Merged revisions 335497 via svnmerge from

Merged revisions 335497 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.8

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  r335497 | russell | 2011-09-13 02:11:36 -0500 (Tue, 13 Sep 2011) | 15 lines

  Fix a crash in res_ais.

  This patch resolves a crash observed in a load testing environment that
  involved the use of the res_ais module.  I observed some crashes where
  the event delivery callback would get called, but the length parameter
  incidcating how much data there was to read was 0.  The code assumed
  (with good reason I would think) that if this callback got called, there
  was an event available to read.  However, if the rare case that there's
  nothing there, catch it and return instead of blowing up.

  More specifically, the change always ensure that the size of the received
  event in the cluster is always big enough to be a real ast_event.

  Review: https://reviewboard.asterisk.org/r/1423/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@335510 65c4cc65-6c06-0410-ace0-fbb531ad65f3