[asterisk-dev] [Code Review] Fix broken redirect out of MeetMe() as well as the deeper issue at hand

[Russell Bryant]

> On 2011-01-24 11:01:25, rmudgett wrote:
> > The features.c:check_goto_on_transfer() is setting _softhangup to zero after doing ast_parseable_goto().  I do not think there will be any hangup flags set at that point though since it is not an async goto.

Thanks.  I don't know why I missed that.  Fixed.


> On 2011-01-24 11:01:25, rmudgett wrote:
> > /branches/1.8/main/channel.c, lines 2611-2624
> > <https://reviewboard.asterisk.org/r/1082/diff/2/?file=15268#file15268line2611>
> >
> >     You do not need to traverse the list.  The END_OF_Q is either the last item in the list or it is not there.
> >     
> >     Look at __ast_queue_frame().  It uses AST_LIST_LAST() and AST_LIST_REMOVE().

Good point, fixed.


- Russell


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On 2011-01-21 17:17:51, Russell Bryant wrote:
> 
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> https://reviewboard.asterisk.org/r/1082/
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> 
> (Updated 2011-01-21 17:17:51)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Summary
> -------
> 
> Mantis issue #18585 reports that a channel redirect out of MeetMe() stopped working properly.  This issue includes a patch that resolves the issue by removing a call to ast_check_hangup() from app_meetme.c.  I left that in my patch, as it doesn't need to be there.  However, the rest of the patch fixes this problem with or without the change to app_meetme.
> 
> The key difference between what happens before and after this patch is the effect of the END_OF_Q control frame.  After END_OF_Q is hit in ast_read(), ast_read() will return NULL.  With the ast_check_hangup() removed, app_meetme sees this which causes it to exit as intended.  Checking ast_check_hangup() caused app_meetme to exit earlier in the process, and the target of the redirect saw the condition where ast_read() returned NULL.
> 
> Removing ast_check_hangup() works around the issue in app_meetme, but doesn't solve the issue if another application did the same thing.  There are also other edge cases where if an application finishes at the same time that a redirect happens, the target of the redirect will think that the channel hung up.  So, I made some changes in pbx.c to resolve it at a deeper level.  There are already places that unset the SOFTHANGUP_ASYNCGOTO flag in an attempt to abort the hangup process.  My patch extends this to remove the END_OF_Q frame from the channel's read queue, making the "abort hangup" more complete. 
> 
> 
> This addresses bug 18585.
>     https://issues.asterisk.org/view.php?id=18585
> 
> 
> Diffs
> -----
> 
>   /branches/1.8/apps/app_meetme.c 303376 
>   /branches/1.8/include/asterisk/channel.h 303376 
>   /branches/1.8/main/channel.c 303376 
>   /branches/1.8/main/pbx.c 303376 
> 
> Diff: https://reviewboard.asterisk.org/r/1082/diff
> 
> 
> Testing
> -------
> 
> I replicated the bug easily.  I verified that removing ast_check_hangup() fixes the issue and determined why it fixes it.  I also verified that the issue is resolved with the pbx.c changes, both with and without ast_check_hangup() still used in app_meetme.
> 
> 
> Thanks,
> 
> Russell
> 
>

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