Files
cpp-httplib/docs-src/pages/en/cookbook/t01-tls-backends.md
yhirose 254e576b50 Add Server::CustomRoute() for HTTP methods outside the built-in set (#2553)
* Add Server::CustomRoute() for HTTP methods outside the built-in set

parse_request_line validates the request method against a fixed whitelist and
rejects anything else with 400 before routing runs. That blocks WebDAV, where
PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK and UNLOCK are ordinary methods
defined by RFC 4918, and it blocks extension methods such as UPnP's SUBSCRIBE.
The need has been open since #847.

Registering a handler is now what makes the server accept a method:

    svr.CustomRoute("PROPFIND", "/dav/:id", handler);

Because custom methods go through the normal dispatch path, patterns work the
way they do for Get() and friends, and the request body is available in
req.body. Serving these methods through set_pre_routing_handler was never
enough: the body has not been read at that point, so PROPPATCH and LOCK, which
require one, could not be implemented at all.

A HandlerWithContentReader overload is available too. The content reader gate
in routing() also fires when a custom method carries no body, matching what
expect_content() does unconditionally for POST/PUT/PATCH/DELETE, so a body-less
PROPFIND (RFC 4918 treats one as allprop) reaches its handler instead of
falling through to 404.

Method names are validated as RFC 9110 tokens, and the ten built-in methods are
refused. Seven of them are dispatched by the if/else chain in routing() before
the custom tables are consulted, so a route registered for one could never
fire; CONNECT, TRACE and PRI carry protocol-level meaning this library does not
route. A refused registration makes is_valid() return false, so listen() fails
rather than starting a server holding a handler that would never run. This is
also why SSLServer::is_valid() now chains to Server::is_valid() instead of only
checking ctx_.

Servers that never call CustomRoute() keep the previous per-request cost: the
built-in method set is checked first and short-circuits, and the custom lookup
returns early on an empty map.

* Add cookbook recipe for custom HTTP methods

The CustomRoute() docs were a section inside S01, which pushed that page to 90
lines, the longest in the cookbook, and mixed a separate feature into a page
about registering GET/POST/PUT/DELETE handlers. Move the section into its own
recipe and give it room for the part that was missing: the OPTIONS handler
returning DAV: and Allow, which WebDAV clients probe for before anything else.
S01 goes back to 68 lines and keeps a pointer to the new page.

The recipe is titled after the API rather than after WebDAV, and says outright
that generating the 207 Multi-Status XML, interpreting Depth and managing locks
are the reader's job. Routing the method is all the library does.

S23 takes order 42, so the TLS, SSE and WebSocket recipes shift to 43-57. That
only moves the sort key. Filenames, the T01/E01/W01 labels, the published URLs
and every cross-reference are untouched.
2026-08-25 19:31:42 -04:00

2.2 KiB

title, order, status
title order status
T01. Choosing Between OpenSSL, mbedTLS, and wolfSSL 43 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:

#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:

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.