[asterisk-bugs] [Asterisk 0017874]: [patch] Q931 - Sending PROGRESS after sending ALERTING is a protocol error

[Asterisk Bug Tracker]

The following issue has been SUBMITTED. 
====================================================================== 
https://issues.asterisk.org/view.php?id=17874 
====================================================================== 
Reported By:                nic_bellamy
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   17874
Category:                   Channels/chan_dahdi
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
Asterisk Version:           SVN 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases):  trunk 
SVN Revision (number only!): 282537 
Request Review:              
====================================================================== 
Date Submitted:             2010-08-16 22:41 CDT
Last Modified:              2010-08-16 22:41 CDT
====================================================================== 
Summary:                    [patch] Q931 - Sending PROGRESS after sending
ALERTING is a protocol error
Description: 
The PRI layer in chan_dadhi will check if a PROGRESS message has already
been sent, and not allow sending another (although that is technically
allowed by the Q931 spec), however it does not protect against sending an
ALERTING and then sending a PROGRESS message, which is a violation of the
specification.

Most switches don't seem to care too deeply about this, but some do, and
will disconnect the call when receiving this invalid sequence.

Issue affects all released versions of Asterisk, plus SVN-trunk.

Protocol specification reference: T-REC-Q.931-199805-I page 235, "Figure
A.5/Q.931 – Overview protocol control (network side) point-point (sheet 3
of 8)"
====================================================================== 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-08-16 22:41 nic_bellamy    New Issue                                    
2010-08-16 22:41 nic_bellamy    Asterisk Version          => SVN             
2010-08-16 22:41 nic_bellamy    Regression                => No              
2010-08-16 22:41 nic_bellamy    SVN Branch (only for SVN checkouts, not tarball
releases) =>  trunk          
2010-08-16 22:41 nic_bellamy    SVN Revision (number only!) => 282537          
======================================================================