PJSIP: Force transport on contact rewrite

If contact rewriting is enabled but the contact differs in transport
from what is actually being used, messages after the initial INVITE
transaction can be sent to an incorrect transport/port combination. In
the case where this bug occurred the remote party never received a BYE
since it was sent to the remote party's TCP port over UDP.

Review: https://reviewboard.asterisk.org/r/4032/
........

Merged revisions 424244 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@424245 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_nat.c

@@ -46,6 +46,11 @@ static pj_bool_t handle_rx_message(struct ast_sip_endpoint *endpoint, pjsip_rx_d
 		pjsip_dialog *dlg = pjsip_rdata_get_dlg(rdata);
 
 		pj_cstr(&uri->host, rdata->pkt_info.src_name);
+		if (strcasecmp("udp", rdata->tp_info.transport->type_name)) {
+			uri->transport_param = pj_str(rdata->tp_info.transport->type_name);
+		} else {
+			uri->transport_param.slen = 0;
+		}
 		uri->port = rdata->pkt_info.src_port;
 
 		/* rewrite the session target since it may have already been pulled from the contact header */