HTTP/1 is deceptive, because you think "oh, I'll just read RFC 2616, make a state machine, and I'm done!". But then writing a browser-compatible HTTP/1 client i

HTTP/1 is deceptive, because you think "oh, I'll just read RFC 2616, make a state machine, and I'm done!". But then writing a browser-compatible HTTP/1 client is a whole another bag of problems that weren't even documented until recently. For example, Content-Length isn't just a single header with an integer, like the spec says. You need to support responses with multiple Content-Length headers and comma-separated lists of potentially contradictory lengths, and then perform garbage error-recovery the way Internet Explorer or Chrome did. Getting this wrong will make your client hang, consume garbage, or allow response stuffing. https://github.com/web-platform-tests/wpt/pull/10548/files https://github.com/web-platform-tests/wpt/pull/10548/files This problem does not exist in HTTP/2.