Dechunk chunked contents on HttpTunnel if client protocol is HTTP/2 or HTTP/3

[masaori335]

Prior to this change, HTTP/2 has its own ChunkedHandler and do de-chunk in Http2Stream. But think about HTTP/1.0, it doesn't support chunked transfer coding either, but HttpTunnel can handle it correctly.

HttpTransact::handle_response_keep_alive_headers() set HttpTransact::ConnectionAttributes::receive_chunked_response depends on the HTTP version and configs, but the conditions doesn't check the HTTP/2 or HTTP/3 correctly.

Mark as draft PR for discussion & testing.

[maskit]

strncmp(s->state_machine->plugin_tag, "http/2", 6) v.s. strncmp(s->state_machine->client_protocol, "http/2", 6) ?

[masaori335]

strncmp(s->state_machine->plugin_tag, "http/2", 6) v.s. strncmp(s->state_machine->client_protocol, "http/2", 6) ?

"Hide whitespace changes" would show the real changes clearly.

[shinrich]

So if the http/1.1 origin returns a chunked response, we would fail to deliver it to a HTTP/2 or 3 client with this change?

What about a HTTP/2 client that sends a post with no content length for the post body?

[masaori335]

So if the http/1.1 origin returns a chunked response, we would fail to deliver it to a HTTP/2 or 3 client with this change?

HttpTunnel does de-chunk the chunked response from the origin server and gives it to HTTP/2 or HTTP/3 TXN. From HTTP/2 and HTTP/3 TXN, it looks a normal response without a Content-Length header.
This is the same behavior of what ATS does when the client is HTTP/1.0 and the origin returns a chunked response.

What about a HTTP/2 client that sends a post with no content length for the post body?

I think this change affects the response side only. Because the action of Http2Stream chunk_handler is DECHUNK. I'll make sure.

[masaori335]

Pushed new commit using ProxyTransaction::is_chunked_encoding_supported() instead of checking HTTP versions.

[masaori335]

I did a test with nghttp and --no-content-length. It looks like this change has no impact on the POST request. https://gist.github.com/masaori335/73e217db5efe70b7b7400c8da7e5501e

Also, Test Case 6 of http2.test.py covers this

trafficserver/tests/gold_tests/h2/http2.test.py

Lines 153 to 160 in 92d4ef1

	# Test Case 6: Post with chunked body
	# While HTTP/2 does not support Tranfer-encoding we pass that into curl to encourage it to not set the content length
	# on the post body
	tr = Test.AddTestRun()
	tr.Processes.Default.Command = 'curl -s -k -H "Transfer-Encoding: chunked" -d "{0}" https://127.0.0.1:{1}/postchunked'.format( post_body, ts.Variables.ssl_port)
	tr.Processes.Default.ReturnCode = 0
	tr.Processes.Default.Streams.All = "gold/post_chunked.gold"
	tr.StillRunningAfter = server

[masaori335]

@vmamidi PTAL. Rebased on the latest master to resolve conflicts.

[zwoop]

Cherry-picked to v9.0.x branch.