[asterisk-dev] Sequence number sign extension problem?

[Kevin P. Fleming]

On 07/28/2011 01:07 PM, Bill Shaw wrote:

> This is repeatable - happens every time for me. It smells like a char
> sign extension problem in the IAX code. Has anyone reported this issue?
> Has it been fixed in a subsequent release? Is there a workaround? Maybe
> a way to reset the sequence number before it overflows 129?

What is "the IAX code" you are referring to? chan_iax2 in Asterisk? Some 
IAX library? An IAX stack you've written?

> One other thing I've noticed about the IAX code can be seen in the same
> 2 areas of this capture - * is using a ping-ack-pong-ack sequence
> instead of ping-pong-ack, and lagrq-ack-lagrp-ack instead of
> lagrq-lagrp-ack as specified in the RFQ. This isn't a problem for me,
> just curious. I've implemented ping-pong-ack and lagrq-lagrp-ack in my
> hardphone per the RFQ.

RFC, not RFQ. You are correct, the diagram in the RFC does show a 
PING/PONG/ACK sequence; the text description of PING could be 
interpreted either way. This needs to be resolved in some manner.

I see at least one other issue in your capture that might be relevant: 
at packet 3364, your phone sends an ACK with an outbound sequence number 
of 0 (zero), whereas the previous full frame it sent (packet 3362) had 
an outbound sequence number of 7 (seven). This repeats again at packet 
5404, and probably further into the call as well.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
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