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Re: DNS issue in libcurl 7.19.3 on Mac OS 10.5

From: Heston Liebowitz <>
Date: Mon, 20 Jul 2009 15:48:18 -0700

On Jul 20, 2009, at 3:18 PM, Daniel Stenberg wrote:

>> I have an array of URLs which I want to loop over and GET in turn.
>> About halfway through the array, one of the URLs results in a
>> malformed packet being sent back from the server (according to
>> Wireshark). After that point, all subsequent GETs have their DNS
>> lookups perturbed in some way. For example, here is a subset of the
>> URLs with the proper DNS resolutions:
> I assume this libcurl is not built to use c-ares for name resolves?
> If so, I simply cannot see anything that would point to this being
> libcurl's fault, but instead rather a problem in the resolver lib/
> function of your operating system. libcurl itself makes no DNS
> packets at all, it just calls defined APIs of underlying libs.
> Can you repeat this problem on any other operating system or libcurl
> built to use c-ares?

This libcurl was not built with c-ares. After trying your suggestions,
I don't see the above-referenced behavior on Ubuntu, but I can
reproduce it consistently on Mac OS. I tried recompiling on Mac OS
with c-ares and the problem went away. So, indeed it looks like
something with the standard resolving library. Do you have any idea
what lib would be used for DNS resolves?

In the meantime, I'll stick with c-ares.

- Heston
Received on 2009-07-21