Websockets

[bagder]

Warning: regular rebase + force-pushes are still performed on this branch.

Initial design thoughts

• setopt documentation
• configure
• decide to not rely on any external websocket library
• Send HTTP request
• Send HTTP request when issued with hyper
• websocket URL parser (+ tests for it)
• curl_version_info() protocols[] fixed
• HTTP Upgrade response check
• extended CURLOPT_CONNECT_ONLY to offer upgrade-only
• curl_ws_send documentation
• curl_ws_recv documentation
• curl_ws_send implementation
• curl_ws_recv implementation
• decide how to do the test server: extend sws
• do proper non-blocking buffer management when reading slow/a lot
• test server support for websockets (partial)
• test cases running (ws test infrastructure working)
• document curl_ws_meta();
• implement curl_ws_meta();
• add test using curl_ws_meta();
• fail gracefully if not getting the expected101 response code + test it
• allow overriding request headers in the ws initial request

Left for follow-up work

• make websockets work with hyper
• do the sha1 response verification
• consider a curl_ws_poll()
• make nc-like functionality for the curl tool
• make sure ws code paths are fuzzed
• disable PING-PONG automation
• CURLWS_COMPRESS

[calvin2021y]

Hi @bagder, thanks for the great work.

I plan to use libcurl with event loop to replace libwebsockets. The new implement will support non-blocked frame recv ?

I guess call curl_ws_recv will blocked, so some thing like CURLOPT_WS_RECVFUNCTION, CURLOPT_WS_RECVDATA should exists to handle the callback inside a event loop. (each call should return a full frame with type: ping, pong, binary, text)

[bagder]

I think maybe it might be better to take this to the discussions rather than to have this "side conversation" here in the PR.

I plan to use libcurl with event loop to replace libwebsockets. The new implement will support non-blocked frame recv ?

I'm not sure what that means. The proposed API is documented in the wiki and in somewhat more detail in the docs section in the files in this PR.

I guess call curl_ws_recv will blocked

It will return a full frame is there is one, I think it might not return anything if there isn't a complete frame to return.

so some thing like CURLOPT_WS_RECVFUNCTION, CURLOPT_WS_RECVDATA should exists to handle the callback inside a event loop.

This has been discussed at length and I am currently providing the websockets data using the "regular" write callback CURLOPT_WRITEFUNCTION. Additional details about the delivered frame will be available from within the callback using the curl_ws_meta() function.

[bagder]

I intend to merge this soon.