why use received as RURI for nathelper OPTIONS ping? - sr-users

7 Jan 2013

Some Fritzbox devices don't accept the OPTIONS ping generated by
kamailio with RURI: sip:11.22.3.4:5060. In the location table we have:
received: sip:11.22.3.4:5060
contact: sip:user@11.22.3.4:5060;uniq=6633BC1386F4D4CC4EBD64DC7E967
path: <sip:lb@127.0.0.1;lr;received='sip:11.22.3.4:5060'>

Kamailio version is 3.3.2 and the nathelper config is nothing fancy:
modparam("nathelper", "natping_interval", 15)
modparam("nathelper", "ping_nated_only", 1)
modparam("nathelper", "sipping_bflag", FLB_NATSIPPING)
modparam("nathelper", "sipping_from",
"sip:pinger@sipwise.local")
modparam("nathelper", "received_avp", "$avp(s:received)")

What I don't understand is why kamailio sets RURI of the OPTIONS message
to value of "received" instead of the contact. I suspect a bug in the
parser somewhere along these lines:

...
                  rval =
ul.get_all_ucontacts(buf,cblen,(ping_nated_only?ul.nat_flag:0),
                    ((unsigned int)(unsigned long)timer_idx)*natping_interval+iteration,
                    natping_processes*natping_interval);
                 if (rval != 0) {
                         pkg_free(buf);
                         goto done;
                 }
         }

         if (buf == NULL)
                 goto done;

         cp = buf;
         while (1) {
                 memcpy(&(c.len), cp, sizeof(c.len));
                 if (c.len == 0)
                         break;
                 c.s = (char*)cp + sizeof(c.len);
                 cp =  (char*)cp + sizeof(c.len) + c.len;
                 memcpy( &send_sock, cp, sizeof(send_sock));
                 cp = (char*)cp + sizeof(send_sock);
                 memcpy( &flags, cp, sizeof(flags));
                 cp = (char*)cp + sizeof(flags);
                 memcpy( &(path.len), cp, sizeof(path.len));
                 path.s = path.len ? ((char*)cp + sizeof(path.len)) : NULL ;
                 cp =  (char*)cp + sizeof(path.len) + path.len;

                 /* determin the destination */
                 if ( path.len && (flags&sipping_flag)!=0 ) {
                         /* send to first URI in path */
                         if (get_path_dst_uri( &path, &opt) < 0) {
                                 LM_ERR("failed to get dst_uri for Path\n");
                                 continue;
                         }
                         /* send to the contact/received */
                         if (parse_uri(opt.s, opt.len, &curi) < 0) {
                                 LM_ERR("can't parse contact dst_uri\n");
                                 continue;
                         }
                 } else { 