[Bug network/14308] getaddrinfo DNS referral response returns host not found when A and AAAA questions are sent and one response is a referral

["gauryogesh.nsit at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

http://sourceware.org/bugzilla/show_bug.cgi?id=14308

Yogesh Gaur <gauryogesh.nsit at gmail dot com> changed:

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                 CC|                            |gauryogesh.nsit at gmail
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--- Comment #1 from Yogesh Gaur <gauryogesh.nsit at gmail dot com> 2013-02-09 08:50:17 UTC ---
Hello All,

This issue is coming because of both message type of T_A and T_AAAA are being
send in parallel for processing through api _nss_dns_gethostbyname4_r().

Actually following conditions happens before coming this issue:
1> Receive request of type T_A, creating session table entry.
                        T_A -- Host address
This is non-referral response and would create its own session table entry.
2> Receive request of type T_AAAA on port x, reusing session table entry from
#1
                        T_AAAA -- Ip6 Address
This is referral response and would reuse previous created session table entry.
3> Respond to T_AAAA request on port x and remove session table entry.
4> Load-balancer receives response from DNS server for T_A request, but since
session table entry is gone, it simply forwards the traffic. 
Client receives a reply from a different IP not from the IP it expects and
simply ignores it.
5> This then lead to message failure and returns with error-code as EAI_NODATA
i.e. No address associated with hostname.

This issue is only coming with some bad DNS server as they are not able to
process the request correctly. There is no proper fix for this is yet been
released by glibc and this bug is being reported from glibc-2.9.

I found this link which contains patch information using which work-around for
this issue can be applied.

http://sourceware.org/bugzilla/show_bug.cgi?id=7060

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