[OpenSER-Users] How to expose the expires value in REGISTER

[Christian Schlatter]

Robert Dyck wrote:
> I am wondering how to expose and test the value of the expires parameter in a 
> REGISTER request.
> 
> I am experimenting with openser as the basis for a home phone network. I use 
> multiple devices with the same user ID. They register locally ( with no 
> reply ) and with an external service provider. The contacts are mangled to 
> show the public address of openser. Multiple registrations result in a single 
> AOR at the external registrar. Incoming calls from the outside are forked and 
> ring the local phones. Local phones can also call each other without the 
> hairpin problem associated with STUN enabled phones.
> 
> The problem is that a softphone will deregister when it is closed or its 
> profile changes. This would deregister the AOR at the external registrar. The 
> remaining phones could not receive calls from the outside until they 
> refreshed their registrations.
> 
> I would like to prevent deregistration at the external registrar unless the 
> phone that was deregistering was the only remaining one. The first step would 
> be to identify REGISTER messages where the expires value is equal to zero.

Both 'Expires' header and 'expires' contact uri parameter have to be 
checked like e.g.

if ((is_present_hf("Expires") && $(hdr(Expires){s.int}) == 0) ||
     ($(ct{param.value,expires}) == '0'))
{
	# someone tries to unregister
}

Have a look at 
http://www.openser.org/dokuwiki/doku.php/transformations:1.2.x if you're 
not familiar with the PV transformations introduced with 1.2.

/Christian

> 
> Any thoughts?
> Thanks Rob
> 
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