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* 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.
2.8 KiB
title, order, status
| title | order | status |
|---|---|---|
| W04. Send and Receive Binary Frames | 55 | 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
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.
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.
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.
Example: send an image
// 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());
});
// 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.