per RFC 6125 §6.4.4 (no CN fallback).
> Mbed TLS 2.x and 3.x are supported. The library automatically detects the version and uses the appropriate API.
> [!NOTE]
> wolfSSL must be built with OpenSSL compatibility layer enabled (`--enable-opensslall`). wolfSSL 5.x is supported.
> [!NOTE]
> **Mbed TLS / wolfSSL limitation:** `get_ca_certs()` and `get_ca_names()` only reflect CA certificates loaded via `load_ca_cert_store()` or `load_ca_cert_store(pem, size)`. Certificates loaded through `set_ca_cert_path()` or system certificates (`load_system_certs`) are not enumerable with these backends.
> [!TIP]
> For macOS: cpp-httplib automatically loads system certs from the Keychain when a TLS backend is enabled. `CoreFoundation` and `Security` must be linked with `-framework`. To disable this, define `CPPHTTPLIB_DISABLE_MACOSX_AUTOMATIC_ROOT_CERTIFICATES`.
```c++
// Use either OpenSSL, Mbed TLS, or wolfSSL
@@ -188,21 +194,27 @@ svr.Get("/", [](const httplib::Request &req, httplib::Response &res) {
});
```
### Platform-specific Certificate Handling
### Windows Certificate Verification
cpp-httplib automatically integrates with the OS certificate store on macOS and Windows. This works with all TLS backends.
On Windows, cpp-httplib automatically performs additional certificate verification using the Windows certificate store via CryptoAPI (`CertGetCertificateChain` / `CertVerifyCertificateChainPolicy`). This works with all TLS backends (OpenSSL, Mbed TLS, and wolfSSL), providing:
| Platform | Behavior | Disable (compile time) |
| :------- | :------- | :--------------------- |
| macOS | Loads system certs from Keychain (link `CoreFoundation` and `Security` with `-framework`). Requires Apple Clang; GCC is not supported for this feature. | `CPPHTTPLIB_DISABLE_MACOSX_AUTOMATIC_ROOT_CERTIFICATES` |
| Windows | Verifies certs via CryptoAPI (`CertGetCertificateChain` / `CertVerifyCertificateChainPolicy`) with revocation checking | `CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE` |
- Real-time certificate validation integrated with Windows Update
- Certificate revocation checking
- SSL/TLS policy verification using the system certificate store (ROOT and CA)
On Windows, verification can also be disabled at runtime:
This feature is enabled by default and can be controlled at runtime:
```c++
// Disable Windows certificate verification (use only OpenSSL/Mbed TLS/wolfSSL verification)
cli.enable_windows_certificate_verification(false);
```
To disable this feature at compile time, define:
```c++
#define CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
```
> [!NOTE]
> When using SSL, it seems impossible to avoid SIGPIPE in all cases, since on some operating systems, SIGPIPE can only be suppressed on a per-message basis, but there is no way to make the OpenSSL library do so for its internal communications. If your program needs to avoid being terminated on SIGPIPE, the only fully general way might be to set up a signal handler for SIGPIPE to handle or ignore it yourself.
@@ -242,8 +254,6 @@ int main(void)
if (req.has_param("key")) {
auto val = req.get_param_value("key");
}
// Get all values for a given key (e.g., ?tag=a&tag=b)
auto values = req.get_param_values("tag");
res.set_content(req.body, "text/plain");
});
@@ -337,11 +347,6 @@ The following are built-in mappings:
> [!WARNING]
> These static file server methods are not thread-safe.
<!-- -->
> [!NOTE]
> On POSIX systems, the static file server rejects requests that resolve (via symlinks) to a path outside the mounted base directory. Ensure that the served directory has appropriate permissions, as managing access to the served directory is the application developer's responsibility.
### File request handler
```cpp
@@ -466,7 +471,7 @@ svr.set_pre_request_handler([](const auto& req, auto& res) {
### Response user data
`res.user_data` is a type-safe key-value store that lets pre-routing or pre-request handlers pass arbitrary data to route handlers.
`res.user_data` is a `std::map<std::string, httplib::any>` that lets pre-routing or pre-request handlers pass arbitrary data to route handlers.
```cpp
struct AuthContext {
@@ -476,12 +481,12 @@ struct AuthContext {
svr.set_pre_routing_handler([](const auto& req, auto& res) {
auto token = req.get_header_value("Authorization");
res.user_data.set("auth", AuthContext{decode_token(token)});
res.user_data["auth"] = AuthContext{decode_token(token)};
return Server::HandlerResponse::Unhandled;
});
svr.Get("/me", [](const auto& /*req*/, auto& res) {
auto* ctx = res.user_data.get<AuthContext>("auth");
auto* ctx = httplib::any_cast<AuthContext>(&res.user_data["auth"]);
if (!ctx) {
res.status = StatusCode::Unauthorized_401;
return;
@@ -490,6 +495,8 @@ svr.Get("/me", [](const auto& /*req*/, auto& res) {
});
```
`httplib::any` mirrors the C++17 `std::any` API. On C++17 and later it is an alias for `std::any`; on C++11/14 a compatible implementation is provided.
### Form data handling
#### URL-encoded form data ('application/x-www-form-urlencoded')
@@ -531,16 +538,16 @@ svr.Post("/multipart", [&](const Request& req, Response& res) {
}
// IMPORTANT: file.filename is an untrusted value from the client.
// Always sanitize to prevent path traversal attacks.
auto safe_name = httplib::sanitize_filename(file.filename);
if (safe_name.empty()) {
// Always extract only the basename to prevent path traversal attacks.
auto safe_name = std::filesystem::path(file.filename).filename();
if (safe_name.empty() || safe_name == "." || safe_name == "..") {
res.status = StatusCode::BadRequest_400;
res.set_content("Invalid filename", "text/plain");
return;
}
// Save to disk
std::ofstream ofs(upload_dir + "/" + safe_name, std::ios::binary);
std::ofstream ofs(upload_dir / safe_name, std::ios::binary);
ofs << file.content;
}
@@ -576,16 +583,6 @@ svr.Post("/multipart", [&](const Request& req, Response& res) {
});
```
#### Filename Sanitization
`file.filename` in multipart uploads is an untrusted value from the client. Always sanitize before using it in file paths:
```cpp
auto safe = httplib::sanitize_filename(file.filename);
```
This function strips path separators (`/`, `\`), null bytes, leading/trailing whitespace, and rejects `.` and `..`. Returns an empty string if the filename is unsafe.
### Receive content with a content receiver
```cpp
@@ -746,10 +743,6 @@ svr.set_keep_alive_timeout(10); // Default is 5
svr.set_read_timeout(5, 0); // 5 seconds
svr.set_write_timeout(5, 0); // 5 seconds
svr.set_idle_interval(0, 100000); // 100 milliseconds
// std::chrono is also supported
svr.set_read_timeout(std::chrono::seconds(5));
svr.set_keep_alive_timeout(std::chrono::seconds(10));
```
### Set maximum payload length for reading a request body
@@ -1060,12 +1053,6 @@ cli.set_write_timeout(5, 0); // 5 seconds
// This method works the same as curl's `--max-time` option
cli.set_max_timeout(5000); // 5 seconds
// std::chrono is also supported
cli.set_connection_timeout(std::chrono::milliseconds(300));
cli.set_read_timeout(std::chrono::seconds(5));
cli.set_write_timeout(std::chrono::seconds(5));
cli.set_max_timeout(std::chrono::seconds(5));
```
### Set maximum payload length for reading a response body
@@ -1181,17 +1168,6 @@ cli.set_proxy_bearer_token_auth("pass");
> [!NOTE]
> OpenSSL is required for Digest Authentication.
#### Bypass the proxy for specific hosts (`NO_PROXY`)
```cpp
cli.set_no_proxy({"internal.corp", "10.0.0.0/8", "*.dev.local"});
```
Each pattern is `*`, a hostname suffix, an IP literal, or a CIDR block.
Hostname matching is case-insensitive with a dot-boundary rule. See the
[NO_PROXY cookbook](https://yhirose.github.io/cpp-httplib/en/cookbook/c16-proxy)
for details and for reading the variable from the environment.
### Range
```cpp
@@ -1476,26 +1452,10 @@ if (ws.connect()) {
SSL is also supported via `wss://` scheme (e.g. `WebSocketClient("wss://example.com/ws")`). Subprotocol negotiation (`Sec-WebSocket-Protocol`) is supported via `SubProtocolSelector` callback.
> **Note:** WebSocket connections occupy a thread for their entire lifetime (plus an additional thread per connection for heartbeat pings). This thread-per-connection model is intended for small- to mid-scale workloads; large numbers of simultaneous WebSocket connections are outside the design target of this library. If you expect many concurrent WebSocket clients, configure a dynamic thread pool (`svr.new_task_queue = [] { return new ThreadPool(8, 64); };`) and measure carefully.
> **WebSocket extensions are not supported.** `permessage-deflate` and other RFC 6455 extensions are not implemented. If a client proposes them via `Sec-WebSocket-Extensions`, the server silently declines them in its handshake response.
> **Unresponsive-peer detection.** Heartbeat pings also serve as a liveness probe when `set_websocket_max_missed_pongs(n)` is set: if the client sends `n` consecutive pings without receiving a pong, it will close the connection. Disabled by default (`0`).
> **Note:** WebSocket connections occupy a thread for their entire lifetime. If you plan to handle many simultaneous WebSocket connections, consider using a dynamic thread pool: `svr.new_task_queue = [] { return new ThreadPool(8, 64); };`
See [README-websocket.md](README-websocket.md) for more details.
## Socket Option Utility
`set_socket_opt` is a convenience wrapper around `setsockopt` for setting integer socket options:
```cpp
auto sock = svr.socket();
httplib::set_socket_opt(sock, IPPROTO_TCP, TCP_NODELAY, 1);
```
> [!TIP]
> For most use cases, prefer `set_tcp_nodelay(true)` or `set_socket_options(callback)` on the Server/Client instead of calling `set_socket_opt` directly.
## Split httplib.h into .h and .cc
```console

View File

@@ -61,7 +61,7 @@ if(@HTTPLIB_IS_USING_ZSTD@)
if(${CMAKE_FIND_PACKAGE_NAME}_FIND_REQUIRED)
set(httplib_fd_zstd_required_arg REQUIRED)
endif()
find_package(zstd 1.5.6 CONFIG QUIET)
find_package(zstd QUIET)
if(NOT zstd_FOUND)
find_package(PkgConfig ${httplib_fd_zstd_quiet_arg} ${httplib_fd_zstd_required_arg})
if(PKG_CONFIG_FOUND)

View File

@@ -10,10 +10,7 @@ if(HTTPLIB_BUILD_MODULES)
target_sources(${PROJECT_NAME}
PUBLIC
FILE_SET CXX_MODULES
BASE_DIRS
"${_httplib_build_includedir}"
FILES
FILE_SET CXX_MODULES FILES
"${_httplib_build_includedir}/httplib.cppm"
)
endif()

1992
docs-gen/Cargo.lock generated Normal file

File diff suppressed because it is too large Load Diff

22
docs-gen/Cargo.toml Normal file
View File

@@ -0,0 +1,22 @@
[package]
name = "docs-gen"
version = "0.1.0"
edition = "2021"
[dependencies]
pulldown-cmark = "0.12"
tera = "1"
walkdir = "2"
serde = { version = "1", features = ["derive"] }
serde_json = "1"
serde_yaml = "0.9"
toml = "0.8"
syntect = "5"
anyhow = "1"
clap = { version = "4", features = ["derive"] }
notify = "7"
tiny_http = "0.12"
tungstenite = "0.24"
open = "5"
tempfile = "3"
socket2 = { version = "0.5", features = ["all"] }

254
docs-gen/README.md Normal file
View File

@@ -0,0 +1,254 @@
# docs-gen
A static site generator for multi-language documentation. Markdown content, Tera templates, and syntax highlighting — all in a single binary.
## Quick Start
```bash
# 1. Scaffold a new project
docs-gen init my-docs
# 2. Start the local dev server with live-reload
docs-gen serve my-docs --open
# 3. Build for production
docs-gen build my-docs --out docs
```
---
## Commands
### `init [DIR]`
Creates a new project scaffold in `DIR` (default: `.`).
Generated files:
```
config.toml
pages/
en/index.md
ja/index.md
templates/
base.html
page.html
portal.html
static/
css/main.css
js/main.js
```
Existing files are never overwritten.
---
### `serve [SRC] [--port PORT] [--open]`
Builds the site into a temporary directory and serves it locally. Watches for changes and live-reloads the browser automatically.
| Option | Default | Description |
|--------|---------|-------------|
| `SRC` | `.` | Source directory |
| `--port` | `8080` | HTTP server port |
| `--open` | — | Open browser on startup |
---
### `build [SRC] [--out OUT]`
Generates the static site from source.
| Option | Default | Description |
|--------|---------|-------------|
| `SRC` | `.` | Source directory |
| `--out` | `docs` | Output directory |
---
## Source Directory Structure
Only `config.toml` and `pages/` are required. `templates/` and `static/` are optional — when absent, built-in defaults are used automatically.
```
my-docs/
├── config.toml # Site configuration (required)
├── pages/ # Markdown content (required)
│ ├── en/
│ │ ├── index.md # Portal page (homepage, no sidebar)
│ │ └── guide/
│ │ ├── index.md # Section index
│ │ ├── 01-intro.md
│ │ └── 02-usage.md
│ └── ja/
│ └── ...
├── templates/ # Override built-in HTML templates (optional)
│ ├── base.html
│ ├── page.html
│ └── portal.html
└── static/ # Override built-in CSS/JS/assets (optional)
├── css/main.css
└── js/main.js
```
---
## config.toml
```toml
[site]
title = "My Project"
version = "1.0.0" # Optional. Shown in header.
hostname = "https://example.github.io" # Optional. Combined with base_path for full URLs.
base_path = "/my-project" # URL prefix. Use "" for local-only.
[[nav]]
label = "Guide"
path = "guide/" # Internal section path (resolved per language)
icon_svg = '<svg ...>...</svg>' # Optional inline SVG icon
[[nav]]
label = "GitHub"
url = "https://github.com/your/repo" # External URL
icon_svg = '<svg ...>...</svg>'
[i18n]
langs = ["en", "ja"] # First entry is the default language
[highlight]
dark_theme = "base16-eighties.dark" # Dark mode theme
light_theme = "InspiredGitHub" # Light mode theme (optional)
```
### `[site]`
| Key | Required | Description |
|-----|----------|-------------|
| `title` | yes | Site title displayed in the header |
| `version` | no | Version string displayed in the header |
| `hostname` | no | Base hostname (e.g. `"https://user.github.io"`). Combined with `base_path` to form `site.base_url` in templates. |
| `base_path` | no | URL path prefix. Use `"/repo-name"` for GitHub Pages, `""` for local development. |
### `[[nav]]` — Toolbar Buttons
Defines buttons in the site header. Each entry supports:
| Key | Required | Description |
|-----|----------|-------------|
| `label` | yes | Button label text |
| `path` | no | Internal section path relative to `<lang>/` (e.g. `"guide/"`). Resolved using the current language. |
| `url` | no | Absolute external URL. Takes precedence over `path` if both are set. |
| `icon_svg` | no | Inline SVG markup displayed as an icon |
### `[i18n]`
| Key | Required | Description |
|-----|----------|-------------|
| `langs` | yes | List of language codes. At least one is required. The first entry is used as the default language. |
### `[highlight]`
| Key | Default | Description |
|-----|---------|-------------|
| `dark_theme` | `base16-ocean.dark` | Theme for dark mode |
| `light_theme` | _(none)_ | Theme for light mode. When set, both dark and light code blocks are emitted and toggled via CSS. |
Available themes: `base16-ocean.dark`, `base16-ocean.light`, `base16-eighties.dark`, `base16-mocha.dark`, `InspiredGitHub`, `Solarized (dark)`, `Solarized (light)`.
---
## Writing Pages
### Frontmatter
Every `.md` file must begin with YAML frontmatter:
```yaml
---
title: "Getting Started"
order: 1
---
Page content goes here...
```
| Field | Required | Description |
|-------|----------|-------------|
| `title` | yes | Page title shown in the heading and browser tab |
| `order` | no | Sort order within the section (default: `0`) |
| `status` | no | Set to `"draft"` to display a DRAFT banner |
### URL Routing
Files are mapped to URLs as follows:
| File | URL |
|------|-----|
| `en/index.md` | `<base_path>/en/` |
| `en/guide/index.md` | `<base_path>/en/guide/` |
| `en/guide/01-intro.md` | `<base_path>/en/guide/01-intro/` |
The root `index.html` is generated automatically and redirects to the default language, respecting the user's `localStorage` language preference.
### Sidebar Navigation
Sidebar navigation is generated automatically:
- Each subdirectory under a language becomes a **section**
- The section's `index.md` title is used as the section heading
- Pages within a section are sorted by `order`, then by filename
- `index.md` at the language root uses `portal.html` (no sidebar)
- All other pages use `page.html` (with sidebar)
---
## Customizing Templates and Assets
When `templates/` or `static/` directories exist in the source, files there override the built-in defaults. Use `docs-gen init` to generate the defaults as a starting point.
Three templates are available:
| Template | Used for |
|----------|----------|
| `base.html` | Shared layout: `<head>`, header, footer, scripts |
| `page.html` | Content pages with sidebar |
| `portal.html` | Homepage (`index.md` at language root), no sidebar |
---
## Template Variables
Templates use [Tera](https://keats.github.io/tera/) syntax. Available variables:
### All templates
| Variable | Type | Description |
|----------|------|-------------|
| `page.title` | string | Page title from frontmatter |
| `page.url` | string | Page URL path |
| `page.status` | string? | `"draft"` or null |
| `content` | string | Rendered HTML (use `{{ content \| safe }}`) |
| `lang` | string | Current language code |
| `site.title` | string | Site title |
| `site.version` | string? | Site version |
| `site.base_url` | string | Full base URL (`hostname` + `base_path`) |
| `site.base_path` | string | URL path prefix |
| `site.langs` | list | All language codes |
| `site.nav` | list | Toolbar button entries |
| `site.nav[].label` | string | Button label |
| `site.nav[].url` | string? | External URL (if set) |
| `site.nav[].path` | string? | Internal section path (if set) |
| `site.nav[].icon_svg` | string? | Inline SVG icon (if set) |
### `page.html` only
| Variable | Type | Description |
|----------|------|-------------|
| `nav` | list | Sidebar sections |
| `nav[].title` | string | Section title |
| `nav[].url` | string | Section index URL |
| `nav[].active` | bool | True if this section contains the current page |
| `nav[].children` | list | Pages within this section |
| `nav[].children[].title` | string | Page title |
| `nav[].children[].url` | string | Page URL |
| `nav[].children[].active` | bool | True if this is the current page |

View File

@@ -0,0 +1,20 @@
[site]
title = "My Docs"
hostname = "https://example.github.io"
base_path = "/my-project"
# [[nav]]
# label = "Guide"
# path = "guide/"
#
# [[nav]]
# label = "GitHub"
# url = "https://github.com/your/repo"
# icon_svg = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M9 19c-5 1.5-5-2.5-7-3m14 6v-3.87a3.37 3.37 0 0 0-.94-2.61c3.14-.35 6.44-1.54 6.44-7A5.44 5.44 0 0 0 20 4.77 5.07 5.07 0 0 0 19.91 1S18.73.65 16 2.48a13.38 13.38 0 0 0-7 0C6.27.65 5.09 1 5.09 1A5.07 5.07 0 0 0 5 4.77a5.44 5.44 0 0 0-1.5 3.78c0 5.42 3.3 6.61 6.44 7A3.37 3.37 0 0 0 9 18.13V22"/></svg>'
[i18n]
langs = ["en"]
[highlight]
dark_theme = "base16-ocean.dark"
light_theme = "InspiredGitHub"

View File

@@ -0,0 +1,10 @@
---
title: Welcome
order: 0
---
## Welcome
This is the home page of your documentation site.
Edit this file at `pages/en/index.md` to get started.

View File

@@ -0,0 +1,10 @@
---
title: ようこそ
order: 0
---
## ようこそ
ドキュメントサイトのトップページです。
`pages/ja/index.md` を編集して始めましょう。

View File

@@ -0,0 +1,603 @@
:root {
--bg: #333;
--bg-secondary: #3c3c3c;
--bg-code: #2a2a2a;
--text: #ccc;
--text-bright: white;
--text-muted: #999;
--text-code: #b0b0b0;
--text-inline-code: plum;
--border: #555;
--border-code: #3a3a3a;
--link: palegoldenrod;
--heading: lightskyblue;
--heading-link: #f0c090;
--header-nav-link: pink;
--emphasis: pink;
--nav-section: #bbb;
--nav-section-active: #ddd;
--content-width: 900px;
--sidebar-width: 280px;
--header-height: 48px;
--line-height: 1.6;
}
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
background-color: var(--bg);
color: var(--text);
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
line-height: var(--line-height);
}
a {
color: var(--link);
text-decoration: none;
}
a:hover {
text-decoration: underline;
}
/* Header */
.header {
position: fixed;
top: 0;
left: 0;
right: 0;
height: var(--header-height);
background-color: var(--bg-secondary);
border-bottom: 1px solid var(--border);
z-index: 100;
}
.header-inner {
height: 100%;
display: flex;
align-items: center;
padding: 0 16px;
gap: 24px;
}
.header-title {
color: var(--text);
font-weight: bold;
font-size: 1.1rem;
white-space: nowrap;
}
.header-title:hover {
text-decoration: none;
color: var(--text-bright);
}
.header-spacer {
flex: 1;
}
.header-nav {
display: flex;
gap: 16px;
}
.header-nav a {
display: flex;
align-items: center;
gap: 4px;
color: var(--header-nav-link);
font-size: 0.9rem;
}
.header-nav a svg {
flex-shrink: 0;
opacity: 0.85;
}
.header-tools {
display: flex;
align-items: center;
gap: 2px;
}
.lang-selector {
position: relative;
}
.lang-btn {
display: flex;
align-items: center;
gap: 5px;
background: none;
border: none;
color: var(--text);
padding: 4px 6px;
border-radius: 4px;
cursor: pointer;
font-size: 0.85rem;
opacity: 0.8;
}
.lang-btn:hover {
opacity: 1;
}
.lang-popup {
display: none;
position: absolute;
right: 0;
top: 100%;
margin-top: 4px;
background: var(--bg-secondary);
border: 1px solid var(--border);
border-radius: 4px;
list-style: none;
min-width: 60px;
z-index: 200;
}
.lang-popup.open {
display: block;
}
.lang-popup li a {
display: block;
padding: 6px 12px;
color: var(--text);
font-size: 0.85rem;
}
.lang-popup li a:hover {
background: var(--bg);
text-decoration: none;
}
.sidebar-toggle {
display: none;
background: none;
border: none;
color: var(--text);
font-size: 1.2rem;
cursor: pointer;
padding: 4px 8px;
}
/* Draft banner */
.draft-banner {
position: fixed;
top: var(--header-height);
right: 0;
background: #c44;
color: white;
padding: 4px 16px;
font-size: 0.75rem;
font-weight: bold;
letter-spacing: 0.1em;
z-index: 99;
}
/* Layout */
.layout {
margin-top: var(--header-height);
display: grid;
grid-template-columns: var(--sidebar-width) minmax(0, 1fr);
min-height: calc(100vh - var(--header-height));
}
.layout.no-sidebar {
grid-template-columns: 1fr;
}
/* Sidebar */
.sidebar {
width: var(--sidebar-width);
flex-shrink: 0;
padding: 24px 16px;
border-right: 1px solid var(--bg-secondary);
position: sticky;
top: var(--header-height);
height: calc(100vh - var(--header-height));
overflow-y: auto;
}
.nav-section {
margin-bottom: 16px;
}
.nav-section-title {
color: var(--nav-section);
font-weight: bold;
font-size: 1.0rem;
display: block;
margin-bottom: 8px;
}
.nav-section-title.active {
color: var(--nav-section-active);
}
.nav-list {
list-style: none;
padding-left: 8px;
}
.nav-list li {
margin-bottom: 4px;
}
.nav-list li a {
color: var(--text-muted);
font-size: 0.85rem;
}
.nav-list li a:hover {
color: var(--text);
}
.nav-list li a.active {
color: var(--emphasis);
font-weight: bold;
}
/* Content */
.content {
min-width: 0;
max-width: var(--content-width);
padding: 32px 24px;
overflow-wrap: break-word;
}
.content.portal {
max-width: var(--content-width);
padding: 48px 24px;
margin: 0 auto;
}
.content article h1 {
font-size: 1.8rem;
margin-bottom: 24px;
color: var(--heading);
}
.content article h2 {
font-size: 1.4rem;
margin-top: 32px;
margin-bottom: 16px;
color: var(--heading-link);
}
.content article h3 {
font-size: 1.1rem;
margin-top: 24px;
margin-bottom: 12px;
color: var(--text);
}
.content article p {
margin-bottom: 12px;
}
.content article ul,
.content article ol {
margin-bottom: 12px;
padding-left: 24px;
}
.content article li {
margin-bottom: 4px;
}
.content article strong {
color: var(--emphasis);
}
.content article code {
background: var(--bg-code);
color: var(--text-inline-code);
padding: 2px 6px;
border-radius: 3px;
font-size: 0.9em;
}
.content article pre {
background: var(--bg-code);
color: var(--text-code);
padding: 16px;
border-radius: 4px;
overflow-x: auto;
margin-bottom: 16px;
border: 1px solid var(--border-code);
}
.content article pre code {
background: none;
padding: 0;
}
.content article table {
width: 100%;
border-collapse: collapse;
margin-bottom: 16px;
}
.content article th,
.content article td {
border: 1px solid var(--bg-secondary);
padding: 8px 12px;
text-align: left;
}
.content article th {
background: var(--bg-secondary);
}
.content article blockquote {
border-left: 3px solid var(--text-muted);
padding-left: 16px;
margin-bottom: 12px;
color: var(--text-muted);
}
/* Code block theme switching: show dark by default, swap on light mode */
.code-block-wrapper > [data-code-theme="light"] {
display: none;
}
html[data-theme="light"] .code-block-wrapper > [data-code-theme="dark"] {
display: none;
}
html[data-theme="light"] .code-block-wrapper > [data-code-theme="light"] {
display: block;
}
/* Footer */
.footer {
padding: 12px 16px;
text-align: center;
color: var(--text-muted);
font-size: 0.8rem;
border-top: 1px solid var(--bg-secondary);
}
/* Responsive */
@media (max-width: 768px) {
.layout {
grid-template-columns: minmax(0, 1fr);
}
.sidebar {
position: fixed;
left: calc(-1 * var(--sidebar-width));
width: var(--sidebar-width);
top: var(--header-height);
height: calc(100vh - var(--header-height));
background: var(--bg);
z-index: 50;
transition: left 0.2s ease;
border-right: 1px solid var(--border);
}
.sidebar.open {
left: 0;
}
.sidebar-toggle {
display: block;
}
.content {
padding: 24px 16px;
}
}
@media (max-width: 480px) {
:root {
--header-height: 44px;
}
.header-inner {
padding: 0 12px;
gap: 12px;
}
.header-nav a {
font-size: 0.8rem;
}
.content article h1 {
font-size: 1.4rem;
}
.content article h2 {
font-size: 1.2rem;
}
}
/* Light mode */
[data-theme="light"] {
--bg: #f5f5f5;
--bg-secondary: #e8e8e8;
--bg-code: #eee;
--text: #333;
--text-bright: #000;
--text-muted: #666;
--text-code: #333;
--text-inline-code: #8b5ca0;
--border: #ccc;
--border-code: #ddd;
--link: #b8860b;
--heading: #2a6496;
--heading-link: #c06020;
--header-nav-link: #c04060;
--emphasis: #c04060;
--nav-section: #666;
--nav-section-active: #333;
}
/* Theme toggle */
.theme-toggle {
display: flex;
align-items: center;
justify-content: center;
background: none;
border: none;
color: var(--text);
padding: 5px 6px;
border-radius: 4px;
cursor: pointer;
opacity: 0.8;
}
.theme-toggle:hover {
opacity: 1;
}
/* Search button */
.search-btn {
display: flex;
align-items: center;
justify-content: center;
background: none;
border: none;
color: var(--text);
padding: 5px 6px;
border-radius: 4px;
cursor: pointer;
opacity: 0.8;
}
.search-btn:hover {
opacity: 1;
}
/* Search overlay & modal */
.search-overlay {
display: none;
position: fixed;
inset: 0;
background: rgba(0, 0, 0, 0.5);
z-index: 300;
justify-content: center;
align-items: flex-start;
padding-top: 12vh;
}
.search-overlay.open {
display: flex;
}
.search-modal {
background: var(--bg-secondary);
border: 1px solid var(--border);
border-radius: 8px;
width: 90%;
max-width: 560px;
box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
overflow: hidden;
}
.search-input-wrap {
display: flex;
align-items: center;
gap: 8px;
padding: 12px 16px;
border-bottom: 1px solid var(--border);
}
.search-input-wrap svg {
flex-shrink: 0;
opacity: 0.5;
}
#search-input {
flex: 1;
background: none;
border: none;
outline: none;
color: var(--text-bright);
font-size: 1rem;
font-family: inherit;
}
#search-input::placeholder {
color: var(--text-muted);
}
.search-esc {
background: var(--bg);
color: var(--text-muted);
padding: 2px 6px;
border-radius: 3px;
font-size: 0.7rem;
border: 1px solid var(--border);
}
.search-results {
list-style: none;
max-height: 50vh;
overflow-y: auto;
padding: 0;
margin: 0;
}
.search-results:empty::after {
content: "";
display: none;
}
.search-results li {
padding: 10px 16px;
cursor: pointer;
border-bottom: 1px solid var(--border);
}
.search-results li:last-child {
border-bottom: none;
}
.search-results li:hover,
.search-results li.active {
background: var(--bg);
}
.search-results li .search-result-title {
color: var(--text-bright);
font-weight: 600;
font-size: 0.9rem;
margin-bottom: 2px;
}
.search-results li .search-result-snippet {
color: var(--text-muted);
font-size: 0.8rem;
line-height: 1.4;
overflow: hidden;
text-overflow: ellipsis;
display: -webkit-box;
-webkit-line-clamp: 2;
-webkit-box-orient: vertical;
}
.search-results li .search-result-snippet mark {
background: rgba(255, 215, 0, 0.3);
color: var(--text-bright);
border-radius: 2px;
padding: 0 1px;
}
[data-theme="light"] .search-results li .search-result-snippet mark {
background: rgba(255, 200, 0, 0.4);
color: var(--text);
}
.search-no-results {
padding: 24px 16px;
text-align: center;
color: var(--text-muted);
font-size: 0.9rem;
}

View File

@@ -0,0 +1,4 @@
<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="size-6">
<path stroke-linecap="round" stroke-linejoin="round" d="M9.594 3.94c.09-.542.56-.94 1.11-.94h2.593c.55 0 1.02.398 1.11.94l.213 1.281c.063.374.313.686.645.87.074.04.147.083.22.127.325.196.72.257 1.075.124l1.217-.456a1.125 1.125 0 0 1 1.37.49l1.296 2.247a1.125 1.125 0 0 1-.26 1.431l-1.003.827c-.293.241-.438.613-.43.992a7.723 7.723 0 0 1 0 .255c-.008.378.137.75.43.991l1.004.827c.424.35.534.955.26 1.43l-1.298 2.247a1.125 1.125 0 0 1-1.369.491l-1.217-.456c-.355-.133-.75-.072-1.076.124a6.47 6.47 0 0 1-.22.128c-.331.183-.581.495-.644.869l-.213 1.281c-.09.543-.56.94-1.11.94h-2.594c-.55 0-1.019-.398-1.11-.94l-.213-1.281c-.062-.374-.312-.686-.644-.87a6.52 6.52 0 0 1-.22-.127c-.325-.196-.72-.257-1.076-.124l-1.217.456a1.125 1.125 0 0 1-1.369-.49l-1.297-2.247a1.125 1.125 0 0 1 .26-1.431l1.004-.827c.292-.24.437-.613.43-.991a6.932 6.932 0 0 1 0-.255c.007-.38-.138-.751-.43-.992l-1.004-.827a1.125 1.125 0 0 1-.26-1.43l1.297-2.247a1.125 1.125 0 0 1 1.37-.491l1.216.456c.356.133.751.072 1.076-.124.072-.044.146-.086.22-.128.332-.183.582-.495.644-.869l.214-1.28Z" />
<path stroke-linecap="round" stroke-linejoin="round" d="M15 12a3 3 0 1 1-6 0 3 3 0 0 1 6 0Z" />
</svg>

After

Width:  |  Height:  |  Size: 1.3 KiB

View File

@@ -0,0 +1,297 @@
// Language selector
(function () {
var btn = document.querySelector('.lang-btn');
var popup = document.querySelector('.lang-popup');
if (!btn || !popup) return;
btn.addEventListener('click', function (e) {
e.stopPropagation();
popup.classList.toggle('open');
});
document.addEventListener('click', function () {
popup.classList.remove('open');
});
popup.addEventListener('click', function (e) {
var link = e.target.closest('[data-lang]');
if (!link) return;
e.preventDefault();
var lang = link.getAttribute('data-lang');
localStorage.setItem('preferred-lang', lang);
var basePath = document.documentElement.getAttribute('data-base-path') || '';
var path = window.location.pathname;
// Strip base path prefix, replace lang, then re-add base path
var pathWithoutBase = path.slice(basePath.length);
var newPath = basePath + pathWithoutBase.replace(/^\/[a-z]{2}\//, '/' + lang + '/');
window.location.href = newPath;
});
})();
// Theme toggle
(function () {
var btn = document.querySelector('.theme-toggle');
if (!btn) return;
// Feather Icons: sun (light mode) and moon (dark mode)
var sunSVG = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="5"/><line x1="12" y1="1" x2="12" y2="3"/><line x1="12" y1="21" x2="12" y2="23"/><line x1="4.22" y1="4.22" x2="5.64" y2="5.64"/><line x1="18.36" y1="18.36" x2="19.78" y2="19.78"/><line x1="1" y1="12" x2="3" y2="12"/><line x1="21" y1="12" x2="23" y2="12"/><line x1="4.22" y1="19.78" x2="5.64" y2="18.36"/><line x1="18.36" y1="5.64" x2="19.78" y2="4.22"/></svg>';
var moonSVG = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"/></svg>';
function getTheme() {
var stored = localStorage.getItem('preferred-theme');
if (stored) return stored;
return window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark';
}
function applyTheme(theme) {
if (theme === 'light') {
document.documentElement.setAttribute('data-theme', 'light');
} else {
document.documentElement.removeAttribute('data-theme');
}
btn.innerHTML = theme === 'light' ? sunSVG : moonSVG;
}
applyTheme(getTheme());
btn.addEventListener('click', function () {
var current = getTheme();
var next = current === 'dark' ? 'light' : 'dark';
localStorage.setItem('preferred-theme', next);
applyTheme(next);
});
})();
// Mobile sidebar toggle
(function () {
