AST-2013-004: Fix crash when handling ACK on dialog that has no channel

A remote exploitable crash vulnerability exists in the SIP channel driver if an
ACK with SDP is received after the channel has been terminated. The handling
code incorrectly assumed that the channel would always be present.

This patch adds a check such that the SDP will only be parsed and applied if
Asterisk has a channel present that is associated with the dialog.

Note that the patch being applied was modified only slightly from the patch
provided by Walter Doekes of OSSO B.V.

(closes issue ASTERISK-21064)
Reported by: Colin Cuthbertson
Tested by: wdoekes, Colin Cutherbertson
patches:
  issueA21064_fix.patch uploaded by wdoekes (License 5674)
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Merged revisions 397710 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 397711 from file:///srv/subversion/repos/asterisk/branches/10


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/10-digiumphones@397743 f38db490-d61c-443f-a65b-d21fe96a405b
AST-2013-005: Fix crash caused by invalid SDP

If the SIP channel driver processes an invalid SDP that defines media
descriptions before connection information, it may attempt to reference
the socket address information even though that information has not yet
been set. This will cause a crash.

This patch adds checks when handling the various media descriptions that
ensures the media descriptions are handled only if we have connection
information suitable for that media.

Thanks to Walter Doekes, OSSO B.V., for reporting, testing, and providing
the solution to this problem.

(closes issue ASTERISK-22007)
Reported by: wdoekes
Tested by: wdoekes
patches:
  issueA22007_sdp_without_c_death.patch uploaded by wdoekes (License 5674)
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Merged revisions 397756 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 397757 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/10-digiumphones@397763 f38db490-d61c-443f-a65b-d21fe96a405b