[Bug libc/12684] New: Multi-request DNS lookups do not properly fall back to secondary nameserver

[Bug libc/12684] New: Multi-request DNS lookups do not properly fall back to secondary nameserver

[pasky at suse dot cz]

http://sourceware.org/bugzilla/show_bug.cgi?id=12684

           Summary: Multi-request DNS lookups do not properly fall back to
                    secondary nameserver
           Product: glibc
           Version: 2.13
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper.fsp@gmail.com
        ReportedBy: pasky@suse.cz


Created attachment 5678
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5678
proposed patch

The resolver does not properly handle a case where AF_UNSPEC query is started,
two requests are therefore dispatched, and something like NOTIMP or SERVFAIL is
returned to one of them (e.g. AF_INET6). In this case, the second nameserver in
queue is not queried even though it should be. It is caused by an omission of
resplen = 0 in the appropriate branch of send_dg() - therefore, when checking
whether next nameserver should be queried, it is assumed that a proper reply
was received from the first one.

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12684

Ulrich Drepper <drepper.fsp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #1 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-05-31 02:52:25 UTC ---
I agree, something is wrong.  But it's a bad idea to try the next server in
case of NOTIMP replies etc for just one of the requests.  Imagine all the
servers return these errors.  In this case it is better to live with the one
successful answer.  I added an appropriate patch.

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=12684

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

--- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> 2011-06-03 10:57:49 UTC ---
$ nss/getent ahosts example.com
;; res_setoptions(" debug
", "conf")..
;;      debug
dots=1, statp->ndots=1, trailing_dot=0, name=example.com
;; res_nquerydomain(example.com, <Nil>, 1, 62321)
;; res_query(example.com, 1, 62321)
;; res_nmkquery(QUERY, example.com, IN, A)
;; res_nmkquery(QUERY, example.com, IN, AAAA)
;; res_send()
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24983
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;      example.com, type = A, class = IN
;; Querying server (# 1) address = 127.0.0.1
res_send: send: Connection refused
;; got answer:
;; ns_initparse: Message too long
;; ns_initparse: Message too long
Segmentation fault

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[vapier at gentoo dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=12684

Mike Frysinger <vapier at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |toolchain at gentoo dot org

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[drepper.fsp at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12684

Ulrich Drepper <drepper.fsp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #3 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-06-16 02:45:38 UTC ---
Don't reopen bugs for reasons like this.  The problem was caused by the patch
but has nothing to do with the original problem.  This is very much misleading.
 I've added a patch to fix two typos which caused crashes.

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[jackie.rosen at hushmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=12684

Jackie Rosen <jackie.rosen at hushmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jackie.rosen at hushmail dot com

--- Comment #4 from Jackie Rosen <jackie.rosen at hushmail dot com> ---
*** Bug 260998 has been marked as a duplicate of this bug. ***
Seen from the domain http://volichat.com
Page where seen: http://volichat.com/adult-chat-rooms
Marked for reference. Resolved as fixed @bugzilla.

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[schwab at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=12684

Andreas Schwab <schwab at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|jackie.rosen at hushmail dot com   |

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=12684

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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[Bug libc/12684] Multi-request DNS lookups do not properly fall back to secondary nameserver

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=12684

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=13013

--- Comment #5 from Florian Weimer <fweimer at redhat dot com> ---
I believe the crash mentioned in comment #2 was also filed as bug 13013.

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