Summary:ASTERISK-12308: [patch] Retransmitted RFC 2833 RTP events do not increment the RTP sequence number
Reporter:Vincent Thomasset (vt)Labels:
Date Opened:2008-07-03 10:01:49Date Closed:2011-04-26 08:09:17
Versions:Frequency of
Environment:Attachments:( 0) dtmf_inc_seqnum_on_end_pkts.diff
Description:All 3 retransmitted ending packets share the same sequence number, which does not comply with RFC 4733 Sect. RTP Sequence Number:

  The RTP sequence number MUST be incremented by one in each successive
  RTP packet sent.  Incrementing applies to retransmitted as well as
  initial instances of event reports, to permit the receiver to detect
  lost packets for RTP Control Protocol (RTCP) receiver reports.
Comments:By: Vincent Thomasset (vt) 2008-07-03 10:06:12

This patch fixes the issue, as well as remove an unneeded (duplicated) line to set the first part of the RTP header which has the marker bit set (?).

By: Vincent Thomasset (vt) 2008-07-14 07:36:43

Any comments on this patch ?

By: Tilghman Lesher (tilghman) 2008-07-14 10:49:41

Generally speaking, we value interop above strict RFC compliance.  Right now, the state of RFC2833 support is such that we have a high degree of interoperability with other implementations, which we would like to keep.  Given that this issue does not address an actual interop problem, I am tempted to allow this change only in pedantic mode.

By: Vincent Thomasset (vt) 2008-07-16 04:36:16

Yes, I understand that. This "issue" was actually reported to me as causing interop problems but after investigation and testing, I realized it was not the case. Anyhow, I had the patch and thought I should as well send it upstream for you to check.

By: Digium Subversion (svnbot) 2008-12-10 10:05:51.000-0600

Repository: asterisk
Revision: 162653

U   branches/1.4/main/rtp.c

r162653 | file | 2008-12-10 10:05:50 -0600 (Wed, 10 Dec 2008) | 6 lines

Increment the sequence number on the end packets for RFC2833. After reading the RFC some more and doing some testing I agree with this change.
(closes issue ASTERISK-12308)
Reported by: vt
     dtmf_inc_seqnum_on_end_pkts.diff uploaded by vt (license 520)