var toggle = document.querySelector('.sidebar-toggle');
var sidebar = document.querySelector('.sidebar');
if (!toggle || !sidebar) return;
toggle.addEventListener('click', function () {
sidebar.classList.toggle('open');
});
document.addEventListener('click', function (e) {
if (!sidebar.contains(e.target) && e.target !== toggle) {
sidebar.classList.remove('open');
}
});
})();
// Site search (⌘K / Ctrl+K)
(function () {
var overlay = document.getElementById('search-overlay');
var input = document.getElementById('search-input');
var resultsList = document.getElementById('search-results');
if (!overlay || !input || !resultsList) return;
var searchBtn = document.querySelector('.search-btn');
var pagesData = null; // cached pages-data.json
var activeIndex = -1;
function getCurrentLang() {
return document.documentElement.getAttribute('lang') || 'en';
}
function getBasePath() {
return document.documentElement.getAttribute('data-base-path') || '';
}
function openSearch() {
overlay.classList.add('open');
input.value = '';
resultsList.innerHTML = '';
activeIndex = -1;
input.focus();
loadPagesData();
}
function closeSearch() {
overlay.classList.remove('open');
input.value = '';
resultsList.innerHTML = '';
activeIndex = -1;
}
function loadPagesData() {
if (pagesData) return;
var basePath = getBasePath();
fetch(basePath + '/pages-data.json')
.then(function (res) { return res.json(); })
.then(function (data) { pagesData = data; })
.catch(function () { pagesData = []; });
}
function escapeRegExp(s) {
return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}
function highlightText(text, query) {
if (!query) return text;
var escaped = escapeRegExp(query);
var re = new RegExp('(' + escaped + ')', 'gi');
return text.replace(re, '<mark>$1</mark>');
}
function buildSnippet(body, query) {
if (!query || !body) return '';
var lower = body.toLowerCase();
var idx = lower.indexOf(query.toLowerCase());
var start, end, snippet;
if (idx === -1) {
snippet = body.substring(0, 120);
} else {
start = Math.max(0, idx - 40);
end = Math.min(body.length, idx + query.length + 80);
snippet = (start > 0 ? '...' : '') + body.substring(start, end) + (end < body.length ? '...' : '');
}
return highlightText(snippet, query);
}
function search(query) {
if (!pagesData || !query) {
resultsList.innerHTML = '';
activeIndex = -1;
return;
}
var lang = getCurrentLang();
var q = query.toLowerCase();
// Score and filter
var scored = [];
for (var i = 0; i < pagesData.length; i++) {
var page = pagesData[i];
if (page.lang !== lang) continue;
var score = 0;
var titleLower = page.title.toLowerCase();
var bodyLower = (page.body || '').toLowerCase();
if (titleLower.indexOf(q) !== -1) {
score += 10;
// Bonus for exact title match
if (titleLower === q) score += 5;
}
if (bodyLower.indexOf(q) !== -1) {
score += 3;
}
if (page.section.toLowerCase().indexOf(q) !== -1) {
score += 1;
}
if (score > 0) {
scored.push({ page: page, score: score });
}
}
// Sort by score descending
scored.sort(function (a, b) { return b.score - a.score; });
// Limit results
var results = scored.slice(0, 20);
if (results.length === 0) {
resultsList.innerHTML = '<li class="search-no-results">No results found.</li>';
activeIndex = -1;
return;
}
var html = '';
for (var j = 0; j < results.length; j++) {
var r = results[j];
var snippet = buildSnippet(r.page.body, query);
html += '<li data-url="' + r.page.url + '">'
+ '<div class="search-result-title">' + highlightText(r.page.title, query) + '</div>'
+ (snippet ? '<div class="search-result-snippet">' + snippet + '</div>' : '')
+ '</li>';
}
resultsList.innerHTML = html;
activeIndex = -1;
}
function setActive(index) {
var items = resultsList.querySelectorAll('li[data-url]');
if (items.length === 0) return;
// Remove previous active
for (var i = 0; i < items.length; i++) {
items[i].classList.remove('active');
}
if (index < 0) index = items.length - 1;
if (index >= items.length) index = 0;
activeIndex = index;
items[activeIndex].classList.add('active');
items[activeIndex].scrollIntoView({ block: 'nearest' });
}
function navigateToActive() {
var items = resultsList.querySelectorAll('li[data-url]');
if (activeIndex >= 0 && activeIndex < items.length) {
var url = items[activeIndex].getAttribute('data-url');
if (url) {
closeSearch();
window.location.href = url;
}
}
}
// Event: search button
if (searchBtn) {
searchBtn.addEventListener('click', function (e) {
e.stopPropagation();
openSearch();
});
}
// Use capture phase to intercept keys before browser default behavior
// (e.g. ESC clearing input text in some browsers)
document.addEventListener('keydown', function (e) {
if ((e.metaKey || e.ctrlKey) && e.key === 'k') {
e.preventDefault();
overlay.classList.contains('open') ? closeSearch() : openSearch();
return;
}
if (!overlay.classList.contains('open')) return;
if (e.key === 'Escape') {
e.preventDefault();
closeSearch();
} else if (e.key === 'ArrowDown') {
e.preventDefault();
setActive(activeIndex + 1);
} else if (e.key === 'ArrowUp') {
e.preventDefault();
setActive(activeIndex - 1);
} else if (e.key === 'Enter') {
e.preventDefault();
navigateToActive();
}
}, true); // capture phase
// Event: click overlay background to close
overlay.addEventListener('click', function (e) {
if (e.target === overlay) {
closeSearch();
}
});
// Event: click result item
resultsList.addEventListener('click', function (e) {
var li = e.target.closest('li[data-url]');
if (!li) return;
var url = li.getAttribute('data-url');
if (url) {
closeSearch();
window.location.href = url;
}
});
// Event: input for live search
var debounceTimer = null;
input.addEventListener('input', function () {
clearTimeout(debounceTimer);
debounceTimer = setTimeout(function () {
search(input.value.trim());
}, 150);
});
})();

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<!DOCTYPE html>
<html lang="{{ lang }}" data-base-path="{{ site.base_path }}">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>{{ page.title }} - {{ site.title }}</title>
<link rel="icon" type="image/svg+xml" href="{{ site.base_path }}/favicon.svg">
<link rel="stylesheet" href="{{ site.base_path }}/css/main.css">
<script>
(function() {
var t = localStorage.getItem('preferred-theme');
if (!t) t = window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark';
if (t === 'light') document.documentElement.setAttribute('data-theme', 'light');
})();
</script>
</head>
<body>
<header class="header">
<div class="header-inner">
<a href="{{ site.base_path }}/{{ lang }}/" class="header-title">{{ site.title }}{% if site.version %} <span style="font-size:0.75em;font-weight:normal;margin-left:4px">v{{ site.version }}</span>{% endif %}</a>
<div class="header-spacer"></div>
<nav class="header-nav">
<a href="{{ site.base_path }}/{{ lang }}/">
<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M3 9l9-7 9 7v11a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"/><polyline points="9 22 9 12 15 12 15 22"/></svg>
Home
</a>
{% for link in site.nav %}
{% if link.url %}
<a href="{{ link.url }}"{% if link.icon_svg %} aria-label="{{ link.label }}"{% endif %}>
{% if link.icon_svg %}{{ link.icon_svg | safe }}{% endif %}
{{ link.label }}
</a>
{% elif link.path %}
<a href="{{ site.base_path }}/{{ lang }}/{{ link.path }}">
{% if link.icon_svg %}{{ link.icon_svg | safe }}{% endif %}
{{ link.label }}
</a>
{% endif %}
{% endfor %}
</nav>
<div class="header-tools">
<button class="search-btn" aria-label="Search (⌘K)">
<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="11" cy="11" r="8"/><line x1="21" y1="21" x2="16.65" y2="16.65"/></svg>
</button>
<button class="theme-toggle" aria-label="Toggle theme"></button>
<div class="lang-selector">
<button class="lang-btn" aria-label="Language">
<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><line x1="2" y1="12" x2="22" y2="12"/><path d="M12 2a15.3 15.3 0 0 1 4 10 15.3 15.3 0 0 1-4 10 15.3 15.3 0 0 1-4-10 15.3 15.3 0 0 1 4-10z"/></svg>
{{ lang | upper }}
</button>
<ul class="lang-popup">
{% for l in site.langs %}
<li><a href="#" data-lang="{{ l }}">{{ l | upper }}</a></li>
{% endfor %}
</ul>
</div>
</div>
{% block sidebar_toggle %}{% endblock %}
</div>
</header>
{% if page.status == "draft" %}
<div class="draft-banner">DRAFT</div>
{% endif %}
<div class="layout {% block layout_class %}{% endblock %}">
{% block body %}{% endblock %}
</div>
<footer class="footer">
&copy; 2026 yhirose. All rights reserved.
</footer>
<!-- Search modal -->
<div class="search-overlay" id="search-overlay">
<div class="search-modal">
<div class="search-input-wrap">
<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="11" cy="11" r="8"/><line x1="21" y1="21" x2="16.65" y2="16.65"/></svg>
<input type="text" id="search-input" placeholder="Search..." autocomplete="off" spellcheck="false">
<kbd class="search-esc">ESC</kbd>
</div>
<ul class="search-results" id="search-results"></ul>
</div>
</div>
<script src="{{ site.base_path }}/js/main.js"></script>
</body>
</html>

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{% extends "base.html" %}
{% block layout_class %}has-sidebar{% endblock %}
{% block sidebar_toggle %}<button class="sidebar-toggle" aria-label="Menu">&#9776;</button>{% endblock %}
{% block body %}
<aside class="sidebar">
<nav class="sidebar-nav">
{% for section in nav %}
<div class="nav-section">
<a href="{{ section.url }}" class="nav-section-title {% if section.active %}active{% endif %}">{{ section.title }}</a>
{% if section.children %}
<ul class="nav-list">
{% for item in section.children %}
<li><a href="{{ item.url }}" class="{% if item.active %}active{% endif %}">{{ item.title }}</a></li>
{% endfor %}
</ul>
{% endif %}
</div>
{% endfor %}
</nav>
</aside>
<main class="content">
<article>
<h1>{{ page.title }}</h1>
{{ content | safe }}
</article>
</main>
{% endblock %}

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{% extends "base.html" %}
{% block layout_class %}no-sidebar{% endblock %}
{% block body %}
<main class="content portal">
<article>
<h1>{{ page.title }}</h1>
{{ content | safe }}
</article>
</main>
{% endblock %}

468
docs-gen/src/builder.rs Normal file
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use crate::config::{NavLink, SiteConfig};
use crate::defaults;
use crate::markdown::{Frontmatter, MarkdownRenderer};
use crate::utils::copy_dir_recursive;
use anyhow::{Context, Result};
use serde::Serialize;
use std::fs;
use std::path::{Path, PathBuf};
use tera::Tera;
use walkdir::WalkDir;
#[derive(Debug, Serialize)]
struct PageContext {
title: String,
url: String,
status: Option<String>,
}
/// Entry for pages-data.json used by client-side search.
#[derive(Debug, Serialize)]
struct PageDataEntry {
title: String,
url: String,
lang: String,
section: String,
/// Plain-text body with HTML tags stripped (truncated to ~500 chars).
body: String,
}
#[derive(Debug, Serialize, Clone)]
struct NavItem {
title: String,
url: String,
children: Vec<NavItem>,
active: bool,
}
#[derive(Debug, Serialize)]
struct SiteContext {
title: String,
version: Option<String>,
base_url: String,
base_path: String,
langs: Vec<String>,
nav: Vec<NavLink>,
}
struct Page {
frontmatter: Frontmatter,
html_content: String,
url: String,
out_path: PathBuf,
rel_path: String,
section: String,
}
pub fn build(src: &Path, out: &Path) -> Result<()> {
let config = SiteConfig::load(src)?;
let renderer = MarkdownRenderer::new(
config.highlight_dark_theme(),
config.highlight_light_theme(),
);
// Build Tera: start with embedded defaults, then override with user templates
let tera = build_tera(src)?;
// Clean output directory
if out.exists() {
fs::remove_dir_all(out).context("Failed to clean output directory")?;
}
fs::create_dir_all(out)?;
// Copy static files: embedded defaults first, then user overrides on top
copy_default_static(out)?;
let static_dir = src.join("static");
if static_dir.exists() {
copy_dir_recursive(&static_dir, out)?;
}
// Collect page data entries for pages-data.json across all languages
let mut page_data_entries: Vec<PageDataEntry> = Vec::new();
// Build each language
for lang in &config.i18n.langs {
let pages_dir = src.join("pages").join(lang);
if !pages_dir.exists() {
eprintln!("Warning: pages directory not found for lang '{}', skipping", lang);
continue;
}
let pages = collect_pages(&pages_dir, lang, out, &renderer, &config.site.base_path)?;
let nav = build_nav(&pages);
for page in &pages {
// Collect search data for pages-data.json
let plain_body = strip_html_tags(&remove_light_theme_blocks(&page.html_content));
let truncated_body: String = plain_body.chars().take(500).collect();
page_data_entries.push(PageDataEntry {
title: page.frontmatter.title.clone(),
url: page.url.clone(),
lang: lang.clone(),
section: page.section.clone(),
body: truncated_body,
});
let template_name = if page.section.is_empty() {
"portal.html"
} else {
"page.html"
};
// Filter nav to only the current section
let section_nav: Vec<&NavItem> = nav
.iter()
.filter(|item| {
let item_section = extract_section(&item.url, &config.site.base_path);
item_section == page.section
})
.collect();
let mut ctx = tera::Context::new();
ctx.insert("page", &PageContext {
title: page.frontmatter.title.clone(),
url: page.url.clone(),
status: page.frontmatter.status.clone(),
});
ctx.insert("content", &page.html_content);
ctx.insert("lang", lang);
ctx.insert("site", &SiteContext {
title: config.site.title.clone(),
version: config.site.version.clone(),
base_url: config.site.base_url(),
base_path: config.site.base_path.clone(),
langs: config.i18n.langs.clone(),
nav: config.nav.clone(),
});
// Set active state and pass nav
let mut nav_with_active: Vec<NavItem> = section_nav
.into_iter()
.cloned()
.map(|mut item| {
set_active(&mut item, &page.url);
item
})
.collect();
// If we're on a section index page, expand its children
if let Some(item) = nav_with_active.first_mut() {
if item.url == page.url {
item.active = true;
}
}
ctx.insert("nav", &nav_with_active);
let html = tera
.render(template_name, &ctx)
.with_context(|| format!("Failed to render template for {}", page.url))?;
if let Some(parent) = page.out_path.parent() {
fs::create_dir_all(parent)?;
}
fs::write(&page.out_path, html)?;
}
}
// Generate pages-data.json for client-side search
let pages_json = serde_json::to_string(&page_data_entries)
.context("Failed to serialize pages-data.json")?;
fs::write(out.join("pages-data.json"), pages_json)?;
// Generate root redirect
generate_root_redirect(out, &config)?;
println!(
"Site generated: {} languages, output at {}",
config.i18n.langs.len(),
out.display()
);
Ok(())
}
fn collect_pages(
pages_dir: &Path,
lang: &str,
out: &Path,
renderer: &MarkdownRenderer,
base_path: &str,
) -> Result<Vec<Page>> {
let mut pages = Vec::new();
for entry in WalkDir::new(pages_dir)
.into_iter()
.filter_map(|e| e.ok())
.filter(|e| {
e.path().extension().map_or(false, |ext| ext == "md")
})
{
let path = entry.path();
let content = fs::read_to_string(path)
.with_context(|| format!("Failed to read {}", path.display()))?;
let (frontmatter, body) = MarkdownRenderer::parse_frontmatter(&content)
.with_context(|| format!("Failed to parse frontmatter in {}", path.display()))?;
let html_content = renderer.render(body);
let rel = path.strip_prefix(pages_dir)?;
let rel_str = rel.to_string_lossy().to_string();
// Compute URL and output path
let (url, out_path) = if rel.file_name().map_or(false, |f| f == "index.md") {
// index.md -> <base_path>/<lang>/dir/
let parent = rel.parent().unwrap_or(Path::new(""));
if parent.as_os_str().is_empty() {
// Root index.md
(
format!("{}/{}/", base_path, lang),
out.join(lang).join("index.html"),
)
} else {
(
format!("{}/{}/{}/", base_path, lang, parent.display()),
out.join(lang).join(parent).join("index.html"),
)
}
} else {
// foo.md -> <base_path>/<lang>/foo/
let stem = rel.with_extension("");
(
format!("{}/{}/{}/", base_path, lang, stem.display()),
out.join(lang).join(&stem).join("index.html"),
)
};
let section = extract_section(&url, base_path);
pages.push(Page {
frontmatter,
html_content,
url,
out_path,
rel_path: rel_str,
section,
});
}
Ok(pages)
}
fn extract_section(url: &str, base_path: &str) -> String {
// Strip base_path prefix before parsing
let stripped = url.strip_prefix(base_path).unwrap_or(url);
// URL format: /<lang>/ or /<lang>/section/...
let parts: Vec<&str> = stripped.trim_matches('/').split('/').collect();
if parts.len() >= 2 {
parts[1].to_string()
} else {
String::new()
}
}
fn build_nav(pages: &[Page]) -> Vec<NavItem> {
// Group pages by section (top-level directory)
let mut sections: std::collections::BTreeMap<String, Vec<&Page>> =
std::collections::BTreeMap::new();
for page in pages {
if page.section.is_empty() {
continue; // Skip root index (portal)
}
sections
.entry(page.section.clone())
.or_default()
.push(page);
}
let mut nav = Vec::new();
for (section, mut section_pages) in sections {
// Sort by order, then by filename
section_pages.sort_by(|a, b| {
a.frontmatter
.order
.cmp(&b.frontmatter.order)
.then_with(|| a.rel_path.cmp(&b.rel_path))
});
// Find the section index page
let index_page = section_pages
.iter()
.find(|p| p.rel_path.ends_with("index.md") && p.section == section);
let section_title = index_page
.map(|p| p.frontmatter.title.clone())
.unwrap_or_else(|| section.clone());
let section_url = index_page
.map(|p| p.url.clone())
.unwrap_or_default();
let children: Vec<NavItem> = section_pages
.iter()
.filter(|p| !p.rel_path.ends_with("index.md") || p.section != section)
.map(|p| NavItem {
title: p.frontmatter.title.clone(),
url: p.url.clone(),
children: Vec::new(),
active: false,
})
.collect();
nav.push(NavItem {
title: section_title,
url: section_url,
children,
active: false,
});
}
// Sort nav sections by order of their index pages
nav
}
fn set_active(item: &mut NavItem, current_url: &str) {
if item.url == current_url {
item.active = true;
}
for child in &mut item.children {
set_active(child, current_url);
if child.active {
item.active = true;
}
}
}
fn generate_root_redirect(out: &Path, config: &SiteConfig) -> Result<()> {
let base_path = &config.site.base_path;
let html = format!(
r#"<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
(function() {{
var lang = localStorage.getItem('preferred-lang') || '{default_lang}';
window.location.replace('{base_path}/' + lang + '/');
}})();
</script>
<meta http-equiv="refresh" content="0;url={base_path}/{default_lang}/">
<title>Redirecting...</title>
</head>
<body>
<p>Redirecting to <a href="{base_path}/{default_lang}/">{base_path}/{default_lang}/</a>...</p>
</body>
</html>"#,
default_lang = config.i18n.default_lang(),
base_path = base_path,
);
fs::write(out.join("index.html"), html)?;
Ok(())
}
/// Build Tera with embedded default templates, then override with any files
/// found in `<src>/templates/`.
fn build_tera(src: &Path) -> Result<Tera> {
let mut tera = Tera::default();
// Register embedded defaults
for (name, source) in defaults::default_templates() {
tera.add_raw_template(name, source)
.with_context(|| format!("Failed to add default template '{}'", name))?;
}
// Override with user-provided templates (if any)
let templates_dir = src.join("templates");
if templates_dir.exists() {
for entry in WalkDir::new(&templates_dir)
.into_iter()
.filter_map(|e| e.ok())
.filter(|e| e.path().extension().map_or(false, |ext| ext == "html"))
{
let path = entry.path();
let rel = path.strip_prefix(&templates_dir)?;
let name = rel.to_string_lossy().replace('\\', "/");
let source = fs::read_to_string(path)
.with_context(|| format!("Failed to read template {}", path.display()))?;
tera.add_raw_template(&name, &source)
.with_context(|| format!("Failed to register template '{}'", name))?;
}
}
Ok(tera)
}
/// Write embedded default static files (css/js) to the output directory.
fn copy_default_static(out: &Path) -> Result<()> {
for (rel_path, content) in defaults::default_static_files() {
let target = out.join(rel_path);
if let Some(parent) = target.parent() {
fs::create_dir_all(parent)?;
}
// Only write if not already present (user file takes precedence via
// the subsequent copy_dir_recursive call, but write defaults first)
fs::write(&target, content)?;
}
Ok(())
}
/// Strip HTML tags from a string and collapse whitespace into a single space,
/// producing a plain-text representation suitable for search indexing.
fn strip_html_tags(html: &str) -> String {
let mut result = String::with_capacity(html.len());
let mut in_tag = false;
for ch in html.chars() {
match ch {
'<' => in_tag = true,
'>' => {
in_tag = false;
// Insert a space to avoid words being glued across tags
result.push(' ');
}
_ if !in_tag => result.push(ch),
_ => {}
}
}
// Collapse whitespace
let collapsed: String = result.split_whitespace().collect::<Vec<_>>().join(" ");
collapsed
}
/// Remove `<div data-code-theme="light">...</div>` blocks so that
/// dual-theme code snippets are only indexed once.
fn remove_light_theme_blocks(html: &str) -> String {
const MARKER: &str = "<div data-code-theme=\"light\"";
let mut result = String::with_capacity(html.len());
let mut remaining = html;
while let Some(start) = remaining.find(MARKER) {
result.push_str(&remaining[..start]);
remaining = &remaining[start..];
let mut depth: usize = 0;
let mut i = 0;
while i < remaining.len() {
if remaining[i..].starts_with("<div") {
depth += 1;
i += 4;
} else if remaining[i..].starts_with("</div>") {
depth -= 1;
i += 6;
if depth == 0 {
break;
}
} else {
i += remaining[i..].chars().next().map_or(1, |c| c.len_utf8());
}
}
remaining = &remaining[i..];
}
result.push_str(remaining);
result
}

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use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::path::Path;
#[derive(Debug, Deserialize)]
pub struct SiteConfig {
pub site: Site,
pub i18n: I18n,
pub highlight: Option<Highlight>,
#[serde(default)]
pub nav: Vec<NavLink>,
}
/// A navigation link entry defined in config.toml under [[nav]].
#[derive(Debug, Deserialize, Serialize, Clone)]
pub struct NavLink {
pub label: String,
/// Absolute or external URL (e.g. GitHub link).
pub url: Option<String>,
/// Path relative to /<base_path>/<lang>/ (e.g. "tour/").
pub path: Option<String>,
/// Optional inline SVG string to display as an icon.
pub icon_svg: Option<String>,
}
#[derive(Debug, Deserialize)]
pub struct Site {
pub title: String,
pub version: Option<String>,
/// Optional hostname (e.g. "https://example.github.io"). Combined with
/// base_path to form the full base URL.
pub hostname: Option<String>,
#[serde(default)]
pub base_path: String,
}
impl Site {
/// Returns the full base URL derived from hostname + base_path.
/// Falls back to base_path alone if hostname is not set.
pub fn base_url(&self) -> String {
match &self.hostname {
Some(h) => format!("{}{}", h.trim_end_matches('/'), self.base_path),
None => self.base_path.clone(),
}
}
}
#[derive(Debug, Deserialize)]
pub struct I18n {
pub langs: Vec<String>,
}
impl I18n {
/// Returns the default language, which is the first entry in langs.
pub fn default_lang(&self) -> &str {
self.langs.first().map(|s| s.as_str()).unwrap_or("en")
}
}
#[derive(Debug, Deserialize)]
pub struct Highlight {
pub dark_theme: Option<String>,
pub light_theme: Option<String>,
}
impl SiteConfig {
pub fn load(src_dir: &Path) -> Result<Self> {
let path = src_dir.join("config.toml");
let content =
std::fs::read_to_string(&path).with_context(|| format!("Failed to read {}", path.display()))?;
let mut config: SiteConfig =
toml::from_str(&content).with_context(|| format!("Failed to parse {}", path.display()))?;
// Validate required fields
if config.i18n.langs.is_empty() {
anyhow::bail!("[i18n] langs must not be empty. Please specify at least one language.");
}
// Normalize base_path: strip trailing slash (but keep empty for root)
let bp = config.site.base_path.trim_end_matches('/').to_string();
config.site.base_path = bp;
Ok(config)
}
pub fn highlight_dark_theme(&self) -> &str {
self.highlight
.as_ref()
.and_then(|h| h.dark_theme.as_deref())
.unwrap_or("base16-ocean.dark")
}
pub fn highlight_light_theme(&self) -> Option<&str> {
self.highlight
.as_ref()
.and_then(|h| h.light_theme.as_deref())
}
}

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// Default embedded theme files. Users can override any of these by placing
// a file with the same name under their <SRC>/templates/ or <SRC>/static/.
pub const TEMPLATE_BASE: &str = include_str!("../defaults/templates/base.html");
pub const TEMPLATE_PAGE: &str = include_str!("../defaults/templates/page.html");
pub const TEMPLATE_PORTAL: &str = include_str!("../defaults/templates/portal.html");
pub const STATIC_CSS_MAIN: &str = include_str!("../defaults/static/css/main.css");
pub const STATIC_JS_MAIN: &str = include_str!("../defaults/static/js/main.js");
pub const STATIC_FAVICON_SVG: &str = include_str!("../defaults/static/favicon.svg");
// Init command templates
pub const INIT_CONFIG_TOML: &str = include_str!("../defaults/config.toml");
pub const INIT_PAGE_EN_INDEX: &str = include_str!("../defaults/pages/en/index.md");
pub const INIT_PAGE_JA_INDEX: &str = include_str!("../defaults/pages/ja/index.md");
/// Returns all default templates as (name, source) pairs for Tera registration.
pub fn default_templates() -> Vec<(&'static str, &'static str)> {
vec![
("base.html", TEMPLATE_BASE),
("page.html", TEMPLATE_PAGE),
("portal.html", TEMPLATE_PORTAL),
]
}
/// Returns all default static files as (relative_path, content) pairs.
pub fn default_static_files() -> Vec<(&'static str, &'static str)> {
vec![
("css/main.css", STATIC_CSS_MAIN),
("js/main.js", STATIC_JS_MAIN),
("favicon.svg", STATIC_FAVICON_SVG),
]
}
/// Returns all init scaffold files as (relative_path, content) pairs.
pub fn init_files() -> Vec<(&'static str, &'static str)> {
vec![
("config.toml", INIT_CONFIG_TOML),
("templates/base.html", TEMPLATE_BASE),
("templates/page.html", TEMPLATE_PAGE),
("templates/portal.html", TEMPLATE_PORTAL),
("static/css/main.css", STATIC_CSS_MAIN),
("static/js/main.js", STATIC_JS_MAIN),
("pages/en/index.md", INIT_PAGE_EN_INDEX),
("pages/ja/index.md", INIT_PAGE_JA_INDEX),
]
}

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mod builder;
mod config;
mod defaults;
mod markdown;
mod serve;
mod utils;
use anyhow::Result;
use clap::{Parser, Subcommand, CommandFactory};
use std::fs;
use std::path::{Path, PathBuf};
#[derive(Parser)]
#[command(version, about = "A simple static site generator")]
struct Cli {
#[command(subcommand)]
command: Option<Command>,
/// Source directory containing config.toml (used when no subcommand given)
#[arg(default_value = ".")]
src: PathBuf,
/// Output directory (used when no subcommand given)
#[arg(long, default_value = "docs")]
out: PathBuf,
}
#[derive(Subcommand)]
enum Command {
/// Build the documentation site
Build {
/// Source directory containing config.toml
#[arg(default_value = ".")]
src: PathBuf,
/// Output directory
#[arg(long, default_value = "docs")]
out: PathBuf,
},
/// Initialize a new docs project with default scaffold files
Init {
/// Target directory to initialize (default: current directory)
#[arg(default_value = ".")]
src: PathBuf,
},
/// Start a local development server with live-reload
Serve {
/// Source directory containing config.toml
#[arg(default_value = ".")]
src: PathBuf,
/// Port number for the HTTP server
#[arg(long, default_value = "8080")]
port: u16,
/// Open browser automatically
#[arg(long)]
open: bool,
},
}
fn main() -> Result<()> {
let cli = Cli::parse();
match cli.command {
Some(Command::Build { src, out }) => builder::build(&src, &out),
Some(Command::Init { src }) => cmd_init(&src),
Some(Command::Serve { src, port, open }) => serve::serve(&src, port, open),
None => {
Cli::command().print_help()?;
println!();
Ok(())
}
}
}
fn cmd_init(target: &Path) -> Result<()> {
let mut skipped = 0usize;
let mut created = 0usize;
for (rel_path, content) in defaults::init_files() {
let dest = target.join(rel_path);
if dest.exists() {
eprintln!("Skipping (already exists): {}", dest.display());
skipped += 1;
continue;
}
if let Some(parent) = dest.parent() {
fs::create_dir_all(parent)?;
}
fs::write(&dest, content)?;
println!("Created: {}", dest.display());
created += 1;
}
println!("\nInit complete: {} file(s) created, {} skipped.", created, skipped);
Ok(())
}

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use anyhow::{Context, Result};
use pulldown_cmark::{CodeBlockKind, Event, Options, Parser, Tag, TagEnd};
use serde::Deserialize;
use syntect::highlighting::ThemeSet;
use syntect::html::highlighted_html_for_string;
use syntect::parsing::SyntaxSet;
#[derive(Debug, Deserialize)]
pub struct Frontmatter {
pub title: String,
#[serde(default)]
pub order: i32,
pub status: Option<String>,
}
pub struct MarkdownRenderer {
syntax_set: SyntaxSet,
theme_set: ThemeSet,
dark_theme: String,
light_theme: Option<String>,
}
impl MarkdownRenderer {
pub fn new(dark_theme: &str, light_theme: Option<&str>) -> Self {
Self {
syntax_set: SyntaxSet::load_defaults_newlines(),
theme_set: ThemeSet::load_defaults(),
dark_theme: dark_theme.to_string(),
light_theme: light_theme.map(|s| s.to_string()),
}
}
pub fn parse_frontmatter(content: &str) -> Result<(Frontmatter, &str)> {
let content = content.trim_start();
if !content.starts_with("---") {
anyhow::bail!("Missing frontmatter delimiter");
}
let after_first = &content[3..];
let end = after_first
.find("\n---")
.context("Missing closing frontmatter delimiter")?;
let yaml = &after_first[..end];
let body = &after_first[end + 4..];
let fm: Frontmatter =
serde_yaml::from_str(yaml).context("Failed to parse frontmatter YAML")?;
Ok((fm, body))
}
pub fn render(&self, markdown: &str) -> String {
let options = Options::ENABLE_TABLES
| Options::ENABLE_STRIKETHROUGH
| Options::ENABLE_TASKLISTS;
let parser = Parser::new_ext(markdown, options);
let mut in_code_block = false;
let mut code_lang = String::new();
let mut code_buf = String::new();
let mut events: Vec<Event> = Vec::new();
for event in parser {
match event {
Event::Start(Tag::CodeBlock(kind)) => {
in_code_block = true;
code_buf.clear();
code_lang = match kind {
CodeBlockKind::Fenced(lang) => lang.to_string(),
CodeBlockKind::Indented => String::new(),
};
}
Event::End(TagEnd::CodeBlock) => {
in_code_block = false;
let html = self.highlight_code(&code_buf, &code_lang);
events.push(Event::Html(html.into()));
}
Event::Text(text) if in_code_block => {
code_buf.push_str(&text);
}
other => events.push(other),
}
}
let mut html_output = String::new();
pulldown_cmark::html::push_html(&mut html_output, events.into_iter());
html_output
}
fn highlight_code(&self, code: &str, lang: &str) -> String {
let syntax = if lang.is_empty() {
self.syntax_set.find_syntax_plain_text()
} else {
self.syntax_set
.find_syntax_by_token(lang)
.unwrap_or_else(|| self.syntax_set.find_syntax_plain_text())
};
let dark_html = self.highlight_with_theme(code, syntax, &self.dark_theme);
match &self.light_theme {
Some(light) => {
let light_html = self.highlight_with_theme(code, syntax, light);
format!(
concat!(
"<div class=\"code-block-wrapper\">",
"<div data-code-theme=\"dark\">{}</div>",
"<div data-code-theme=\"light\">{}</div>",
"</div>",
),
dark_html, light_html
)
}
None => dark_html,
}
}
fn highlight_with_theme(
&self,
code: &str,
syntax: &syntect::parsing::SyntaxReference,
theme_name: &str,
) -> String {
let theme = self
.theme_set
.themes
.get(theme_name)
.unwrap_or_else(|| {
self.theme_set
.themes
.values()
.next()
.expect("No themes available")
});
match highlighted_html_for_string(code, &self.syntax_set, syntax, theme) {
Ok(html) => html,
Err(_) => format!("<pre><code>{}</code></pre>", escape_html(code)),
}
}
}
fn escape_html(s: &str) -> String {
s.replace('&', "&amp;")
.replace('<', "&lt;")
.replace('>', "&gt;")
}

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use crate::builder;
use crate::config::SiteConfig;
use crate::utils::copy_dir_recursive;
use anyhow::{Context, Result};
use notify::{Event, RecursiveMode, Watcher};
use socket2::{Domain, Protocol, Socket, Type};
use std::fs;
use std::io::Write;
use std::net::{TcpListener, TcpStream};
use std::path::Path;
use std::sync::mpsc;
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;
use walkdir::WalkDir;
/// Live-reload WebSocket script injected into every HTML page during serve.
