[M] Change in osmo-ttcn3-hacks[master]: 5gc: Obtain amf_id from NGAP_Emulation - gerrit-log

21 Aug 2025

pespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/40891?usp=email )
Change subject: 5gc: Obtain amf_id from NGAP_Emulation
......................................................................
5gc: Obtain amf_id from NGAP_Emulation
This will be needed in a follow-up commit in order to be able to
transmit UE Context Release Request.
Change-Id: I49cb6d7fe9f18734c49bb49ecceb671e8122ce88
---
M 5gc/C5G_Tests.ttcn
M 5gc/ConnHdlr.ttcn
M library/NGAP_Emulation.ttcn
3 files changed, 52 insertions(+), 13 deletions(-)
Approvals:
  Jenkins Builder: Verified
  fixeria: Looks good to me, but someone else must approve
  laforge: Looks good to me, approved

diff --git a/5gc/C5G_Tests.ttcn b/5gc/C5G_Tests.ttcn
index 0b71059..608bcf8 100644
--- a/5gc/C5G_Tests.ttcn
+++ b/5gc/C5G_Tests.ttcn
@@ -86,6 +86,8 @@
    usim_key := mp_usim_key,
    usim_opc := mp_usim_opc,
    apn := mp_apn,
+	ran_id := idx,
+	amf_id := omit,
    run_prog_pars := ts_RunProgParams(idx),
    ran_gtpu_ip := mp_local_gtpu_ip,
    ran_gtpu_teid := int2oct(idx + 1, 4),
diff --git a/5gc/ConnHdlr.ttcn b/5gc/ConnHdlr.ttcn
index 01dcb1a..2f3344b 100644
--- a/5gc/ConnHdlr.ttcn
+++ b/5gc/ConnHdlr.ttcn
@@ -73,6 +73,8 @@
    octetstring usim_key,
    octetstring usim_opc,
    charstring apn,
+	RAN_UE_NGAP_ID ran_id,
+	AMF_UE_NGAP_ID amf_id optional,
    RunProgParams run_prog_pars,
    charstring ran_gtpu_ip,
    OCT4 ran_gtpu_teid,
@@ -308,10 +310,11 @@
private altstep as_ngap_handle_InitialCtxReq_withPDUSessionList() runs on ConnHdlr {
    var NGAP_PDU rx_ngap;
+	var template (present) NGAP_PDU exp_ngap :=
+		mw_ngap_initMsg(mw_n2_InitialContextSetupRequest_withPDUSessionList(g_pars.ue_pars.amf_id,
+									 	    g_pars.ue_pars.ran_id));
-	[] NGAP.receive(mw_ngap_initMsg(mw_n2_InitialContextSetupRequest_withPDUSessionList)) -> value rx_ngap {
-		var AMF_UE_NGAP_ID amf_id := valueof(f_NGAP_get_AMF_UE_NGAP_ID(rx_ngap));
-		var RAN_UE_NGAP_ID ran_id := valueof(f_NGAP_get_RAN_UE_NGAP_ID(rx_ngap));
+	[] NGAP.receive(exp_ngap) -> value rx_ngap {
    	var InitialContextSetupRequest ctx_setup_req := rx_ngap.initiatingMessage.value_.initialContextSetupRequest;
    	var PDUSessionResourceSetupListCxtRes resources;
@@ -322,7 +325,9 @@
    		var PDUSessionResourceSetupListCxtReq li := ctx_setup_req.protocolIEs[i].value_.pDUSessionResourceSetupListCxtReq;
    		resources := f_pdu_handle_session_resource_setup_list(li);
    	}
-		NGAP.send(m_ngap_succMsg(m_n2_InitialContextSetupResponse(amf_id, ran_id, resources)));
+		NGAP.send(m_ngap_succMsg(m_n2_InitialContextSetupResponse(g_pars.ue_pars.amf_id,
+									  g_pars.ue_pars.ran_id,
+									  resources)));
    }
 }
@@ -369,7 +374,7 @@
    								  f_SUCI_IMSI()),
