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Summary:ASTERISK-13701: [patch] SIP Attended Transfer fails
Reporter:klaus3000 (klaus3000)Labels:
Date Opened:2009-03-05 11:10:42.000-0600Date Closed:2009-03-10 20:04:05
Priority:MinorRegression?No
Status:Closed/CompleteComponents:Channels/chan_sip/Interoperability
Versions:Frequency of
Occurrence
Related
Issues:
Environment:Attachments:( 0) attended-transfer-fails-trace-anonymized.txt
( 1) patch_chan_sip_attended_transfer_1.4.23.txt
Description:Hi!
The attended trasfer fails in the following scenario:
PBX: Aterisk 1.4.23
Extensions: 1, 2 and 3

Extension 2 call extension 1.
Extension 1 puts extension 2 on hold.
Extension 1 calls extension 3.
Extension 1 put extensions 3 on hold.
Extension 1 refers extension 3 to extension 2  

--> Asterisk sends NOTIFY with message/sipfrag:
 SIP/2.0 481 Call leg/transaction does not exist

and the transfer fails.

The failure happens only if the REFER is sent to extension 3. If extensions 1 refers extension 2 to extension 3, then everything works fine.

I have tested with recent SNOM and eyebeam clients - same result, transfer does not work.





****** ADDITIONAL INFORMATION ******

see attached trace
Comments:By: klaus3000 (klaus3000) 2009-03-06 04:15:58.000-0600

one more: the attended transfer always fails if the call which is "replaced" is an incoming call.

e.g. if extenxion 1 receives call from 2 and 3. If the extensions 1 wants to transfer 2 to 3 or transfer 3 to 2 it always fails. if extensions 1 calls extension 2 and 3, then the transfer always works.
By: klaus3000 (klaus3000) 2009-03-06 07:08:19.000-0600

Attached patch fixes the bug. The problem is that Asterisk changed compared wrong tags for outgoing calls. This is wrong, as the RFC states:

> In other words, the to-tag parameter is compared to the local
> tag, and the from-tag parameter is compared to the remote tag.

There is no difference if a call is incoming or outgoing - the local tag should always be compared to the to-tag. Trunk also uses the wrong logic and needs to be fixed.

btw: attended transfer tested and works now fine in all scenarios (incoming, outgoing calls) with eyebeam and SNOM phones.
By: Mark Michelson (mmichelson) 2009-03-09 09:44:10

You haven't mentioned this explicitly, but does the failure only occur with pedantic mode enabled? The patch you have submitted seems to only affect processing with pedantic mode enabled.

By the way, I really like the patch, especially the citation of RFC 3891. If you can confirm that the failure does not occur if you do not have pedantic mode enabled, then I think this patch should go in as soon as possible. Thanks!
By: klaus3000 (klaus3000) 2009-03-09 18:38:45

You are correct - this patch affects only pedantic mode. With pedantic mode turned off, the tags are not checked at all (at least in 1.4, I have not reviewed 1.6 and trunk). That's probably the reason why this bug is there since long time - most users do not use pedantic mode (probably they do not even know that it exists).

PS: Please remove pedantic=no :-)
By: Digium Subversion (svnbot) 2009-03-10 19:30:27

Repository: asterisk
Revision: 181029

U   branches/1.4/channels/chan_sip.c

------------------------------------------------------------------------
r181029 | mmichelson | 2009-03-10 19:30:26 -0500 (Tue, 10 Mar 2009) | 9 lines

Fix incorrect tag checking on transfers when pedantic=yes is enabled.

(closes issue ASTERISK-13701)
Reported by: klaus3000
Patches:
     patch_chan_sip_attended_transfer_1.4.23.txt uploaded by klaus3000 (license 65)
Tested by: klaus3000


------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=181029
By: Digium Subversion (svnbot) 2009-03-10 19:46:48

Repository: asterisk
Revision: 181032

_U  trunk/
U   trunk/channels/chan_sip.c

------------------------------------------------------------------------
r181032 | mmichelson | 2009-03-10 19:46:48 -0500 (Tue, 10 Mar 2009) | 19 lines

Merged revisions 181029,181031 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
 r181029 | mmichelson | 2009-03-10 19:30:26 -0500 (Tue, 10 Mar 2009) | 9 lines
 
 Fix incorrect tag checking on transfers when pedantic=yes is enabled.
 
 (closes issue ASTERISK-13701)
 Reported by: klaus3000
 Patches:
       patch_chan_sip_attended_transfer_1.4.23.txt uploaded by klaus3000 (license 65)
 Tested by: klaus3000
........
 r181031 | mmichelson | 2009-03-10 19:32:40 -0500 (Tue, 10 Mar 2009) | 3 lines
 
 Remove unused variables.
........

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=181032
By: Digium Subversion (svnbot) 2009-03-10 19:52:23

Repository: asterisk
Revision: 181034

_U  branches/1.6.0/
U   branches/1.6.0/channels/chan_sip.c

------------------------------------------------------------------------
r181034 | mmichelson | 2009-03-10 19:52:23 -0500 (Tue, 10 Mar 2009) | 30 lines

Merged revisions 181032-181033 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

................
 r181032 | mmichelson | 2009-03-10 19:46:47 -0500 (Tue, 10 Mar 2009) | 19 lines
 
 Merged revisions 181029,181031 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/branches/1.4
 
 ........
   r181029 | mmichelson | 2009-03-10 19:30:26 -0500 (Tue, 10 Mar 2009) | 9 lines
   
   Fix incorrect tag checking on transfers when pedantic=yes is enabled.
   
   (closes issue ASTERISK-13701)
   Reported by: klaus3000
   Patches:
         patch_chan_sip_attended_transfer_1.4.23.txt uploaded by klaus3000 (license 65)
   Tested by: klaus3000
 ........
   r181031 | mmichelson | 2009-03-10 19:32:40 -0500 (Tue, 10 Mar 2009) | 3 lines
   
   Remove unused variables.
 ........
................
 r181033 | mmichelson | 2009-03-10 19:49:00 -0500 (Tue, 10 Mar 2009) | 3 lines
 
 Add missing comment that quotes RFC 3891
................

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=181034
By: Digium Subversion (svnbot) 2009-03-10 20:04:04

Repository: asterisk
Revision: 181035

_U  branches/1.6.1/
U   branches/1.6.1/channels/chan_sip.c

------------------------------------------------------------------------
r181035 | mmichelson | 2009-03-10 20:04:04 -0500 (Tue, 10 Mar 2009) | 30 lines

Merged revisions 181032-181033 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

................
 r181032 | mmichelson | 2009-03-10 19:46:47 -0500 (Tue, 10 Mar 2009) | 19 lines
 
 Merged revisions 181029,181031 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/branches/1.4
 
 ........
   r181029 | mmichelson | 2009-03-10 19:30:26 -0500 (Tue, 10 Mar 2009) | 9 lines
   
   Fix incorrect tag checking on transfers when pedantic=yes is enabled.
   
   (closes issue ASTERISK-13701)
   Reported by: klaus3000
   Patches:
         patch_chan_sip_attended_transfer_1.4.23.txt uploaded by klaus3000 (license 65)
   Tested by: klaus3000
 ........
   r181031 | mmichelson | 2009-03-10 19:32:40 -0500 (Tue, 10 Mar 2009) | 3 lines
   
   Remove unused variables.
 ........
................
 r181033 | mmichelson | 2009-03-10 19:49:00 -0500 (Tue, 10 Mar 2009) | 3 lines
 
 Add missing comment that quotes RFC 3891
................

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=181035