Suport HTTP Protocol Upgrade Mechanism

[qqvm]

Is there a possibility to upgrade existing HTTP/1 connection to HTTP/2 on the server side?
Mozilla Doc about "Protocol Upgrade": https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Upgrade

[Lukasa]

We've never implemented support for it, and in practice the plaintext upgrade functionality was essentially never deployed. In fact, it's being removed from the revision of the specification for HTTP/2 because of how little it was used.

[qqvm]

I am trying to do that manually, and streamChannel does not get initialized with my final handler. But handshake and settings exchange are successful.

[Lukasa]

Can you show me what your pipeline setup looks like?

[qqvm]

I have something like this:

self.deleteAllHandlers(context)

context.channel.configureHTTP2Pipeline(mode: .server) { streamChannel -> EventLoopFuture<Void> in
    print("configureHTTP2Pipeline triggered")
    return streamChannel.pipeline.addHandler(HTTP2FramePayloadToHTTP1ServerCodec(normalizeHTTPHeaders: true)).flatMap { () -> EventLoopFuture<Void> in
        streamChannel.pipeline.addHandler(PlainHTTPHandler(fromHTTP2: true)).flatMap { () -> EventLoopFuture<Void> in
            streamChannel.pipeline.addHandler(ErrorHandler())
        }
    }
}.flatMap { (_: HTTP2StreamMultiplexer) in
    context.channel.pipeline.addHandler(ErrorHandler())
}

[Lukasa]

And to be clear, this is attempting to do plaintext upgrade?

[qqvm]

Yes, this is a plaintext upgrade from HTTP/1.

[Lukasa]

Ok, without changes to the core state machine this cannot work. HTTP/2 has a defined upgrade pattern from HTTP/1.1 that requires passing a SETTINGS frame in via a header, and consuming the body payload from the HTTP/1.1 request. You'd need to update the HTTP2Handler and associated state machines in order to get this to work.