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

Jeff Pyle jpyle at fidelityvoice.com
Tue Feb 8 20:40:17 CET 2011


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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