> On Jul 2, 2021, at 4:33 AM, Daniel Stenberg via curl-library > <curl-library@cool.haxx.se> wrote: > > On Thu, 1 Jul 2021, Weston Schmidt wrote: > >> I like the simplicity of the CURLOPT_CONNECT_ONLY=2L + ws:// or wss:// plan. >> >> If libcurl stops at the _The WebSocket Connection is Established_ point >> (https://datatracker.ietf.org/doc/html/rfc6455#page-20) when >> CURLOPT_CONNECT_ONLY=2L, then by definition that is only after the HTTP >> response 101 Upgrade stuff has happened. This means that redirects and >> other HTTP magic happens as normal. Libcurl then does not need to support >> or be altered for extensions or subprotocols. > > I think that's a decent plan for the initial bootstrap-into-websockets step. > I could even imagine that CURLOPT_CONNECT_ONLY=2L could be implied by the > explicit use of ws:// or wss:// in the URL. > > What's a little unclearer to me is what we need for the next phase, once the > connection is done and setup. curl_easy_send/recv seem inadequate for > websockets, which might imply that we need to provide curl_ws_send/recv. If > so: A) how should they work and B) what else do we need?
The send interface could look much like curl_easy_send(): curl_ws_send( easy, buffer, buflen, &sent, enum curl_ws_message_type type, enum curl_ws_flags flags ) … where type is the frame type (as per the RFC) and where flags are: CURL_WS_NOCOMPRESS - no-op if there’s no compression anyway CURL_WS_MORE - omit WS’s FIN flag The above assumes curl would hold a bit of state in order to sanity-check the calls and provide conveniences like auto-adding WS’s “initial” flag. ----- Most WS libraries that I’ve seen implement reception as a callback, with a separate control to pause reception of incoming messages. Maybe the following callback signature: void curl_ws_on_recv_message( buffer, buflen, enum curl_ws_message_type type, enum curl_ws_flags flags ) … where “flags” would just be CURL_WS_NOCOMPRESS. The “pause” could maybe be: curl_easy_setopt(easy, CURLOPT_WS_PAUSE, 1)? Canonically, user applications aren’t meant to receive individual WS frames, but only entire messages. If, though, it’s desired that the client also be able to receive individual frames, perhaps the following: void curl_ws_on_recv_frame( buffer, buflen, enum curl_ws_message_type type, enum curl_ws_flags flags ) -FG ------------------------------------------------------------------- Unsubscribe: https://cool.haxx.se/list/listinfo/curl-library Etiquette: https://curl.se/mail/etiquette.html