const LIVE_RELOAD_SCRIPT: &str = r#"<script>
(function() {
var ws = new WebSocket('ws://' + location.hostname + ':{{WS_PORT}}');
ws.onmessage = function(e) { if (e.data === 'reload') location.reload(); };
ws.onclose = function() {
setTimeout(function() { location.reload(); }, 2000);
};
})();
</script>"#;
/// Run the serve command: build, start HTTP + WebSocket servers, watch for changes.
pub fn serve(src: &Path, port: u16, open_browser: bool) -> Result<()> {
let config = SiteConfig::load(src)?;
let base_path = config.site.base_path.clone();
let ws_port = port + 1;
// Create temp directory for serving
let tmp_dir = tempfile::tempdir().context("Failed to create temp directory")?;
let serve_root = tmp_dir.path().to_path_buf();
println!("Serving from temp directory: {}", serve_root.display());
// Initial build
build_and_copy(src, &serve_root, &base_path, ws_port)?;
// Track connected WebSocket clients
let clients: Arc<Mutex<Vec<TcpStream>>> = Arc::new(Mutex::new(Vec::new()));
// Create HTTP and WebSocket listeners upfront with SO_REUSEADDR
// so that rapid restarts (after Ctrl+C) don't hit "address in use".
let http_listener = create_reuse_listener(port)
.with_context(|| format!("Failed to bind HTTP server to port {}", port))?;
let ws_listener = create_reuse_listener(ws_port)
.with_context(|| format!("Failed to bind WebSocket server to port {}", ws_port))?;
// Start WebSocket server for live-reload notifications
let ws_clients = clients.clone();
thread::spawn(move || {
if let Err(e) = run_ws_server(ws_listener, ws_clients) {
eprintln!("WebSocket server error: {}", e);
}
});
// Start HTTP server
let http_root = serve_root.clone();
thread::spawn(move || {
if let Err(e) = run_http_server(http_listener, &http_root) {
eprintln!("HTTP server error: {}", e);
}
});
let url = if base_path.is_empty() {
format!("http://localhost:{}/", port)
} else {
format!("http://localhost:{}{}/", port, base_path)
};
println!("\n Local: {}", url);
println!(" Press Ctrl+C to stop.\n");
if open_browser {
let _ = open::that(&url);
}
// File watcher
let (tx, rx) = mpsc::channel();
let mut watcher = notify::recommended_watcher(move |res: Result<Event, notify::Error>| {
if let Ok(event) = res {
if event.kind.is_modify() || event.kind.is_create() || event.kind.is_remove() {
let _ = tx.send(());
}
}
})?;
let src_abs = fs::canonicalize(src)?;
watcher.watch(&src_abs, RecursiveMode::Recursive)?;
println!("Watching for changes in {}...", src_abs.display());
// Debounce: wait for changes, then rebuild
loop {
// Block until a change notification arrives
if rx.recv().is_err() {
break;
}
// Drain any additional events within a short debounce window
thread::sleep(Duration::from_millis(200));
while rx.try_recv().is_ok() {}
println!("Change detected, rebuilding...");
match build_and_copy(src, &serve_root, &base_path, ws_port) {
Ok(()) => {
println!("Rebuild complete. Notifying browser...");
notify_clients(&clients);
}
Err(e) => {
eprintln!("Rebuild failed: {}", e);
}
}
}
Ok(())
}
/// Build site into a temp build dir, then copy to serve_root/<base_path>/
/// with live-reload script injected.
fn build_and_copy(src: &Path, serve_root: &Path, base_path: &str, ws_port: u16) -> Result<()> {
// Build into a temporary output directory
let build_tmp = tempfile::tempdir().context("Failed to create build temp dir")?;
let build_out = build_tmp.path();
builder::build(src, build_out)?;
// Determine the target directory under serve_root
let target = if base_path.is_empty() {
serve_root.to_path_buf()
} else {
let bp = base_path.trim_start_matches('/');
serve_root.join(bp)
};
// Clean target and copy
if target.exists() {
fs::remove_dir_all(&target).ok();
}
copy_dir_recursive(build_out, &target)?;
// Inject live-reload script into all HTML files
inject_live_reload(&target, ws_port)?;
Ok(())
}
/// Inject live-reload WebSocket script into all HTML files under dir.
fn inject_live_reload(dir: &Path, ws_port: u16) -> Result<()> {
let script = LIVE_RELOAD_SCRIPT.replace("{{WS_PORT}}", &ws_port.to_string());
for entry in WalkDir::new(dir)
.into_iter()
.filter_map(|e| e.ok())
.filter(|e| {
e.path()
.extension()
.map_or(false, |ext| ext == "html")
})
{
let path = entry.path();
let content = fs::read_to_string(path)?;
if let Some(pos) = content.rfind("</body>") {
let injected = format!("{}{}{}", &content[..pos], script, &content[pos..]);
fs::write(path, injected)?;
}
}
Ok(())
}
/// Simple HTTP static file server using tiny_http.
fn run_http_server(listener: TcpListener, root: &Path) -> Result<()> {
let server = tiny_http::Server::from_listener(listener, None)
.map_err(|e| anyhow::anyhow!("HTTP server: {}", e))?;
for request in server.incoming_requests() {
let url_path = percent_decode(request.url());
let rel = url_path.trim_start_matches('/');
let file_path = if rel.is_empty() {
root.join("index.html")
} else {
let candidate = root.join(rel);
if candidate.is_dir() {
candidate.join("index.html")
} else {
candidate
}
};
if file_path.exists() && file_path.is_file() {
let content = fs::read(&file_path).unwrap_or_default();
let mime = guess_mime(&file_path);
let response = tiny_http::Response::from_data(content)
.with_header(
tiny_http::Header::from_bytes(&b"Content-Type"[..], mime.as_bytes()).unwrap(),
);
let _ = request.respond(response);
} else {
let response = tiny_http::Response::from_string("404 Not Found")
.with_status_code(404);
let _ = request.respond(response);
}
}
Ok(())
}
/// WebSocket server that accepts connections and stores them for later notification.
fn run_ws_server(listener: TcpListener, clients: Arc<Mutex<Vec<TcpStream>>>) -> Result<()> {
for stream in listener.incoming().flatten() {
let clients = clients.clone();
thread::spawn(move || {
if let Ok(ws) = tungstenite::accept(stream.try_clone().unwrap()) {
// Store the underlying TCP stream for later notification
if let Ok(mut list) = clients.lock() {
list.push(stream);
}
// Keep the WebSocket connection alive - read until closed
let mut ws = ws;
loop {
match ws.read() {
Ok(msg) => {
if msg.is_close() {
break;
}
}
Err(_) => break,
}
}
}
});
}
Ok(())
}
/// Send "reload" to all connected WebSocket clients.
fn notify_clients(clients: &Arc<Mutex<Vec<TcpStream>>>) {
if let Ok(mut list) = clients.lock() {
let mut alive = Vec::new();
for stream in list.drain(..) {
if stream.try_clone().is_ok() {
// Re-wrap as WebSocket and send reload message
// Since we can't easily re-wrap existing TCP streams,
// we'll use a simpler approach: raw WebSocket frame
if send_ws_text_frame(&stream, "reload").is_ok() {
alive.push(stream);
}
}
}
*list = alive;
}
}
/// Send a WebSocket text frame directly on a TCP stream.
fn send_ws_text_frame(mut stream: &TcpStream, msg: &str) -> Result<()> {
let payload = msg.as_bytes();
let len = payload.len();
// WebSocket text frame: opcode 0x81
let mut frame = Vec::new();
frame.push(0x81);
if len < 126 {
frame.push(len as u8);
} else if len < 65536 {
frame.push(126);
frame.push((len >> 8) as u8);
frame.push((len & 0xFF) as u8);
}
frame.extend_from_slice(payload);
stream.write_all(&frame)?;
stream.flush()?;
Ok(())
}
fn guess_mime(path: &Path) -> String {
match path.extension().and_then(|e| e.to_str()) {
Some("html") => "text/html; charset=utf-8".to_string(),
Some("css") => "text/css; charset=utf-8".to_string(),
Some("js") => "application/javascript; charset=utf-8".to_string(),
Some("json") => "application/json; charset=utf-8".to_string(),
Some("svg") => "image/svg+xml".to_string(),
Some("png") => "image/png".to_string(),
Some("jpg") | Some("jpeg") => "image/jpeg".to_string(),
Some("gif") => "image/gif".to_string(),
Some("ico") => "image/x-icon".to_string(),
Some("wasm") => "application/wasm".to_string(),
Some("woff") => "font/woff".to_string(),
Some("woff2") => "font/woff2".to_string(),
Some("ttf") => "font/ttf".to_string(),
_ => "application/octet-stream".to_string(),
}
}
fn percent_decode(input: &str) -> String {
let mut result = String::with_capacity(input.len());
let mut chars = input.bytes();
while let Some(b) = chars.next() {
if b == b'%' {
let hi = chars.next().and_then(|c| hex_val(c));
let lo = chars.next().and_then(|c| hex_val(c));
if let (Some(h), Some(l)) = (hi, lo) {
result.push((h << 4 | l) as char);
}
} else {
result.push(b as char);
}
}
result
}
fn hex_val(b: u8) -> Option<u8> {
match b {
b'0'..=b'9' => Some(b - b'0'),
b'a'..=b'f' => Some(b - b'a' + 10),
b'A'..=b'F' => Some(b - b'A' + 10),
_ => None,
}
}
/// Create a TCP listener with SO_REUSEADDR (and SO_REUSEPORT on Unix) set,
/// so that rapid restarts after Ctrl+C don't fail with "address in use".
fn create_reuse_listener(port: u16) -> Result<TcpListener> {
let socket = Socket::new(Domain::IPV4, Type::STREAM, Some(Protocol::TCP))?;
socket.set_reuse_address(true)?;
#[cfg(unix)]
socket.set_reuse_port(true)?;
let addr: std::net::SocketAddr = format!("0.0.0.0:{}", port).parse()?;
socket.bind(&addr.into())?;
socket.listen(128)?;
Ok(socket.into())
}

22
docs-gen/src/utils.rs Normal file
View File

@@ -0,0 +1,22 @@
use anyhow::Result;
use std::fs;
use std::path::Path;
use walkdir::WalkDir;
pub fn copy_dir_recursive(src: &Path, dst: &Path) -> Result<()> {
for entry in WalkDir::new(src).into_iter().filter_map(|e| e.ok()) {
let path = entry.path();
let rel = path.strip_prefix(src)?;
let target = dst.join(rel);
if path.is_dir() {
fs::create_dir_all(&target)?;
} else {
if let Some(parent) = target.parent() {
fs::create_dir_all(parent)?;
}
fs::copy(path, &target)?;
}
}
Ok(())
}

View File

@@ -1,30 +1,22 @@
[system]
theme = "monotone"
langs = ["en", "ja"]
[site]
title = "cpp-httplib"
version = "0.46.1"
version = "0.36.0"
hostname = "https://yhirose.github.io"
base_path = "/cpp-httplib"
footer_message = "© 2026 Yuji Hirose. All rights reserved."
[[nav]]
label = "Tour"
path = "tour/"
icon_svg = '<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><polygon points="16.24 7.76 14.12 14.12 7.76 16.24 9.88 9.88 16.24 7.76"/></svg>'
[[nav]]
label = "Cookbook"
path = "cookbook/"
icon_svg = '<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M4 19.5A2.5 2.5 0 0 1 6.5 17H20"/><path d="M6.5 2H20v20H6.5A2.5 2.5 0 0 1 4 19.5v-15A2.5 2.5 0 0 1 6.5 2z"/></svg>'
[[nav]]
label = "LLM App"
path = "llm-app/"
icon_svg = '<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M4 19.5A2.5 2.5 0 0 1 6.5 17H20"/><path d="M6.5 2H20v20H6.5A2.5 2.5 0 0 1 4 19.5v-15A2.5 2.5 0 0 1 6.5 2z"/></svg>'
[[nav]]
label = "GitHub"
url = "https://github.com/yhirose/cpp-httplib"
icon_svg = '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M9 19c-5 1.5-5-2.5-7-3m14 6v-3.87a3.37 3.37 0 0 0-.94-2.61c3.14-.35 6.44-1.54 6.44-7A5.44 5.44 0 0 0 20 4.77 5.07 5.07 0 0 0 19.91 1S18.73.65 16 2.48a13.38 13.38 0 0 0-7 0C6.27.65 5.09 1 5.09 1A5.07 5.07 0 0 0 5 4.77a5.44 5.44 0 0 0-1.5 3.78c0 5.42 3.3 6.61 6.44 7A3.37 3.37 0 0 0 9 18.13V22"/></svg>'
[i18n]
langs = ["en", "ja"]
[highlight]
dark_theme = "base16-eighties.dark"
light_theme = "InspiredGitHub"

View File

@@ -1,60 +0,0 @@
---
title: "C01. Get the Response Body / Save to a File"
order: 1
status: "draft"
---
## Get it as a string
```cpp
httplib::Client cli("http://localhost:8080");
auto res = cli.Get("/hello");
if (res && res->status == 200) {
std::cout << res->body << std::endl;
}
```
`res->body` is a `std::string`, ready to use as-is. The entire response is loaded into memory.
> **Warning:** If you fetch a large file with `res->body`, it all goes into memory. For large downloads, use a `ContentReceiver` as shown below.
## Save to a file
```cpp
httplib::Client cli("http://localhost:8080");
std::ofstream ofs("output.bin", std::ios::binary);
if (!ofs) {
std::cerr << "Failed to open file" << std::endl;
return 1;
}
auto res = cli.Get("/large-file",
[&](const char *data, size_t len) {
ofs.write(data, len);
return static_cast<bool>(ofs);
});
```
With a `ContentReceiver`, data arrives in chunks. You can write each chunk straight to disk without buffering the whole body in memory — perfect for large file downloads.
Return `false` from the callback to abort the download. In the example above, if writing to `ofs` fails, the download stops automatically.
> **Detail:** Want to check response headers like Content-Length before downloading? Combine a `ResponseHandler` with a `ContentReceiver`.
>
> ```cpp
> auto res = cli.Get("/large-file",
> [](const httplib::Response &res) {
> auto len = res.get_header_value("Content-Length");
> std::cout << "Size: " << len << std::endl;
> return true; // return false to skip the download
> },
> [&](const char *data, size_t len) {
> ofs.write(data, len);
> return static_cast<bool>(ofs);
> });
> ```
>
> The `ResponseHandler` is called after headers arrive but before the body. Return `false` to skip the download entirely.
> To show download progress, see [C11. Use the progress callback](c11-progress-callback).

View File

@@ -1,36 +0,0 @@
---
title: "C02. Send and Receive JSON"
order: 2
status: "draft"
---
cpp-httplib doesn't include a JSON parser. Use a library like [nlohmann/json](https://github.com/nlohmann/json) to build and parse JSON. The examples here use `nlohmann/json`.
## Send JSON
```cpp
httplib::Client cli("http://localhost:8080");
nlohmann::json j = {{"name", "Alice"}, {"age", 30}};
auto res = cli.Post("/api/users", j.dump(), "application/json");
```
Pass the JSON string as the second argument to `Post()` and the Content-Type as the third. The same pattern works with `Put()` and `Patch()`.
> **Warning:** If you omit the Content-Type (the third argument), the server may not recognize the body as JSON. Always specify `"application/json"`.
## Receive a JSON response
```cpp
auto res = cli.Get("/api/users/1");
if (res && res->status == 200) {
auto j = nlohmann::json::parse(res->body);
std::cout << j["name"] << std::endl;
}
```
`res->body` is a `std::string`, so you can pass it straight to your JSON library.
> **Note:** Servers sometimes return HTML on errors. Check the status code before parsing to be safe. Some APIs also require an `Accept: application/json` header. If you're calling a JSON API repeatedly, [C03. Set default headers](c03-default-headers) can save you some boilerplate.
> For how to receive and return JSON on the server side, see [S02. Receive JSON requests and return JSON responses](s02-json-api).

View File

@@ -1,55 +0,0 @@
---
title: "C03. Set Default Headers"
order: 3
status: "draft"
---
When you want the same headers on every request, use `set_default_headers()`. Once set, they're attached automatically to every request sent from that client.
## Basic usage
```cpp
httplib::Client cli("https://api.example.com");
cli.set_default_headers({
{"Accept", "application/json"},
{"User-Agent", "my-app/1.0"},
});
auto res = cli.Get("/users");
```
Register the headers you need on every API call — like `Accept` or `User-Agent` — in one place. No need to repeat them on each request.
## Send a Bearer token on every request
```cpp
httplib::Client cli("https://api.example.com");
cli.set_default_headers({
{"Authorization", "Bearer " + token},
{"Accept", "application/json"},
});
auto res1 = cli.Get("/me");
auto res2 = cli.Get("/projects");
```
Set the auth token once, and every subsequent request carries it. Handy when you're writing an API client that hits multiple endpoints.
> **Note:** `set_default_headers()` **replaces** the existing default headers. Even if you only want to add one, pass the full set again.
## Combine with per-request headers
You can still pass extra headers on individual requests, even with defaults set.
```cpp
httplib::Headers headers = {
{"X-Request-ID", "abc-123"},
};
auto res = cli.Get("/users", headers);
```
Per-request headers are **added** on top of the defaults. Both are sent to the server.
> For details on Bearer token auth, see [C06. Call an API with a Bearer token](c06-bearer-token).

View File

@@ -1,38 +0,0 @@
---
title: "C04. Follow Redirects"
order: 4
status: "draft"
---
By default, cpp-httplib does not follow HTTP redirects (3xx). If the server returns `302 Found`, you'll get it as a response with status code 302 — nothing more.
To follow redirects automatically, call `set_follow_location(true)`.
## Follow redirects
```cpp
httplib::Client cli("http://example.com");
cli.set_follow_location(true);
auto res = cli.Get("/old-path");
if (res && res->status == 200) {
std::cout << res->body << std::endl;
}
```
With `set_follow_location(true)`, the client reads the `Location` header and reissues the request to the new URL automatically. The final response ends up in `res`.
## Redirects from HTTP to HTTPS
```cpp
httplib::Client cli("http://example.com");
cli.set_follow_location(true);
auto res = cli.Get("/");
```
Many sites redirect HTTP traffic to HTTPS. With `set_follow_location(true)` on, this case is handled transparently — the client follows redirects even when the scheme or host changes.
> **Warning:** To follow redirects to HTTPS, you need to build cpp-httplib with OpenSSL (or another TLS backend). Without TLS support, redirects to HTTPS will fail.
> **Note:** Following redirects adds to the total request time. See [C12. Set timeouts](c12-timeouts) for timeout configuration.

View File

@@ -1,46 +0,0 @@
---
title: "C05. Use Basic Authentication"
order: 5
status: "draft"
---
For endpoints that require Basic authentication, pass the username and password to `set_basic_auth()`. cpp-httplib builds the `Authorization: Basic ...` header for you.
## Basic usage
```cpp
httplib::Client cli("https://api.example.com");
cli.set_basic_auth("alice", "s3cret");
auto res = cli.Get("/private");
if (res && res->status == 200) {
std::cout << res->body << std::endl;
}
```
Set it once, and every request from that client carries the credentials. No need to build the header each time.
## Per-request usage
If you want credentials on only one specific request, pass headers directly.
```cpp
httplib::Headers headers = {
httplib::make_basic_authentication_header("alice", "s3cret"),
};
auto res = cli.Get("/private", headers);
```
`make_basic_authentication_header()` builds the Base64-encoded header for you.
> **Warning:** Basic authentication **encodes** credentials in Base64 — it does not encrypt them. Always use it over HTTPS. Over plain HTTP, your password travels the network in the clear.
## Digest authentication
For the more secure Digest authentication scheme, use `set_digest_auth()`. This is only available when cpp-httplib is built with OpenSSL (or another TLS backend).
```cpp
cli.set_digest_auth("alice", "s3cret");
```
> To call an API with a Bearer token, see [C06. Call an API with a Bearer token](c06-bearer-token).

View File

@@ -1,50 +0,0 @@
---
title: "C06. Call an API with a Bearer Token"
order: 6
status: "draft"
---
For Bearer token authentication — common in OAuth 2.0 and modern Web APIs — use `set_bearer_token_auth()`. Pass the token and cpp-httplib builds the `Authorization: Bearer <token>` header for you.
## Basic usage
```cpp
httplib::Client cli("https://api.example.com");
cli.set_bearer_token_auth("eyJhbGciOiJIUzI1NiIs...");
auto res = cli.Get("/me");
if (res && res->status == 200) {
std::cout << res->body << std::endl;
}
```
Set it once and every subsequent request carries the token. This is the go-to pattern for token-based APIs like GitHub, Slack, or your own OAuth service.
## Per-request usage
When you want the token on only one request — or need a different token per request — pass it via headers.
```cpp
httplib::Headers headers = {
httplib::make_bearer_token_authentication_header(token),
};
auto res = cli.Get("/me", headers);
```
`make_bearer_token_authentication_header()` builds the `Authorization` header for you.
## Refresh the token
When a token expires, just call `set_bearer_token_auth()` again with the new one.
```cpp
if (res && res->status == 401) {
auto new_token = refresh_token();
cli.set_bearer_token_auth(new_token);
res = cli.Get("/me");
}
```
> **Warning:** A Bearer token is itself a credential. Always send it over HTTPS, and never hard-code it into source or config files.
> To set multiple headers at once, see [C03. Set default headers](c03-default-headers).

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@@ -1,52 +0,0 @@
---
title: "C07. Upload a File as Multipart Form Data"
order: 7
status: "draft"
---
When you want to send a file the same way an HTML `<input type="file">` does, use multipart form data (`multipart/form-data`). cpp-httplib offers two APIs — `UploadFormDataItems` and `FormDataProviderItems` — and you pick between them based on **file size**.
## Send a small file
Read the file into memory first, then send it. For small files, this is the simplest path.
```cpp
httplib::Client cli("http://localhost:8080");
std::ifstream ifs("avatar.png", std::ios::binary);
std::string content((std::istreambuf_iterator<char>(ifs)),
std::istreambuf_iterator<char>());
httplib::UploadFormDataItems items = {
{"name", "Alice", "", ""},
{"avatar", content, "avatar.png", "image/png"},
};
auto res = cli.Post("/upload", items);
```
Each `UploadFormData` entry is `{name, content, filename, content_type}`. For plain text fields, leave `filename` and `content_type` empty.
## Stream a large file
To avoid loading the whole file into memory, use `make_file_provider()`. It reads the file in chunks as it sends — so even huge files won't blow up your memory footprint.
```cpp
httplib::Client cli("http://localhost:8080");
httplib::UploadFormDataItems items = {
{"name", "Alice", "", ""},
};
httplib::FormDataProviderItems provider_items = {
httplib::make_file_provider("video", "large-video.mp4", "", "video/mp4"),
};
auto res = cli.Post("/upload", httplib::Headers{}, items, provider_items);
```
The arguments to `make_file_provider()` are `(form name, file path, file name, content type)`. Leave the file name empty to use the file path as-is.
> **Note:** You can mix `UploadFormDataItems` and `FormDataProviderItems` in the same request. A clean split is: text fields in `UploadFormDataItems`, files in `FormDataProviderItems`.
> To show upload progress, see [C11. Use the progress callback](c11-progress-callback).

View File

@@ -1,34 +0,0 @@
---
title: "C08. POST a File as Raw Binary"
order: 8
status: "draft"
---
Sometimes you want to send a file's contents as the request body directly — no multipart wrapping. This is common for S3-compatible APIs or endpoints that take raw image data. For this, use `make_file_body()`.
## Basic usage
```cpp
httplib::Client cli("https://storage.example.com");
auto [size, provider] = httplib::make_file_body("backup.tar.gz");
if (size == 0) {
std::cerr << "Failed to open file" << std::endl;
return 1;
}
auto res = cli.Put("/bucket/backup.tar.gz", size,
provider, "application/gzip");
```
`make_file_body()` returns a pair of file size and a `ContentProvider`. Pass them to `Post()` or `Put()` and the file contents flow straight into the request body.
The `ContentProvider` reads the file in chunks, so even huge files never sit fully in memory.
## When the file can't be opened
If the file can't be opened, `make_file_body()` returns `size` as `0` and `provider` as an empty function object. Sending that would produce garbage — always check `size` first.
> **Warning:** `make_file_body()` needs to fix the Content-Length up front, so it reads the file size ahead of time. If the file size might change mid-upload, this API isn't the right fit.
> To send the file as multipart form data instead, see [C07. Upload a file as multipart form data](c07-multipart-upload).

View File

@@ -1,47 +0,0 @@
---
title: "C09. Send the Body with Chunked Transfer"
order: 9
status: "draft"
---
When you don't know the body size up front — for data generated on the fly or piped from another stream — use `ContentProviderWithoutLength`. The client sends the body with HTTP chunked transfer encoding.
## Basic usage
```cpp
httplib::Client cli("http://localhost:8080");
auto res = cli.Post("/stream",
[&](size_t offset, httplib::DataSink &sink) {
std::string chunk = produce_next_chunk();
if (chunk.empty()) {
sink.done(); // done sending
return true;
}
return sink.write(chunk.data(), chunk.size());
},
"application/octet-stream");
```
The lambda's job is just: produce the next chunk and send it with `sink.write()`. When there's no more data, call `sink.done()` and you're finished.
## When the size is known
If you **do** know the total size ahead of time, use the `ContentProvider` overload (taking `size_t offset, size_t length, DataSink &sink`) and pass the total size as well.
```cpp
size_t total_size = get_total_size();
auto res = cli.Post("/upload", total_size,
[&](size_t offset, size_t length, httplib::DataSink &sink) {
auto data = read_range(offset, length);
return sink.write(data.data(), data.size());
},
"application/octet-stream");
```
With a known size, the request carries a Content-Length header — so the server can show progress. Prefer this form when you can.
> **Detail:** `sink.write()` returns a `bool` indicating whether the write succeeded. If it returns `false`, the connection is gone — return `false` from the lambda to stop.
> If you're just sending a file, `make_file_body()` is easier. See [C08. POST a file as raw binary](c08-post-file-body).

View File

@@ -1,52 +0,0 @@
---
title: "C10. Receive a Response as a Stream"
order: 10
status: "draft"
---
To receive a response body chunk by chunk, use a `ContentReceiver`. It's the obvious choice for large files, but it's equally handy for NDJSON (newline-delimited JSON) or log streams where you want to start processing data as it arrives.
## Process each chunk
```cpp
httplib::Client cli("http://localhost:8080");
auto res = cli.Get("/logs/stream",
[](const char *data, size_t len) {
std::cout.write(data, len);
std::cout.flush();
return true; // return false to stop receiving
});
```
Data arrives in the lambda in the order it's received from the server. Return `false` from the callback to stop the download partway through.
## Parse NDJSON line by line
Here's a buffered approach for processing newline-delimited JSON one line at a time.
```cpp
std::string buffer;
auto res = cli.Get("/events",
[&](const char *data, size_t len) {
buffer.append(data, len);
size_t pos;
while ((pos = buffer.find('\n')) != std::string::npos) {
auto line = buffer.substr(0, pos);
buffer.erase(0, pos + 1);
if (!line.empty()) {
auto j = nlohmann::json::parse(line);
handle_event(j);
}
}
return true;
});
```
Accumulate into a buffer, then pull out and parse one line each time you see a newline. This is the standard pattern for consuming a streaming API in real time.
> **Warning:** When you pass a `ContentReceiver`, `res->body` stays **empty**. Store or process the body inside the callback yourself.
> To track download progress, combine this with [C11. Use the progress callback](c11-progress-callback).
> For Server-Sent Events (SSE), see [E04. Receive SSE on the client](e04-sse-client).

View File

@@ -1,59 +0,0 @@
---
title: "C11. Use the Progress Callback"
order: 11
status: "draft"
---
To display download or upload progress, pass a `DownloadProgress` or `UploadProgress` callback. Both take two arguments: `(current, total)`.
## Download progress
```cpp
httplib::Client cli("http://localhost:8080");
auto res = cli.Get("/large-file",
[](size_t current, size_t total) {
auto percent = (total > 0) ? (current * 100 / total) : 0;
std::cout << "\rDownloading: " << percent << "% ("
<< current << "/" << total << ")" << std::flush;
return true; // return false to abort
});
std::cout << std::endl;
```
The callback fires each time data arrives. `total` comes from the Content-Length header — if the server doesn't send one, it may be `0`. In that case, you can't compute a percentage, so just display bytes received.
## Upload progress
Uploads work the same way. Pass an `UploadProgress` as the last argument to `Post()` or `Put()`.
```cpp
httplib::Client cli("http://localhost:8080");
std::string body = load_large_body();
auto res = cli.Post("/upload", body, "application/octet-stream",
[](size_t current, size_t total) {
auto percent = current * 100 / total;
std::cout << "\rUploading: " << percent << "%" << std::flush;
return true;
});
std::cout << std::endl;
```
## Cancel mid-transfer
Return `false` from the callback to abort the transfer. This is how you wire up a "Cancel" button in a UI — flip a flag, and the next progress tick stops the transfer.
```cpp
std::atomic<bool> cancelled{false};
auto res = cli.Get("/large-file",
[&](size_t current, size_t total) {
return !cancelled.load();
});
```
> **Note:** `ContentReceiver` and the progress callback can be used together. When you want to stream to a file and show progress at the same time, pass both.
> For a concrete example of saving to a file, see [C01. Get the response body / save to a file](c01-get-response-body).

View File

@@ -1,50 +0,0 @@
---
title: "C12. Set Timeouts"
order: 12
status: "draft"
---
The client has three kinds of timeouts, each set independently.
| Kind | API | Default | Meaning |
| --- | --- | --- | --- |
| Connection | `set_connection_timeout` | 300s | Time to wait for the TCP connection to establish |
| Read | `set_read_timeout` | 300s | Time to wait for a single `recv` when receiving the response |
| Write | `set_write_timeout` | 5s | Time to wait for a single `send` when sending the request |
## Basic usage
```cpp
httplib::Client cli("http://localhost:8080");
cli.set_connection_timeout(5, 0); // 5 seconds
cli.set_read_timeout(10, 0); // 10 seconds
cli.set_write_timeout(10, 0); // 10 seconds
auto res = cli.Get("/api/data");
```
Pass seconds and microseconds as two arguments. If you don't need the sub-second part, you can omit the second argument.
## Use `std::chrono`
There's also an overload that takes a `std::chrono` duration directly. It's easier to read — recommended.
```cpp
using namespace std::chrono_literals;
cli.set_connection_timeout(5s);
cli.set_read_timeout(10s);
cli.set_write_timeout(500ms);
```
## Watch out for the long 300s default
Connection and read timeouts default to **300 seconds (5 minutes)**. If the server hangs, you'll be waiting five minutes by default. Shorter values are usually a better idea.
```cpp
cli.set_connection_timeout(3s);
cli.set_read_timeout(10s);
```
> **Warning:** The read timeout covers a single receive call — not the whole request. If data keeps trickling in during a large download, the request can take half an hour without ever hitting the timeout. To cap the total request time, use [C13. Set an overall timeout](c13-max-timeout).

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@@ -1,42 +0,0 @@
---
title: "C13. Set an Overall Timeout"
order: 13
status: "draft"
---
The three timeouts from [C12. Set timeouts](c12-timeouts) all apply to a single `send` or `recv` call. To cap the total time a request can take, use `set_max_timeout()`.
## Basic usage
```cpp
httplib::Client cli("http://localhost:8080");
cli.set_max_timeout(5000); // 5 seconds (in milliseconds)
auto res = cli.Get("/slow-endpoint");
```
The value is in milliseconds. Connection, send, and receive together — the whole request is aborted if it exceeds the limit.
## Use `std::chrono`
There's also an overload that takes a `std::chrono` duration.
