[OpenSIPS-Users] b2b top-hiding and SDP origin line

[Dave Singer]

Jeff,

I ran into this too. I was not using opensips to do the SIP top hiding
but was for the SDP using media_proxy. Media proxy doesn't touch "o"
unfortunately.
So I used fix_nated_sdp :
  fix_nated_sdp("8","$Ri"); #the recieved on IP (my IP)
That fixed the "o" header but it created a "oldip" or "origip" or
something like that in the sdp.
So I ended up modifying the source to not add the extra sdp header and
it worked good.
Not sure this will work for your situation but worth mentioning.
It would be nice if media_proxy and nat_helper had params for changing
the "o" header at the same time as the "c".
I looked at doing that in source but it was a little beyond my confort zone. :-)

Dave


On Tue, Feb 8, 2011 at 11:40 AM, Jeff Pyle <jpyle at fidelityvoice.com> wrote:
> Hello,
> Since the top-hiding scenario doesn't touch the SDP, it seems some
> extracurricular textops may be required to fully hide the topology of the
> network.  I've been trying various subst_body() functions on my b2b Opensips
> instance, each failing in a new and wonderful way.
>
> route[b2b_request] {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> b2b_request\n");
>                 subst_body('/^o=.*/o=request 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
> route[b2b_reply] {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> b2b_reply\n");
>                 subst_body('/^o=.*/o=reply 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
> local_route {
>         if (search("Content-Type: application/sdp")) {
>                 xlog("L_INFO", "Attempting to rewrite origin line in
> local_route\n");
>                 subst_body('/^o=.*/o=local 12345 67890 IN IP4 8.4.6.2/');
>         }
> }
>
> With the above config, the initial INVITE b2b'd through
> with b2b_init_request("top hiding") does have it's origin line operated
> upon.  After that, I see two xlogs hit from within b2b_reply on the 183 and
> 200 coming back through, but the subst_body commands have no effect.
> No, I'm not really going to rewrite my origin lines to a static value like
> this; this is just for testing.  And the test is not going well.
> How does one affect the origin line in a b2b environment for true topology
> hiding?  Or, is that the key, that it must be done outside of a b2b
> environment?
>
> - Jeff
>
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