[OpenSIPS-Users] [OpenSIPS-Devel] Planning next release - Roadmap

[Ovidiu Sas]

The dialog module is bound to a transaction not to a branch and
therefore, at this point in time, it is not branch aware.

On Tue, Aug 26, 2008 at 10:49 AM, Iñaki Baz Castillo <ibc at in.ilimit.es> wrote:
> El Tuesday 26 August 2008 16:42:44 Iñaki Baz Castillo escribió:
>> El Tuesday 26 August 2008 16:30:55 Ovidiu Sas escribió:
>> > This is a little bit tricky, because you need to keep tracking of the
>> > cseq for the received and sent message (each OPTION will increase the
>> > sent cseq number).  Each in dialog request that will come from the far
>> > end UAC will need to have the cseq altered to be in synch with the
>> > previous sent OPTION.
>> > It can be done, but it is more work.  Sending OPTIONS from the dialog
>> > module itself is quite easy.  I implemented and tested that, but then
>> > I got lazy in implementing the cseq mangling stuff.
>>
>> If a proxy changes the CSeq in a request it must also change it in the
>> responses to the client.
>>
>> Also note the problem handling PRACK since a PRACK message is an in-dialog
>> request containing CSeq and Rseq, and the reply must contain Cseq and RAck.
>> Example:
>>
>> UAC  -------->   UAS
>>
>>   INVITE --->
>>   Cseq: 10
>>
>>      <-- 180
>>           CSeq: 10
>>           Require: 10res
>>           Rseq: 555
>>
>>   PRACK --->
>>   Cseq: 11
>>   RAck: 555 10
>>
>>
>> So IMHO it's not so easy to handle and modify it in a proxy. Also this
>> seems to me more a B2BUA task.
>
> Also take in mind the case in which the proxy does parallel forking and just
> one of the branches requieres PRACK.
> Then the UAC must create a new in-dialog PRACK (with CSeq+1) just for that
> endpoint, so incrementing in one the local CSeq just for that early-dialog.
>
> In case of parallel forking, does OpenSIPS mantain a dialog (early-dialog) for
> each branch? If not, the proxy cannot manage the CSeq correctly.
>
>
>
> --
> Iñaki Baz Castillo
> ibc at in.ilimit.es
>
> _______________________________________________
> Users mailing list
> Users at lists.opensips.org
> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
>