Use :authority psueod-header on HTTP/2 if available

[kitsonk]

@kitsonk :authority is a drop in replacement for Host. I try to read the Host in a proxy that I am building right now and it seems I'm unable to do so. Despite alpnProtocols: ["h2", "http/1.1"] by default, context.request.headers does not contain :authority and modern browsers don't send the Host header anymore. context.request.headers.get(":authority") is undefined, but I can confirm it being set in the browser via DevTools.

Originally posted by @martin-braun in #571 (comment)

[kitsonk]

I looked into this, Host will likely still be set when the connection is HTTP/1 to the server. If the connection is HTTP/2 then the :authority pseudo-header will be set from a browser. oak should look for the pseudo-header. This is distinct from #571 so I have split it out.

The additional problem though is that either Deno does not process the header. context.request.headers simply takes what Deno offers to it, nothing more nothing less. I am not sure if you are talking about Deno runtime or Deno Deploy (or some other runtime) but the header being missing should addressed with the runtime engine.

[martin-braun]

@kitsonk Thanks for the clarification and the split, nothing to be concerned about. So you say Deno itself doesn't provide the headers? Could you please link me to the relevant code that "simply takes what Deno offers to it"? I would be happy to bubble the issue up, but I couldn't pin-point the exact code where Oak receives the headers from Deno.

And yes, you are correct about your findings, and most (if not all) common browsers switched to HTTP/2 as far as I can tell.

Thank you!

[kitsonk]

The headers on the request are from the server request:

oak/request.ts

Lines 70 to 72 in 77d50d6

	get headers(): Headers {
	return this.#serverRequest.headers;
	}

And the server request used for Deno uses the headers from the Request object provided:

oak/http_server_native_request.ts

Lines 65 to 67 in 77d50d6

	get headers(): Headers {
	return this.#request.headers;
	}

The indirection is there is because of the evolution of Deno HTTP since 2018 and the need to support multiple runtimes.