[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:                
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Project:                    Asterisk
Issue ID:                   10052
Category:                   Channels/chan_sip/Registration
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
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:              08-29-2007 18:29 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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---------------------------------------------------------------------- 
 raarts - 08-29-07 18:29  
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Must confess I haven't tried 1.4 yet, I decided to give it a go
only after Digium starts selling commercial support for it. When they
trust it, I'll try it.

But I bet that if oej reads the description of this bug he'll
either say: "Already know this" or "fixed in 1.4" ;-)

I stopped searching by the way. Couldn't spare the time to go 
to the bottom of it, changed the auto-answer=0 to autoanswer=1
customer was ok with this. But it definitely is a problem. 
I also encountered it where a SNOM has BOTH a subscription 
to itself AND to the phone it is calling. As soon as the call is ringing,
the SNOM receives two NOTIFY's in rapid succession and asterisk 
gets confused when it receives the OK to the first notify. 

Issue History 
Date Modified   Username       Field                    Change               
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08-29-07 18:29  raarts         Note Added: 0069676                          
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