```cpp
using namespace std::chrono_literals;
cli.set_max_timeout(5s);
```
## When to use which
`set_read_timeout` fires when no data arrives for a while. If data keeps trickling in bit by bit, it will never fire. An endpoint that sends one byte per second can make `set_read_timeout` useless no matter how short you set it.
`set_max_timeout` caps elapsed time, so it handles those cases cleanly. It's great for calls to external APIs or anywhere you don't want users waiting forever.
```cpp
cli.set_connection_timeout(3s);
cli.set_read_timeout(10s);
cli.set_max_timeout(30s); // abort if the whole request takes over 30s
```
> **Note:** `set_max_timeout()` works alongside the regular timeouts. Short stalls get caught by `set_read_timeout`; long-running requests get capped by `set_max_timeout`. Use both for a safety net.

View File

@@ -1,53 +0,0 @@
---
title: "C14. Understand Connection Reuse and Keep-Alive"
order: 14
status: "draft"
---
When you send multiple requests through the same `httplib::Client` instance, the TCP connection is reused automatically. HTTP/1.1 Keep-Alive does the work for you — you don't pay the TCP and TLS handshake cost on every call.
## Connections are reused automatically
```cpp
httplib::Client cli("https://api.example.com");
auto res1 = cli.Get("/users/1");
auto res2 = cli.Get("/users/2"); // reuses the same connection
auto res3 = cli.Get("/users/3"); // reuses the same connection
```
No special config required. Just hold on to `cli` — internally, the socket stays open across calls. The effect is especially noticeable over HTTPS, where the TLS handshake is expensive.
## Disable Keep-Alive explicitly
To force a fresh connection every time, call `set_keep_alive(false)`. Mostly useful for testing.
```cpp
cli.set_keep_alive(false);
```
For normal use, leave it on (the default).
## Don't create a `Client` per request
If you create a `Client` inside a loop and let it fall out of scope each iteration, you lose the reuse benefit. Create the instance outside the loop.
```cpp
// Bad: a new connection every iteration
for (auto id : ids) {
httplib::Client cli("https://api.example.com");
cli.Get("/users/" + id);
}
// Good: the connection is reused
httplib::Client cli("https://api.example.com");
for (auto id : ids) {
cli.Get("/users/" + id);
}
```
## Concurrent requests
If you want to send requests in parallel from multiple threads, give each thread its own `Client` instance. A single `Client` uses a single TCP connection, so firing concurrent requests at the same instance ends up serializing them anyway.
> **Note:** If the server closes the connection after its Keep-Alive timeout, cpp-httplib reconnects and retries transparently. You don't need to handle this in application code.

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@@ -1,47 +0,0 @@
---
title: "C15. Enable Compression"
order: 15
status: "draft"
---
cpp-httplib supports compression when sending and decompression when receiving. You just need to build it with zlib or Brotli enabled.
## Build-time setup
To use compression, define these macros before including `httplib.h`:
```cpp
#define CPPHTTPLIB_ZLIB_SUPPORT // gzip / deflate
#define CPPHTTPLIB_BROTLI_SUPPORT // brotli
#include <httplib.h>
```
You'll also need to link against `zlib` or `brotli`.
## Compress the request body
```cpp
httplib::Client cli("https://api.example.com");
cli.set_compress(true);
std::string big_payload = build_payload();
auto res = cli.Post("/api/data", big_payload, "application/json");
```
With `set_compress(true)`, the body of POST or PUT requests gets gzipped before sending. The server needs to handle compressed bodies too.
## Decompress the response
```cpp
httplib::Client cli("https://api.example.com");
cli.set_decompress(true); // on by default
auto res = cli.Get("/api/data");
std::cout << res->body << std::endl;
```
With `set_decompress(true)`, the client automatically decompresses responses that arrive with `Content-Encoding: gzip` or similar. `res->body` contains the decompressed data.
It's on by default, so normally you don't need to do anything. Set it to `false` only if you want the raw compressed bytes.
> **Warning:** If you build without `CPPHTTPLIB_ZLIB_SUPPORT`, calling `set_compress()` or `set_decompress()` does nothing. If compression isn't working, check the macro definition first.

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@@ -1,87 +0,0 @@
---
title: "C16. Send Requests Through a Proxy"
order: 16
status: "draft"
---
To route traffic through a corporate network or a specific path, send requests via an HTTP proxy. Just pass the proxy host and port to `set_proxy()`.
## Basic usage
```cpp
httplib::Client cli("https://api.example.com");
cli.set_proxy("proxy.internal", 8080);
auto res = cli.Get("/users");
```
The request goes through the proxy. For HTTPS, the client uses the CONNECT method to tunnel through — no extra setup required.
## Proxy authentication
If the proxy itself requires authentication, use `set_proxy_basic_auth()` or `set_proxy_bearer_token_auth()`.
```cpp
cli.set_proxy("proxy.internal", 8080);
cli.set_proxy_basic_auth("user", "password");
```
```cpp
cli.set_proxy_bearer_token_auth("token");
```
If cpp-httplib is built with OpenSSL (or another TLS backend), you can also use Digest authentication for the proxy.
```cpp
cli.set_proxy_digest_auth("user", "password");
```
## Combine with end-server authentication
Proxy authentication is separate from authenticating to the end server ([C05. Use Basic authentication](c05-basic-auth), [C06. Call an API with a Bearer token](c06-bearer-token)). When both are needed, set both.
```cpp
cli.set_proxy("proxy.internal", 8080);
cli.set_proxy_basic_auth("proxy-user", "proxy-pass");
cli.set_bearer_token_auth("api-token"); // for the end server
```
`Proxy-Authorization` is sent to the proxy, `Authorization` to the end server.
## Bypass the proxy for specific hosts
You often want internal endpoints to skip the proxy. Configure a bypass list with `set_no_proxy()`.
```cpp
cli.set_proxy("proxy.internal", 8080);
cli.set_no_proxy({"internal.corp", "10.0.0.0/8", "*.dev.local"});
```
Each entry is one of:
- `*` — bypass the proxy for all hosts
- a hostname suffix (e.g. `example.com`) — matches `example.com` itself and any subdomain (`foo.example.com`). A leading dot is permitted but informational; both forms are equivalent.
- a single IP literal (e.g. `192.168.1.1`, `::1`)
- a CIDR block (e.g. `10.0.0.0/8`, `fe80::/10`)
Hostname matching is case-insensitive and uses a dot-boundary rule, so an entry of `example.com` does **not** match `evilexample.com`. IP comparisons are normalized through `inet_pton`, so `127.0.0.1` cannot be bypassed via alternate string forms (e.g. `127.000.000.001`). When an entry matches, the `Proxy-Authorization` header is suppressed as well.
Malformed entries are silently dropped. Port-specific entries such as `example.com:8080` are not supported (cpp-httplib's other host-keyed APIs are also keyed on hostname only).
## Read proxy settings from the environment
cpp-httplib doesn't touch `HTTP_PROXY` / `HTTPS_PROXY` / `NO_PROXY` on its own — the config API is always explicit, the same way `set_ca_cert_path()` is. If you'd like that behavior, read the variables in your application and feed them to `set_proxy()` and `set_no_proxy()`.
```cpp
if (const char *v = std::getenv("no_proxy")) {
std::vector<std::string> patterns;
std::stringstream ss(v);
for (std::string item; std::getline(ss, item, ',');) {
if (!item.empty()) { patterns.push_back(item); }
}
cli.set_no_proxy(patterns);
}
```
If you also read `HTTP_PROXY` yourself, honor the lowercase `http_proxy` only. The uppercase form is poisoned in CGI/FastCGI environments by the `Proxy:` request header ([CVE-2016-5385 / "httpoxy"](https://httpoxy.org/)). `HTTPS_PROXY` and `NO_PROXY` are safe in either case because their names don't begin with `HTTP_`.

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@@ -1,63 +0,0 @@
---
title: "C17. Handle Error Codes"
order: 17
status: "draft"
---
`cli.Get()`, `cli.Post()`, and friends return a `Result`. When the request fails — can't reach the server, times out, etc. — the result is "falsy". To get the specific reason, use `Result::error()`.
## Basic check
```cpp
httplib::Client cli("http://localhost:8080");
auto res = cli.Get("/api/data");
if (res) {
// the request was sent and a response came back
std::cout << "status: " << res->status << std::endl;
} else {
// the network layer failed
std::cerr << "error: " << httplib::to_string(res.error()) << std::endl;
}
```
Use `if (res)` to check success. On failure, `res.error()` returns a `httplib::Error` enum value. Pass it to `to_string()` to get a human-readable description.
## Common errors
| Value | Meaning |
| --- | --- |
| `Error::Connection` | Couldn't connect to the server |
| `Error::ConnectionTimeout` | Connection timeout (`set_connection_timeout`) |
| `Error::Read` / `Error::Write` | Error during send or receive |
| `Error::Timeout` | Overall timeout set via `set_max_timeout` |
| `Error::ExceedRedirectCount` | Too many redirects |
| `Error::SSLConnection` | TLS handshake failed |
| `Error::SSLServerVerification` | Server certificate verification failed |
| `Error::Canceled` | A progress callback returned `false` |
## Network errors vs. HTTP errors
Even when `res` is truthy, the HTTP status code can still be 4xx or 5xx. These are two different things.
```cpp
auto res = cli.Get("/api/data");
if (!res) {
// network error (no response received at all)
std::cerr << "network error: " << httplib::to_string(res.error()) << std::endl;
return 1;
}
if (res->status >= 400) {
// HTTP error (response received, but the status is bad)
std::cerr << "http error: " << res->status << std::endl;
return 1;
}
// success
std::cout << res->body << std::endl;
```
Keep them separated in your head: network-layer errors go through `res.error()`, HTTP-level errors through `res->status`.
> To dig deeper into SSL-related errors, see [C18. Handle SSL errors](c18-ssl-errors).

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@@ -1,51 +0,0 @@
---
title: "C18. Handle SSL Errors"
order: 18
status: "draft"
---
When an HTTPS request fails, `res.error()` returns values like `Error::SSLConnection` or `Error::SSLServerVerification`. Sometimes that's not enough to pinpoint the cause. That's where `Result::ssl_error()` and `Result::ssl_backend_error()` help.
## Get the SSL error details
```cpp
httplib::Client cli("https://api.example.com");
auto res = cli.Get("/");
if (!res) {
auto err = res.error();
std::cerr << "error: " << httplib::to_string(err) << std::endl;
if (err == httplib::Error::SSLConnection ||
err == httplib::Error::SSLServerVerification) {
std::cerr << "ssl_error: " << res.ssl_error() << std::endl;
std::cerr << "ssl_backend_error: " << res.ssl_backend_error() << std::endl;
}
}
```
`ssl_error()` returns the error code from the SSL library (e.g., OpenSSL's `SSL_get_error()`). `ssl_backend_error()` gives you the backend's more detailed error value — for OpenSSL, that's `ERR_get_error()`.
## Format OpenSSL errors as strings
When you have a value from `ssl_backend_error()`, pass it to OpenSSL's `ERR_error_string()` to get a readable message.
```cpp
#include <openssl/err.h>
if (res.ssl_backend_error() != 0) {
char buf[256];
ERR_error_string_n(res.ssl_backend_error(), buf, sizeof(buf));
std::cerr << "openssl: " << buf << std::endl;
}
```
## Common causes
| Symptom | Usual suspect |
| --- | --- |
| `SSLServerVerification` | CA certificate path isn't configured, or the cert is self-signed |
| `SSLServerHostnameVerification` | The cert's CN/SAN doesn't match the host |
| `SSLConnection` | TLS version mismatch, no shared cipher suite |
> To change certificate verification settings, see [T02. Control SSL certificate verification](t02-cert-verification).

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@@ -1,57 +0,0 @@
---
title: "C19. Set a Logger on the Client"
order: 19
status: "draft"
---
To log requests sent and responses received by the client, use `set_logger()`. If you only care about errors, there's a separate `set_error_logger()`.
## Log requests and responses
```cpp
httplib::Client cli("https://api.example.com");
cli.set_logger([](const httplib::Request &req, const httplib::Response &res) {
std::cout << req.method << " " << req.path
<< " -> " << res.status << std::endl;
});
auto res = cli.Get("/users");
```
The callback you pass to `set_logger()` fires once for each completed request. You get both the request and the response as arguments — so you can log the method, path, status, headers, body, or whatever else you need.
## Catch errors only
When a network-layer error happens (like `Error::Connection`), `set_logger()` is **not** called — there's no response to log. For those cases, use `set_error_logger()`.
```cpp
cli.set_error_logger([](const httplib::Error &err, const httplib::Request *req) {
std::cerr << "error: " << httplib::to_string(err);
if (req) {
std::cerr << " (" << req->method << " " << req->path << ")";
}
std::cerr << std::endl;
});
```
The second argument `req` can be null — it happens when the failure occurred before the request was built. Always null-check before dereferencing.
## Use both together
A nice pattern is to log successes through one, failures through the other.
```cpp
cli.set_logger([](const auto &req, const auto &res) {
std::cout << "[ok] " << req.method << " " << req.path
<< " " << res.status << std::endl;
});
cli.set_error_logger([](const auto &err, const auto *req) {
std::cerr << "[ng] " << httplib::to_string(err);
if (req) std::cerr << " " << req->method << " " << req->path;
std::cerr << std::endl;
});
```
> **Note:** The log callbacks run synchronously on the same thread as the request. Heavy work inside them slows the request down — push it to a background queue if you need to do anything expensive.

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@@ -1,87 +0,0 @@
---
title: "E01. Implement an SSE Server"
order: 47
status: "draft"
---
Server-Sent Events (SSE) is a simple protocol for pushing events one-way from server to client. The connection stays open, and the server can send data whenever it wants. It's lighter than WebSocket and fits entirely within HTTP — a nice combination.
cpp-httplib doesn't have a dedicated SSE server API, but you can implement one with `set_chunked_content_provider()` and `text/event-stream`.
## Basic SSE server
```cpp
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/event-stream",
[](size_t offset, httplib::DataSink &sink) {
std::string message = "data: hello\n\n";
sink.write(message.data(), message.size());
std::this_thread::sleep_for(std::chrono::seconds(1));
return true;
});
});
```
Three things matter here:
1. Content-Type is `text/event-stream`
2. Messages follow the format `data: <content>\n\n` (the double newline separates events)
3. Each `sink.write()` delivers data to the client
The provider lambda keeps being called as long as the connection is alive.
## A continuous stream
Here's a simple example that sends the current time once per second.
```cpp
svr.Get("/time", [](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/event-stream",
[&req](size_t offset, httplib::DataSink &sink) {
if (req.is_connection_closed()) {
sink.done();
return true;
}
auto now = std::chrono::system_clock::now();
auto t = std::chrono::system_clock::to_time_t(now);
std::string msg = "data: " + std::string(std::ctime(&t)) + "\n";
sink.write(msg.data(), msg.size());
std::this_thread::sleep_for(std::chrono::seconds(1));
return true;
});
});
```
When the client disconnects, call `sink.done()` to stop. Details in [S16. Detect client disconnection](s16-disconnect).
## Heartbeats via comment lines
Lines starting with `:` are SSE comments — clients ignore them, but they **keep the connection alive**. Handy for preventing proxies and load balancers from closing idle connections.
```cpp
// heartbeat every 30 seconds
if (tick_count % 30 == 0) {
std::string ping = ": ping\n\n";
sink.write(ping.data(), ping.size());
}
```
## Relationship with the thread pool
SSE connections stay open, so each client holds a worker thread. For lots of concurrent connections, enable dynamic scaling on the thread pool.
```cpp
svr.new_task_queue = [] {
return new httplib::ThreadPool(8, 128);
};
```
See [S21. Configure the thread pool](s21-thread-pool).
> **Note:** When `data:` contains newlines, split it into multiple `data:` lines — one per line. This is how the SSE spec requires multiline data to be transmitted.
> For event names, see [E02. Use named events in SSE](e02-sse-event-names). For the client side, see [E04. Receive SSE on the client](e04-sse-client).

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@@ -1,84 +0,0 @@
---
title: "E02. Use Named Events in SSE"
order: 48
status: "draft"
---
SSE lets you send multiple kinds of events over the same stream. Give each one a name with the `event:` field, and the client can dispatch to a different handler per type. Great for things like "new message", "user joined", "user left" in a chat app.
## Send events with names
```cpp
auto send_event = [](httplib::DataSink &sink,
const std::string &event,
const std::string &data) {
std::string msg = "event: " + event + "\n"
+ "data: " + data + "\n\n";
sink.write(msg.data(), msg.size());
};
svr.Get("/chat/stream", [&](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/event-stream",
[&, send_event](size_t offset, httplib::DataSink &sink) {
send_event(sink, "message", "Hello!");
std::this_thread::sleep_for(std::chrono::seconds(2));
send_event(sink, "join", "alice");
std::this_thread::sleep_for(std::chrono::seconds(2));
send_event(sink, "leave", "bob");
std::this_thread::sleep_for(std::chrono::seconds(2));
return true;
});
});
```
A message is `event:``data:` → blank line. If you omit `event:`, the client treats it as a default `"message"` event.
## Attach IDs for reconnect
When you include an `id:` field, the client automatically sends it back as `Last-Event-ID` on reconnect, telling the server "here's how far I got."
```cpp
auto send_event = [](httplib::DataSink &sink,
const std::string &event,
const std::string &data,
const std::string &id) {
std::string msg = "id: " + id + "\n"
+ "event: " + event + "\n"
+ "data: " + data + "\n\n";
sink.write(msg.data(), msg.size());
};
send_event(sink, "message", "Hello!", "42");
```
The ID format is up to you. Monotonic counters or UUIDs both work — just pick something unique and orderable on the server side. See [E03. Handle SSE reconnection](e03-sse-reconnect) for details.
## JSON payloads in data
For structured data, the usual move is to put JSON in `data:`.
```cpp
nlohmann::json payload = {
{"user", "alice"},
{"text", "Hello!"},
};
send_event(sink, "message", payload.dump(), "42");
```
On the client, parse the incoming `data` as JSON to get the original object back.
## Data with newlines
If the data value contains newlines, split it across multiple `data:` lines.
```cpp
std::string msg = "data: line1\n"
"data: line2\n"
"data: line3\n\n";
sink.write(msg.data(), msg.size());
```
On the client side, these come back as a single `data` string with newlines.
> **Note:** Using `event:` makes client-side dispatch cleaner, but it also helps in the browser DevTools — events are easier to filter by type. That matters more than you'd expect while debugging.

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@@ -1,85 +0,0 @@
---
title: "E03. Handle SSE Reconnection"
order: 49
status: "draft"
---
SSE connections drop for all sorts of network reasons. Clients automatically try to reconnect, so it's a good idea to make your server resume from where it left off.
## Read `Last-Event-ID`
When the client reconnects, it sends the ID of the last event it received in the `Last-Event-ID` header. The server reads that and picks up from the next one.
```cpp
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
auto last_id = req.get_header_value("Last-Event-ID");
int start = last_id.empty() ? 0 : std::stoi(last_id) + 1;
res.set_chunked_content_provider(
"text/event-stream",
[start](size_t offset, httplib::DataSink &sink) mutable {
static int next_id = 0;
if (next_id < start) { next_id = start; }
std::string msg = "id: " + std::to_string(next_id) + "\n"
+ "data: event " + std::to_string(next_id) + "\n\n";
sink.write(msg.data(), msg.size());
++next_id;
std::this_thread::sleep_for(std::chrono::seconds(1));
return true;
});
});
```
On the first connect, `Last-Event-ID` is empty, so start from `0`. On reconnect, resume from the next ID. Event history is the server's responsibility — you need to keep recent events around somewhere.
## Set the reconnect interval
Sending a `retry:` field tells the client how long to wait before reconnecting, in milliseconds.
```cpp
std::string msg = "retry: 5000\n\n"; // reconnect after 5 seconds
sink.write(msg.data(), msg.size());
```
Usually you send this once at the start. During peak load or maintenance windows, a longer retry interval helps reduce reconnect storms.
## Buffer recent events
To support reconnection, keep a rolling buffer of recent events on the server.
```cpp
struct EventBuffer {
std::mutex mu;
std::deque<std::pair<int, std::string>> events; // {id, data}
int next_id = 0;
void push(const std::string &data) {
std::lock_guard<std::mutex> lock(mu);
events.push_back({next_id++, data});
if (events.size() > 1000) { events.pop_front(); }
}
std::vector<std::pair<int, std::string>> since(int id) {
std::lock_guard<std::mutex> lock(mu);
std::vector<std::pair<int, std::string>> out;
for (const auto &e : events) {
if (e.first >= id) { out.push_back(e); }
}
return out;
}
};
```
When a client reconnects, call `since(last_id)` to send any events it missed.
## How much to keep
The buffer size is a tradeoff between memory and how far back a client can resume. It depends on the use case:
- Real-time chat: a few minutes to half an hour
- Notifications: the last N items
- Trading data: persist to a database and pull from there
> **Warning:** `Last-Event-ID` is a client-provided value — don't trust it blindly. If you read it as a number, validate the range. If it's a string, sanitize it.

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@@ -1,99 +0,0 @@
---
title: "E04. Receive SSE on the Client"
order: 50
status: "draft"
---
cpp-httplib ships a dedicated `sse::SSEClient` class. It handles auto-reconnect, per-event-name dispatch, and `Last-Event-ID` tracking for you — so receiving SSE is painless.
## Basic usage
```cpp
#include <httplib.h>
httplib::Client cli("http://localhost:8080");
httplib::sse::SSEClient sse(cli, "/events");
sse.on_message([](const httplib::sse::SSEMessage &msg) {
std::cout << "data: " << msg.data << std::endl;
});
sse.start(); // blocking
```
Build an `SSEClient` with a `Client` and a path, register a callback with `on_message()`, and call `start()`. The event loop kicks in and automatically reconnects if the connection drops.
## Dispatch by event name
When the server sends events with an `event:` field, register a handler per name via `on_event()`.
```cpp
sse.on_event("message", [](const auto &msg) {
std::cout << "chat: " << msg.data << std::endl;
});
sse.on_event("join", [](const auto &msg) {
std::cout << msg.data << " joined" << std::endl;
});
sse.on_event("leave", [](const auto &msg) {
std::cout << msg.data << " left" << std::endl;
});
```
`on_message()` serves as a generic fallback for unnamed events (the default `message` type).
## Connection lifecycle and errors
```cpp
sse.on_open([] {
std::cout << "connected" << std::endl;
});
sse.on_error([](httplib::Error err) {
std::cerr << "error: " << httplib::to_string(err) << std::endl;
});
```
Hook into connection open and error events. Even when the error handler fires, `SSEClient` keeps trying to reconnect in the background.
## Run asynchronously
If you don't want to block the main thread, use `start_async()`.
```cpp
sse.start_async();
// main thread continues to do other things
do_other_work();
// when you're done, stop it
sse.stop();
```
`start_async()` spawns a background thread to run the event loop. Use `stop()` to shut it down cleanly.
## Configure reconnection
You can tune the reconnect interval and maximum retries.
```cpp
sse.set_reconnect_interval(5000); // 5 seconds
sse.set_max_reconnect_attempts(10); // up to 10 (0 = unlimited)
```
If the server sends a `retry:` field, that takes precedence.
## Automatic Last-Event-ID
`SSEClient` tracks the `id` of each received event internally and sends it back as `Last-Event-ID` on reconnect. As long as the server sends events with `id:`, this all works automatically.
```cpp
std::cout << "last id: " << sse.last_event_id() << std::endl;
```
Use `last_event_id()` to read the current value.
> **Note:** `SSEClient::start()` blocks, which is fine for a one-off command-line tool. For GUI apps or embedded in a server, the `start_async()` + `stop()` pair is the usual pattern.
> For the server side, see [E01. Implement an SSE server](e01-sse-server).

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@@ -1,96 +1,8 @@
---
title: "Cookbook"
order: 0
status: "draft"
order: 1
---
A collection of recipes that answer "How do I...?" questions. Each recipe is self-contained — read only what you need. For an introduction to the basics, see the [Tour](../tour/).
This section is under construction.
## Client
### Basics
- [C01. Get the response body / save to a file](c01-get-response-body)
- [C02. Send and receive JSON](c02-json)
- [C03. Set default headers](c03-default-headers)
- [C04. Follow redirects](c04-follow-location)
### Authentication
- [C05. Use Basic authentication](c05-basic-auth)
- [C06. Call an API with a Bearer token](c06-bearer-token)
### File Upload
- [C07. Upload a file as multipart form data](c07-multipart-upload)
- [C08. POST a file as raw binary](c08-post-file-body)
- [C09. Send the body with chunked transfer](c09-chunked-upload)
### Streaming & Progress
- [C10. Receive a response as a stream](c10-stream-response)
- [C11. Use the progress callback](c11-progress-callback)
### Connection & Performance
- [C12. Set timeouts](c12-timeouts)
- [C13. Set an overall timeout](c13-max-timeout)
- [C14. Understand connection reuse and Keep-Alive behavior](c14-keep-alive)
- [C15. Enable compression](c15-compression)
- [C16. Send requests through a proxy](c16-proxy)
### Error Handling & Debugging
- [C17. Handle error codes](c17-error-codes)
- [C18. Handle SSL errors](c18-ssl-errors)
- [C19. Set up client logging](c19-client-logger)
## Server
### Basics
- [S01. Register GET / POST / PUT / DELETE handlers](s01-handlers)
- [S02. Receive JSON requests and return JSON responses](s02-json-api)
- [S03. Use path parameters](s03-path-params)
- [S04. Set up a static file server](s04-static-files)
### Streaming & Files
- [S05. Stream a large file in the response](s05-stream-response)
- [S06. Return a file download response](s06-download-response)
- [S07. Receive multipart data as a stream](s07-multipart-reader)
- [S08. Return a compressed response](s08-compress-response)
### Handler Chain
- [S09. Add pre-processing to all routes](s09-pre-routing)
- [S10. Add response headers with a post-routing handler](s10-post-routing)
- [S11. Authenticate per route with a pre-request handler](s11-pre-request)
- [S12. Pass data between handlers with `res.user_data`](s12-user-data)
### Error Handling & Debugging
- [S13. Return custom error pages](s13-error-handler)
- [S14. Catch exceptions](s14-exception-handler)
- [S15. Log requests](s15-server-logger)
- [S16. Detect client disconnection](s16-disconnect)
### Operations & Tuning
- [S17. Bind to any available port](s17-bind-any-port)
- [S18. Control startup order with `listen_after_bind`](s18-listen-after-bind)
- [S19. Shut down gracefully](s19-graceful-shutdown)
- [S20. Tune Keep-Alive](s20-keep-alive)
- [S21. Configure the thread pool](s21-thread-pool)
- [S22. Talk over a Unix domain socket](s22-unix-socket)
## TLS / Security
- [T01. Choosing between OpenSSL, mbedTLS, and wolfSSL](t01-tls-backends)
- [T02. Control SSL certificate verification](t02-cert-verification)
- [T03. Start an SSL/TLS server](t03-ssl-server)
- [T04. Configure mTLS](t04-mtls)
- [T05. Access the peer certificate on the server](t05-peer-cert)
## SSE
- [E01. Implement an SSE server](e01-sse-server)
- [E02. Use named events in SSE](e02-sse-event-names)
- [E03. Handle SSE reconnection](e03-sse-reconnect)
- [E04. Receive SSE on the client](e04-sse-client)
## WebSocket
- [W01. Implement a WebSocket echo server and client](w01-websocket-echo)
- [W02. Set a WebSocket heartbeat](w02-websocket-ping)
- [W03. Handle connection close](w03-websocket-close)
- [W04. Send and receive binary frames](w04-websocket-binary)
Check back soon for a collection of recipes organized by topic.

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@@ -1,66 +0,0 @@
---
title: "S01. Register GET / POST / PUT / DELETE Handlers"
order: 20
status: "draft"
---
With `httplib::Server`, you register a handler per HTTP method. Just pass a pattern and a lambda to `Get()`, `Post()`, `Put()`, or `Delete()`.
## Basic usage
```cpp
#include <httplib.h>
int main() {
httplib::Server svr;
svr.Get("/hello", [](const httplib::Request &req, httplib::Response &res) {
res.set_content("Hello, World!", "text/plain");
});
svr.Post("/api/items", [](const httplib::Request &req, httplib::Response &res) {
// req.body holds the request body
res.status = 201;
res.set_content("Created", "text/plain");
});
svr.Put("/api/items/1", [](const httplib::Request &req, httplib::Response &res) {
res.set_content("Updated", "text/plain");
});
svr.Delete("/api/items/1", [](const httplib::Request &req, httplib::Response &res) {
res.status = 204;
});
svr.listen("0.0.0.0", 8080);
}
```
Handlers take `(const Request&, Response&)`. Use `res.set_content()` to set the body and Content-Type, and `res.status` for the status code. `listen()` starts the server and blocks.
## Read query parameters
```cpp
svr.Get("/search", [](const httplib::Request &req, httplib::Response &res) {
auto q = req.get_param_value("q");
auto limit = req.get_param_value("limit");
res.set_content("q=" + q + ", limit=" + limit, "text/plain");
});
```
`req.get_param_value()` pulls a value from the query string. Use `req.has_param("q")` if you want to check existence first.
## Read request headers
```cpp
svr.Get("/me", [](const httplib::Request &req, httplib::Response &res) {
auto ua = req.get_header_value("User-Agent");
res.set_content("UA: " + ua, "text/plain");
});
```
To add a response header, use `res.set_header("Name", "Value")`.
> **Note:** `listen()` is a blocking call. To run it on a different thread, wrap it in `std::thread`. If you need non-blocking startup, see [S18. Control startup order with `listen_after_bind`](s18-listen-after-bind).
> To use path parameters like `/users/:id`, see [S03. Use path parameters](s03-path-params).

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@@ -1,74 +0,0 @@
---
title: "S02. Receive a JSON Request and Return a JSON Response"
order: 21
status: "draft"
---
cpp-httplib doesn't include a JSON parser. On the server side, combine it with something like [nlohmann/json](https://github.com/nlohmann/json). The examples below use `nlohmann/json`.
## Receive and return JSON
```cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
int main() {
httplib::Server svr;
svr.Post("/api/users", [](const httplib::Request &req, httplib::Response &res) {
try {
auto in = nlohmann::json::parse(req.body);
nlohmann::json out = {
{"id", 42},
{"name", in["name"]},
{"created_at", "2026-04-10T12:00:00Z"},
};
res.status = 201;
res.set_content(out.dump(), "application/json");
} catch (const std::exception &e) {
res.status = 400;
res.set_content("{\"error\":\"invalid json\"}", "application/json");
}
});
svr.listen("0.0.0.0", 8080);
}
```
`req.body` is a plain `std::string`, so you pass it straight to your JSON library. For the response, `dump()` to a string and set the Content-Type to `application/json`.
## Check the Content-Type
```cpp
svr.Post("/api/users", [](const httplib::Request &req, httplib::Response &res) {
auto content_type = req.get_header_value("Content-Type");
if (content_type.find("application/json") == std::string::npos) {
res.status = 415; // Unsupported Media Type
return;
}
// ...
});
```
When you strictly want JSON only, verify the Content-Type up front.
## A helper for JSON responses
If you're writing the same pattern repeatedly, a small helper saves typing.
```cpp
auto send_json = [](httplib::Response &res, int status, const nlohmann::json &j) {
res.status = status;
res.set_content(j.dump(), "application/json");
};
svr.Get("/api/health", [&](const auto &req, auto &res) {
send_json(res, 200, {{"status", "ok"}});
});
```
> **Note:** A large JSON body ends up entirely in `req.body`, which means it all sits in memory. For huge payloads, consider streaming reception — see [S07. Receive multipart data as a stream](s07-multipart-reader).
> For the client side, see [C02. Send and receive JSON](c02-json).

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@@ -1,53 +0,0 @@
---
title: "S03. Use Path Parameters"
order: 22
status: "draft"
---
For dynamic URLs like `/users/:id` — the staple of REST APIs — just put `:name` in the path pattern. The matched values end up in `req.path_params`.
## Basic usage
```cpp
svr.Get("/users/:id", [](const httplib::Request &req, httplib::Response &res) {
auto id = req.path_params.at("id");
res.set_content("user id: " + id, "text/plain");
});
```
A request to `/users/42` fills `req.path_params["id"]` with `"42"`. `path_params` is a `std::unordered_map<std::string, std::string>`, so use `at()` to read it.
## Multiple parameters
You can have as many as you need.
```cpp
svr.Get("/orgs/:org/repos/:repo", [](const httplib::Request &req, httplib::Response &res) {
auto org = req.path_params.at("org");
auto repo = req.path_params.at("repo");
res.set_content(org + "/" + repo, "text/plain");
});
```
This matches paths like `/orgs/anthropic/repos/cpp-httplib`.
## Regex patterns
For more flexible matching, use a `std::regex`-based pattern.
```cpp
svr.Get(R"(/users/(\d+))", [](const httplib::Request &req, httplib::Response &res) {
auto id = req.matches[1];
res.set_content("user id: " + std::string(id), "text/plain");
});
```
Parentheses in the pattern become captures in `req.matches`. `req.matches[0]` is the full match; `req.matches[1]` onward are the captures.
## Which to use
- For plain IDs or slugs, `:name` is enough — readable, and the shape is obvious
- Use regex when you want to constrain the URL to, say, numbers only or a UUID format
- Mixing both can get confusing — stick with one style per project
> **Note:** Path parameters come in as strings. If you need an integer, convert with `std::stoi()` and don't forget to handle conversion errors.

