Re: [OpenSIPStack] Incoming requests handling in upper registration mode

[Joegen E. B. <joe...@gm...>]

Hi Andrew,

I fully understand your situation.  I think the best solution here is to 
let PortaSIP rewrite the To URI as well.  Is this not a posibility?   As 
you can see OpenSBC tried its best here to act closest to the specs how 
the request would have been routed.  Let's say hypothetically that this 
maybe configurable.    Assume there is a user registered to OpenSBC as 
sip:61...@op....  Imagine what will happen if OpenSBC received 
an INVITE like this:

INVITE sip:61...@fw... SIP/2.0
From: "alice" <sip:al...@wo...>;tag=123
To: "Free World Dial-up Echo Server" <sip:61...@fw...>

This would clearly be a relay at first glance and OpenSBC should forward 
this to the real destination.   However, since 613 might be a registered 
user, in this case sip:61...@op..., the hypothetical behavior 
would be to back off and send the call originally intended for 
sip:61...@fw... to the 613 user of opensbcdomain.com.

At first glance this is doable but would entail more work for OpenSBC 
when in fact the sender could have just written the To URI correctly. 

I am not closing my doors for this case.  If you think there is an 
important real-world reason to let OpenSBC handle this behavior then 
lets start discussing a possible path to take.

Joegen

Andrew Pogrebennyk wrote:
> Dear all,
>
> I am trying to use OpenSBC in b2bua upper registration mode with 
> PortaSIP softswitch. Registration and outgoing calls for UAs behind 
> OpenSBC are OK, requests are forwarded through OpenSBC to PortaSIP. 
> Contact header hijacking works like a charm. But when it comes to 
> incoming calls or, say, NOTIFY from external application server, there 
> is a trouble. Rules that govern distinguishing between local and remote 
> domains do backfire: since incoming requests hit PortaSIP first, an IP 
> in To header does not match the IP address of OpenSBC's listener 
> interface. It contains the IP address of PortaSIP.
> So OpenSBC first checks the IP in Request-URI, sees that it matches the 
> IP address of OpenSBC's listener interface, then checks the To header, 
> sees it does not match AND sends request back to PortaSIP. This leads to 
> a routing loop.
> Can I instruct OpenSBC to overwrite IP address in To header with an AOR 
> it knows for the request target and then send it out? Or I am missing 
> something? Thanks in advance.
>
>