Fix keepalive timeout task will not execute to close transport

[pacoyang]

When transport can not kick off the HTTP protocol, the on_response_complete method will not be executed to start a keep-alive timeout task, in this situation if the client-side stream sends EOF, the server-side will not close this transport by timeout task and this TCP connection will keep CLOSE_WAIT status.

Start a TCP connection with telnet can replicate this issue. Expect the connection should be close after the keep-alive is timeout.

telnet 127.0.0.1 8000

Relates to #160. Some applications like Chrome or wrk will start a TCP connection to send empty-bytes at first before start the HTTP protocol TCP connection.

[Kludex]

You said this on #1332:

The keep-alive timeout task trigger still has issue, when a TCP connection is established and the client does not send any bytes, the server does not close this connection when keep-alive timeout. It can be reproduced by telnet.

You were referring to this PR/the issue the PR solves, right?

[pacoyang]

You were referring to this PR/the issue the PR solves, right?

@Kludex As #1332 has merged, Not sure this PR is there any conflicts. I will check and submit another PR later.

[bevinhex]

this still exists on 0.23.2

[bevinhex]

[bevinhex]

log_level="trace" shows "HTTP connection made" when telnet connected, but it keeps that way forever, never timeout

[bevinhex]

tested on both h11, httptools

[bevinhex]

traced the error to

somehow keep alive handler only set when response complete, not when request just received, thus people can connect and keep tcp connection open , do slow loris attack

[bevinhex]

starting timer once connection_made seems to be fixing the issue for me, not sure if I am doing it correctly though, will see