Parsing of Sec-WebSocket-Protocol doesn't handle space after comma

[sbc100]

I'm not sure if the spec is clear on this but the example shown in https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Sec-WebSocket-Protocol seems to show a space after the comma.

e.g. Sec-WebSocket-Protocol: soap, wamp

But websockify does not seem to handle this in protocols = headers.get('Sec-WebSocket-Protocol', '').split(',') and will produce a list of protocols that looks like ['soap', ' wamp'] in this case.

I noticed this in emscripten when trying to switch from the ws npm module to node's builtin WebSocket client: emscripten-core/emscripten#26682.

It seems like the builtin node WebSocket client will always produce this list with a space after each comma.

[sbc100]

It looks like node uses , (with a trailing space) when passing mulitple values in http headers.

See https://github.com/nodejs/node/blob/ecf3435daa53a20dbfd7826163888f63482221a3/deps/undici/src/lib/web/fetch/headers.js#L246

And https://github.com/nodejs/node/blob/ecf3435daa53a20dbfd7826163888f63482221a3/deps/undici/src/lib/web/websocket/connection.js#L74-L79

[CendioOssman]

Indeed. We should probably use the Python standard library to handle headers.

Thanks for reporting!