[asterisk-dev] [Code Review] Cancel retries for all dialogs when the remote host isn't answering

[Tilghman Lesher]

> On 2009-12-09 13:18:43, Mark Michelson wrote:
> > I really really really do not like this method. Like Vossel suggested, it is really confusing to see that the last transmitted method was a CANCEL when we haven't even sent a cancel yet.
> > 
> > If I understand the problem correctly, it's that we send an INVITE out and never get a final response for it (in the description it says the packet is never ACKed, but in SIP INVITEs aren't ACKed, their final response is). The result is that retrans_pkt should eventually reach the maximum number of retries and remove the packet from the sip_pvt. Now, in __sip_autodestruct, the problem is that even though the sip_pvt is free of packets, the SIP_NEEDDESTROY flag is not set. So couldn't this problem be solved by setting the SIP_NEEDDESTROY flag in retrans_pkt?

For some reason, though, p->packets is not getting cleared, yet there are no scheduled events firing to retransmit (according to the various related bug reports).  The ONLY SIP history event is the one located within the __sip_autodestruct routine.

In fact, it appears this situation is due to your __sip_semi_ack routine.  The packets remain, but retrans_pkt is cancelled, and the invite state stays in INV_CALLING.  Hence, we cannot send an actual cancel, but we'll never receive a response packet, so we're infinitely hung.


- Tilghman


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On 2009-12-09 09:52:44, Tilghman Lesher wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/446/
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> 
> (Updated 2009-12-09 09:52:44)
> 
> 
> Review request for Asterisk Developers and Russell Bryant.
> 
> 
> Summary
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> 
> Currently, certain dialogs, including INVITE, may never deallocate resources, if the remote host does not ACK the packets.  This is due to a retry loop in the autodestruct function that has no terminating condition.
> 
> 
> This addresses bug 15627.
>     https://issues.asterisk.org/view.php?id=15627
> 
> 
> Diffs
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> 
>   /branches/1.4/channels/chan_sip.c 233049 
> 
> Diff: https://reviewboard.asterisk.org/r/446/diff
> 
> 
> Testing
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> 
> Works to solve reporter's problem.
> 
> 
> Thanks,
> 
> Tilghman
> 
>