[asterisk-dev] [Code Review] Don't miss control frames if a call is answered and hung up very quickly

[David Vossel]

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Okay here is another thing that may be a problem with this change. We have mix match usage of how we set the _softhangup flag in Asterisk.  When we use the ast_sofhangup() function we are actually queuing up a NULL frame on the channel, but when we set it explicitly using chan->_softhangup =| HANGUP; then no NULL frame gets queued (some channel drivers do this).  This could matter because we are depending on that NULL frame to be read at some point to stop the read.  I don't know what the behavior is if a NULL frame isn't queued, can more frames get added to the queue even though softhangup is set?  That would be a problem.

- David


On 2010-06-30 00:41:28, Terry Wilson wrote:
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> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/740/
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> (Updated 2010-06-30 00:41:28)
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> Review request for Asterisk Developers, Russell Bryant and David Vossel.
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> Summary
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> When an outgoing call is answered and hung up by the far end *very* quickly, we may not read any frames and therefor end up with a call that displays the wrong disposition/DIALSTATUS. The reason is because ast_queue_hangup() immediately sets the _softhangup flag on the channel and then queues the HANGUP control frame, but __ast_read refuses to read any frames if ast_check_hangup() indicates that a hangup request has been made (which it will if _softhangup is set). So, we end up losing control frames.
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> This change makes __ast_read continue to read frames even if a soft hangup has been requested. I believe this should be safe as we actually check farther down in __ast_read for HANGUP frames and return NULL just like we would have if we skipped the read via the goto done statement, and we don't call into any of the channel tech callbacks unless the readq is empty.
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> This addresses bug 16946.
>     https://issues.asterisk.org/view.php?id=16946
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> Diffs
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>   /trunk/include/asterisk/channel.h 272961 
>   /trunk/main/channel.c 272961 
>   /trunk/main/pbx.c 272961 
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> Diff: https://reviewboard.asterisk.org/r/740/diff
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> Testing
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> I have verified via sipp that when placing an outbound call that is answered and immediately hung up that the call shows up as answered (where it doesn't w/o the patch). I have also run the testsuite and verified that all tests continue to pass.
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> Thanks,
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> Terry
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>