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@@ -1,55 +0,0 @@
---
title: "S04. Serve Static Files"
order: 23
status: "draft"
---
To serve static files like HTML, CSS, and images, use `set_mount_point()`. Just map a URL path to a local directory, and the whole directory becomes accessible.
## Basic usage
```cpp
httplib::Server svr;
svr.set_mount_point("/", "./public");
svr.listen("0.0.0.0", 8080);
```
`./public/index.html` is now reachable at `http://localhost:8080/index.html`, and `./public/css/style.css` at `http://localhost:8080/css/style.css`. The directory layout maps directly to URLs.
## Multiple mount points
You can register more than one mount point.
```cpp
svr.set_mount_point("/", "./public");
svr.set_mount_point("/assets", "./dist/assets");
svr.set_mount_point("/uploads", "./var/uploads");
```
You can even mount multiple directories at the same path — they're searched in registration order, and the first hit wins.
## Combine with API handlers
Static files and API handlers coexist happily. Handlers registered with `Get()` and friends take priority; the mount points are searched only when nothing matches.
```cpp
svr.Get("/api/users", [](const auto &req, auto &res) {
res.set_content("[]", "application/json");
});
svr.set_mount_point("/", "./public");
```
This gives you an SPA-friendly setup: `/api/*` hits the handlers, everything else is served from `./public/`.
## Add MIME types
cpp-httplib ships with a built-in extension-to-Content-Type map, but you can add your own.
```cpp
svr.set_file_extension_and_mimetype_mapping("wasm", "application/wasm");
```
> **Warning:** The static file server methods are **not thread-safe**. Don't call them after `listen()` — configure everything before starting the server.
> For download-style responses, see [S06. Return a file download response](s06-download-response).

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@@ -1,63 +0,0 @@
---
title: "S05. Stream a Large File in the Response"
order: 24
status: "draft"
---
When the response is a huge file or data generated on the fly, loading the whole thing into memory isn't realistic. Use `Response::set_content_provider()` to produce data in chunks as you send it.
## When the size is known
```cpp
svr.Get("/download", [](const httplib::Request &req, httplib::Response &res) {
size_t total_size = get_file_size("large.bin");
res.set_content_provider(
total_size, "application/octet-stream",
[](size_t offset, size_t length, httplib::DataSink &sink) {
auto data = read_range_from_file("large.bin", offset, length);
sink.write(data.data(), data.size());
return true;
});
});
```
The lambda is called repeatedly with `offset` and `length`. Read just that range and write it to `sink`. Only a small chunk sits in memory at any given time.
## Just send a file
If you only want to serve a file, `set_file_content()` is far simpler.
```cpp
svr.Get("/download", [](const httplib::Request &req, httplib::Response &res) {
res.set_file_content("large.bin", "application/octet-stream");
});
```
It streams internally, so even huge files are safe. Omit the Content-Type and it's guessed from the extension.
## When the size is unknown — chunked transfer
For data generated on the fly, where you don't know the total size up front, use `set_chunked_content_provider()`. It's sent with HTTP chunked transfer encoding.
```cpp
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/plain",
[](size_t offset, httplib::DataSink &sink) {
auto chunk = produce_next_chunk();
if (chunk.empty()) {
sink.done(); // done sending
return true;
}
sink.write(chunk.data(), chunk.size());
return true;
});
});
```
Call `sink.done()` to signal the end.
> **Note:** The provider lambda is called multiple times. Watch out for the lifetime of captured variables — wrap them in a `std::shared_ptr` if needed.
> To serve the file as a download, see [S06. Return a file download response](s06-download-response).

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@@ -1,50 +0,0 @@
---
title: "S06. Return a File Download Response"
order: 25
status: "draft"
---
To force a browser to show a **download dialog** instead of rendering inline, send a `Content-Disposition` header. There's no special cpp-httplib API for this — it's just a header.
## Basic usage
```cpp
svr.Get("/download/report", [](const httplib::Request &req, httplib::Response &res) {
res.set_header("Content-Disposition", "attachment; filename=\"report.pdf\"");
res.set_file_content("reports/2026-04.pdf", "application/pdf");
});
```
`Content-Disposition: attachment` makes the browser pop up a "Save As" dialog. The `filename=` parameter becomes the default save name.
## Non-ASCII file names
For file names with non-ASCII characters or spaces, use the RFC 5987 `filename*` form.
```cpp
svr.Get("/download/report", [](const httplib::Request &req, httplib::Response &res) {
res.set_header(
"Content-Disposition",
"attachment; filename=\"report.pdf\"; "
"filename*=UTF-8''%E3%83%AC%E3%83%9D%E3%83%BC%E3%83%88.pdf");
res.set_file_content("reports/2026-04.pdf", "application/pdf");
});
```
The part after `filename*=UTF-8''` is URL-encoded UTF-8. Keep the ASCII `filename=` too, as a fallback for older browsers.
## Download dynamically generated data
You don't need a real file — you can serve a generated string as a download directly.
```cpp
svr.Get("/export.csv", [](const httplib::Request &req, httplib::Response &res) {
std::string csv = build_csv();
res.set_header("Content-Disposition", "attachment; filename=\"export.csv\"");
res.set_content(csv, "text/csv");
});
```
This is the classic pattern for CSV exports.
> **Note:** Some browsers will trigger a download based on Content-Type alone, even without `Content-Disposition`. Conversely, setting `inline` tries to render the content in the browser when possible.

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@@ -1,71 +0,0 @@
---
title: "S07. Receive Multipart Data as a Stream"
order: 26
status: "draft"
---
A naive upload handler puts the whole request into `req.body`, which blows up memory for large files. Use `HandlerWithContentReader` to receive the body chunk by chunk.
## Basic usage
```cpp
svr.Post("/upload",
[](const httplib::Request &req, httplib::Response &res,
const httplib::ContentReader &content_reader) {
if (req.is_multipart_form_data()) {
content_reader(
// headers of each part
[&](const httplib::FormData &file) {
std::cout << "name: " << file.name
<< ", filename: " << file.filename << std::endl;
return true;
},
// body of each part (called multiple times)
[&](const char *data, size_t len) {
// write to disk here, for example
return true;
});
} else {
// plain request body
content_reader([&](const char *data, size_t len) {
return true;
});
}
res.set_content("ok", "text/plain");
});
```
The `content_reader` has two call shapes. For multipart data, pass two callbacks (one for headers, one for body). For plain bodies, pass just one.
## Write directly to disk
Here's how to stream an uploaded file to disk.
```cpp
svr.Post("/upload",
[](const httplib::Request &req, httplib::Response &res,
const httplib::ContentReader &content_reader) {
std::ofstream ofs;
content_reader(
[&](const httplib::FormData &file) {
if (!file.filename.empty()) {
ofs.open("uploads/" + file.filename, std::ios::binary);
}
return static_cast<bool>(ofs);
},
[&](const char *data, size_t len) {
ofs.write(data, len);
return static_cast<bool>(ofs);
});
res.set_content("uploaded", "text/plain");
});
```
Only a small chunk sits in memory at any moment, so gigabyte-scale files are no problem.
> **Warning:** When you use `HandlerWithContentReader`, `req.body` stays **empty**. Handle the body yourself inside the callbacks.
> For the client side of multipart uploads, see [C07. Upload a file as multipart form data](c07-multipart-upload).

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@@ -1,53 +0,0 @@
---
title: "S08. Return a Compressed Response"
order: 27
status: "draft"
---
cpp-httplib automatically compresses response bodies when the client indicates support via `Accept-Encoding`. The handler doesn't need to do anything special. Supported encodings are gzip, Brotli, and Zstd.
## Build-time setup
To enable compression, define the relevant macros before including `httplib.h`:
```cpp
#define CPPHTTPLIB_ZLIB_SUPPORT // gzip
#define CPPHTTPLIB_BROTLI_SUPPORT // brotli
#define CPPHTTPLIB_ZSTD_SUPPORT // zstd
#include <httplib.h>
```
You'll also need to link `zlib`, `brotli`, and `zstd` respectively. Enable only what you need.
## Usage
```cpp
svr.Get("/api/data", [](const httplib::Request &req, httplib::Response &res) {
std::string body = build_large_response();
res.set_content(body, "application/json");
});
```
That's it. If the client sent `Accept-Encoding: gzip`, cpp-httplib compresses the response with gzip automatically. `Content-Encoding: gzip` and `Vary: Accept-Encoding` are added for you.
## Encoding priority
When the client accepts multiple encodings, cpp-httplib picks in this order (among those enabled at build time): Brotli → Zstd → gzip. Your code doesn't need to care — you always get the most efficient option available.
## Streaming responses are compressed too
Streaming responses via `set_chunked_content_provider()` get the same automatic compression.
```cpp
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/plain",
[](size_t offset, httplib::DataSink &sink) {
// ...
});
});
```
> **Note:** Tiny responses barely benefit from compression and just waste CPU time. cpp-httplib skips compression for bodies that are too small to bother with.
> For the client-side counterpart, see [C15. Enable compression](c15-compression).

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@@ -1,54 +0,0 @@
---
title: "S09. Add Pre-Processing to All Routes"
order: 28
status: "draft"
---
Sometimes you want the same logic to run before every request — auth checks, logging, rate limiting. Register those with `set_pre_routing_handler()`.
## Basic usage
```cpp
svr.set_pre_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
std::cout << req.method << " " << req.path << std::endl;
return httplib::Server::HandlerResponse::Unhandled;
});
```
The pre-routing handler runs **before routing**. It catches every request — including ones that don't match any handler.
The `HandlerResponse` return value is key:
- Return `Unhandled` → continue normally (routing and the actual handler run)
- Return `Handled` → the response is considered complete, skip the rest
## Use it for authentication
Put your shared auth check in one place.
```cpp
svr.set_pre_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
if (req.path.rfind("/public", 0) == 0) {
return httplib::Server::HandlerResponse::Unhandled; // no auth needed
}
auto auth = req.get_header_value("Authorization");
if (auth.empty()) {
res.status = 401;
res.set_content("unauthorized", "text/plain");
return httplib::Server::HandlerResponse::Handled;
}
return httplib::Server::HandlerResponse::Unhandled;
});
```
If auth fails, return `Handled` to respond with 401 immediately. If it passes, return `Unhandled` and let routing take over.
## For per-route auth
If you want different auth rules per route rather than a single global check, `set_pre_request_handler()` is a better fit. See [S11. Authenticate per route with a pre-request handler](s11-pre-request).
> **Note:** If all you want is to modify the response, `set_post_routing_handler()` is the right tool. See [S10. Add response headers with a post-routing handler](s10-post-routing).

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@@ -1,56 +0,0 @@
---
title: "S10. Add Response Headers with a Post-Routing Handler"
order: 29
status: "draft"
---
Sometimes you want to add shared headers to the response after the handler has run — CORS headers, security headers, a request ID, and so on. That's what `set_post_routing_handler()` is for.
## Basic usage
```cpp
svr.set_post_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
res.set_header("X-Request-ID", generate_request_id());
});
```
The post-routing handler runs **after the route handler, before the response is sent**. From here you can call `res.set_header()` or `res.headers.erase()` to add or remove headers across every response in one place.
## Add CORS headers
CORS is a classic use case.
```cpp
svr.set_post_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
res.set_header("Access-Control-Allow-Origin", "*");
res.set_header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
res.set_header("Access-Control-Allow-Headers", "Content-Type, Authorization");
});
```
For the preflight `OPTIONS` requests, register a separate handler — or handle them in the pre-routing handler.
```cpp
svr.Options("/.*", [](const auto &req, auto &res) {
res.status = 204;
});
```
## Bundle your security headers
Manage browser security headers in one spot.
```cpp
svr.set_post_routing_handler(
[](const httplib::Request &req, httplib::Response &res) {
res.set_header("X-Content-Type-Options", "nosniff");
res.set_header("X-Frame-Options", "DENY");
res.set_header("Referrer-Policy", "strict-origin-when-cross-origin");
});
```
No matter which handler produced the response, the same headers get attached.
> **Note:** The post-routing handler also runs for responses that didn't match any route and for responses from error handlers. That's exactly what you want when you need certain headers on every response, guaranteed.

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@@ -1,47 +0,0 @@
---
title: "S11. Authenticate Per Route with a Pre-Request Handler"
order: 30
status: "draft"
---
The `set_pre_routing_handler()` from [S09. Add pre-processing to all routes](s09-pre-routing) runs **before routing**, so it has no idea which route matched. When you want per-route behavior, `set_pre_request_handler()` is what you need.
## Pre-routing vs. pre-request
| Hook | When it runs | Route info |
| --- | --- | --- |
| `set_pre_routing_handler` | Before routing | Not available |
| `set_pre_request_handler` | After routing, right before the route handler | Available via `req.matched_route` |
In a pre-request handler, `req.matched_route` holds the **pattern string** that matched. You can vary behavior based on the route definition itself.
## Switch auth per route
```cpp
svr.set_pre_request_handler(
[](const httplib::Request &req, httplib::Response &res) {
// require auth for routes starting with /admin
if (req.matched_route.rfind("/admin", 0) == 0) {
auto token = req.get_header_value("Authorization");
if (!is_admin_token(token)) {
res.status = 403;
res.set_content("forbidden", "text/plain");
return httplib::Server::HandlerResponse::Handled;
}
}
return httplib::Server::HandlerResponse::Unhandled;
});
```
`matched_route` is the pattern **before** path parameters are expanded (e.g. `/admin/users/:id`). You compare against the route definition, not the actual request path, so IDs or names don't throw you off.
## Return values
Same as pre-routing — return `HandlerResponse`.
- `Unhandled`: continue (the route handler runs)
- `Handled`: we're done, skip the route handler
## Passing auth info to the route handler
To pass decoded user info into the route handler, use `res.user_data`. See [S12. Pass data between handlers with `res.user_data`](s12-user-data).

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@@ -1,56 +0,0 @@
---
title: "S12. Pass Data Between Handlers with res.user_data"
order: 31
status: "draft"
---
Say your pre-request handler decodes an auth token and you want the route handler to use the result. That "data handoff between handlers" is what `res.user_data` is for — it holds values of arbitrary types.
## Basic usage
```cpp
struct AuthUser {
std::string id;
std::string name;
bool is_admin;
};
svr.set_pre_request_handler(
[](const httplib::Request &req, httplib::Response &res) {
auto token = req.get_header_value("Authorization");
auto user = decode_token(token); // decode the auth token
res.user_data.set("user", user);
return httplib::Server::HandlerResponse::Unhandled;
});
svr.Get("/me", [](const httplib::Request &req, httplib::Response &res) {
auto *user = res.user_data.get<AuthUser>("user");
if (!user) {
res.status = 401;
return;
}
res.set_content("Hello, " + user->name, "text/plain");
});
```
`user_data.set()` stores a value of any type, and `user_data.get<T>()` retrieves it. If you give the wrong type you get `nullptr` back — so be careful.
## Typical value types
Strings, numbers, structs, `std::shared_ptr` — anything copyable or movable works.
```cpp
res.user_data.set("user_id", std::string{"42"});
res.user_data.set("is_admin", true);
res.user_data.set("started_at", std::chrono::steady_clock::now());
```
## Where to set, where to read
The usual flow is: set it in `set_pre_routing_handler()` or `set_pre_request_handler()`, read it in the route handler. Pre-request runs after routing, so you can combine it with `req.matched_route` to set values only for specific routes.
## A gotcha
`user_data` lives on `Response`, not `Request`. That's because handlers get `Response&` (mutable) but only `const Request&`. It looks odd at first, but it makes sense once you think of it as "the mutable context shared between handlers."
> **Warning:** `user_data.get<T>()` returns `nullptr` when the type doesn't match. Use the exact same type on set and get. Storing as `AuthUser` and fetching as `const AuthUser` won't work.

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@@ -1,51 +0,0 @@
---
title: "S13. Return a Custom Error Page"
order: 32
status: "draft"
---
To customize the response for 4xx or 5xx errors, use `set_error_handler()`. You can replace the plain default error page with your own HTML or JSON.
## Basic usage
```cpp
svr.set_error_handler([](const httplib::Request &req, httplib::Response &res) {
auto body = "<h1>Error " + std::to_string(res.status) + "</h1>";
res.set_content(body, "text/html");
});
```
The error handler runs right before an error response is sent — any time `res.status` is 4xx or 5xx. Replace the body with `res.set_content()` and every error response uses the same template.
## Branch by status code
```cpp
svr.set_error_handler([](const httplib::Request &req, httplib::Response &res) {
if (res.status == 404) {
res.set_content("<h1>Not Found</h1><p>" + req.path + "</p>", "text/html");
} else if (res.status >= 500) {
res.set_content("<h1>Server Error</h1>", "text/html");
}
});
```
Checking `res.status` lets you show a custom message for 404s and a "contact support" link for 5xx errors.
## JSON error responses
For an API server, you probably want errors as JSON.
```cpp
svr.set_error_handler([](const httplib::Request &req, httplib::Response &res) {
nlohmann::json j = {
{"error", true},
{"status", res.status},
{"path", req.path},
};
res.set_content(j.dump(), "application/json");
});
```
Now every error comes back in a consistent JSON shape.
> **Note:** `set_error_handler()` also fires for 500 responses caused by exceptions thrown from a route handler. To get at the exception itself, combine it with `set_exception_handler()`. See [S14. Catch exceptions](s14-exception-handler).

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@@ -1,67 +0,0 @@
---
title: "S14. Catch Exceptions"
order: 33
status: "draft"
---
When a route handler throws, cpp-httplib keeps the server running and responds with 500. By default, though, very little of the error information reaches the client. `set_exception_handler()` lets you intercept exceptions and build your own response.
## Basic usage
```cpp
svr.set_exception_handler(
[](const httplib::Request &req, httplib::Response &res,
std::exception_ptr ep) {
try {
std::rethrow_exception(ep);
} catch (const std::exception &e) {
res.status = 500;
res.set_content(std::string("error: ") + e.what(), "text/plain");
} catch (...) {
res.status = 500;
res.set_content("unknown error", "text/plain");
}
});
```
The handler receives a `std::exception_ptr`. The idiomatic move is to rethrow it with `std::rethrow_exception()` and catch by type. You can vary status code and message based on the exception type.
## Branch on custom exception types
If you throw your own exception types, you can map them to 400 or 404 responses.
```cpp
struct NotFound : std::runtime_error {
using std::runtime_error::runtime_error;
};
struct BadRequest : std::runtime_error {
using std::runtime_error::runtime_error;
};
svr.set_exception_handler(
[](const auto &req, auto &res, std::exception_ptr ep) {
try {
std::rethrow_exception(ep);
} catch (const NotFound &e) {
res.status = 404;
res.set_content(e.what(), "text/plain");
} catch (const BadRequest &e) {
res.status = 400;
res.set_content(e.what(), "text/plain");
} catch (const std::exception &e) {
res.status = 500;
res.set_content("internal error", "text/plain");
}
});
```
Now throwing `NotFound("user not found")` inside a handler is enough to return 404. No per-handler try/catch needed.
## Relationship with set_error_handler
`set_exception_handler()` runs the moment the exception is thrown. After that, if `res.status` is 4xx or 5xx, `set_error_handler()` also runs. The order is `exception_handler``error_handler`. Think of their roles as:
- **Exception handler**: interpret the exception, set the status and message
- **Error handler**: see the status and wrap it in the shared template
> **Note:** Without an exception handler, cpp-httplib returns a default 500 response and the exception details never make it to logs. Always set one for anything you want to debug.

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@@ -1,64 +0,0 @@
---
title: "S15. Log Requests on the Server"
order: 34
status: "draft"
---
To log the requests the server receives and the responses it returns, use `Server::set_logger()`. The callback fires once per completed request, making it the foundation for access logs and metrics collection.
## Basic usage
```cpp
svr.set_logger([](const httplib::Request &req, const httplib::Response &res) {
std::cout << req.remote_addr << " "
<< req.method << " " << req.path
<< " -> " << res.status << std::endl;
});
```
The log callback receives both the `Request` and the `Response`. You can grab the method, path, status, client IP, headers, body — whatever you need.
## Access-log style format
Here's an Apache/Nginx-ish access log format.
```cpp
svr.set_logger([](const auto &req, const auto &res) {
auto now = std::time(nullptr);
char timebuf[32];
std::strftime(timebuf, sizeof(timebuf), "%Y-%m-%d %H:%M:%S",
std::localtime(&now));
std::cout << timebuf << " "
<< req.remote_addr << " "
<< "\"" << req.method << " " << req.path << "\" "
<< res.status << " "
<< res.body.size() << "B"
<< std::endl;
});
```
## Measure request time
To include request duration in the log, stash a start timestamp in `res.user_data` from a pre-routing handler, then subtract in the logger.
```cpp
svr.set_pre_routing_handler([](const auto &req, auto &res) {
res.user_data.set("start", std::chrono::steady_clock::now());
return httplib::Server::HandlerResponse::Unhandled;
});
svr.set_logger([](const auto &req, const auto &res) {
auto *start = res.user_data.get<std::chrono::steady_clock::time_point>("start");
auto elapsed = start
? std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now() - *start).count()
: 0;
std::cout << req.method << " " << req.path
<< " " << res.status << " " << elapsed << "ms" << std::endl;
});
```
For more on `user_data`, see [S12. Pass data between handlers with `res.user_data`](s12-user-data).
> **Note:** The logger runs synchronously on the same thread as request processing. Heavy work inside it hurts throughput — push it to a queue and process asynchronously if you need anything expensive.

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@@ -1,55 +0,0 @@
---
title: "S16. Detect When the Client Has Disconnected"
order: 35
status: "draft"
---
During a long-running response, the client might close the connection. There's no point continuing to do work no one's waiting for. In cpp-httplib, check `req.is_connection_closed()`.
## Basic usage
```cpp
svr.Get("/long-task", [](const httplib::Request &req, httplib::Response &res) {
for (int i = 0; i < 1000; ++i) {
if (req.is_connection_closed()) {
std::cout << "client disconnected" << std::endl;
return;
}
do_heavy_work(i);
}
res.set_content("done", "text/plain");
});
```
`is_connection_closed` is a `std::function<bool()>`, so call it with `()`. It returns `true` when the client is gone.
## With a streaming response
The same check works inside `set_chunked_content_provider()`. Capture the request by reference.
```cpp
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/event-stream",
[&req](size_t offset, httplib::DataSink &sink) {
if (req.is_connection_closed()) {
sink.done();
return true;
}
auto event = generate_next_event();
sink.write(event.data(), event.size());
return true;
});
});
```
When you detect a disconnect, call `sink.done()` to stop the provider from being called again.
## How often should you check?
The call itself is cheap, but calling it in a tight inner loop doesn't add much value. Check at **boundaries where interrupting is safe** — after producing a chunk, after a database query, etc.
> **Warning:** `is_connection_closed()` is not guaranteed to reflect reality instantly. Because of how TCP works, sometimes you only notice the disconnect when you try to send. Don't expect pixel-perfect real-time detection — think of it as "we'll notice eventually."

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@@ -1,52 +0,0 @@
---
title: "S17. Bind to Any Available Port"
order: 36
status: "draft"
---
Standing up a test server often hits port conflicts. With `bind_to_any_port()`, you let the OS pick a free port and then read back which one it gave you.
## Basic usage
```cpp
httplib::Server svr;
svr.Get("/", [](const auto &req, auto &res) {
res.set_content("hello", "text/plain");
});
int port = svr.bind_to_any_port("0.0.0.0");
std::cout << "listening on port " << port << std::endl;
svr.listen_after_bind();
```
`bind_to_any_port()` is equivalent to passing `0` as the port — the OS assigns a free one. The return value is the port actually used.
After that, call `listen_after_bind()` to start accepting. You can't combine bind and listen into a single call here, so you work in two steps.
## Useful in tests
This pattern is great for tests that spin up a server and hit it.
```cpp
httplib::Server svr;
svr.Get("/ping", [](const auto &, auto &res) { res.set_content("pong", "text/plain"); });
int port = svr.bind_to_any_port("127.0.0.1");
std::thread t([&] { svr.listen_after_bind(); });
// run the test while the server is up on another thread
httplib::Client cli("127.0.0.1", port);
auto res = cli.Get("/ping");
assert(res && res->body == "pong");
svr.stop();
t.join();
```
Because the port is assigned at runtime, parallel test runs don't collide.
> **Note:** `bind_to_any_port()` returns `-1` on failure (permission errors, no available ports, etc.). Always check the return value.
> To stop the server, see [S19. Shut down gracefully](s19-graceful-shutdown).

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@@ -1,57 +0,0 @@
---
title: "S18. Control Startup Order with listen_after_bind"
order: 37
status: "draft"
---
Normally `svr.listen("0.0.0.0", 8080)` handles bind and listen in one shot. When you need to do something between the two, split them into two calls.
## Separate bind and listen
```cpp
httplib::Server svr;
svr.Get("/", [](const auto &, auto &res) { res.set_content("ok", "text/plain"); });
if (!svr.bind_to_port("0.0.0.0", 8080)) {
std::cerr << "bind failed" << std::endl;
return 1;
}
// bind is done here. accept hasn't started yet.
drop_privileges();
signal_ready_to_parent_process();
svr.listen_after_bind(); // start the accept loop
```
`bind_to_port()` reserves the port; `listen_after_bind()` actually starts accepting. Splitting them gives you a window between the two steps.
## Common use cases
**Privilege drop**: Binding to a port under 1024 requires root. Bind as root, drop to a normal user, and all subsequent request handling runs with reduced privileges.
```cpp
svr.bind_to_port("0.0.0.0", 80);
drop_privileges();
svr.listen_after_bind();
```
**Startup notification**: Tell the parent process or systemd "I'm ready" before starting to accept connections.
**Test synchronization**: In tests, you can reliably catch "the moment the server is bound" and start the client after that.
## Check the return values
`bind_to_port()` returns `false` on failure — typically when the port is already taken. Always check it.
```cpp
if (!svr.bind_to_port("0.0.0.0", 8080)) {
std::cerr << "port already in use" << std::endl;
return 1;
}
```
`listen_after_bind()` blocks until the server stops and returns `true` on a clean shutdown.
> **Note:** To auto-pick a free port, see [S17. Bind to any available port](s17-bind-any-port). Under the hood, that's just `bind_to_any_port()` + `listen_after_bind()`.

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@@ -1,57 +0,0 @@
---
title: "S19. Shut Down Gracefully"
order: 38
status: "draft"
---
To stop the server, call `Server::stop()`. It's safe to call even while requests are in flight, so you can wire it to SIGINT or SIGTERM for a graceful shutdown.
## Basic usage
```cpp
httplib::Server svr;
svr.Get("/", [](const auto &, auto &res) { res.set_content("ok", "text/plain"); });
std::thread t([&] { svr.listen("0.0.0.0", 8080); });
// wait for input on the main thread, or whatever
std::cin.get();
svr.stop();
t.join();
```
`listen()` blocks, so the typical pattern is: run the server on a background thread and call `stop()` from the main thread. After `stop()`, `listen()` returns and you can `join()`.
## Shut down on a signal
Here's how to stop the server on SIGINT (Ctrl+C) or SIGTERM.
```cpp
#include <csignal>
httplib::Server svr;
// global so the signal handler can reach it
httplib::Server *g_svr = nullptr;
int main() {
svr.Get("/", [](const auto &, auto &res) { res.set_content("ok", "text/plain"); });
g_svr = &svr;
std::signal(SIGINT, [](int) { if (g_svr) g_svr->stop(); });
std::signal(SIGTERM, [](int) { if (g_svr) g_svr->stop(); });
svr.listen("0.0.0.0", 8080);
std::cout << "server stopped" << std::endl;
}
```
`stop()` is thread-safe and signal-safe — you can call it from a signal handler. Even when `listen()` is running on the main thread, the signal pulls it out cleanly.
## What happens to in-flight requests
When you call `stop()`, new connections are refused, but requests already being processed are **allowed to finish**. Once all workers drain, `listen()` returns. That's what makes it graceful.
> **Warning:** There's a wait between calling `stop()` and `listen()` returning — it's the time in-flight requests take to finish. To enforce a timeout, you'll need to add your own shutdown timer in application code.

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@@ -1,57 +0,0 @@
---
title: "S20. Tune Keep-Alive"
order: 39
status: "draft"
---
`httplib::Server` enables HTTP/1.1 Keep-Alive automatically. From the client's perspective, connections are reused — so they don't pay the TCP handshake cost on every request. When you need to tune the behavior, there are two setters.
## What you can configure
| API | Default | Meaning |
| --- | --- | --- |
| `set_keep_alive_max_count` | 100 | Max requests served over a single connection |
| `set_keep_alive_timeout` | 5s | How long an idle connection is kept before closing |
## Basic usage
```cpp
httplib::Server svr;
svr.set_keep_alive_max_count(20);
svr.set_keep_alive_timeout(10); // 10 seconds
svr.listen("0.0.0.0", 8080);
```
`set_keep_alive_timeout()` also has a `std::chrono` overload.
```cpp
using namespace std::chrono_literals;
svr.set_keep_alive_timeout(10s);
```
## Tuning ideas
**Too many idle connections eating resources**
Shorten the timeout so idle connections drop and release their worker threads.
```cpp
svr.set_keep_alive_timeout(2s);
```
**API is hammered and you want max reuse**
Raising the per-connection request cap improves benchmark numbers.
```cpp
svr.set_keep_alive_max_count(1000);
```
**Never reuse connections**
Set `set_keep_alive_max_count(1)` and every request gets its own connection. Mostly only useful for debugging or compatibility testing.
## Relationship with the thread pool
A Keep-Alive connection holds a worker thread for its entire lifetime. If `connections × concurrent requests` exceeds the thread pool size, new requests wait. For thread counts, see [S21. Configure the thread pool](s21-thread-pool).
> **Note:** For the client side, see [C14. Understand connection reuse and Keep-Alive behavior](c14-keep-alive). Even when the server closes the connection on timeout, the client reconnects automatically.

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@@ -1,69 +0,0 @@
---
title: "S21. Configure the Thread Pool"
order: 40
status: "draft"
---
cpp-httplib serves requests from a thread pool. By default, the base thread count is the greater of `std::thread::hardware_concurrency() - 1` and `8`, and it can scale up dynamically to 4× that. To set thread counts explicitly, provide your own factory via `new_task_queue`.
## Set thread counts
```cpp
httplib::Server svr;
svr.new_task_queue = [] {
return new httplib::ThreadPool(/*base_threads=*/8, /*max_threads=*/64);
};
svr.listen("0.0.0.0", 8080);
```
The factory is a lambda returning a `TaskQueue*`. Pass `base_threads` and `max_threads` to `ThreadPool` and the pool scales between them based on load. Idle threads exit after a timeout (3 seconds by default).
## Also cap the queue
The pending queue can eat memory if it grows unchecked. You can cap it too.
```cpp
svr.new_task_queue = [] {
return new httplib::ThreadPool(
/*base_threads=*/12,
/*max_threads=*/0, // disable dynamic scaling
/*max_queued_requests=*/18);
};
```
`max_threads=0` disables dynamic scaling — you get a fixed `base_threads`. Requests that don't fit in `max_queued_requests` are rejected.
## Use your own thread pool
You can plug in a fully custom thread pool by subclassing `TaskQueue` and returning it from the factory.
```cpp
class MyTaskQueue : public httplib::TaskQueue {
public:
MyTaskQueue(size_t n) { pool_.start_with_thread_count(n); }
bool enqueue(std::function<void()> fn) override { return pool_.post(std::move(fn)); }
void shutdown() override { pool_.shutdown(); }
private:
MyThreadPool pool_;
};
svr.new_task_queue = [] { return new MyTaskQueue(12); };
```
Handy when you already have a thread pool in your project and want to keep thread management unified.
## Compile-time tuning
You can set the defaults with macros if you want compile-time configuration.
```cpp
#define CPPHTTPLIB_THREAD_POOL_COUNT 16 // base thread count
#define CPPHTTPLIB_THREAD_POOL_MAX_COUNT 128 // max thread count
#define CPPHTTPLIB_THREAD_POOL_IDLE_TIMEOUT 5 // seconds before idle threads exit
#include <httplib.h>
```
> **Note:** A WebSocket connection holds a worker thread for its entire lifetime. For lots of simultaneous WebSocket connections, enable dynamic scaling (e.g. `ThreadPool(8, 64)`).

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@@ -1,64 +0,0 @@
---
title: "S22. Talk Over a Unix Domain Socket"
order: 41
status: "draft"
---
When you want to talk only to other processes on the same host, a Unix domain socket is a nice fit. It avoids TCP overhead and uses filesystem permissions for access control. Local IPC and services sitting behind a reverse proxy are classic use cases.
## Server side
```cpp
httplib::Server svr;
svr.set_address_family(AF_UNIX);
svr.Get("/", [](const auto &, auto &res) {
res.set_content("hello from unix socket", "text/plain");
});
svr.listen("/tmp/httplib.sock", 80);
```
Call `set_address_family(AF_UNIX)` first, then pass the socket file path as the first argument to `listen()`. The port number is unused but required by the signature — pass any value.
## Client side
```cpp
httplib::Client cli("/tmp/httplib.sock");
cli.set_address_family(AF_UNIX);
auto res = cli.Get("/");
if (res) {
std::cout << res->body << std::endl;
}
```
Pass the socket file path to the `Client` constructor and call `set_address_family(AF_UNIX)`. Everything else works like a normal HTTP request.
## When to use it
- **Behind a reverse proxy**: An nginx-to-backend setup over a Unix socket is faster than TCP and sidesteps port management
- **Local-only APIs**: IPC between tools that shouldn't be reachable from outside
- **In-container IPC**: Process-to-process communication within the same pod or container
- **Dev environments**: No more worrying about port conflicts
## Clean up the socket file
A Unix domain socket creates a real file in the filesystem. It doesn't get removed on shutdown, so delete it before starting if needed.
