[Twisted-Python] HTTP Agent persistent connections not closed for some HTTPS sites

[Cory Benfield]

> On 5 Mar 2017, at 14:25, Tristan Seligmann <mithrandi at mithrandi.net> wrote:
> 
> On Sun, 5 Mar 2017 at 15:36 Adi Roiban <adi at roiban.ro <mailto:adi at roiban.ro>> wrote:
> I have observed this while running some end to end tests in which the
> pool.closeCachedConnections() deferred was not called, even after a
> generous amount of seconds :)
> 
> The code to abort an HTTP client connection is here:
> 
> https://github.com/twisted/twisted/blob/twisted-17.1.0/src/twisted/web/_newclient.py#L1657 <https://github.com/twisted/twisted/blob/twisted-17.1.0/src/twisted/web/_newclient.py#L1657>
> 
> This calls loseConnection which for a TLS connection will try to do a TLS shutdown under most circumstances (in some cases it can't, and will abortConnection on the underlying transport instead). If the remote end has stopped responding to the connection, I think this may end up hanging forever.
> 
> I think this code should either call abortConnection directly, or set a timer which will abort the connection after a little while if a clean shutdown from loseConnection has not completed yet. I’

Yeah, this looks right. We hit it in the server side code too: it’s a very unintuitive API in that sense.

Cory

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