[asterisk-bugs] [Asterisk 0017005]: [patch] Asterisk sends session-timer with "require" after 15 minutes

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=17005 
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Reported By:                alexrecarey
Assigned To:                dvossel
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Project:                    Asterisk
Issue ID:                   17005
Category:                   Channels/chan_sip/Interoperability
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     acknowledged
Target Version:             1.6.2.13
Asterisk Version:           SVN 
JIRA:                       SWP-1067 
Regression:                 No 
Reviewboard Link:           https://reviewboard.asterisk.org/r/698/ 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-03-10 21:02 CST
Last Modified:              2010-09-08 16:47 CDT
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Summary:                    [patch] Asterisk sends session-timer with "require"
after 15 minutes
Description: 
When asterisk is set to defaults in session timer handling, after 15
minutes it will send a re-invite with the "required" tag.

This will cause an asterisk server with session-timers=refuse setting to
respond with a sip 420 and disconnect the call.

According to developer documentation at
https://issues.asterisk.org/file_download.php?file_id=15454&type=bug
asterisk should NEVER send a session timer with the "require" tag even if
set to session-timers=force

This issue is easily reproduced by registering a sip client with one
asterisk, set to session-timers=refuse, and place a call to another
asterisk with default session-timers settings. After exactly 15 minutes the
call will drop.

I have included a SIP Trace of the last 30 seconds of the call.
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 (0126758) svnbot (reporter) - 2010-09-08 16:47
 https://issues.asterisk.org/view.php?id=17005#c126758 
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Repository: asterisk
Revision: 285563

U   branches/1.6.2/channels/chan_sip.c

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r285563 | dvossel | 2010-09-08 16:47:30 -0500 (Wed, 08 Sep 2010) | 54
lines

Fixes interoperability problems with session timer behavior in Asterisk.

CHANGES:
1. Never put "timer" in "Require" header.  This is not to our benefit
and RFC 4028 section 7.1 even warns against it.  It is possible for one
endpoint to perform session-timer refreshes while the other endpoint does
not support them.  If in this case the end point performing the refreshing
puts "timer" in the Require field during a refresh, the dialog will
likely get terminated by the other end.

2. Change the behavior of 'session-timer=accept' in sip.conf (which is
the default behavior of Asterisk with no session timer configuration
specified) to only run session-timers as result of an incoming INVITE
request if the INVITE contains an "Session-Expires" header... Asterisk is
currently treating having the "timer" option in the "Supported" header as
a request for session timers by the UAC.  I do not agree with this. 
Session
timers should only be negotiated in "accept" mode when the incoming INVITE
supplies a "Session-Expires" header, otherwise RFC 4028 says we should
treat a request containing no "Session-Expires" header as a session with
no expiration.

Below I have outlined some situations and what Asterisk's behavior is.
The table reflects the behavior changes implemented by this patch.

SITUATIONS:
-Asterisk as UAS
1. Incoming INVITE: NO  "Session-Expires"
2. Incoming INVITE: HAS "Session-Expires"

-Asterisk as UAC
3. Outgoing INVITE: NO  "Session-Expires". 200 Ok Response HAS
"Session-Expires" header
4. Outgoing INVITE: NO  "Session-Expires". 200 Ok Response NO 
"Session-Expires" header
5. Outgoing INVITE: HAS "Session-Expires".

Active   - Asterisk will have an active refresh timer regardless if the
other endpoint does.
Inactive - Asterisk does not have an active refresh timer regardless if
the other endpoint does.
XXXXXXX  - Not possible for mode.
______________________________________
|SITUATIONS | 'session-timer' MODES  |
|___________|________________________|
|           | originate  |  accept   |
|-----------|------------|-----------|
|1.         |   Active   | Inactive  |
|2.         |   Active   |  Active   |
|3.         | XXXXXXXX   | Active    |
|4.         | XXXXXXXX   | Inactive  |
|5.         |   Active   | XXXXXXXX  |
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(closes issue https://issues.asterisk.org/view.php?id=17005)
Reported by: alexrecarey


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http://svn.digium.com/view/asterisk?view=rev&revision=285563 

Issue History 
Date Modified    Username       Field                    Change               
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2010-09-08 16:47 svnbot         Note Added: 0126758                          
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