```cpp
std::remove("/tmp/httplib.sock");
svr.listen("/tmp/httplib.sock", 80);
```
## Permissions
You control who can connect via the socket file's permissions.
```cpp
svr.listen("/tmp/httplib.sock", 80);
// from another process or thread
chmod("/tmp/httplib.sock", 0660); // owner and group only
```
> **Warning:** Some Windows versions support AF_UNIX, but the implementation and behavior differ by platform. Test thoroughly before running cross-platform in production.

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@@ -1,49 +0,0 @@
---
title: "T01. Choosing Between OpenSSL, mbedTLS, and wolfSSL"
order: 42
status: "draft"
---
cpp-httplib doesn't ship its own TLS implementation — it uses one of three backends that you pick at build time via a macro.
| Backend | Macro | Character |
| --- | --- | --- |
| OpenSSL | `CPPHTTPLIB_OPENSSL_SUPPORT` | Most widely used, richest feature set |
| mbedTLS | `CPPHTTPLIB_MBEDTLS_SUPPORT` | Lightweight, aimed at embedded |
| wolfSSL | `CPPHTTPLIB_WOLFSSL_SUPPORT` | Embedded-friendly, commercial support available |
## Build-time selection
Define the macro for your chosen backend before including `httplib.h`:
```cpp
#define CPPHTTPLIB_OPENSSL_SUPPORT
#include <httplib.h>
```
You'll also need to link against the backend's libraries (`libssl`, `libcrypto`, `libmbedtls`, `libwolfssl`, etc.).
## Which to pick
**When in doubt, OpenSSL**
It has the most features and the best documentation. For normal server use or Linux desktop apps, start here — you probably won't need anything else.
**To shrink binary size or target embedded**
mbedTLS or wolfSSL are a better fit. They're far more compact than OpenSSL and run on memory-constrained devices.
**When you need commercial support**
wolfSSL offers commercial licensing and support. If you're shipping in a product, it's worth considering.
## Supporting multiple backends
The usual approach is to treat each backend as a build variant and recompile the same source with different macros. cpp-httplib smooths over most of the API differences, but the backends are not 100% identical — always test.
## APIs that work across all backends
Certificate verification control, standing up an SSLServer, reading the peer certificate — these all share the same API across backends:
- [T02. Control SSL certificate verification](t02-cert-verification)
- [T03. Start an SSL/TLS server](t03-ssl-server)
- [T05. Access the peer certificate on the server](t05-peer-cert)
> **Note:** On macOS with an OpenSSL-family backend, cpp-httplib automatically loads root certificates from the system keychain (via `CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN`, on by default). To disable this, define `CPPHTTPLIB_DISABLE_MACOSX_AUTOMATIC_ROOT_CERTIFICATES`.

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@@ -1,53 +0,0 @@
---
title: "T02. Control SSL Certificate Verification"
order: 43
status: "draft"
---
By default, an HTTPS client verifies the server certificate — it uses the OS root certificate store to check the chain and the hostname. Here are the APIs for changing that behavior.
## Specify a custom CA certificate
When connecting to a server whose certificate is signed by an internal CA, use `set_ca_cert_path()`.
```cpp
httplib::Client cli("https://internal.example.com");
cli.set_ca_cert_path("/etc/ssl/certs/internal-ca.pem");
auto res = cli.Get("/");
```
The first argument is the CA certificate file; the second is an optional CA directory. With the OpenSSL backend, you can also pass an `X509_STORE*` directly via `set_ca_cert_store()`.
## Disable certificate verification (not recommended)
For development servers or self-signed certificates, you can skip verification entirely.
```cpp
httplib::Client cli("https://self-signed.example.com");
cli.enable_server_certificate_verification(false);
auto res = cli.Get("/");
```
That's all it takes to disable chain verification.
> **Warning:** Disabling certificate verification removes protection against man-in-the-middle attacks. **Never do this in production.** If you find yourself needing it outside of dev/test, pause and make sure you're not doing something wrong.
## Disable hostname verification only
There's an in-between option: verify the certificate chain, but skip the hostname check. Useful when you need to reach a server whose cert CN/SAN doesn't match the request's hostname.
```cpp
cli.enable_server_hostname_verification(false);
```
The certificate itself is still validated, so this is safer than fully disabling verification — but still not recommended in production.
## Use the OS cert store as-is
On most Linux distributions, root certificates live in a single file like `/etc/ssl/certs/ca-certificates.crt`. cpp-httplib reads the OS default store at startup, so for most servers you don't need to configure anything.
> The same APIs work on the mbedTLS and wolfSSL backends. For choosing between backends, see [T01. Choosing between OpenSSL, mbedTLS, and wolfSSL](t01-tls-backends).
> For details on diagnosing failures, see [C18. Handle SSL errors](c18-ssl-errors).

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@@ -1,78 +0,0 @@
---
title: "T03. Start an SSL/TLS Server"
order: 44
status: "draft"
---
To stand up an HTTPS server, use `httplib::SSLServer` instead of `httplib::Server`. Pass a certificate and private key to the constructor, and you get back something that works exactly like `Server`.
## Basic usage
```cpp
#define CPPHTTPLIB_OPENSSL_SUPPORT
#include <httplib.h>
int main() {
httplib::SSLServer svr("cert.pem", "key.pem");
svr.Get("/", [](const auto &req, auto &res) {
res.set_content("hello over TLS", "text/plain");
});
svr.listen("0.0.0.0", 443);
}
```
Pass the server certificate (PEM format) and private key file paths to the constructor. That's all you need for a TLS-enabled server. Registering handlers and calling `listen()` work the same as with `Server`.
## Password-protected private keys
The fifth argument is the private key password.
```cpp
httplib::SSLServer svr("cert.pem", "key.pem",
nullptr, nullptr, "password");
```
The third and fourth arguments are for client certificate verification (mTLS, see [T04. Configure mTLS](t04-mtls)). For now, pass `nullptr`.
## Load PEM data from memory
When you want to load certs from memory instead of files, use the `PemMemory` struct.
```cpp
httplib::SSLServer::PemMemory pem{};
pem.cert_pem = cert_data.data();
pem.cert_pem_len = cert_data.size();
pem.key_pem = key_data.data();
pem.key_pem_len = key_data.size();
httplib::SSLServer svr(pem);
```
Handy when you pull certificates from environment variables or a secrets manager.
## Rotate certificates
Before a certificate expires, you may want to swap it out without restarting the server. That's what `update_certs_pem()` is for.
```cpp
svr.update_certs_pem(new_cert_pem, new_key_pem);
```
Existing connections keep using the old cert; new connections use the new one.
## Generating a test certificate
For a throwaway self-signed cert, use the `openssl` CLI.
```sh
openssl req -x509 -newkey rsa:2048 -days 365 -nodes \
-keyout key.pem -out cert.pem -subj "/CN=localhost"
```
In production, use certificates from Let's Encrypt or your internal CA.
> **Warning:** Binding an HTTPS server to port 443 requires root. For a safe way to do that, see the privilege-drop pattern in [S18. Control startup order with `listen_after_bind`](s18-listen-after-bind).
> For mutual TLS (client certificates), see [T04. Configure mTLS](t04-mtls).

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@@ -1,70 +0,0 @@
---
title: "T04. Configure mTLS"
order: 45
status: "draft"
---
Regular TLS verifies the server certificate only. **mTLS** (mutual TLS) adds the other direction: the client presents a certificate too, and the server verifies it. It's common for zero-trust API-to-API traffic and internal system authentication.
## Server side
Pass the CA used to verify client certificates as the third (and fourth) argument to `SSLServer`.
```cpp
httplib::SSLServer svr(
"server-cert.pem", // server certificate
"server-key.pem", // server private key
"client-ca.pem", // CA that signs valid client certs
nullptr // CA directory (none)
);
svr.Get("/", [](const httplib::Request &req, httplib::Response &res) {
res.set_content("authenticated", "text/plain");
});
svr.listen("0.0.0.0", 443);
```
With this, any connection whose client certificate isn't signed by `client-ca.pem` is rejected at the handshake. By the time a handler runs, the client is already authenticated.
## Configure with in-memory PEM
```cpp
httplib::SSLServer::PemMemory pem{};
pem.cert_pem = server_cert.data();
pem.cert_pem_len = server_cert.size();
pem.key_pem = server_key.data();
pem.key_pem_len = server_key.size();
pem.client_ca_pem = client_ca.data();
pem.client_ca_pem_len = client_ca.size();
httplib::SSLServer svr(pem);
```
This is the clean way when you load certificates from environment variables or a secrets manager.
## Client side
On the client side, pass the client certificate and key to `SSLClient`.
```cpp
httplib::SSLClient cli("api.example.com", 443,
"client-cert.pem",
"client-key.pem");
auto res = cli.Get("/");
```
Note you're using `SSLClient` directly, not `Client`. If the private key has a password, pass it as the fifth argument.
## Read client info from a handler
To see which client connected from inside a handler, use `req.peer_cert()`. Details in [T05. Access the peer certificate on the server](t05-peer-cert).
## Use cases
- **Microservice-to-microservice calls**: Issue a cert per service, use the cert as identity
- **IoT device management**: Burn a cert into each device and use it to gate API access
- **An alternative to internal VPN**: Put cert-based auth in front of public endpoints so internal resources can be reached safely
> **Note:** Issuing and revoking client certificates is more operational work than password-based auth. You'll need either an internal PKI setup or an automated flow using ACME-family tools.

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@@ -1,88 +0,0 @@
---
title: "T05. Access the Peer Certificate on the Server Side"
order: 46
status: "draft"
---
In an mTLS setup, you can read the client's certificate from inside a handler. Pull out the CN or SAN to identify the user or log the request.
## Basic usage
```cpp
svr.Get("/me", [](const httplib::Request &req, httplib::Response &res) {
auto cert = req.peer_cert();
if (!cert) {
res.status = 401;
res.set_content("no client certificate", "text/plain");
return;
}
auto cn = cert.subject_cn();
res.set_content("hello, " + cn, "text/plain");
});
```
`req.peer_cert()` returns a `tls::PeerCert`. It's convertible to `bool`, so check whether a cert is present before using it.
## Available fields
From a `PeerCert`, you can get:
```cpp
auto cert = req.peer_cert();
std::string cn = cert.subject_cn(); // CN
std::string issuer = cert.issuer_name(); // issuer
std::string serial = cert.serial(); // serial number
time_t not_before, not_after;
cert.validity(not_before, not_after); // validity period
auto sans = cert.sans(); // SANs
for (const auto &san : sans) {
std::cout << san.value << std::endl;
}
```
There's also a helper to check if a hostname is covered by the SAN list:
```cpp
if (cert.check_hostname("alice.corp.example.com")) {
// matches
}
```
## Cert-based authorization
You can gate routes by CN or SAN.
```cpp
svr.set_pre_request_handler(
[](const httplib::Request &req, httplib::Response &res) {
auto cert = req.peer_cert();
if (!cert) {
res.status = 401;
return httplib::Server::HandlerResponse::Handled;
}
if (req.matched_route.rfind("/admin", 0) == 0) {
auto cn = cert.subject_cn();
if (!is_admin_cn(cn)) {
res.status = 403;
return httplib::Server::HandlerResponse::Handled;
}
}
return httplib::Server::HandlerResponse::Unhandled;
});
```
Combined with a pre-request handler, you can keep all authorization logic in one place. See [S11. Authenticate per route with a pre-request handler](s11-pre-request).
## SNI (Server Name Indication)
cpp-httplib handles SNI automatically. If one server hosts multiple domains, SNI is used under the hood — but normally handlers don't need to care.
> **Warning:** `req.peer_cert()` only returns a meaningful value when mTLS is enabled and the client actually presented a certificate. For plain TLS, you get an empty `PeerCert`. Always do the `bool` check before using it.
> To set up mTLS, see [T04. Configure mTLS](t04-mtls).

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@@ -1,88 +0,0 @@
---
title: "W01. Implement a WebSocket Echo Server and Client"
order: 51
status: "draft"
---
WebSocket is a protocol for **two-way** messaging between client and server. cpp-httplib provides APIs for both sides. Let's start with the simplest example: an echo server.
## Server: echo server
```cpp
#include <httplib.h>
int main() {
httplib::Server svr;
svr.WebSocket("/echo", [](const httplib::Request &req, httplib::ws::WebSocket &ws) {
std::string msg;
while (ws.is_open()) {
auto result = ws.read(msg);
if (result == httplib::ws::ReadResult::Fail) {
break;
}
ws.send(msg); // echo back what we received
}
});
svr.listen("0.0.0.0", 8080);
}
```
Register a WebSocket handler with `svr.WebSocket()`. By the time the handler runs, the WebSocket handshake is already complete. Inside the loop, just `ws.read()` and `ws.send()` to get a working echo.
The `read()` return value is a `ReadResult` enum:
- `ReadResult::Text`: received a text message
- `ReadResult::Binary`: received a binary message
- `ReadResult::Fail`: error, or connection closed
## Client: talk to the echo server
```cpp
#include <httplib.h>
int main() {
httplib::ws::WebSocketClient cli("ws://localhost:8080/echo");
if (!cli.connect()) {
std::cerr << "failed to connect" << std::endl;
return 1;
}
cli.send("Hello, WebSocket!");
std::string msg;
if (cli.read(msg) != httplib::ws::ReadResult::Fail) {
std::cout << "received: " << msg << std::endl;
}
cli.close();
}
```
Use a `ws://` (plain) or `wss://` (TLS) URL. Call `connect()` to do the handshake, then `send()` and `read()` work the same as on the server side.
## Text vs. binary
`send()` has two overloads that let you choose the frame type.
```cpp
ws.send("Hello"); // text frame
ws.send(binary_data, binary_data_size); // binary frame
```
The `std::string` overload sends as **text**; the `const char*` + size overload sends as **binary**. A bit subtle, but once you know it, it's intuitive. See [W04. Send and receive binary frames](w04-websocket-binary) for details.
## Thread pool implications
A WebSocket handler holds its worker thread for the entire life of the connection — one connection per thread. For many concurrent clients, configure a dynamic thread pool.
```cpp
svr.new_task_queue = [] {
return new httplib::ThreadPool(8, 128);
};
```
See [S21. Configure the thread pool](s21-thread-pool).
> **Note:** To run WebSocket over HTTPS, use `httplib::SSLServer` instead of `httplib::Server` — the same `WebSocket()` handler just works. On the client side, use a `wss://` URL.

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@@ -1,80 +0,0 @@
---
title: "W02. Set a WebSocket Heartbeat"
order: 52
status: "draft"
---
WebSocket connections stay open for a long time, and proxies or load balancers will sometimes drop them for being "idle." To prevent that, you periodically send Ping frames to keep the connection alive. cpp-httplib can do this for you automatically.
## Server side
```cpp
svr.set_websocket_ping_interval(30); // ping every 30 seconds
svr.WebSocket("/chat", [](const auto &req, auto &ws) {
// ...
});
```
Just pass the interval in seconds. Every WebSocket connection this server accepts will be pinged on that interval.
There's a `std::chrono` overload too.
```cpp
using namespace std::chrono_literals;
svr.set_websocket_ping_interval(30s);
```
## Client side
The client has the same API.
```cpp
httplib::ws::WebSocketClient cli("ws://localhost:8080/chat");
cli.set_websocket_ping_interval(30);
cli.connect();
```
Call it before `connect()`.
## The default
The default interval is set by the build-time macro `CPPHTTPLIB_WEBSOCKET_PING_INTERVAL_SECOND`. Usually you won't need to change it, but adjust downward if you're dealing with an aggressive proxy.
## What about Pong?
The WebSocket protocol requires that Ping frames are answered with Pong frames. cpp-httplib responds to Pings automatically — you don't need to think about it in application code.
## Picking an interval
| Environment | Suggested |
| --- | --- |
| Normal internet | 3060s |
| Strict proxies (e.g. AWS ALB) | 1530s |
| Mobile networks | 60s+ (too short drains battery) |
Too short wastes bandwidth; too long and connections get dropped. As a rule of thumb, target about **half the idle timeout** of whatever's between you and the client.
> **Warning:** A very short ping interval spawns background work per connection and increases CPU usage. For servers with many connections, keep the interval modest.
## Detecting an unresponsive peer
Sending pings alone doesn't tell you anything if the peer just silently dies — the TCP socket might still look open while the process on the other end is long gone. To catch that, enable the max-missed-pongs check: if N consecutive pings go unanswered, the connection is closed.
```cpp
cli.set_websocket_max_missed_pongs(2); // close after 2 consecutive unacked pings
```
The server side has the same `set_websocket_max_missed_pongs()`.
With a 30-second ping interval and `max_missed_pongs = 2`, a dead peer is detected within roughly 60 seconds and the connection is closed with `CloseStatus::GoingAway` and the reason `"pong timeout"`.
The counter is reset whenever `read()` consumes an incoming Pong frame, so this only works if your code is actively calling `read()` in a loop — which is what a normal WebSocket client does anyway.
### Why the default is 0
`max_missed_pongs` defaults to `0`, which means "never close the connection because of missing pongs." Pings are still sent on the heartbeat interval, but their responses aren't checked. If you want unresponsive-peer detection, set it explicitly to `1` or higher.
Even with `0`, a dead connection won't linger forever: while your code is inside `read()`, `CPPHTTPLIB_WEBSOCKET_READ_TIMEOUT_SECOND` (default **300 seconds = 5 minutes**) acts as a backstop and `read()` fails if no frame arrives in time. Think of `max_missed_pongs` as the knob for detecting an unresponsive peer **faster** than that.
> For handling a closed connection, see [W03. Handle connection close](w03-websocket-close).

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@@ -1,91 +0,0 @@
---
title: "W03. Handle Connection Close"
order: 53
status: "draft"
---
A WebSocket ends when either side closes it explicitly, or when the network drops. Handle close cleanly, and your cleanup and reconnect logic stays tidy.
## Detect a closed connection
When `ws.read()` returns `ReadResult::Fail`, the connection is gone — either cleanly or with an error. Break out of the loop and the handler will finish.
```cpp
svr.WebSocket("/chat", [](const httplib::Request &req, httplib::ws::WebSocket &ws) {
std::string msg;
while (ws.is_open()) {
auto result = ws.read(msg);
if (result == httplib::ws::ReadResult::Fail) {
std::cout << "disconnected" << std::endl;
break;
}
handle_message(ws, msg);
}
// cleanup runs once we're out of the loop
cleanup_user_session(req);
});
```
You can also check `ws.is_open()` — it's the same signal from a different angle.
## Close from the server side
To close explicitly, call `close()`.
```cpp
ws.close(httplib::ws::CloseStatus::Normal, "bye");
```
The first argument is the close status; the second is an optional reason. Common `CloseStatus` values:
| Value | Meaning |
| --- | --- |
| `Normal` (1000) | Normal closure |
| `GoingAway` (1001) | Server is shutting down |
| `ProtocolError` (1002) | Protocol violation detected |
| `UnsupportedData` (1003) | Received data that can't be handled |
| `PolicyViolation` (1008) | Violated a policy |
| `MessageTooBig` (1009) | Message too large |
| `InternalError` (1011) | Server-side error |
## Close from the client side
The client API is identical.
```cpp
cli.close(httplib::ws::CloseStatus::Normal);
```
Destroying the client also closes the connection, but calling `close()` explicitly makes the intent clearer.
## Graceful shutdown
To notify in-flight clients that the server is going down, use `GoingAway`.
```cpp
ws.close(httplib::ws::CloseStatus::GoingAway, "server restarting");
```
The client can inspect that status and decide whether to reconnect.
## Example: a tiny chat with quit
```cpp
svr.WebSocket("/chat", [](const auto &req, auto &ws) {
std::string msg;
while (ws.is_open()) {
if (ws.read(msg) == httplib::ws::ReadResult::Fail) break;
if (msg == "/quit") {
ws.send("goodbye");
ws.close(httplib::ws::CloseStatus::Normal, "user quit");
break;
}
ws.send("echo: " + msg);
}
});
```
> **Note:** On a sudden network drop, `read()` returns `Fail` with no chance to call `close()`. Put your cleanup at the end of the handler, and both paths — clean close and abrupt disconnect — end up in the same place.

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@@ -1,85 +0,0 @@
---
title: "W04. Send and Receive Binary Frames"
order: 54
status: "draft"
---
WebSocket has two frame types: text and binary. JSON and plain text go in text frames; images and raw protocol bytes go in binary. In cpp-httplib, `send()` picks the right type via overload.
## How to pick a frame type
```cpp
ws.send(std::string("Hello")); // text
ws.send("Hello", 5); // binary
ws.send(binary_data, binary_data_size); // binary
```
The `std::string` overload sends as **text**. The `const char*` + size overload sends as **binary**. A bit subtle, but once you know it, it sticks.
If you have a `std::string` and want to send it as binary, pass `.data()` and `.size()` explicitly.
```cpp
std::string raw = build_binary_payload();
ws.send(raw.data(), raw.size()); // binary frame
```
## Detect frame type on receive
The return value of `ws.read()` tells you whether the received frame was text or binary.
```cpp
std::string msg;
auto result = ws.read(msg);
switch (result) {
case httplib::ws::ReadResult::Text:
std::cout << "text: " << msg << std::endl;
break;
case httplib::ws::ReadResult::Binary:
std::cout << "binary: " << msg.size() << " bytes" << std::endl;
handle_binary(msg.data(), msg.size());
break;
case httplib::ws::ReadResult::Fail:
// error or closed
break;
}
```
Binary frames still come back in a `std::string`, but treat its contents as raw bytes — use `msg.data()` and `msg.size()`.
## When binary is the right call
- **Images, video, audio**: No Base64 overhead
- **Custom protocols**: protobuf, MessagePack, or any structured binary format
- **Game networking**: When latency matters
- **Sensor data streams**: Push numeric arrays directly
## Ping is binary-ish, but hidden
WebSocket Ping/Pong frames are close cousins of binary frames at the opcode level, but cpp-httplib handles them automatically — you don't touch them. See [W02. Set a WebSocket heartbeat](w02-websocket-ping).
## Example: send an image
```cpp
// Server: push an image
svr.WebSocket("/image", [](const auto &req, auto &ws) {
auto img = read_image_file("logo.png");
ws.send(img.data(), img.size());
});
```
```cpp
// Client: receive and save
httplib::ws::WebSocketClient cli("ws://localhost:8080/image");
cli.connect();
std::string buf;
if (cli.read(buf) == httplib::ws::ReadResult::Binary) {
std::ofstream ofs("received.png", std::ios::binary);
ofs.write(buf.data(), buf.size());
}
```
You can mix text and binary in the same connection. A common pattern: JSON for control messages, binary for the actual data — you get efficient handling of metadata and payload both.
> **Note:** WebSocket frames don't have an infinite size limit. For very large data, chunk it in your application code. cpp-httplib can handle a big frame in one shot, but it does load it all into memory at once.

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@@ -18,8 +18,4 @@ Under the hood, it uses blocking I/O with a thread pool. It's not built for hand
## Documentation
- [A Tour of cpp-httplib](tour/) — A step-by-step tutorial covering the basics. Start here if you're new
- [Building a Desktop LLM App](llm-app/) — A hands-on guide to building a desktop app with llama.cpp, step by step
## Stay Tuned
- [Cookbook](cookbook/) — A collection of recipes organized by topic. Jump to whatever you need

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---
title: "1. Setting Up the Project Environment"
order: 1
---
Let's incrementally build a text translation REST API server using llama.cpp as the inference engine. By the end, a request like this will return a translation result.
```bash
curl -X POST http://localhost:8080/translate \
-H "Content-Type: application/json" \
-d '{"text": "The weather is nice today. Shall we go for a walk?", "target_lang": "ja"}'
```
```json
{
"translation": "今日はいい天気ですね。散歩に行きましょうか?"
}
```
The "Translation API" is just one example. By swapping out the prompt, you can adapt this to any LLM application you like, such as summarization, code generation, or a chatbot.
Here's the full list of APIs the server will provide.
| Method | Path | Description | Chapter |
| -------- | ---- | ---- | -- |
| `GET` | `/health` | Returns server status | 1 |
| `POST` | `/translate` | Translates text and returns JSON | 2 |
| `POST` | `/translate/stream` | SSE streaming on a per-token basis | 3 |
| `GET` | `/models` | Model list (available / downloaded / selected) | 4 |
| `POST` | `/models/select` | Select a model (automatically downloads if not yet downloaded) | 4 |
In this chapter, let's set up the project environment. We'll fetch the dependency libraries, create the directory structure, configure the build settings, and grab the model file, so that we're ready to start writing code in the next chapter.
## Prerequisites
- A C++20-compatible compiler (GCC 10+, Clang 10+, MSVC 2019 16.8+)
- CMake 3.20 or later
- OpenSSL (used for the HTTPS client in Chapter 4. macOS: `brew install openssl`, Ubuntu: `sudo apt install libssl-dev`)
- Sufficient disk space (model files can be several GB)
## 1.1 What We Will Use
Here are the libraries we'll use.
| Library | Role |
| ----------- | ------ |
| [cpp-httplib](https://github.com/yhirose/cpp-httplib) | HTTP server/client |
| [nlohmann/json](https://github.com/nlohmann/json) | JSON parser |
| [cpp-llamalib](https://github.com/yhirose/cpp-llamalib) | llama.cpp wrapper |
| [llama.cpp](https://github.com/ggml-org/llama.cpp) | LLM inference engine |
| [webview/webview](https://github.com/webview/webview) | Desktop WebView (used in Chapter 6) |
cpp-httplib, nlohmann/json, and cpp-llamalib are header-only libraries. You could just download a single header file with `curl` and `#include` it, but in this book we use CMake's `FetchContent` to fetch them automatically. Declare them in `CMakeLists.txt`, and `cmake -B build` downloads and builds everything for you. webview is used in Chapter 6, so you don't need to worry about it for now.
## 1.2 Directory Structure
The final structure will look like this.
```ascii
translate-app/
├── CMakeLists.txt
├── models/
│ └── (GGUF files)
└── src/
└── main.cpp
```
We don't include library source code in the project. CMake's `FetchContent` fetches them automatically at build time, so all you need is your own code.
Let's create the project directory and initialize a git repository.
```bash
mkdir translate-app && cd translate-app
mkdir src models
git init
```
## 1.3 Obtaining the GGUF Model File
You need a model file for LLM inference. GGUF is the model format used by llama.cpp, and you can find many models on Hugging Face.
Let's start by trying a small model. The quantized version of Google's Gemma 2 2B (~1.6 GB) is a good starting point. It's lightweight but supports multiple languages and works well for translation tasks.
```bash
curl -L -o models/gemma-2-2b-it-Q4_K_M.gguf \
https://huggingface.co/bartowski/gemma-2-2b-it-GGUF/resolve/main/gemma-2-2b-it-Q4_K_M.gguf
```
In Chapter 4, we'll add the ability to download models from within the app using cpp-httplib's client functionality.
## 1.4 CMakeLists.txt
Create a `CMakeLists.txt` in the project root. By declaring dependencies with `FetchContent`, CMake will automatically download and build them for you.
<!-- data-file="CMakeLists.txt" -->
```cmake
cmake_minimum_required(VERSION 3.20)
project(translate-server CXX)
set(CMAKE_CXX_STANDARD 20)
include(FetchContent)
# llama.cpp (LLM inference engine)
FetchContent_Declare(llama
GIT_REPOSITORY https://github.com/ggml-org/llama.cpp
GIT_TAG master
GIT_SHALLOW TRUE
)
FetchContent_MakeAvailable(llama)
# cpp-httplib (HTTP server/client)
FetchContent_Declare(httplib
GIT_REPOSITORY https://github.com/yhirose/cpp-httplib
GIT_TAG master
)
FetchContent_MakeAvailable(httplib)
# nlohmann/json (JSON parser)
FetchContent_Declare(json
URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz
)
FetchContent_MakeAvailable(json)
# cpp-llamalib (header-only llama.cpp wrapper)
FetchContent_Declare(cpp_llamalib
GIT_REPOSITORY https://github.com/yhirose/cpp-llamalib
GIT_TAG main
)
FetchContent_MakeAvailable(cpp_llamalib)
add_executable(translate-server src/main.cpp)
target_link_libraries(translate-server PRIVATE
httplib::httplib
nlohmann_json::nlohmann_json
cpp-llamalib
)
```
`FetchContent_Declare` tells CMake where to find each library, and `FetchContent_MakeAvailable` fetches and builds them. The first `cmake -B build` will take some time because it downloads all libraries and builds llama.cpp, but subsequent runs will use the cache.
Just link with `target_link_libraries`, and each library's CMake configuration sets up include paths and build settings for you.
## 1.5 Creating the Skeleton Code
We'll use this skeleton code as a base and add functionality chapter by chapter.
<!-- data-file="main.cpp" -->
```cpp
// src/main.cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
#include <csignal>
#include <iostream>
using json = nlohmann::json;
httplib::Server svr;
// Graceful shutdown on `Ctrl+C`
void signal_handler(int sig) {
if (sig == SIGINT || sig == SIGTERM) {
std::cout << "\nReceived signal, shutting down gracefully...\n";
svr.stop();
}
}
int main() {
// Log requests and responses
svr.set_logger([](const auto &req, const auto &res) {
std::cout << req.method << " " << req.path << " -> " << res.status
<< std::endl;
});
// Health check
svr.Get("/health", [](const auto &, auto &res) {
res.set_content(json{{"status", "ok"}}.dump(), "application/json");
});
// Stub implementations for each endpoint (replaced with real ones in later chapters)
svr.Post("/translate",
[](const auto &req, auto &res) {
res.set_content(json{{"translation", "TODO"}}.dump(), "application/json");
});
svr.Post("/translate/stream",
[](const auto &req, auto &res) {
res.set_content("data: \"TODO\"\n\ndata: [DONE]\n\n", "text/event-stream");
});
svr.Get("/models",
[](const auto &req, auto &res) {
res.set_content(json{{"models", json::array()}}.dump(), "application/json");
});
svr.Post("/models/select",
[](const auto &req, auto &res) {
res.set_content(json{{"status", "TODO"}}.dump(), "application/json");
});
// Allow the server to be stopped with `Ctrl+C` (`SIGINT`) or `kill` (`SIGTERM`)
signal(SIGINT, signal_handler);
signal(SIGTERM, signal_handler);
// Start the server
std::cout << "Listening on http://127.0.0.1:8080" << std::endl;
svr.listen("127.0.0.1", 8080);
}
```
## 1.6 Building and Verifying
Build the project, start the server, and verify that requests work with curl.
```bash
cmake -B build
cmake --build build -j
./build/translate-server
```
From another terminal, try it with curl.
```bash
curl http://localhost:8080/health
# => {"status":"ok"}
```
If you see JSON come back, the setup is complete.
## Next Chapter
Now that the environment is set up, in the next chapter we'll implement the translation REST API on top of this skeleton. We'll run inference with llama.cpp and expose it as an HTTP endpoint with cpp-httplib.
**Next:** [Integrating llama.cpp to Build a REST API](../ch02-rest-api)

View File

@@ -1,212 +0,0 @@
---
title: "2. Integrating llama.cpp to Build a REST API"
order: 2
---
In the skeleton from Chapter 1, `/translate` simply returned `"TODO"`. In this chapter we integrate llama.cpp inference and turn it into an API that actually returns translation results.
Calling the llama.cpp API directly makes the code quite long, so we use a thin wrapper library called [cpp-llamalib](https://github.com/yhirose/cpp-llamalib). It lets you load a model and run inference in just a few lines, keeping the focus on cpp-httplib.
## 2.1 Initializing the LLM
Simply pass the path to a model file to `llamalib::Llama`, and model loading, context creation, and sampler configuration are all taken care of. If you downloaded a different model in Chapter 1, adjust the path accordingly.
```cpp
#include <cpp-llamalib.h>
int main() {
auto llm = llamalib::Llama{"models/gemma-2-2b-it-Q4_K_M.gguf"};
// LLM inference takes time, so set a longer timeout (default is 5 seconds)
svr.set_read_timeout(300);
svr.set_write_timeout(300);
// ... Build and start the HTTP server ...
}
```
If you want to change the number of GPU layers, context length, or other settings, you can specify them via `llamalib::Options`.
```cpp
auto llm = llamalib::Llama{"models/gemma-2-2b-it-Q4_K_M.gguf", {
.n_gpu_layers = 0, // CPU only
.n_ctx = 4096,
}};
```
## 2.2 The `/translate` Handler
We replace the handler that returned dummy JSON in Chapter 1 with actual inference.
```cpp
svr.Post("/translate",
[&](const httplib::Request &req, httplib::Response &res) {
// Parse JSON (3rd arg `false`: don't throw on failure, check with `is_discarded()`)
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
// Validate required fields
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja"); // Default is Japanese
// Build the prompt and run inference
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
try {
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(),
"application/json");
} catch (const std::exception &e) {
res.status = 500;
res.set_content(json{{"error", e.what()}}.dump(), "application/json");
}
});
```
`llm.chat()` can throw exceptions during inference (for example, when the context length is exceeded). By catching them with `try/catch` and returning the error as JSON, we prevent the server from crashing.
## 2.3 Complete Code
Here is the finished code with all the changes so far.
