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

Christian Schlatter cs at unc.edu
Thu Nov 1 04:45:34 CET 2007


Christian Schlatter wrote:
> 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
> }

Of course this only makes sense for REGISTER messages:

if (is_method("REGISTER")) ...

/Christian

> 
> 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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> 
> 
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