HttpServerRequest::receiveContent() never emits any value nor completes when HTTP/1.1 TLS Upgrade (RFC-2817) kicks in

[reta]

We have run into the issue with latest Apache HttpClient5 5.4.1 / Apache HttpCore5 5.3.1 as a client (Reactor Netty as the HTTP server with HTTP/1.1 and H2C protocols) that now tries HTTP/1.1 TLS Upgrade (RFC-2817) by default, see please [1] for context. The HttpServerRequest::receiveContent() never emits any value nor completes since no next / completion callbacks are called.

I have traced this problem to HttpServerOperations, specifically to this block of code https://github.com/reactor/reactor-netty/blob/main/reactor-netty-http/src/main/java/reactor/netty/http/server/HttpServerOperations.java#L812:

                      if (isFullHttpRequest) {
				FullHttpRequest request = (FullHttpRequest) msg;
				if (request.content().readableBytes() > 0) {
					super.onInboundNext(ctx, msg);
				}
				else {
					request.release();
				}
				if (isHttp2()) {
					//force auto read to enable more accurate close selection now inbound is done
					channel().config().setAutoRead(true);
					onInboundComplete();
				}
			}

In case of upgrade flow (which happens only for GET/OPTIONS/HEAD), the channel pipeline involves HttpObjectAggregator and emits the FullHttpRequest instance (precisely, HttpObjectAggregator.AggregatedFullHttpRequest) with empty content, which deviates from non-upgrade flow that emits DefaultHttpRequest, followed by last content. As the result, onInboundNext is not called, and because the upgrade did not switch protocols and stayed on HTTP/1.1, onInboundComplete is also not called.

[1] https://github.com/apache/httpcomponents-client/pull/542/files

Expected Behavior

The HttpServerRequest::receiveContent() should complete with empty result.

Actual Behavior

The HttpServerRequest::receiveContent() hangs.

Steps to Reproduce

I have published a full reproducer here [2], it is very small but has pom.xml + client + server (easier to start with).

[2] https://github.com/reta/httpclient5-upgrade-reproducer

Possible Solution

I assume that calling onInboundComplete() would be the right thing to do here, since there is no content and inbound request is processed.

Your Environment

• Reactor version(s) used: 1.2.24
• Other relevant libraries versions (eg. netty, ...): Apache HttpClient5 5.4.1, Apache HttpCore5 5.3.1
• JVM version (java -version): 11 / 17 / 21
• OS and version (eg. uname -a): any

[reta]

@violetagg I have an idea how to fix the problem, but would really appreciate the guidance if it makes sense, happy to help in any case. Thank you.

[violetagg]

@reta I think your analysis is correct. Would you like to provide a PR?

[reta]

@reta I think your analysis is correct. Would you like to provide a PR?

Absolutely, on it, thank you!