[asterisk-bugs] [Asterisk 0011231]: [patch] Many retransmits when chan_sip generates multiple outstanding requests

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A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=11231 
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Reported By:                flefoll
Assigned To:                oej
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Project:                    Asterisk
Issue ID:                   11231
Category:                   Channels/chan_sip/General
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     assigned
Asterisk Version:            SVN 
SVN Branch (only for SVN checkouts, not tarball releases):  1.4  
SVN Revision (number only!): 89184 
Disclaimer on File?:        N/A 
Request Review:              
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Date Submitted:             11-13-2007 08:08 CST
Last Modified:              02-04-2008 04:39 CST
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Summary:                    [patch] Many retransmits when chan_sip generates
multiple outstanding requests
Description: 
I opened issue 10946 in october http://bugs.digium.com/view.php?id=10946 on
the same subject, but it was closed last week, together with issue 9567 and
issue 10915 (sorry, I was away last week).

All 3 issues were closed when chan_skip rev 89097 was committed. This
revision adds support for one outgoing transaction with the new
"lastnoninvite" field.

So, I have given a try to modification brought by chan_skip rev 89097. But
it does not solve the retransmit problem for me.

Typically, try with a series of SendText(ABC) in your extensions.conf :
the SIP peer will never respond quickly enough, and all (except last)
MESSAGE messages will be retransmitted. Silly test, but easy to reproduce
!
The problem also most probably still occurs when REFER handling provokes
too many and too quick NOTIFY messages (not re-tried yet, but new
"lastnoninvite" can handle one NOTIFY only).

Consequently, I propose another patch : this one won't remove code :-) but
it will add a few more lines instead, in order to cancel retransmits when
chan_sip receives a "late" response.

I know, it does not respond to file's dream of "a chan_sip with real
transaction support" :-)

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Relationships       ID      Summary
----------------------------------------------------------------------
related to          0010915 Problems when doing an attended and una...
related to          0010052 NOTIFY race condition when state change...
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---------------------------------------------------------------------- 
 flefoll - 02-04-08 04:39  
---------------------------------------------------------------------- 
Here are the results of my test.
- the patch won't work as is : a "return AST_SUCCESS;" should terminate
the new code "Check if we already have an open NOTIFY transaction" in
transmit_notify_with_sipfrag(), otherwise we queue the new NOTIFY, but we
send it anyway :-)
- in my call scenarios, the 200 response to first NOTIFY is handled in the
"Responses to OUTGOING SIP requests on INCOMING calls" section of
handle_response(). Bad luck :-) for me. In fact, handle_response() contains
a huge  "if (ast_test_flag(&p->flags[0], SIP_OUTGOING)) { ... } else {
...}" where  both parts of the if/else contain a "case 200" and I think
that both parts should include the NOTIFY de-queuing code, or even better,
the de-queuing code may be common and reside outside the incoming/outgoing
alternative.

But : if I add the "return" in transmit_notify_with_sipfrag() and I
duplicate the de-queuing code where it is useful (although I don't like
this solution very much), I obtain indeed a delayed NOTIFY transmission. 

Issue History 
Date Modified   Username       Field                    Change               
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02-04-08 04:39  flefoll        Note Added: 0081642                          
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