[asterisk-bugs] [Asterisk 0010052]: NOTIFY race condition when state changes happen very fast

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=10052 
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Reported By:                raarts
Assigned To:                oej
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Project:                    Asterisk
Issue ID:                   10052
Category:                   Channels/chan_sip/Registration
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     feedback
Asterisk Version:            1.2.19  
SVN Branch (only for SVN checkouts, not tarball releases): N/A  
SVN Revision (number only!):  
Disclaimer on File?:        Yes 
Request Review:              
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Date Submitted:             06-25-2007 08:47 CDT
Last Modified:              03-17-2008 12:01 CDT
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Summary:                    NOTIFY race condition when state changes happen very
fast
Description: 
This particular problem was encountered with SNOM360 phones, but it is not
specific to it.

What happens:
- SNOM has subscribed a LED to another phone
- SNOM user dials this other phone. 
- dialplan adds an answer-after=0 SIP header.
- asterisk send INVITE to the other phone
- other phone send back RINGING, this is sent back to the SNOM as well
- asterisk send NOTIFY 'early' to the SNOM
- meanwhile, the other phone answers very quickly
- asterisk sends OK to INVITE to SNOM to indicate the other phone 
  has answered the line, and immediately after that, a NOTIFY 'confirmed'.

  At this point in time the OK to the previous NOTIFY 'early' has not 
  been sent yet by the SNOM.

Now the system is confused, because the SNOM finally sends the OK
to the NOTIFY 'early', but asterisk is only expecting an OK to the
last sent NOTIFY, and starts retrying. See attached trace.

I think asterisk should not sent a new NOTIFY. I think ideally NOTIFY's
should be queued on a per-channel basis. Or should asterisk remember
earlier



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Relationships       ID      Summary
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related to          0011736 sip hung channels and UDP ports
related to          0011231 [patch] Many retransmits when chan_sip ...
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---------------------------------------------------------------------- 
 one47 - 03-17-08 12:01  
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Given that I (and seemingly others) am widely using the "else if" to "if"
fix from this bug so widely now, I suspect that it is a valid fix.

The code changes that are in
http://bugs.digium.com/view.php?id=11231/http://bugs.digium.com/view.php?id=11736
are more of a feature
enhancement, which will improve the code and reduce or remove the need for
this change in a future release. 

Issue History 
Date Modified   Username       Field                    Change               
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03-17-08 12:01  one47          Note Added: 0084075                          
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