5gc: Add helper to get incremental PTI field

Change-Id: I9d32024b58799bbd3ef547cdc73ee73d7f7275d2
---
M 5gc/C5G_Tests.ttcn
M 5gc/ConnHdlr.ttcn
2 files changed, 18 insertions(+), 2 deletions(-)


git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks refs/changes/94/40894/1

diff --git a/5gc/C5G_Tests.ttcn b/5gc/C5G_Tests.ttcn
index f9a9057..ae8260c 100644
--- a/5gc/C5G_Tests.ttcn
+++ b/5gc/C5G_Tests.ttcn
@@ -103,6 +103,7 @@
 	ran_id := idx,
 	amf_id := omit,
 	guti := omit,
+	pti := '00'O,
 	sess_pars := ts_PDUSessionParams(id := 1,
 					 run_prog_pars := ts_RunProgParams(idx),
 					 ran_gtpu_teid := int2oct(idx + 1, 4))
diff --git a/5gc/ConnHdlr.ttcn b/5gc/ConnHdlr.ttcn
index ccee880..ebac2ae 100644
--- a/5gc/ConnHdlr.ttcn
+++ b/5gc/ConnHdlr.ttcn
@@ -87,6 +87,7 @@
 	RAN_UE_NGAP_ID ran_id,
 	AMF_UE_NGAP_ID amf_id optional,
 	octetstring guti optional,
+	ProcedureTransactionIdentifier pti,
 	PDUSessionParams sess_pars
 };
 
@@ -168,6 +169,19 @@
 	}
 }
 
+/* 3GPP TS 24.501 9.6, 3GPP TS 24.007 11.2.3.1a.
+ * 0 = "No procedure transaction identity assigned", 255 = "Reserved". */
+private function f_next_pti() runs on ConnHdlr return ProcedureTransactionIdentifier
+{
+	var integer i := oct2int(g_pars.ue_pars.pti);
+	if (i >= 254) {
+		g_pars.ue_pars.pti := '01'O;
+	} else {
+		g_pars.ue_pars.pti := int2oct(i + 1, 1);
+	}
+	return g_pars.ue_pars.pti;
+}
+
 /* 3GPP TS 24.501 5.4.1.3.2, 3GPP TS 33.501 6.1.3.2 */
 private altstep as_ngap_handle_auth(boolean allow_resync := true) runs on ConnHdlr {
 	var NG_NAS_DL_Message_Type rx_nas;
@@ -342,9 +356,10 @@
 	var template (value) NG_NAS_UL_Message_Type nas_ul_msg;
 	var NAS_PDU nas_pdu;
 	var NG_NAS_DL_Message_Type rx_nas, inner_nas;
+	var ProcedureTransactionIdentifier pti := f_next_pti();
 	var OCT1 pdu_sess_id := int2oct(g_pars.ue_pars.sess_pars.id, 1);
 
-	nas_ul_msg := cs_NG_PDU_SESSION_ESTABLISHMENT_REQUEST(cs_NG_PDU_SessionIdV(pdu_sess_id), '01'O,
+	nas_ul_msg := cs_NG_PDU_SESSION_ESTABLISHMENT_REQUEST(cs_NG_PDU_SessionIdV(pdu_sess_id), pti,
 							      p_IntegrityProtMaxDataRate := cs_IntegrityProtMaxDataRateV('FF'O, 'FF'O),
 							      p_PDU_SessionType := cs_PDU_SessionTypeTV('001'B), /* IPv4 */
 							      p_SSC_Mode := cs_SSC_ModeTV('001'B));
@@ -559,7 +574,7 @@
 	var template (value) NG_NAS_UL_Message_Type nas_ul_msg;
 	var NAS_PDU nas_pdu;
 	var NG_NAS_DL_Message_Type rx_nas, inner_nas;
-	var ProcedureTransactionIdentifier pti := '02'O;
+	var ProcedureTransactionIdentifier pti := f_next_pti();
 	var NAS_CauseValue_Type cause_val := c_5GSM_Cause_RegularDeactivation;
 	var OCT1 pdu_sess_id := int2oct(g_pars.ue_pars.sess_pars.id, 1);
 

