[asterisk-dev] [Code Review] SIP: session timer behavior in Asterisk

[Benny Amorsen]

"David Vossel" <dvossel at digium.com> writes:

> 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.

I have no comments on the actual patches, but I think those two goals
are a great way to get better interoperability!

I look forward to testing these patches when I get back from vacation.


/Benny