Support Websockets over HTTP/2

[yschimke]

https://tools.ietf.org/html/draft-ietf-httpbis-h2-websockets-00

Bootstrapping WebSockets with HTTP/2
draft-ietf-httpbis-h2-websockets-00

Abstract

This document defines a mechanism for running the WebSocket Protocol
[RFC6455] over a single stream of an HTTP/2 connection.

[JakeWharton]

Been following this from the HYBI mailing list. I wish they'd address more of the design flaws of the protocol as part of this.

[yschimke]

Is the idea you use existing connections you probably have (e.g. webbrowser opened when getting HTML + JS). Just curious for service usage, are you meant to try HTTP/2, see if supported then re-establish with HTTP/1.1 if not?

[JakeWharton]

I haven't been paying that close attention so I'm not sure. Mostly just interested in it because web sockets are giant inefficient balls of terrible with the XOR-ing of bytes and the need for a dedicated connection. This at least aims to solve the second problem.

[yschimke]

On second thought I think that's what I like about the spec. It isn't actually anything specific to websockets, it's just socket (bidirectional streams) over HTTP/2. ALPN over HTTP/2.

They just chose this registry https://www.iana.org/assignments/http-upgrade-tokens/http-upgrade-tokens.xhtml

over this one https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids

Great way to get secure tunnels supported in an almost undetectable and unstoppable way. Great for the dissidents of the world.

[yschimke]

Implementation wise, generalising RealWebSocket.Streams looks really doable.

[crossle]

When support?

[yschimke]

Very early PR is here, but I haven't started on HTTP/2 parts yet, just refactoring with HTTP/1.1. It's not my day job, but I hope I'll have a chance to push forward on it in next week or so.

Realistically it won't be in 3.11, so maybe experimental support in 3.12 is more likely.

[yschimke]

@crossle do you know any servers that already support this?

[crossle]

@yschimke Sorry, before we developing server use WS over HTTP/2, but okhttp not support, so we switch to HTTP/1.1, 😅

[mostroverkhov]

libwebsockets supports rfc8441 so websockets-over-http2 becomes viable option if primary clients are native mobile.
I have netty based impl of both server and client https://github.com/jauntsdn/netty-websocket-http2 that should work on android without much modifications, though It would be nice to have client implemented here given okhttp is dependency of every mobile project.