StreamResponse use Transfer-Encoding: chunked for 204 responses

[arthurdarcet]

🐞
This server :

from aiohttp import web

async def hello(request):
	return web.StreamResponse(status=204)
	
app = web.Application()
app.add_routes([web.get('/', hello)])
web.run_app(app)

returns invalid HTTP responses:

% echo -ne 'GET / HTTP/1.1\r\n\r\n' | nc -i 1 127.0.0.1 8080
HTTP/1.1 204 No Content
Transfer-Encoding: chunked
Content-Type: application/octet-stream
Date: Fri, 23 Oct 2020 14:14:39 GMT
Server: Python/3.8 aiohttp/3.6.3

0

(i am using OSX, so netcat is the BSD variant, the -i 1 is not needed on linux)

The HTTP RFC specifies that a 204 response MUST NOT contain a body and is considered done after the first empty line after the headers.

Although I'm not exactly sure whether or not a 0\r\n\r\n body is consider an empty body or not when using Transfer-Encoding: chunked - so your call whether or not this should be fixed here.

The eventual bug for us is caused more by this issue https://trac.nginx.org/nginx/ticket/2066#ticket , which stacks with this one to crash our node clients.

[asvetlov]

Ok, let's not send empty body for 204 (and drop Content-Type with Transfer-Encoding headers).
IIRC we already handle such cases on the client.

Would you prepare a patch?

[arthurdarcet]

perfect, thanks @derlih !