Re: Fix potential hang in https handshake.

From: Jeff King <peff@peff.net>
Date: Oct 19, 2012, 20:40 UTC
Message-ID: <20121019204035.GA24448@sigill.intra.peff.net>
In-Reply-To: <CAHOQ7J8D-8++vgMh=c0rcTtAKrhWUCQx2nSd_spBzFe=QdXwBw@mail.gmail.com>

On Fri, Oct 19, 2012 at 01:37:06PM -0700, Stefan Zager wrote:

Show 26 quoted lines

> > diff --git a/http.c b/http.c
> > index df9bb71..cd07cdf 100644
> > --- a/http.c
> > +++ b/http.c
> > @@ -631,6 +631,19 @@ void run_active_slot(struct active_request_slot *slot)
> >                         FD_ZERO(&excfds);
> >                         curl_multi_fdset(curlm, &readfds, &writefds, &excfds, &max_fd);
> >
> > +                       /*
> > +                        * Sometimes curl will give a really long timeout for a
> > +                        * CONNECT when there are no fds to read, but we can
> > +                        * get better results by running curl_multi_perform
> > +                        * more frequently.
> > +                        */
> > +                       if (maxfd < 0 &&
> > +                           (select_timeout.tv_sec > 0 ||
> > +                            select_timeout.tv_usec > 50000)) {
> > +                               select_timeout.tv_sec = 0;
> > +                               select_timeout.tv_usec = 50000;
> > +                       }
> > +
> >                         select(max_fd+1, &readfds, &writefds, &excfds, &select_timeout);
> >                 }
> >         }
> >
> I have no objection to this; any one else?

If you wouldn't mind, I was hoping you could flesh out the comment a bit more with real details of when this happens (and/or put them in the commit message). If this is indeed a bug to be worked around, it will be a huge help to somebody reading this code in a year who can confirm that modern curl does not need it anymore.

-Peff