[OpenSIPS-Users] on routing invite's in a trunk context.

[Ben Newlin]

Johan,

I think you must have left some pieces out of your initial description then. You stated that node A is sending directly to your OpenSIPS node, so the source IP and Via would both point to node A.

As I mentioned, changes to Contact and Record-Route headers will only affect the routing of sequential requests for the dialog. They will not impact the routing of responses. I don’t think that OpenSIPS provides any mechanism to change the destination of responses it proxies, since as you said this is outside of the RFC.

Ben Newlin

From: Users <users-bounces at lists.opensips.org> on behalf of Johan De Clercq <johan at democon.be>
Date: Saturday, October 7, 2023 at 1:40 AM
To: OpenSIPS users mailling list <users at lists.opensips.org>
Subject: Re: [OpenSIPS-Users] on routing invite's in a trunk context.
 EXTERNAL EMAIL - Please use caution with links and attachments

________________________________
It’s a very non rfc scenario. Source ip and via are the ip of a loadbalancer that I need to skip …. ;-(. The contact does have the correct ip. Anyway, you gave me a good hint. I will add the contact ip as record route and see what that gives.

Verzonden vanuit Outlook voor iOS<https://aka.ms/o0ukef>
________________________________
Van: Users <users-bounces at lists.opensips.org> namens Ben Newlin <Ben.Newlin at genesys.com>
Verzonden: Friday, October 6, 2023 5:35:40 PM
Aan: OpenSIPS users mailling list <users at lists.opensips.org>
Onderwerp: Re: [OpenSIPS-Users] on routing invite's in a trunk context.


Johan,



This is actually a pretty standard SIP flow that we use all the time. I recommend this article [1] for an overview of how routing works in SIP.



In short, the Contact and Record-Route headers are only used for routing of requests not responses, and mostly only sequential requests which are requests within a dialog. The topology_hiding_match and loose_route functions both operate on requests only, so they can both only be called from a request_route [1] [2].



The 200 OK is a response within the initial INVITE transaction. Responses within a SIP transaction are routed based on the source IP of request and/or the Via headers. OpenSIPS should just handle that for you, unless you have some strange routing.



[1] https://kb.smartvox.co.uk/opensips/contact-and-record-route-headers-explained/<https://kb.smartvox.co.uk/opensips/contact-and-record-route-headers-explained/>

[2] https://opensips.org/docs/modules/3.2.x/topology_hiding.html#func_topology_hiding_match<https://opensips.org/docs/modules/3.2.x/topology_hiding.html#func_topology_hiding_match>

[3] https://opensips.org/docs/modules/3.2.x/rr.html#func_loose_route<https://opensips.org/docs/modules/3.2.x/rr.html#func_loose_route>



Ben Newlin



From: Users <users-bounces at lists.opensips.org> on behalf of johan <johan at democon.be>
Date: Friday, October 6, 2023 at 10:30 AM
To: OpenSIPS users mailling list <users at lists.opensips.org>
Subject: [OpenSIPS-Users] on routing invite's in a trunk context.

 EXTERNAL EMAIL - Please use caution with links and attachments

This is a general question on routing (to be honest: it is a really
strange case).


A has a sip trunk to B (opensips), B has a sip trunk to C



A sends an invite to B with contact header A'   and record-route header
to A''

B string the record_route header , calls topology hiding and droutes the
call to C

C sends 200 OK back but it needs to be routed on the content of the
contact header.


Now how does this route to A ?   Is this the default
topology_hiding_match() case ? Or do I need to do something special ?






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