<details>
<summary data-file="main.cpp">Complete code (main.cpp)</summary>
```cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
#include <cpp-llamalib.h>
#include <csignal>
#include <iostream>
using json = nlohmann::json;
httplib::Server svr;
// Graceful shutdown on `Ctrl+C`
void signal_handler(int sig) {
if (sig == SIGINT || sig == SIGTERM) {
std::cout << "\nReceived signal, shutting down gracefully...\n";
svr.stop();
}
}
int main() {
// Load the model downloaded in Chapter 1
auto llm = llamalib::Llama{"models/gemma-2-2b-it-Q4_K_M.gguf"};
// LLM inference takes time, so set a longer timeout (default is 5 seconds)
svr.set_read_timeout(300);
svr.set_write_timeout(300);
// Log requests and responses
svr.set_logger([](const auto &req, const auto &res) {
std::cout << req.method << " " << req.path << " -> " << res.status
<< std::endl;
});
svr.Get("/health", [](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "ok"}}.dump(), "application/json");
});
svr.Post("/translate",
[&](const httplib::Request &req, httplib::Response &res) {
// Parse JSON (3rd arg `false`: don't throw on failure, check with `is_discarded()`)
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
// Validate required fields
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja"); // Default is Japanese
// Build the prompt and run inference
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
try {
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(),
"application/json");
} catch (const std::exception &e) {
res.status = 500;
res.set_content(json{{"error", e.what()}}.dump(), "application/json");
}
});
// Dummy implementations to be replaced with real ones in later chapters
svr.Get("/models",
[](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"models", json::array()}}.dump(), "application/json");
});
svr.Post("/models/select",
[](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "TODO"}}.dump(), "application/json");
});
// Allow the server to be stopped with `Ctrl+C` (`SIGINT`) or `kill` (`SIGTERM`)
signal(SIGINT, signal_handler);
signal(SIGTERM, signal_handler);
// Start the server (blocks until `stop()` is called)
std::cout << "Listening on http://127.0.0.1:8080" << std::endl;
svr.listen("127.0.0.1", 8080);
}
```
</details>
## 2.4 Testing It Out
Rebuild and start the server, then verify that it now returns actual translation results.
```bash
cmake --build build -j
./build/translate-server
```
```bash
curl -X POST http://localhost:8080/translate \
-H "Content-Type: application/json" \
-d '{"text": "I had a great time visiting Tokyo last spring. The cherry blossoms were beautiful.", "target_lang": "ja"}'
# => {"translation":"去年の春に東京を訪れた。桜が綺麗だった。"}
```
In Chapter 1 the response was `"TODO"`, but now you get an actual translation back.
## Next Chapter
The REST API we built in this chapter waits for the entire translation to complete before sending the response, so for long texts the user has to wait with no indication of progress.
In the next chapter, we use SSE (Server-Sent Events) to stream tokens back in real time as they are generated.
**Next:** [Adding Token Streaming with SSE](../ch03-sse-streaming)

View File

@@ -1,264 +0,0 @@
---
title: "3. Adding Token Streaming with SSE"
order: 3
---
The `/translate` endpoint from Chapter 2 returned the entire translation at once after completion. This is fine for short sentences, but for longer text the user has to wait several seconds with nothing displayed.
In this chapter, we add a `/translate/stream` endpoint that uses SSE (Server-Sent Events) to return tokens in real time as they are generated. This is the same approach used by the ChatGPT and Claude APIs.
## 3.1 What is SSE?
SSE is a way to send HTTP responses as a stream. When a client sends a request, the server keeps the connection open and gradually returns events. The format is simple text.
```text
data: "去年の"
data: "春に"
data: "東京を"
data: [DONE]
```
Each line starts with `data:` and events are separated by blank lines. The Content-Type is `text/event-stream`. Tokens are sent as escaped JSON strings, so they appear enclosed in double quotes (we implement this in Section 3.3).
## 3.2 Streaming with cpp-httplib
In cpp-httplib, you can use `set_chunked_content_provider` to send responses incrementally. Each time you write to `sink.os` inside the callback, data is sent to the client.
```cpp
res.set_chunked_content_provider(
"text/event-stream",
[](size_t offset, httplib::DataSink &sink) {
sink.os << "data: hello\n\n";
sink.done();
return true;
});
```
Calling `sink.done()` ends the stream. If the client disconnects mid-stream, writing to `sink.os` will fail and `sink.os.fail()` will return `true`. You can use this to detect disconnection and abort unnecessary inference.
## 3.3 The `/translate/stream` Handler
JSON parsing and validation are the same as the `/translate` endpoint from Chapter 2. The only difference is how the response is returned. We combine the streaming callback of `llm.chat()` with `set_chunked_content_provider`.
```cpp
svr.Post("/translate/stream",
[&](const httplib::Request &req, httplib::Response &res) {
// ... JSON parsing and validation same as /translate ...
res.set_chunked_content_provider(
"text/event-stream",
[&, prompt](size_t, httplib::DataSink &sink) {
try {
llm.chat(prompt, [&](std::string_view token) {
sink.os << "data: "
<< json(std::string(token)).dump(
-1, ' ', false, json::error_handler_t::replace)
<< "\n\n";
return sink.os.good(); // Abort inference on disconnect
});
sink.os << "data: [DONE]\n\n";
} catch (const std::exception &e) {
sink.os << "data: " << json({{"error", e.what()}}).dump() << "\n\n";
}
sink.done();
return true;
});
});
```
A few key points:
- When you pass a callback to `llm.chat()`, it is called each time a token is generated. If the callback returns `false`, generation is aborted
- After writing to `sink.os`, you can check whether the client is still connected with `sink.os.good()`. If the client has disconnected, it returns `false` to stop inference
- Each token is escaped as a JSON string using `json(token).dump()` before sending. This is safe even for tokens containing newlines or quotes
- The first three arguments of `dump(-1, ' ', false, ...)` are the defaults. What matters is the fourth argument, `json::error_handler_t::replace`. Since the LLM returns tokens at the subword level, multi-byte characters (such as Japanese) can be split mid-character across tokens. Passing an incomplete UTF-8 byte sequence directly to `dump()` would throw an exception, so `replace` safely substitutes them. The browser reassembles the bytes on its end, so everything displays correctly
- The entire lambda is wrapped in `try/catch`. `llm.chat()` can throw exceptions for reasons such as exceeding the context window. If an exception goes uncaught inside the lambda, the server will crash, so we return the error as an SSE event instead
- `data: [DONE]` follows the OpenAI API convention to signal the end of the stream to the client
## 3.4 Complete Code
Here is the complete code with the `/translate/stream` endpoint added to the code from Chapter 2.
<details>
<summary data-file="main.cpp">Complete code (main.cpp)</summary>
```cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
#include <cpp-llamalib.h>
#include <csignal>
#include <iostream>
using json = nlohmann::json;
httplib::Server svr;
// Graceful shutdown on `Ctrl+C`
void signal_handler(int sig) {
if (sig == SIGINT || sig == SIGTERM) {
std::cout << "\nReceived signal, shutting down gracefully...\n";
svr.stop();
}
}
int main() {
// Load the GGUF model
auto llm = llamalib::Llama{"models/gemma-2-2b-it-Q4_K_M.gguf"};
// LLM inference takes time, so set a longer timeout (default is 5 seconds)
svr.set_read_timeout(300);
svr.set_write_timeout(300);
// Log requests and responses
svr.set_logger([](const auto &req, const auto &res) {
std::cout << req.method << " " << req.path << " -> " << res.status
<< std::endl;
});
svr.Get("/health", [](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "ok"}}.dump(), "application/json");
});
// Standard translation endpoint from Chapter 2
svr.Post("/translate",
[&](const httplib::Request &req, httplib::Response &res) {
// JSON parsing and validation (see Chapter 2 for details)
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
try {
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(),
"application/json");
} catch (const std::exception &e) {
res.status = 500;
res.set_content(json{{"error", e.what()}}.dump(), "application/json");
}
});
// SSE streaming translation endpoint
svr.Post("/translate/stream",
[&](const httplib::Request &req, httplib::Response &res) {
// JSON parsing and validation (same as /translate)
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
res.set_chunked_content_provider(
"text/event-stream",
[&, prompt](size_t, httplib::DataSink &sink) {
try {
llm.chat(prompt, [&](std::string_view token) {
sink.os << "data: "
<< json(std::string(token)).dump(
-1, ' ', false, json::error_handler_t::replace)
<< "\n\n";
return sink.os.good(); // Abort inference on disconnect
});
sink.os << "data: [DONE]\n\n";
} catch (const std::exception &e) {
sink.os << "data: " << json({{"error", e.what()}}).dump() << "\n\n";
}
sink.done();
return true;
});
});
// Dummy implementations to be replaced in later chapters
svr.Get("/models",
[](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"models", json::array()}}.dump(), "application/json");
});
svr.Post("/models/select",
[](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "TODO"}}.dump(), "application/json");
});
// Allow the server to be stopped with `Ctrl+C` (`SIGINT`) or `kill` (`SIGTERM`)
signal(SIGINT, signal_handler);
signal(SIGTERM, signal_handler);
// Start the server (blocks until `stop()` is called)
std::cout << "Listening on http://127.0.0.1:8080" << std::endl;
svr.listen("127.0.0.1", 8080);
}
```
</details>
## 3.5 Testing It Out
Build and start the server.
```bash
cmake --build build -j
./build/translate-server
```
Using curl's `-N` option to disable buffering, you can see tokens displayed in real time as they arrive.
```bash
curl -N -X POST http://localhost:8080/translate/stream \
-H "Content-Type: application/json" \
-d '{"text": "I had a great time visiting Tokyo last spring. The cherry blossoms were beautiful.", "target_lang": "ja"}'
```
```text
data: "去年の"
data: "春に"
data: "東京を"
data: "訪れた"
data: "。"
data: "桜が"
data: "綺麗だった"
data: "。"
data: [DONE]
```
You should see tokens streaming in one by one. The `/translate` endpoint from Chapter 2 continues to work as well.
## Next Chapter
The server's translation functionality is now complete. In the next chapter, we use cpp-httplib's client functionality to add the ability to fetch and manage models from Hugging Face.
**Next:** [Adding Model Download and Management](../ch04-model-management)

View File

@@ -1,788 +0,0 @@
---
title: "4. Adding Model Download and Management"
order: 4
---
By the end of Chapter 3, the server's translation functionality was fully in place. However, the only model file available is the one we manually downloaded in Chapter 1. In this chapter, we'll use cpp-httplib's **client functionality** to enable downloading and switching Hugging Face models from within the app.
Once complete, you'll be able to manage models with requests like these:
```bash
# Get the list of available models
curl http://localhost:8080/models
```
```json
{
"models": [
{"name": "gemma-2-2b-it", "params": "2B", "size": "1.6 GB", "downloaded": true, "selected": true},
{"name": "gemma-2-9b-it", "params": "9B", "size": "5.8 GB", "downloaded": false, "selected": false},
{"name": "Llama-3.1-8B-Instruct", "params": "8B", "size": "4.9 GB", "downloaded": false, "selected": false}
]
}
```
```bash
# Select a different model (automatically downloads if not yet available)
curl -N -X POST http://localhost:8080/models/select \
-H "Content-Type: application/json" \
-d '{"model": "gemma-2-9b-it"}'
```
```text
data: {"status":"downloading","progress":0}
data: {"status":"downloading","progress":12}
...
data: {"status":"downloading","progress":100}
data: {"status":"loading"}
data: {"status":"ready"}
```
## 4.1 httplib::Client Basics
So far we've only used `httplib::Server`, but cpp-httplib also provides client functionality. Since Hugging Face uses HTTPS, we need a TLS-capable client.
```cpp
#include <httplib.h>
// Including the URL scheme automatically uses SSLClient
httplib::Client cli("https://huggingface.co");
// Automatically follow redirects (Hugging Face redirects to a CDN)
cli.set_follow_location(true);
auto res = cli.Get("/api/models");
if (res && res->status == 200) {
std::cout << res->body << std::endl;
}
```
To use HTTPS, you need to enable OpenSSL at build time. Add the following to your `CMakeLists.txt`:
```cmake
find_package(OpenSSL REQUIRED)
target_link_libraries(translate-server PRIVATE OpenSSL::SSL OpenSSL::Crypto)
target_compile_definitions(translate-server PRIVATE CPPHTTPLIB_OPENSSL_SUPPORT)
# macOS: required for loading system certificates
if(APPLE)
target_link_libraries(translate-server PRIVATE "-framework CoreFoundation" "-framework Security")
endif()
```
Defining `CPPHTTPLIB_OPENSSL_SUPPORT` enables `httplib::Client("https://...")` to make TLS connections. On macOS, you also need to link the CoreFoundation and Security frameworks to access the system certificate store. See Section 4.8 for the complete `CMakeLists.txt`.
## 4.2 Defining the Model List
Let's define the list of models that the app can handle. Here are four models we've verified for translation tasks.
```cpp
struct ModelInfo {
std::string name; // Display name
std::string params; // Parameter count
std::string size; // GGUF Q4 size
std::string repo; // Hugging Face repository
std::string filename; // GGUF filename
};
const std::vector<ModelInfo> MODELS = {
{
.name = "gemma-2-2b-it",
.params = "2B",
.size = "1.6 GB",
.repo = "bartowski/gemma-2-2b-it-GGUF",
.filename = "gemma-2-2b-it-Q4_K_M.gguf",
},
{
.name = "gemma-2-9b-it",
.params = "9B",
.size = "5.8 GB",
.repo = "bartowski/gemma-2-9b-it-GGUF",
.filename = "gemma-2-9b-it-Q4_K_M.gguf",
},
{
.name = "Llama-3.1-8B-Instruct",
.params = "8B",
.size = "4.9 GB",
.repo = "bartowski/Meta-Llama-3.1-8B-Instruct-GGUF",
.filename = "Meta-Llama-3.1-8B-Instruct-Q4_K_M.gguf",
},
};
```
## 4.3 Model Storage Location
Up through Chapter 3, we stored models in the `models/` directory within the project. However, when managing multiple models, a dedicated app directory makes more sense. On macOS/Linux we use `~/.translate-app/models/`, and on Windows we use `%APPDATA%\translate-app\models\`.
```cpp
std::filesystem::path get_models_dir() {
#ifdef _WIN32
auto env = std::getenv("APPDATA");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / "translate-app" / "models";
#else
auto env = std::getenv("HOME");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / ".translate-app" / "models";
#endif
}
```
If the environment variable isn't set, it falls back to the current directory. The app creates this directory at startup (`create_directories` won't error even if it already exists).
## 4.4 Rewriting Model Initialization
We rewrite the model initialization at the beginning of `main()`. In Chapter 1 we hardcoded the path, but from here on we support model switching. We track the currently loaded filename in `selected_model` and load the first entry in `MODELS` at startup. The `GET /models` and `POST /models/select` handlers reference and update this variable.
Since cpp-httplib runs handlers concurrently on a thread pool, reassigning `llm` while another thread is calling `llm.chat()` would crash. We add a `std::mutex` to protect against this.
```cpp
int main() {
auto models_dir = get_models_dir();
std::filesystem::create_directories(models_dir);
std::string selected_model = MODELS[0].filename;
auto path = models_dir / selected_model;
// Automatically download the default model if not yet present
if (!std::filesystem::exists(path)) {
std::cout << "Downloading " << selected_model << "..." << std::endl;
if (!download_model(MODELS[0], [](int pct) {
std::cout << "\r" << pct << "%" << std::flush;
return true;
})) {
std::cerr << "\nFailed to download model." << std::endl;
return 1;
}
std::cout << std::endl;
}
auto llm = llamalib::Llama{path};
std::mutex llm_mutex; // Protect access during model switching
// ...
}
```
This ensures that users don't need to manually download models with curl on first launch. It uses the `download_model` function from Section 4.6 and displays progress on the console.
## 4.5 The `GET /models` Handler
This returns the model list with information about whether each model has been downloaded and whether it's currently selected.
```cpp
svr.Get("/models",
[&](const httplib::Request &, httplib::Response &res) {
auto arr = json::array();
for (const auto &m : MODELS) {
auto path = get_models_dir() / m.filename;
arr.push_back({
{"name", m.name},
{"params", m.params},
{"size", m.size},
{"downloaded", std::filesystem::exists(path)},
{"selected", m.filename == selected_model},
});
}
res.set_content(json{{"models", arr}}.dump(), "application/json");
});
```
## 4.6 Downloading Large Files
GGUF models are several gigabytes, so we can't load the entire file into memory. By passing callbacks to `httplib::Client::Get`, we can receive data chunk by chunk.
```cpp
// content_receiver: callback that receives data chunks
// progress: download progress callback
cli.Get(url,
[&](const char *data, size_t len) { // content_receiver
ofs.write(data, len);
return true; // returning false aborts the download
},
[&](size_t current, size_t total) { // progress
int pct = total ? (int)(current * 100 / total) : 0;
std::cout << pct << "%" << std::endl;
return true; // returning false aborts the download
});
```
Let's use this to create a function that downloads models from Hugging Face.
```cpp
#include <filesystem>
#include <fstream>
// Download a model and report progress via progress_cb.
// If progress_cb returns false, the download is aborted.
bool download_model(const ModelInfo &model,
std::function<bool(int)> progress_cb) {
httplib::Client cli("https://huggingface.co");
cli.set_follow_location(true);
cli.set_read_timeout(std::chrono::hours(1));
auto url = "/" + model.repo + "/resolve/main/" + model.filename;
auto path = get_models_dir() / model.filename;
auto tmp_path = std::filesystem::path(path).concat(".tmp");
std::ofstream ofs(tmp_path, std::ios::binary);
if (!ofs) { return false; }
auto res = cli.Get(url,
[&](const char *data, size_t len) {
ofs.write(data, len);
return ofs.good();
},
[&](size_t current, size_t total) {
return progress_cb(total ? (int)(current * 100 / total) : 0);
});
ofs.close();
if (!res || res->status != 200) {
std::filesystem::remove(tmp_path);
return false;
}
// Write to .tmp first, then rename, so that an incomplete file
// is never mistaken for a usable model if the download is interrupted
std::filesystem::rename(tmp_path, path);
return true;
}
```
## 4.7 The `/models/select` Handler
This handles model selection requests. We always respond with SSE, reporting status in sequence: download progress, loading, and ready.
```cpp
svr.Post("/models/select",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded() || !input.contains("model")) {
res.status = 400;
res.set_content(json{{"error", "'model' is required"}}.dump(),
"application/json");
return;
}
auto name = input["model"].get<std::string>();
// Find the model in the list
auto it = std::find_if(MODELS.begin(), MODELS.end(),
[&](const ModelInfo &m) { return m.name == name; });
if (it == MODELS.end()) {
res.status = 404;
res.set_content(json{{"error", "Unknown model"}}.dump(),
"application/json");
return;
}
const auto &model = *it;
// Always respond with SSE (same format whether already downloaded or not)
res.set_chunked_content_provider(
"text/event-stream",
[&, model](size_t, httplib::DataSink &sink) {
// SSE event sending helper
auto send = [&](const json &event) {
sink.os << "data: " << event.dump() << "\n\n";
};
// Download if not yet present (report progress via SSE)
auto path = get_models_dir() / model.filename;
if (!std::filesystem::exists(path)) {
bool ok = download_model(model, [&](int pct) {
send({{"status", "downloading"}, {"progress", pct}});
return sink.os.good(); // Abort download on client disconnect
});
if (!ok) {
send({{"status", "error"}, {"message", "Download failed"}});
sink.done();
return true;
}
}
// Load and switch to the model
send({{"status", "loading"}});
{
std::lock_guard<std::mutex> lock(llm_mutex);
llm = llamalib::Llama{path};
selected_model = model.filename;
}
send({{"status", "ready"}});
sink.done();
return true;
});
});
```
A few notes:
- We send SSE events directly from the `download_model` progress callback. This is an application of `set_chunked_content_provider` + `sink.os` from Chapter 3
- Since the callback returns `sink.os.good()`, the download stops if the client disconnects. The cancel button we add in Chapter 5 uses this
- When we update `selected_model`, it's reflected in the `selected` flag of `GET /models`
- The `llm` reassignment is protected by `llm_mutex`. The `/translate` and `/translate/stream` handlers also lock the same mutex, so inference can't run during a model switch (see the complete code)
## 4.8 Complete Code
Here is the complete code with model management added to the Chapter 3 code.
<details>
<summary data-file="CMakeLists.txt">Complete code (CMakeLists.txt)</summary>
```cmake
cmake_minimum_required(VERSION 3.20)
project(translate-server CXX)
set(CMAKE_CXX_STANDARD 20)
include(FetchContent)
# llama.cpp
FetchContent_Declare(llama
GIT_REPOSITORY https://github.com/ggml-org/llama.cpp
GIT_TAG master
GIT_SHALLOW TRUE
)
FetchContent_MakeAvailable(llama)
# cpp-httplib
FetchContent_Declare(httplib
GIT_REPOSITORY https://github.com/yhirose/cpp-httplib
GIT_TAG master
)
FetchContent_MakeAvailable(httplib)
# nlohmann/json
FetchContent_Declare(json
URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz
)
FetchContent_MakeAvailable(json)
# cpp-llamalib
FetchContent_Declare(cpp_llamalib
GIT_REPOSITORY https://github.com/yhirose/cpp-llamalib
GIT_TAG main
)
FetchContent_MakeAvailable(cpp_llamalib)
find_package(OpenSSL REQUIRED)
add_executable(translate-server src/main.cpp)
target_link_libraries(translate-server PRIVATE
httplib::httplib
nlohmann_json::nlohmann_json
cpp-llamalib
OpenSSL::SSL OpenSSL::Crypto
)
target_compile_definitions(translate-server PRIVATE CPPHTTPLIB_OPENSSL_SUPPORT)
if(APPLE)
target_link_libraries(translate-server PRIVATE
"-framework CoreFoundation"
"-framework Security"
)
endif()
```
</details>
<details>
<summary data-file="main.cpp">Complete code (main.cpp)</summary>
```cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
#include <cpp-llamalib.h>
#include <algorithm>
#include <csignal>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <mutex>
using json = nlohmann::json;
// -------------------------------------------------------------------------
// Model definitions
// -------------------------------------------------------------------------
struct ModelInfo {
std::string name;
std::string params;
std::string size;
std::string repo;
std::string filename;
};
const std::vector<ModelInfo> MODELS = {
{
.name = "gemma-2-2b-it",
.params = "2B",
.size = "1.6 GB",
.repo = "bartowski/gemma-2-2b-it-GGUF",
.filename = "gemma-2-2b-it-Q4_K_M.gguf",
},
{
.name = "gemma-2-9b-it",
.params = "9B",
.size = "5.8 GB",
.repo = "bartowski/gemma-2-9b-it-GGUF",
.filename = "gemma-2-9b-it-Q4_K_M.gguf",
},
{
.name = "Llama-3.1-8B-Instruct",
.params = "8B",
.size = "4.9 GB",
.repo = "bartowski/Meta-Llama-3.1-8B-Instruct-GGUF",
.filename = "Meta-Llama-3.1-8B-Instruct-Q4_K_M.gguf",
},
};
// -------------------------------------------------------------------------
// Model storage directory
// -------------------------------------------------------------------------
std::filesystem::path get_models_dir() {
#ifdef _WIN32
auto env = std::getenv("APPDATA");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / "translate-app" / "models";
#else
auto env = std::getenv("HOME");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / ".translate-app" / "models";
#endif
}
// -------------------------------------------------------------------------
// Model download
// -------------------------------------------------------------------------
// If progress_cb returns false, the download is aborted
bool download_model(const ModelInfo &model,
std::function<bool(int)> progress_cb) {
httplib::Client cli("https://huggingface.co");
cli.set_follow_location(true); // Hugging Face redirects to a CDN
cli.set_read_timeout(std::chrono::hours(1)); // Set a long timeout for large models
auto url = "/" + model.repo + "/resolve/main/" + model.filename;
auto path = get_models_dir() / model.filename;
auto tmp_path = std::filesystem::path(path).concat(".tmp");
std::ofstream ofs(tmp_path, std::ios::binary);
if (!ofs) { return false; }
auto res = cli.Get(url,
// content_receiver: receive data chunk by chunk and write to file
[&](const char *data, size_t len) {
ofs.write(data, len);
return ofs.good();
},
// progress: report download progress (returning false aborts)
[&, last_pct = -1](size_t current, size_t total) mutable {
int pct = total ? (int)(current * 100 / total) : 0;
if (pct == last_pct) return true; // Skip if same value
last_pct = pct;
return progress_cb(pct);
});
ofs.close();
if (!res || res->status != 200) {
std::filesystem::remove(tmp_path);
return false;
}
// Rename after download completes
std::filesystem::rename(tmp_path, path);
return true;
}
// -------------------------------------------------------------------------
// Server
// -------------------------------------------------------------------------
httplib::Server svr;
void signal_handler(int sig) {
if (sig == SIGINT || sig == SIGTERM) {
std::cout << "\nReceived signal, shutting down gracefully...\n";
svr.stop();
}
}
int main() {
// Create the model storage directory
auto models_dir = get_models_dir();
std::filesystem::create_directories(models_dir);
// Automatically download the default model if not yet present
std::string selected_model = MODELS[0].filename;
auto path = models_dir / selected_model;
if (!std::filesystem::exists(path)) {
std::cout << "Downloading " << selected_model << "..." << std::endl;
if (!download_model(MODELS[0], [](int pct) {
std::cout << "\r" << pct << "%" << std::flush;
return true;
})) {
std::cerr << "\nFailed to download model." << std::endl;
return 1;
}
std::cout << std::endl;
}
auto llm = llamalib::Llama{path};
std::mutex llm_mutex; // Protect access during model switching
// Set a long timeout since LLM inference takes time (default is 5 seconds)
svr.set_read_timeout(300);
svr.set_write_timeout(300);
svr.set_logger([](const auto &req, const auto &res) {
std::cout << req.method << " " << req.path << " -> " << res.status
<< std::endl;
});
svr.Get("/health", [](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "ok"}}.dump(), "application/json");
});
// --- Translation endpoint (Chapter 2) ------------------------------------
svr.Post("/translate",
[&](const httplib::Request &req, httplib::Response &res) {
// JSON parsing and validation (see Chapter 2 for details)
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
try {
std::lock_guard<std::mutex> lock(llm_mutex);
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(),
"application/json");
} catch (const std::exception &e) {
res.status = 500;
res.set_content(json{{"error", e.what()}}.dump(), "application/json");
}
});
// --- SSE streaming translation (Chapter 3) -------------------------------
svr.Post("/translate/stream",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
res.set_chunked_content_provider(
"text/event-stream",
[&, prompt](size_t, httplib::DataSink &sink) {
std::lock_guard<std::mutex> lock(llm_mutex);
try {
llm.chat(prompt, [&](std::string_view token) {
sink.os << "data: "
<< json(std::string(token)).dump(
-1, ' ', false, json::error_handler_t::replace)
<< "\n\n";
return sink.os.good(); // Abort inference on disconnect
});
sink.os << "data: [DONE]\n\n";
} catch (const std::exception &e) {
sink.os << "data: " << json({{"error", e.what()}}).dump() << "\n\n";
}
sink.done();
return true;
});
});
// --- Model list (Chapter 4) ----------------------------------------------
svr.Get("/models",
[&](const httplib::Request &, httplib::Response &res) {
auto models_dir = get_models_dir();
auto arr = json::array();
for (const auto &m : MODELS) {
auto path = models_dir / m.filename;
arr.push_back({
{"name", m.name},
{"params", m.params},
{"size", m.size},
{"downloaded", std::filesystem::exists(path)},
{"selected", m.filename == selected_model},
});
}
res.set_content(json{{"models", arr}}.dump(), "application/json");
});
// --- Model selection (Chapter 4) -----------------------------------------
svr.Post("/models/select",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded() || !input.contains("model")) {
res.status = 400;
res.set_content(json{{"error", "'model' is required"}}.dump(),
"application/json");
return;
}
auto name = input["model"].get<std::string>();
auto it = std::find_if(MODELS.begin(), MODELS.end(),
[&](const ModelInfo &m) { return m.name == name; });
if (it == MODELS.end()) {
res.status = 404;
res.set_content(json{{"error", "Unknown model"}}.dump(),
"application/json");
return;
}
const auto &model = *it;
// Always respond with SSE (same format whether already downloaded or not)
res.set_chunked_content_provider(
"text/event-stream",
[&, model](size_t, httplib::DataSink &sink) {
// SSE event sending helper
auto send = [&](const json &event) {
sink.os << "data: " << event.dump() << "\n\n";
};
// Download if not yet present (report progress via SSE)
auto path = get_models_dir() / model.filename;
if (!std::filesystem::exists(path)) {
bool ok = download_model(model, [&](int pct) {
send({{"status", "downloading"}, {"progress", pct}});
return sink.os.good(); // Abort download on client disconnect
});
if (!ok) {
send({{"status", "error"}, {"message", "Download failed"}});
sink.done();
return true;
}
}
// Load and switch to the model
send({{"status", "loading"}});
{
std::lock_guard<std::mutex> lock(llm_mutex);
llm = llamalib::Llama{path};
selected_model = model.filename;
}
send({{"status", "ready"}});
sink.done();
return true;
});
});
// Allow the server to be stopped with `Ctrl+C` (`SIGINT`) or `kill` (`SIGTERM`)
signal(SIGINT, signal_handler);
signal(SIGTERM, signal_handler);
std::cout << "Listening on http://127.0.0.1:8080" << std::endl;
svr.listen("127.0.0.1", 8080);
}
```
</details>
## 4.9 Testing
Since we added OpenSSL configuration to CMakeLists.txt, we need to re-run CMake before building.
```bash
cmake -B build
cmake --build build -j
./build/translate-server
```
### Checking the Model List
```bash
curl http://localhost:8080/models
```
The gemma-2-2b-it model downloaded in Chapter 1 should show `downloaded: true` and `selected: true`.
### Switching to a Different Model
```bash
curl -N -X POST http://localhost:8080/models/select \
-H "Content-Type: application/json" \
-d '{"model": "gemma-2-9b-it"}'
```
Download progress streams via SSE, and `"ready"` appears when it's done.
### Comparing Translations Across Models
Let's translate the same sentence with different models.
```bash
# Translate with gemma-2-9b-it (the model we just switched to)
curl -X POST http://localhost:8080/translate \
-H "Content-Type: application/json" \
-d '{"text": "The quick brown fox jumps over the lazy dog.", "target_lang": "ja"}'
# Switch back to gemma-2-2b-it
curl -N -X POST http://localhost:8080/models/select \
-H "Content-Type: application/json" \
-d '{"model": "gemma-2-2b-it"}'
# Translate the same sentence
curl -X POST http://localhost:8080/translate \
-H "Content-Type: application/json" \
-d '{"text": "The quick brown fox jumps over the lazy dog.", "target_lang": "ja"}'
```
Translation results vary depending on the model, even with the same code and the same prompt. Since cpp-llamalib automatically applies the appropriate chat template for each model, no code changes are needed.
## Next Chapter
The server's main features are now complete: REST API, SSE streaming, and model download and switching. In the next chapter, we'll add static file serving and build a Web UI you can use from a browser.
**Next:** [Adding a Web UI](../ch05-web-ui)

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@@ -1,724 +0,0 @@
---
title: "6. Turning It into a Desktop App with WebView"
order: 6
---
In Chapter 5, we completed a translation app you can use from a browser. But every time, you have to start the server, open the URL in a browser... Wouldn't it be nice to just double-click and start using it, like a normal app?
In this chapter, we'll do two things:
1. **WebView integration** — Use [webview/webview](https://github.com/webview/webview) to turn it into a desktop app that runs without a browser
2. **Single binary packaging** — Use [cpp-embedlib](https://github.com/yhirose/cpp-embedlib) to embed HTML/CSS/JS into the binary, making the distributable a single file
When finished, you'll be able to just run `./translate-app` to open a window and start translating.
![Desktop App](../app.png#large-center)
The model downloads automatically on first launch, so the only thing you need to give users is the single binary.
## 6.1 Introducing webview/webview
[webview/webview](https://github.com/webview/webview) is a library that lets you use the OS's native WebView component (WKWebView on macOS, WebKitGTK on Linux, WebView2 on Windows) from C/C++. Unlike Electron, it doesn't bundle its own browser, so the impact on binary size is negligible.
We'll fetch it with CMake. Add the following to your `CMakeLists.txt`:
```cmake
# webview/webview
FetchContent_Declare(webview
GIT_REPOSITORY https://github.com/webview/webview
GIT_TAG master
)
FetchContent_MakeAvailable(webview)
```
This makes the `webview::core` CMake target available. When you link it with `target_link_libraries`, it automatically sets up include paths and platform-specific frameworks.
> **macOS**: No additional dependencies are needed. WKWebView is built into the system.
>
> **Linux**: WebKitGTK is required. Install it with `sudo apt install libwebkit2gtk-4.1-dev`.
>
> **Windows**: The WebView2 runtime is required. It comes pre-installed on Windows 11. For Windows 10, download it from the [official Microsoft website](https://developer.microsoft.com/en-us/microsoft-edge/webview2/).
## 6.2 Running the Server on a Background Thread
Up through Chapter 5, the server's `listen()` was blocking the main thread. To use WebView, we need to run the server on a separate thread and run the WebView event loop on the main thread.
```cpp
#include "webview/webview.h"
#include <thread>
int main() {
// ... (server setup is the same as Chapter 5) ...
