[Kamailio-Users] Multiple SIP Proxy Environment / Socket Information

[Klaus Darilion]

Hi Brandon!

Back to the original email ....

Brandon Armstead schrieb:
> Hello guys,
> 
>     Is there a method upon using lookup("location") to also pull out the 
> "socket" information for the original location the UAC registered to, 
> for scenarios of this example:
> 
> P1 & P2 share same usrloc database.
> 
> UA1 registers to P1
> UA2 registers to P2
> 
> UA1 calls UA2
> 
> UA1 invites -> P1 -> INVITES -> UA2 (bypassing P2 -- where the actual 
> nat binding is).
> 
> Now upon P1 looking up usrloc for UA2, I would like to recognize that P1 
> is not the Proxy to deliver the call, and forward the request to P2 to 
> send to UA2.
> 
> So currently I have:
> 
> UA1 INVITE -> P1 INVITE -> UA2
> 
> I wish to have:
> 
> UA1 INVITE -> P1 INVITE -> P2 INVITE -> UA2
> 
> Is there an easy method to do this?  I have been looking at the new nat 
> traversal module it looks like it is doable with this (any further input 
> as far as that?).  Also is it possible with the classic Nat Helper 
> module?  Any input is appreciated, thanks!

I think the nat_traversal module can not help you in this case, nor 
nathelper.

One possibility would be to spoof at P1 the IP address of P2 - 
nevertheless this would cause the reply sent back to P2, but the 
transaction is created in P1. (and you need to hack Kamailio for IP 
spoofing).

Another easy solution would be: In P1 set a certain branch-flag when the 
client registers, e.g. bflag 1. In P2 set a certain branch-flag when the 
client registers, e.g. bflag 2.

Now, if a user is called, just make a lookup() and t_relay. Further in 
the branch_route check if:
  in P1: isbflagset(2) --> forward to P2
  in P2: isbflagset(1) --> forward to P1

klaus




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