[SR-Users] Add Record-Route on 200 OK

[Alex Balashov]

Igor,

I don't know of a simple way to do that, and I'm not sure the value you're seeing in Via is the value you'd want to put into Record-Route.

Regardless, this is not the solution to the problem. You can't fix such basic, fundamental protocol breakage with a proxy. Proxies are very limited in the amount of interop breakage they can be used to fix. Kamailio does provide a lot of text transformation functions, but using them in this way falls under "just because you can doesn't mean you should"; there are all kinds of unexpected complications in tinkering with a broken client-side state machine.

For example, even if you force the RR header into the 2xx reply, does that mean the UAS will exhibit correct behaviour for loose-routed sequential requests (reinvite, BYE, etc) in placing the ‎Record-Route value into a Route set? If not, you'll end up having to "patch" that, too, and it can rapidly mushroom into something complex, unsustainable and degenerative.

The solution is to fix the UAS, which is not RFC 3261-compliant. :-)

-- Alex

--
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

Sent from my BlackBerry.
  Original Message  
From: Igor Potjevlesch
Sent: Wednesday, January 6, 2016 10:48
To: 'Kamailio (SER) - Users Mailing List'
Reply To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] Add Record-Route on 200 OK

Hi Alex,

You're right, it was my mistake. It's one of the UA in the call-flow which
not put the Record-Route into the replies.
So, the issue is not on Kamalio.

Nevertheless, the UA put the Record-Route into Via headers. Is there a
simple way to copy the Via into Record-route headers?

Regards,

Igor.


-----Message d'origine-----
De : sr-users [mailto:sr-users-bounces at lists.sip-router.org] De la part de
Alex Balashov
Envoyé : mercredi 6 janvier 2016 16:42
À : Igor Potjevlesch <sr-users at lists.sip-router.org>
Objet : Re: [SR-Users] Add Record-Route on 200 OK

Kamailio has no hand in this behaviour. It appends the Record-Route header
to the initial invite, but dealing with it from that point onward, including
ensuring that it is copied into replies sent back to the initiator, is
entirely the responsibility of the user agents/endpoints, not the proxy.

--
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

Sent from my BlackBerry.
  Original Message
From: Igor Potjevlesch
Sent: Wednesday, January 6, 2016 10:30
To: 'Kamailio (SER) - Users Mailing List'
Reply To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] Add Record-Route on 200 OK

Hi Alex,

It what I was thinking. What could cause this into Kamailio?

Regards,

Igor.

-----Message d'origine-----
De : sr-users [mailto:sr-users-bounces at lists.sip-router.org] De la part de
Alex Balashov Envoyé : mercredi 6 janvier 2016 15:39 À :
sr-users at lists.sip-router.org Objet : Re: [SR-Users] Add Record-Route on 200
OK

Igor,

No, that is not normal. The UAS (the server receiving the initial
INVITE) is required to copy the Record-Route into dialog-forming responses.

>From RFC 3261 Section 12.1.1 ("UAS Behavior"):

When a UAS responds to a request with a response that establishes a dialog
(such as a 2xx to INVITE), the UAS MUST copy all Record-Route header field
values from the request into the response (including the URIs, URI
parameters, and any Record-Route header field parameters, whether they are
known or unknown to the UAS) and MUST maintain the order of those values.

-- Alex

--
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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