[SR-Users] Manually add Via Header

[Andreas Granig]

Hi,

Sorry for hijacking this thread, but I've a similar but different
question which bugs me since a while :)

Is there a way in kamailio to statelessy forward a request without
putting its own Via header into the message? Consider an example where a
stateless load-balancer sends a request to a proxy A, which again
statelessy forwards it to another proxy B, while it's not interested in
staying in the path even for replies. It's not necessary either because
the load-balancer, which would receive the replies from B then, can pass
them along according to the Via path, so no tm or something is involved.

This might break some RFC, but it would remove proxy A completely out of
the path once the request got forwarded. In theory this seems possible
if it's ensured that both the load-balancer and proxy A act strictly
stateless, no?

Andreas

On 10/25/2012 12:03 PM, Daniel-Constantin Mierla wrote:
> You better use t_reply("487", "Cancelled") in a failure_route.
> 
> Adding a proper Via header might be a tricky task.
> 
> Cheers,
> Daniel
> 
> On 10/25/12 11:43 AM, Vassilis Radis wrote:
>> I have a situation where a far end SIP provider doesn't behave
>> properly when sending 487 replies. The scenario is this:
>>
>> I have a registered user calling into my kamailio which ,using lcr
>> module, routes the call to a SIP provider. When the caller Cancels the
>> call, my kamailio forwards the cancel message to the provider (along
>> with a 200 Cancelling message to the caller). The problem is with the
>> 487 sent by the provider to my kamailio: It does not contain all the
>> two Via headers. It only contains the via header that names my
>> kamailio. So when kamailio gets the 487, it removes its Via header and
>> sends the 487 back to the caller, which now doesnt find any via header. 
>>
>> Note that the far end provider, correctly sends all the Via Headers in
>> other replies (183 etc). 
>>
>> So now I am trying to "intercept" the 487 from this specific provider
>> in the onreply route, and patch it with the header that the provider
>> should have included. How can I do it? The problem is twofold:
>> 1.I need to detect which header I should manually add (maybe store the
>> Via Header set from the initial invites or the 183 replies, and get it
>> from there? .I dont know how to do that)
>> 2.I need to add it. (How can I manually add a Via header? .This seems
>> easier
>>
>> Can anyone help me, maybe with another solution? 
>>
>>
>> _______________________________________________
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>> sr-users at lists.sip-router.org
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> 
> -- 
> Daniel-Constantin Mierla - http://www.asipto.com
> http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
> Kamailio Advanced Training, Berlin, Nov 5-8, 2012 - http://asipto.com/u/kat
> Kamailio Advanced Training, Miami, USA, Nov 12-14, 2012 - http://asipto.com/u/katu
> 
> 
> 
> _______________________________________________
> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
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