Hi all.

For some time now, about 0.1% of my user base has kept reporting that
they can under no circumstance connect to my application's update
server. Not being a highly cooperative bunch, I was unable to track the
problem until now.

Actually, I'm still not certain what the problem is. The fact is,
though, that when I switched libcurl from c-ares back to the standard
name resolver, they were able to connect.

I was able to get system configuration dumps from a couple of users. The
only odd thing I could find about their systems was that they had more
than one NIC.

curl_easy_perform returns CURLcode 28, which is
CURLE_OPERATION_TIMEOUTED. I use a CURLOPT_CONNECTTIMEOUT of 15. I am
positive that this was not generated by firewalls or any similar
nuisances. Another module of my application uses WinINET to connect to
the Internet, and that worked fine. The libcurl module also started
working the moment I built it without c-ares.

OS: Windows XP SP2, Windows 2000 SP4
cURL: The issue occurs with both libcurl 7.12.1 and 7.12.3, as with both
c-ares 1.2.0 and 1.2.1.
URL: Any HTTP URL. It's caused by the name resolver.

I can try to get some more information, but I do not know what you may
be interested in. I can build libcurl with a version of c-ares that logs
its progress, if you have one.

--Tn
Received on 2004-12-21