[OpenSIPS-Users] Trouble accepting an ACK to 200-OK with a bad rUri

[Bogdan-Andrei Iancu]

Hi Shawn,

If you say that the problem is with the contact in 200 OK, maybe you 
should address it there : when handling replies in onreply_route, if the 
contact IP is private ( use nat_uac_test() - 
http://www.opensips.org/html/docs/modules/1.6.x/nathelper.html#id294025 
, test "1") replace it with the layer 3 IP by using fix_nated_contact() 
function

Regards,
Bogdan

On 03/16/2011 07:55 PM, Shawn Smith wrote:
>
> I'm looking for suggestions on how to create a server-side workaround 
> for an issue I'm getting in the field where the ALG logic in certain 
> customer routers is putting bad data into the contact of a 200-OK 
> message causing the resulting ACK back to the server to have the wrong 
> rURI on it.
>
> Here is an example of the content in the bad-ACK:
>
>  Request-Line: ACKsip:5000 at 192.X.X.X:45219;transport=udpSIP/2.0
>  To: <sip:5000 at 206.Y.Y.Y>;tag=vtK3jeZ4yQmmF
>  From: "805ZZZZZ" <sip:805ZZZZZ at 206.Y.Y.Y>
>  Route: <sip:206.Y.Y.Y;lr=on;did=c27.9ebcc7c7>
>  Via: SIP/2.0/UDP 96.A.B.C:45219;branch=z9hG4bKiZKdxRM8VrEaYoN8;rport
>
> I've sanitized the addresses.  206.Y.Y.Y is the address of the 
> openSIPS server.  192.X.X.X is the bogus NAT'd address which the ALG 
> modified 200-OK caused to be placed in the ACK.
>
> With a standard-issue openSIPS config, the above ACK is given to 
> loose_route() and then route(1), which decides it should be forwarded 
> to the 192.X.X.X address - it's relayed to that (bogus) IP, and since 
> the ACK never gets processed openSIPS keeps sending retries of the 
> 200-OK, eventually giving up and tearing down the call.
>
> I can easily detect this problem by seeing that the To: domain doesn't 
> match the rURI.
>
> I've tried setting modparam("tm", "ruri_matching", 0).  That has no 
> effect.
>
> I've modified the config to examine all ACK's for the above issue, and 
> set $rd = $td before calling loose_route() in hopes that this would 
> convince the dialog to accept the ACK and advance to the established 
> state.  This seems like it should work, and I see the ACC module 
> saying the 200 request was acknowledged.  But then openSIPS continues 
> sending out 200-OK retries and the call is eventually torn down.
>
> I'm looking for advice.  I need a server side workaround for this - I 
> can't do it in the client.  What can I do in the openSIPS config to 
> get the dialog to accept these mangled ACK's to the 200-OK and let the 
> call move to established.
>
> Thanks in advance for any help.
>
>    -Shawn Smith

-- 
Bogdan-Andrei Iancu
OpenSIPS eBootcamp - 2nd of May 2011
OpenSIPS solutions and "know-how"

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