// Start the server on a background thread
auto port = svr.bind_to_any_port("127.0.0.1");
std::thread server_thread([&]() { svr.listen_after_bind(); });
std::cout << "Listening on http://127.0.0.1:" << port << std::endl;
// Display the UI with WebView
webview::webview w(false, nullptr);
w.set_title("Translate App");
w.set_size(1024, 768, WEBVIEW_HINT_NONE);
w.navigate("http://127.0.0.1:" + std::to_string(port));
w.run(); // Block until the window is closed
// Stop the server when the window is closed
svr.stop();
server_thread.join();
}
```
Let's look at the key points:
- **`bind_to_any_port`** — Instead of `listen("127.0.0.1", 8080)`, we let the OS choose an available port. Since desktop apps can be launched multiple times, using a fixed port would cause conflicts
- **`listen_after_bind`** — Starts accepting requests on the port reserved by `bind_to_any_port`. While `listen()` does bind and listen in one call, we need to know the port number first, so we split the operations
- **Shutdown order** — When the WebView window is closed, we stop the server with `svr.stop()` and wait for the thread to finish with `server_thread.join()`. If we reversed the order, WebView would lose access to the server
The `signal_handler` from Chapter 5 is no longer needed. In a desktop app, closing the window means terminating the application.
## 6.3 Embedding Static Files with cpp-embedlib
In Chapter 5, we served files from the `public/` directory, so you'd need to distribute `public/` alongside the binary. With [cpp-embedlib](https://github.com/yhirose/cpp-embedlib), you can embed HTML, CSS, and JavaScript into the binary, packaging the distributable into a single file.
### CMakeLists.txt
Fetch cpp-embedlib and embed `public/`:
```cmake
# cpp-embedlib
FetchContent_Declare(cpp-embedlib
GIT_REPOSITORY https://github.com/yhirose/cpp-embedlib
GIT_TAG main
)
FetchContent_MakeAvailable(cpp-embedlib)
# Embed the public/ directory into the binary
cpp_embedlib_add(WebAssets
FOLDER ${CMAKE_CURRENT_SOURCE_DIR}/public
NAMESPACE Web
)
target_link_libraries(translate-app PRIVATE
WebAssets # Embedded files
cpp-embedlib-httplib # cpp-httplib integration
)
```
`cpp_embedlib_add` converts the files under `public/` into binary data at compile time and creates a static library called `WebAssets`. When linked, you can access the embedded files through a `Web::FS` object. `cpp-embedlib-httplib` is a helper library that provides the `httplib::mount()` function.
### Replacing set_mount_point with httplib::mount
Simply replace Chapter 5's `set_mount_point` with cpp-embedlib's `httplib::mount`:
```cpp
#include <cpp-embedlib-httplib.h>
#include "WebAssets.h"
// Chapter 5:
// svr.set_mount_point("/", "./public");
// Chapter 6:
httplib::mount(svr, Web::FS);
```
`httplib::mount` registers handlers that serve the files embedded in `Web::FS` over HTTP. MIME types are automatically determined from file extensions, so there's no need to manually set `Content-Type`.
The file contents are directly mapped to the binary's data segment, so no memory copies or heap allocations occur.
## 6.4 macOS: Adding the Edit Menu
If you try to paste text into the input field with `Cmd+V`, you'll find it doesn't work. On macOS, keyboard shortcuts like `Cmd+V` (paste) and `Cmd+C` (copy) are routed through the application's menu bar. Since webview/webview doesn't create one, these shortcuts never reach the WebView. We need to add a macOS Edit menu using the Objective-C runtime:
```cpp
#ifdef __APPLE__
#include <objc/objc-runtime.h>
void setup_macos_edit_menu() {
auto cls = [](const char *n) { return (id)objc_getClass(n); };
auto sel = sel_registerName;
auto msg = reinterpret_cast<id (*)(id, SEL)>(objc_msgSend);
auto msg_s = reinterpret_cast<id (*)(id, SEL, const char *)>(objc_msgSend);
auto msg_id = reinterpret_cast<id (*)(id, SEL, id)>(objc_msgSend);
auto msg_v = reinterpret_cast<void (*)(id, SEL, id)>(objc_msgSend);
auto msg_mi = reinterpret_cast<id (*)(id, SEL, id, SEL, id)>(objc_msgSend);
auto str = [&](const char *s) {
return msg_s(cls("NSString"), sel("stringWithUTF8String:"), s);
};
id app = msg(cls("NSApplication"), sel("sharedApplication"));
id mainMenu = msg(msg(cls("NSMenu"), sel("alloc")), sel("init"));
id editItem = msg(msg(cls("NSMenuItem"), sel("alloc")), sel("init"));
id editMenu = msg_id(msg(cls("NSMenu"), sel("alloc")),
sel("initWithTitle:"), str("Edit"));
struct { const char *title; const char *action; const char *key; } items[] = {
{"Undo", "undo:", "z"},
{"Redo", "redo:", "Z"},
{"Cut", "cut:", "x"},
{"Copy", "copy:", "c"},
{"Paste", "paste:", "v"},
{"Select All", "selectAll:", "a"},
};
for (auto &[title, action, key] : items) {
id mi = msg_mi(msg(cls("NSMenuItem"), sel("alloc")),
sel("initWithTitle:action:keyEquivalent:"),
str(title), sel(action), str(key));
msg_v(editMenu, sel("addItem:"), mi);
}
msg_v(editItem, sel("setSubmenu:"), editMenu);
msg_v(mainMenu, sel("addItem:"), editItem);
msg_v(app, sel("setMainMenu:"), mainMenu);
}
#endif
```
Call this before `w.run()`:
```cpp
#ifdef __APPLE__
setup_macos_edit_menu();
#endif
w.run();
```
On Windows and Linux, keyboard shortcuts are delivered directly to the focused control without going through the menu bar, so this workaround is macOS-specific.
## 6.5 Complete Code
<details>
<summary data-file="CMakeLists.txt">Complete code (CMakeLists.txt)</summary>
```cmake
cmake_minimum_required(VERSION 3.20)
project(translate-app CXX)
set(CMAKE_CXX_STANDARD 20)
include(FetchContent)
# llama.cpp
FetchContent_Declare(llama
GIT_REPOSITORY https://github.com/ggml-org/llama.cpp
GIT_TAG master
GIT_SHALLOW TRUE
)
FetchContent_MakeAvailable(llama)
# cpp-httplib
FetchContent_Declare(httplib
GIT_REPOSITORY https://github.com/yhirose/cpp-httplib
GIT_TAG master
)
FetchContent_MakeAvailable(httplib)
# nlohmann/json
FetchContent_Declare(json
URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz
)
FetchContent_MakeAvailable(json)
# cpp-llamalib
FetchContent_Declare(cpp_llamalib
GIT_REPOSITORY https://github.com/yhirose/cpp-llamalib
GIT_TAG main
)
FetchContent_MakeAvailable(cpp_llamalib)
# webview/webview
FetchContent_Declare(webview
GIT_REPOSITORY https://github.com/webview/webview
GIT_TAG master
)
FetchContent_MakeAvailable(webview)
# cpp-embedlib
FetchContent_Declare(cpp-embedlib
GIT_REPOSITORY https://github.com/yhirose/cpp-embedlib
GIT_TAG main
)
FetchContent_MakeAvailable(cpp-embedlib)
# Embed the public/ directory into the binary
cpp_embedlib_add(WebAssets
FOLDER ${CMAKE_CURRENT_SOURCE_DIR}/public
NAMESPACE Web
)
find_package(OpenSSL REQUIRED)
add_executable(translate-app src/main.cpp)
target_link_libraries(translate-app PRIVATE
httplib::httplib
nlohmann_json::nlohmann_json
cpp-llamalib
OpenSSL::SSL OpenSSL::Crypto
WebAssets
cpp-embedlib-httplib
webview::core
)
if(APPLE)
target_link_libraries(translate-app PRIVATE
"-framework CoreFoundation"
"-framework Security"
)
endif()
target_compile_definitions(translate-app PRIVATE
CPPHTTPLIB_OPENSSL_SUPPORT
)
```
</details>
<details>
<summary data-file="main.cpp">Complete code (main.cpp)</summary>
```cpp
#include <httplib.h>
#include <nlohmann/json.hpp>
#include <cpp-llamalib.h>
#include <cpp-embedlib-httplib.h>
#include "WebAssets.h"
#include "webview/webview.h"
#ifdef __APPLE__
#include <objc/objc-runtime.h>
#endif
#include <algorithm>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <mutex>
#include <thread>
using json = nlohmann::json;
// -------------------------------------------------------------------------
// macOS Edit menu (Cmd+C/V/X/A require an Edit menu on macOS)
// -------------------------------------------------------------------------
#ifdef __APPLE__
void setup_macos_edit_menu() {
auto cls = [](const char *n) { return (id)objc_getClass(n); };
auto sel = sel_registerName;
auto msg = reinterpret_cast<id (*)(id, SEL)>(objc_msgSend);
auto msg_s = reinterpret_cast<id (*)(id, SEL, const char *)>(objc_msgSend);
auto msg_id = reinterpret_cast<id (*)(id, SEL, id)>(objc_msgSend);
auto msg_v = reinterpret_cast<void (*)(id, SEL, id)>(objc_msgSend);
auto msg_mi = reinterpret_cast<id (*)(id, SEL, id, SEL, id)>(objc_msgSend);
auto str = [&](const char *s) {
return msg_s(cls("NSString"), sel("stringWithUTF8String:"), s);
};
id app = msg(cls("NSApplication"), sel("sharedApplication"));
id mainMenu = msg(msg(cls("NSMenu"), sel("alloc")), sel("init"));
id editItem = msg(msg(cls("NSMenuItem"), sel("alloc")), sel("init"));
id editMenu = msg_id(msg(cls("NSMenu"), sel("alloc")),
sel("initWithTitle:"), str("Edit"));
struct { const char *title; const char *action; const char *key; } items[] = {
{"Undo", "undo:", "z"},
{"Redo", "redo:", "Z"},
{"Cut", "cut:", "x"},
{"Copy", "copy:", "c"},
{"Paste", "paste:", "v"},
{"Select All", "selectAll:", "a"},
};
for (auto &[title, action, key] : items) {
id mi = msg_mi(msg(cls("NSMenuItem"), sel("alloc")),
sel("initWithTitle:action:keyEquivalent:"),
str(title), sel(action), str(key));
msg_v(editMenu, sel("addItem:"), mi);
}
msg_v(editItem, sel("setSubmenu:"), editMenu);
msg_v(mainMenu, sel("addItem:"), editItem);
msg_v(app, sel("setMainMenu:"), mainMenu);
}
#endif
// -------------------------------------------------------------------------
// Model definitions
// -------------------------------------------------------------------------
struct ModelInfo {
std::string name;
std::string params;
std::string size;
std::string repo;
std::string filename;
};
const std::vector<ModelInfo> MODELS = {
{
.name = "gemma-2-2b-it",
.params = "2B",
.size = "1.6 GB",
.repo = "bartowski/gemma-2-2b-it-GGUF",
.filename = "gemma-2-2b-it-Q4_K_M.gguf",
},
{
.name = "gemma-2-9b-it",
.params = "9B",
.size = "5.8 GB",
.repo = "bartowski/gemma-2-9b-it-GGUF",
.filename = "gemma-2-9b-it-Q4_K_M.gguf",
},
{
.name = "Llama-3.1-8B-Instruct",
.params = "8B",
.size = "4.9 GB",
.repo = "bartowski/Meta-Llama-3.1-8B-Instruct-GGUF",
.filename = "Meta-Llama-3.1-8B-Instruct-Q4_K_M.gguf",
},
};
// -------------------------------------------------------------------------
// Model storage directory
// -------------------------------------------------------------------------
std::filesystem::path get_models_dir() {
#ifdef _WIN32
auto env = std::getenv("APPDATA");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / "translate-app" / "models";
#else
auto env = std::getenv("HOME");
auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
return base / ".translate-app" / "models";
#endif
}
// -------------------------------------------------------------------------
// Model download
// -------------------------------------------------------------------------
// Abort the download if progress_cb returns false
bool download_model(const ModelInfo &model,
std::function<bool(int)> progress_cb) {
httplib::Client cli("https://huggingface.co");
cli.set_follow_location(true); // Hugging Face redirects to a CDN
cli.set_read_timeout(std::chrono::hours(1)); // Long timeout for large models
auto url = "/" + model.repo + "/resolve/main/" + model.filename;
auto path = get_models_dir() / model.filename;
auto tmp_path = std::filesystem::path(path).concat(".tmp");
std::ofstream ofs(tmp_path, std::ios::binary);
if (!ofs) { return false; }
auto res = cli.Get(url,
// content_receiver: Receive data chunk by chunk and write to file
[&](const char *data, size_t len) {
ofs.write(data, len);
return ofs.good();
},
// progress: Report download progress (return false to abort)
[&, last_pct = -1](size_t current, size_t total) mutable {
int pct = total ? (int)(current * 100 / total) : 0;
if (pct == last_pct) return true; // Skip if the value hasn't changed
last_pct = pct;
return progress_cb(pct);
});
ofs.close();
if (!res || res->status != 200) {
std::filesystem::remove(tmp_path);
return false;
}
// Rename after download completes
std::filesystem::rename(tmp_path, path);
return true;
}
// -------------------------------------------------------------------------
// Server
// -------------------------------------------------------------------------
int main() {
httplib::Server svr;
// Create the model storage directory
auto models_dir = get_models_dir();
std::filesystem::create_directories(models_dir);
// Auto-download the default model if not already present
std::string selected_model = MODELS[0].filename;
auto path = models_dir / selected_model;
if (!std::filesystem::exists(path)) {
std::cout << "Downloading " << selected_model << "..." << std::endl;
if (!download_model(MODELS[0], [](int pct) {
std::cout << "\r" << pct << "%" << std::flush;
return true;
})) {
std::cerr << "\nFailed to download model." << std::endl;
return 1;
}
std::cout << std::endl;
}
auto llm = llamalib::Llama{path};
std::mutex llm_mutex; // Protect access during model switching
// Set a long timeout since LLM inference takes time (default is 5 seconds)
svr.set_read_timeout(300);
svr.set_write_timeout(300);
svr.set_logger([](const auto &req, const auto &res) {
std::cout << req.method << " " << req.path << " -> " << res.status
<< std::endl;
});
svr.Get("/health", [](const httplib::Request &, httplib::Response &res) {
res.set_content(json{{"status", "ok"}}.dump(), "application/json");
});
// --- Translation endpoint (Chapter 2) ------------------------------------
svr.Post("/translate",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
try {
std::lock_guard<std::mutex> lock(llm_mutex);
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(),
"application/json");
} catch (const std::exception &e) {
res.status = 500;
res.set_content(json{{"error", e.what()}}.dump(), "application/json");
}
});
// --- SSE streaming translation (Chapter 3) -------------------------------
svr.Post("/translate/stream",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded()) {
res.status = 400;
res.set_content(json{{"error", "Invalid JSON"}}.dump(),
"application/json");
return;
}
if (!input.contains("text") || !input["text"].is_string() ||
input["text"].get<std::string>().empty()) {
res.status = 400;
res.set_content(json{{"error", "'text' is required"}}.dump(),
"application/json");
return;
}
auto text = input["text"].get<std::string>();
auto target_lang = input.value("target_lang", "ja");
auto prompt = "Translate the following text to " + target_lang +
". Output only the translation, nothing else.\n\n" + text;
res.set_chunked_content_provider(
"text/event-stream",
[&, prompt](size_t, httplib::DataSink &sink) {
std::lock_guard<std::mutex> lock(llm_mutex);
try {
llm.chat(prompt, [&](std::string_view token) {
sink.os << "data: "
<< json(std::string(token)).dump(
-1, ' ', false, json::error_handler_t::replace)
<< "\n\n";
return sink.os.good(); // Abort inference on disconnect
});
sink.os << "data: [DONE]\n\n";
} catch (const std::exception &e) {
sink.os << "data: " << json({{"error", e.what()}}).dump() << "\n\n";
}
sink.done();
return true;
});
});
// --- Model list (Chapter 4) ----------------------------------------------
svr.Get("/models",
[&](const httplib::Request &, httplib::Response &res) {
auto models_dir = get_models_dir();
auto arr = json::array();
for (const auto &m : MODELS) {
auto path = models_dir / m.filename;
arr.push_back({
{"name", m.name},
{"params", m.params},
{"size", m.size},
{"downloaded", std::filesystem::exists(path)},
{"selected", m.filename == selected_model},
});
}
res.set_content(json{{"models", arr}}.dump(), "application/json");
});
// --- Model selection (Chapter 4) -----------------------------------------
svr.Post("/models/select",
[&](const httplib::Request &req, httplib::Response &res) {
auto input = json::parse(req.body, nullptr, false);
if (input.is_discarded() || !input.contains("model")) {
res.status = 400;
res.set_content(json{{"error", "'model' is required"}}.dump(),
"application/json");
return;
}
auto name = input["model"].get<std::string>();
auto it = std::find_if(MODELS.begin(), MODELS.end(),
[&](const ModelInfo &m) { return m.name == name; });
if (it == MODELS.end()) {
res.status = 404;
res.set_content(json{{"error", "Unknown model"}}.dump(),
"application/json");
return;
}
const auto &model = *it;
// Always respond with SSE (same format whether downloaded or not)
res.set_chunked_content_provider(
"text/event-stream",
[&, model](size_t, httplib::DataSink &sink) {
// SSE event sending helper
auto send = [&](const json &event) {
sink.os << "data: " << event.dump() << "\n\n";
};
// Download if not yet downloaded (report progress via SSE)
auto path = get_models_dir() / model.filename;
if (!std::filesystem::exists(path)) {
bool ok = download_model(model, [&](int pct) {
send({{"status", "downloading"}, {"progress", pct}});
return sink.os.good(); // Abort download on client disconnect
});
if (!ok) {
send({{"status", "error"}, {"message", "Download failed"}});
sink.done();
return true;
}
}
// Load and switch to the model
send({{"status", "loading"}});
{
std::lock_guard<std::mutex> lock(llm_mutex);
llm = llamalib::Llama{path};
selected_model = model.filename;
}
send({{"status", "ready"}});
sink.done();
return true;
});
});
// --- Embedded file serving (Chapter 6) ------------------------------------
// Chapter 5: svr.set_mount_point("/", "./public");
httplib::mount(svr, Web::FS);
// Start the server on a background thread
auto port = svr.bind_to_any_port("127.0.0.1");
std::thread server_thread([&]() { svr.listen_after_bind(); });
std::cout << "Listening on http://127.0.0.1:" << port << std::endl;
// Display the UI with WebView
webview::webview w(false, nullptr);
w.set_title("Translate App");
w.set_size(1024, 768, WEBVIEW_HINT_NONE);
w.navigate("http://127.0.0.1:" + std::to_string(port));
#ifdef __APPLE__
setup_macos_edit_menu();
#endif
w.run(); // Block until the window is closed
// Stop the server when the window is closed
svr.stop();
server_thread.join();
}
```
</details>
To summarize the changes from Chapter 5:
- `#include <csignal>` replaced with `#include <thread>`, `<cpp-embedlib-httplib.h>`, `"WebAssets.h"`, `"webview/webview.h"`
- Removed the `signal_handler` function
- `svr.set_mount_point("/", "./public")` replaced with `httplib::mount(svr, Web::FS)`
- `svr.listen("127.0.0.1", 8080)` replaced with `bind_to_any_port` + `listen_after_bind` + WebView event loop
Not a single line of handler code has changed. The REST API, SSE streaming, and model management built through Chapter 5 all work as-is.
## 6.6 Building and Testing
```bash
cmake -B build
cmake --build build -j
```
Launch the app:
```bash
./build/translate-app
```
No browser is needed. A window opens automatically. The same UI from Chapter 5 appears as-is, and translation and model switching all work just the same.
When you close the window, the server shuts down automatically. There's no need for `Ctrl+C`.
### What Needs to Be Distributed
You only need to distribute:
- The single `translate-app` binary
That's it. You don't need the `public/` directory. HTML, CSS, and JavaScript are embedded in the binary. Model files download automatically on first launch, so there's no need to ask users to prepare anything in advance.
## Next Chapter
Congratulations! 🎉
In Chapter 1, `/health` just returned `{"status":"ok"}`. Now we have a desktop app where you type text and translations stream in real time, pick a different model from a dropdown and it downloads automatically, and closing the window cleanly shuts everything down — all in a single distributable binary.
What we changed in this chapter was just the static file serving and the server startup. Not a single line of handler code changed. The REST API, SSE streaming, and model management we built through Chapter 5 all work as a desktop app, as-is.
In the next chapter, we'll shift perspective and read through the code of llama.cpp's own `llama-server`. Let's compare our simple server with a production-quality one and see what design decisions differ and why.
**Next:** [Reading the llama.cpp Server Source Code](../ch07-code-reading)

View File

@@ -1,154 +0,0 @@
---
title: "7. Reading the llama.cpp Server Source Code"
order: 7
---
Over the course of six chapters, we built a translation desktop app from scratch. We have a working product, but it's ultimately a "learning-oriented" implementation. So how does "production-quality" code differ? Let's read the source code of `llama-server`, the official server bundled with llama.cpp, and compare.
`llama-server` is located at `llama.cpp/tools/server/`. It uses the same cpp-httplib, so you can read the code the same way as in the previous chapters.
## 7.1 Source Code Location
```ascii
llama.cpp/tools/server/
├── server.cpp # Main server implementation
├── httplib.h # cpp-httplib (bundled version)
└── ...
```
The code is contained in a single `server.cpp`. It runs to several thousand lines, but once you understand the structure, you can narrow down the parts worth reading.
## 7.2 OpenAI-Compatible API
The biggest difference between the server we built and `llama-server` is the API design.
**Our API:**
```text
POST /translate → {"translation": "..."}
POST /translate/stream → SSE: data: "token"
```
**llama-server's API:**
```text
POST /v1/chat/completions → OpenAI-compatible JSON
POST /v1/completions → OpenAI-compatible JSON
POST /v1/embeddings → Text embedding vectors
```
`llama-server` conforms to [OpenAI's API specification](https://platform.openai.com/docs/api-reference). This means OpenAI's official client libraries (such as the Python `openai` package) work out of the box.
```python
# Example of connecting to llama-server with the OpenAI client
from openai import OpenAI
client = OpenAI(base_url="http://localhost:8080/v1", api_key="dummy")
response = client.chat.completions.create(
model="local-model",
messages=[{"role": "user", "content": "Hello!"}]
)
```
Compatibility with existing tools and libraries is a big design decision. We designed a simple translation-specific API, but if you're building a general-purpose server, OpenAI compatibility has become the de facto standard.
## 7.3 Concurrent Request Handling
Our server processes requests one at a time. If another request arrives while a translation is in progress, it waits until the previous inference finishes. This is fine for a desktop app used by one person, but it becomes a problem for a server shared by multiple users.
`llama-server` handles concurrent requests through a mechanism called **slots**.
![llama-server's slot management](../slots.svg#half)
The key point is that tokens from each slot are not inferred **one by one in sequence**, but rather **all at once in a single batch**. GPUs excel at parallel processing, so processing two users simultaneously takes almost the same time as processing one. This is called "continuous batching."
In our server, cpp-httplib's thread pool assigns one thread per request, but the inference itself runs single-threaded inside `llm.chat()`. `llama-server` consolidates this inference step into a shared batch processing loop.
## 7.4 Differences in SSE Format
The streaming mechanism itself is the same (`set_chunked_content_provider` + SSE), but the data format differs.
**Our format:**
```text
data: "去年の"
data: "春に"
data: [DONE]
```
**llama-server (OpenAI-compatible):**
```text
data: {"id":"chatcmpl-xxx","object":"chat.completion.chunk","choices":[{"delta":{"content":"去年の"}}]}
data: {"id":"chatcmpl-xxx","object":"chat.completion.chunk","choices":[{"delta":{"content":"春に"}}]}
data: [DONE]
```
Our format simply sends the tokens. Because `llama-server` follows the OpenAI specification, even a single token comes wrapped in JSON. It may look verbose, but it includes useful information for clients, like an `id` to identify the request and a `finish_reason` to indicate why generation stopped.
## 7.5 KV Cache Reuse
In our server, we process the entire prompt from scratch on every request. Our translation app's prompt is short ("Translate the following text to ja..." + input text), so this isn't a problem.
`llama-server` reuses the KV cache for the prefix portion when a request shares a common prompt prefix with a previous request.
![KV cache reuse](../kv-cache.svg#half)
For chatbots that send a long system prompt and few-shot examples with every request, this alone dramatically reduces response time. The difference is night and day: processing several thousand tokens of system prompt every time versus reading them from cache in an instant.
For our translation app, where the system prompt is just a single sentence, the benefit is limited. However, it's an optimization worth keeping in mind when applying this to your own applications.
## 7.6 Structured Output
Since our translation API returns plain text, there was no need to constrain the output format. But what if you want the LLM to respond in JSON?
```text
Prompt: Analyze the sentiment of the following text and return it as JSON.
LLM output (expected): {"sentiment": "positive", "score": 0.8}
LLM output (reality): Here are the results of the sentiment analysis. {"sentiment": ...
```
LLMs sometimes ignore instructions and add extraneous text. `llama-server` solves this problem with **grammar constraints**.
```bash
curl http://localhost:8080/v1/chat/completions \
-d '{
"messages": [{"role": "user", "content": "Analyze sentiment..."}],
"json_schema": {
"type": "object",
"properties": {
"sentiment": {"type": "string", "enum": ["positive", "negative", "neutral"]},
"score": {"type": "number"}
},
"required": ["sentiment", "score"]
}
}'
```
When you specify `json_schema`, tokens that don't conform to the grammar are excluded during token generation. This guarantees that the output is always valid JSON, so there's no need to worry about `json::parse` failing.
When embedding LLMs into applications, whether you can reliably parse the output directly impacts reliability. Grammar constraints are unnecessary for free-text output like translation, but they're essential for use cases where you need to return structured data as an API response.
## 7.7 Summary
Let's organize the differences we've covered.
| Aspect | Our Server | llama-server |
|------|-------------|--------------|
| API design | Translation-specific | OpenAI-compatible |
| Concurrent requests | Sequential processing | Slots + continuous batching |
| SSE format | Tokens only | OpenAI-compatible JSON |
| KV cache | Cleared each time | Prefix reuse |
| Structured output | None | JSON Schema / grammar constraints |
| Code size | ~200 lines | Several thousand lines |
Our code is simple because of the assumption that "one person uses it as a desktop app." If you're building a server for multiple users or one that integrates with the existing ecosystem, `llama-server`'s design serves as a valuable reference.
Conversely, even 200 lines of code is enough to make a fully functional translation app. I hope this code reading exercise has also conveyed the value of "building only what you need."
## Next Chapter
In the next chapter, we'll cover the key points for swapping in your own library and customizing the app to make it truly yours.
**Next:** [Making It Your Own](../ch08-customization)

View File

@@ -1,120 +0,0 @@
---
title: "8. Making It Your Own"
order: 8
---
Through Chapter 7, we've built a translation desktop app and studied how production-quality code differs. In this chapter, let's go over the key points for **turning this app into something entirely your own**.
The translation app was just a vehicle. Replace llama.cpp with your own library, and the same architecture works for any application.
## 8.1 Swapping Out the Build Configuration
First, replace the llama.cpp-related `FetchContent` entries in `CMakeLists.txt` with your own library.
```cmake
# Remove: llama.cpp and cpp-llamalib FetchContent
# Add: your own library
FetchContent_Declare(my_lib
GIT_REPOSITORY https://github.com/yourname/my-lib
GIT_TAG main
)
FetchContent_MakeAvailable(my_lib)
target_link_libraries(my-app PRIVATE
httplib::httplib
nlohmann_json::nlohmann_json
my_lib # Your library instead of cpp-llamalib
# ...
)
```
If your library doesn't support CMake, you can place the header and source files directly in `src/` and add them to `add_executable`. Keep cpp-httplib, nlohmann/json, and webview as they are.
## 8.2 Adapting the API to Your Task
Change the translation API's endpoints and parameters to match your task.
| Translation app | Your app (e.g., image processing) |
|---|---|
| `POST /translate` | `POST /process` |
| `{"text": "...", "target_lang": "ja"}` | `{"image": "base64...", "filter": "blur"}` |
| `POST /translate/stream` | `POST /process/stream` |
| `GET /models` | `GET /filters` or `GET /presets` |
Then update each handler's implementation. For example, just replace the `llm.chat()` calls with your own library's API.
```cpp
// Before: LLM translation
auto translation = llm.chat(prompt);
res.set_content(json{{"translation", translation}}.dump(), "application/json");
// After: e.g., an image processing library
auto result = my_lib::process(input_image, options);
res.set_content(json{{"result", result}}.dump(), "application/json");
```
The same goes for SSE streaming. If your library has a function that reports progress via a callback, you can use the exact same pattern from Chapter 3 to send incremental responses. SSE isn't limited to LLMs — it's useful for any time-consuming task: image processing progress, data conversion steps, long-running computations.
## 8.3 Design Considerations
### Libraries with Expensive Initialization
In this book, we load the LLM model at the top of `main()` and keep it in a variable. This is intentional. Loading the model on every request would take several seconds, so we load it once at startup and reuse it. If your library has expensive initialization (loading large data files, acquiring GPU resources, etc.), the same approach works well.
### Thread Safety
cpp-httplib processes requests concurrently using a thread pool. In Chapter 4 we protected the `llm` object with a `std::mutex` to prevent crashes during model switching. The same pattern applies when integrating your own library. If your library isn't thread-safe or you need to swap objects at runtime, protect access with a `std::mutex`.
## 8.4 Customizing the UI
Edit the three files in `public/`.
- **`index.html`** — Change the input form layout. Swap `<textarea>` for `<input type="file">`, add parameter fields, etc.
- **`style.css`** — Adjust the layout and colors. Keep the two-column design or switch to a single column
- **`script.js`** — Update the `fetch()` target URLs, request bodies, and how responses are displayed
Even without changing any server code, just swapping the HTML makes the app look completely different. Since these are static files, you can iterate quickly — just reload the browser without restarting the server.
This book used plain HTML, CSS, and JavaScript, but combining them with a frontend framework like Vue or React, or a CSS framework, would let you build an even more polished app.
## 8.5 Distribution Considerations
### Licenses
Check the licenses of the libraries you're using. cpp-httplib (MIT), nlohmann/json (MIT), and webview (MIT) all allow commercial use. Don't forget to check the license of your own library and its dependencies too.
### Models and Data Files
The download mechanism we built in Chapter 4 isn't limited to LLM models. If your app needs large data files, the same pattern lets you auto-download them on first launch, keeping the binary small while sparing users the manual setup.
If the data is small, you can embed it directly into the binary with cpp-embedlib.
### Cross-Platform Builds
webview supports macOS, Linux, and Windows. When building for each platform:
- **macOS** — No additional dependencies
- **Linux** — Requires `libwebkit2gtk-4.1-dev`
- **Windows** — Requires the WebView2 runtime (pre-installed on Windows 11)
Consider setting up cross-platform builds in CI (e.g., GitHub Actions) too.
## Closing
Thank you so much for reading to the end. 🙏
This book started with `/health` returning `{"status":"ok"}` in Chapter 1. From there we built a REST API, added SSE streaming, downloaded models from Hugging Face, created a browser-based Web UI, and packaged it all into a single-binary desktop app. In Chapter 7 we read through `llama-server`'s code and learned how production-quality servers differ in their design. It's been quite a journey, and I'm truly grateful you stuck with it all the way through.
Looking back, we used several key cpp-httplib features hands-on:
- **Server**: routing, JSON responses, SSE streaming with `set_chunked_content_provider`, static file serving with `set_mount_point`
- **Client**: HTTPS connections, redirect following, large downloads with content receivers, progress callbacks
- **WebView integration**: `bind_to_any_port` + `listen_after_bind` for background threading
cpp-httplib offers many more features beyond what we covered here, including multipart file uploads, authentication, timeout control, compression, and range requests. See [A Tour of cpp-httplib](../../tour/) for details.
These patterns aren't limited to a translation app. If you want to add a web API to your C++ library, give it a browser UI, or ship it as an easy-to-distribute desktop app — I hope this book serves as a useful reference.
Take your own library, build your own app, and have fun with it. Happy hacking! 🚀

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@@ -1,26 +0,0 @@
---
title: "Building a Desktop LLM App with cpp-httplib"
order: 0
---
Have you ever wanted to add a web API to your own C++ library, or quickly build an Electron-like desktop app? In Rust you might reach for "Tauri + axum," but in C++ it always seemed out of reach.
With [cpp-httplib](https://github.com/yhirose/cpp-httplib), [webview/webview](https://github.com/webview/webview), and [cpp-embedlib](https://github.com/yhirose/cpp-embedlib), you can take the same approach in pure C++ — and produce a small, easy-to-distribute single binary.
In this tutorial we build an LLM-powered translation app using [llama.cpp](https://github.com/ggml-org/llama.cpp), progressing step by step from "REST API" to "SSE streaming" to "Web UI" to "desktop app." Translation is just the vehicle — replace llama.cpp with your own library and the same architecture works for any application.
![Desktop App](app.png#large-center)
If you know basic C++17 and understand the basics of HTTP / REST APIs, you're ready to start.
## Chapters
1. **[Set up the project](ch01-setup)** — Fetch dependencies, configure the build, write scaffold code
2. **[Embed llama.cpp and create a REST API](ch02-rest-api)** — Return translation results as JSON
3. **[Add token streaming with SSE](ch03-sse-streaming)** — Stream responses token by token
4. **[Add model discovery and management](ch04-model-management)** — Download and switch models from Hugging Face
5. **[Add a Web UI](ch05-web-ui)** — A browser-based translation interface
6. **[Turn it into a desktop app with WebView](ch06-desktop-app)** — A single-binary desktop application
7. **[Reading the llama.cpp server source code](ch07-code-reading)** — Compare with production-quality code
8. **[Making it your own](ch08-customization)** — Swap in your own library and customize

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