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[curl:bugs] #1346 resolver error

From: Christian Hesse <eworm_at_users.sf.net>
Date: Mon, 17 Mar 2014 20:07:40 +0000

Hmm, probably this really is not curl's fault...

I wrote a little demo program that uses getaddrinfo() to resolve the hostname, and even that fails.

Thaking a deeper look at the dump you can see that the TCP request includes both, A *and* AAAA query. So who or what is to blame? glibc?

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** [bugs:#1346] resolver error**
**Status:** open
**Labels:** dns 
**Created:** Mon Mar 17, 2014 03:40 PM UTC by Christian Hesse
**Last Updated:** Mon Mar 17, 2014 04:06 PM UTC
**Owner:** Daniel Stenberg
libcurl has a resolver bug that requires some conditions to trigger:
* libcurl tries to resolv A and AAAA records
* DNS response is too long to fit into a UDP packet
What happens:
* libcurl sends two DNS UDP requests, one for A record, one for AAAA record
* libcurl receives one truncated UDP response
* libcurl sends TCP request
* libcurl receives TCP response
* libcurl sends TCP reset, ignoring the response
Everything works just fine when querying only A record (give option -4).
A capture demonstrating the problem is attached.
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Received on 2014-03-17

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