asterisk: IMS: Fix PRACK 200 OK Tx with wrong branch

PRACK (and also UPDATE) are new transactions, and hence should have a
new branch. Update the branch we transmit in the response too.

Change-Id: Ia4a23f20ae69ee5facdcff7ae276ab823e860d06
---
M asterisk/IMS_ConnectionHandler.ttcn
1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index 8c4186e..a46d62f 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -1378,7 +1378,7 @@
 
 	[] SIP.receive(exp_req) -> value g_rx_sip_req {
 		var template (value) PDU_SIP_Response tx_resp;
-		var Via via;
+		var Via invite_via;
 		var template (omit) charstring tx_sdp;
 		var integer invite_seq_nr;
 		var boolean peer_support_precondition := match(g_rx_sip_req.msgHeader.supported.optionsTags,
@@ -1386,7 +1386,7 @@
 
 		/* Obtain params: */
 		f_ConnHdlr_parse_initial_SIP_INVITE(g_rx_sip_req);
-		via := g_rx_sip_req.msgHeader.via;
+		invite_via := g_rx_sip_req.msgHeader.via;
 		invite_seq_nr := g_pars.subscr.cp.sip_seq_nr;
 
 		f_ims_validate_register_P_Access_Network_info(g_rx_sip_req, exp_present := true);
@@ -1404,7 +1404,7 @@
 		tx_resp := ts_SIP_Response_Trying(g_pars.subscr.cp.sip_call_id,
 						   g_pars.subscr.cp.from_addr,
 						   g_pars.subscr.cp.to_addr,
-						   via,
+						   invite_via,
 						   g_pars.subscr.cp.sip_seq_nr,
 						   "INVITE",
 						   allow := omit,
@@ -1444,7 +1444,7 @@
 			tx_resp := ts_SIP_Response_SessionProgress(g_pars.subscr.cp.sip_call_id,
 							g_pars.subscr.cp.from_addr,
 							g_pars.subscr.cp.to_addr,
-							via,
+							invite_via,
 							g_pars.subscr.cp.sip_seq_nr,
 							rseq := ts_RSeq(1),
 							body := tx_sdp);
@@ -1455,7 +1455,7 @@
 					g_pars.subscr.cp.sip_call_id,
 					g_pars.subscr.cp.from_addr,
 					g_pars.subscr.cp.to_addr,
-					f_tr_Via_response(via),
+					f_tr_Via_response(invite_via),
 					g_pars.subscr.cp.sip_seq_nr + 1,
 					rack := tr_RAck(1, g_pars.subscr.cp.sip_seq_nr, "INVITE"),
 					body := omit);
@@ -1468,7 +1468,7 @@
 						"PRACK", 200,
 						g_pars.subscr.cp.sip_seq_nr + 1,
 						"OK",
-						via,
+						g_rx_sip_req.msgHeader.via /* PRACK's new branch */,
 						body := omit);
 			SIP.send(tx_resp);
 
@@ -1477,7 +1477,7 @@
 					g_pars.subscr.cp.sip_call_id,
 					g_pars.subscr.cp.from_addr,
 					g_pars.subscr.cp.to_addr,
-					f_tr_Via_response(via),
+					f_tr_Via_response(invite_via),
 					g_pars.subscr.cp.sip_seq_nr + 2,
 					require := tr_Require(superset("precondition")),
 					body := ?);
@@ -1509,7 +1509,7 @@
 						"UPDATE", 200,
 						g_pars.subscr.cp.sip_seq_nr + 2,
 						"OK",
-						via,
+						g_rx_sip_req.msgHeader.via /* UPDATE's new branch */,
 						body := tx_sdp);
 			SIP.send(tx_resp);
 
@@ -1535,7 +1535,7 @@
 		tx_resp := ts_SIP_Response_Ringing(g_pars.subscr.cp.sip_call_id,
 						g_pars.subscr.cp.from_addr,
 						g_pars.subscr.cp.to_addr,
-						via,
+						invite_via,
 						invite_seq_nr);
 		SIP.send(tx_resp);
 
@@ -1548,7 +1548,7 @@
 					   "INVITE", 200,
 					   invite_seq_nr,
 					   "OK",
-					   via,
+					   invite_via,
 					   body := tx_sdp);
 		SIP.send(tx_resp);
 
@@ -1557,7 +1557,7 @@
 				      g_pars.subscr.cp.sip_call_id,
 				      g_pars.subscr.cp.from_addr,
 				      g_pars.subscr.cp.to_addr,
-				      f_tr_Via_response(via),
+				      f_tr_Via_response(invite_via),
 				      invite_seq_nr, *);
 		as_SIP_expect_req(exp_req);
 	}

