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[Bug 1527902] Re: 3.13.0-71: IPv6 UDP DNS packets are not received


Looks like that program dig is not affected, so not all stub resolvers
are non working.

Kopete uses libiris xmpp library which uses jdns resolver. It is 100%

I tested also new upstream 4.x kernels and they do not have this
problem. Only ubuntu kernels >= 3.13.0-69.

If you need to test jdns library, upstream project has also example dns lookup cmdline tool in git repo:

(Call it with arg "-6" against some IPv6 DNS server)

I tested it and it reacts exactly same as Kopete, on 3.13.0-69 kernel
(and above) just do not receive UDP IPv6 packets. As I wrote in
description strace show that every recvfrom() calls just return -EAGAIN.
But wireshark see that packets was received.

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  3.13.0-71: IPv6 UDP DNS packets are not received

Status in linux package in Ubuntu:
  In Progress
Status in linux-lts-trusty package in Ubuntu:
  In Progress

Bug description:
  After upgrading linux kernel from version 3.13.0-68 to 3.13.0-71 then
  Kopete (IM messenger) stopped working, cannot connect to any jabber

  I started debugging this problem and found out that, problem resolve
  when I boot back 3.13.0-68 kernel version (without touching any system
  files or packages). When I boot 3.13.0-71 Kopete always does not

  Next I debugged that problem on 3.13.0-71 is just when
  /etc/resolv.conf contains only IPv6 addresses of DNS servers.

  Problem is comes down to dns resolver (jabber in Kopete has its own
  for SRV records) and syscall recvfrom() (on IPv6 socket) always return
  error -EAGAIN without any data returned. But wireshark see that DNS
  response was recevied.

  So it looks like that after 3.13.0-68 kernel was included some change
  which broke receiving UDP packets via IPv6 socket. IPv4 is OK.

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