[OpenSIPS-Users] problem with loose_route()/t_relay() across multiple interfaces

[Jeff Pyle]

Hello,

I'm attempting to write a config to perform near-end NAT traversal on
Opensips 1.7.  I'm having a problem with the loose_route of the ACK after
the 200 OK, and if I wait long enough, the BYE as well.

Here's the scenario.  An INVITE comes in the WAN side and is t_relay'd to
the LAN side.  The LAN-side UAS sends a 200 OK, and that is relayed back to
the WAN-side UAC.  So far, so good.  Then the WAN-side UAC sends the ACK to
the 200.  Opensips relays this from its own WAN IP to its own LAN IP - I
found it with ngrep on the lo interface.  Eventually Opensips sends a 408
back to the UAC.

Here's the relevant portion of the config, based largely on the included
sample.  This works fine with single-interface configurations:

        if (has_totag()) {
                if (loose_route()) {
                        if (method=="INVITE") record_route();
                        if (!t_relay()) sl_reply_error();
                        exit;
                } else {
                        if (method == "ACK") {
                                if (t_check_trans()) {
                                        if (!t_relay()) sl_reply_error();
                                        exit;
                                } else {
                                        exit;
                                }
                        }
                        sl_send_reply("404", "Not Here");
                }
                exit;
        }

I've verified with xlogs the ACK hits in the loose_route() portion of the
config.  It does hit t_relay, but it relays the message to itself on its
'other' IP.  I've tried to look the extended debugs but I'm not finding
anything telling.  Unfortunately I don't have any experience with multiple
interface configurations.  I suspect it has something to do with the double
Via lines added, one from each interface.  Perhaps it's not detecting the
second Via as its own?  (Even if that were the case, I can't explain why
it's not responding to itself on the lo interface.)

I do have mhomed=1 enabled.  Without it the initial invite doesn't arrive
at the LAN-side UAS.

I've experimented with check_via, aliases, etc.  No effect.  Any
suggestions on where to go from here?



- Jeff
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