    					 p_UESecurityCap := f_UE_SecurityCapability());
    nas_pdu := enc_NG_NAS_UL_Message_Type(valueof(nas_ul_msg));
-	tx_pdu := m_ngap_initMsg(m_n2_initialUeMessage(g_pars.ue_pars.idx,
+	tx_pdu := m_ngap_initMsg(m_n2_initialUeMessage(g_pars.ue_pars.ran_id,
    					       nas_pdu, /* Registration request */
    					       f_ULI(),
    					       mo_Signalling));
@@ -388,6 +393,9 @@
    as_ngap_handle_auth();
    as_ngap_handle_sec_mode();
+	/* After receiving DL NAS Transport above, the UE-AMF-Id became known in NGAP_Emulation: */
+	g_pars.ue_pars.amf_id := f_ngap_obtain_amf_id();
+
    NGAP.receive(cr_NG_REGISTRATION_ACCEPT) -> value rx_nas;
    g_pars.ue_pars.guti := rx_nas.registration_Accept.guti.otherDigits;
    NGAP.send(cs_NG_REGISTRATION_COMPLETE);
@@ -443,11 +451,16 @@
 /* 3GPP TS 38.413 8.3.3 UE Context Release (AMF initiated) */
 private altstep as_ngap_handle_UeContextReleaseCmd() runs on ConnHdlr {
    var NGAP_PDU rx_ngap;
+	var template (present) NGAP_PDU exp_ngap :=
+		mw_ngap_initMsg(mw_n2_UEContextReleaseCommand(
+					mw_uE_NGAP_IDs_uE_NGAP_ID_pair(
+						mw_uE_NGAP_ID_pair(g_pars.ue_pars.amf_id,
+								   g_pars.ue_pars.ran_id))));
-	[] NGAP.receive(mw_ngap_initMsg(mw_n2_UEContextReleaseCommand)) -> value rx_ngap {
-		var AMF_UE_NGAP_ID amf_id := valueof(f_NGAP_get_AMF_UE_NGAP_ID(rx_ngap));
-		var RAN_UE_NGAP_ID ran_id := valueof(f_NGAP_get_RAN_UE_NGAP_ID(rx_ngap));
-		NGAP.send(m_ngap_succMsg(f_ts_n2_UEContextReleaseComplete(amf_id, ran_id, f_ULI())));
+	[] NGAP.receive(exp_ngap) -> value rx_ngap {
+		NGAP.send(m_ngap_succMsg(f_ts_n2_UEContextReleaseComplete(g_pars.ue_pars.amf_id,
+									  g_pars.ue_pars.ran_id,
+									  f_ULI())));
    }
 }
@@ -484,10 +497,12 @@
private altstep as_ngap_handle_PDUSessionReleaseCommand() runs on ConnHdlr {
    var NGAP_PDU rx_ngap;
+	var template (present) NGAP_PDU exp_ngap :=
+		mw_ngap_initMsg(f_tr_n2_PDUSessionResourceReleaseCommand(g_pars.ue_pars.amf_id,
+									 g_pars.ue_pars.ran_id,
+									 ?, ?));
-	[] NGAP.receive(mw_ngap_initMsg(f_tr_n2_PDUSessionResourceReleaseCommand(?, ?, ?, ?))) -> value rx_ngap {
-		var AMF_UE_NGAP_ID amf_id := valueof(f_NGAP_get_AMF_UE_NGAP_ID(rx_ngap));
-		var RAN_UE_NGAP_ID ran_id := valueof(f_NGAP_get_RAN_UE_NGAP_ID(rx_ngap));
+	[] NGAP.receive(exp_ngap) -> value rx_ngap {
    	var PDUSessionResourceReleaseCommand rel_cmd := rx_ngap.initiatingMessage.value_.PDUSessionResourceReleaseCommand;
    	var PDUSessionResourceReleasedListRelRes resources;
@@ -498,7 +513,9 @@
    		var PDUSessionResourceToReleaseListRelCmd li := rel_cmd.protocolIEs[i].value_.pDUSessionResourceToReleaseListRelCmd;
    		resources := f_pdu_handle_session_resource_released_list(li);
    	}
-		NGAP.send(m_ngap_succMsg(m_n2_PDUSessionResourceReleaseResponse(amf_id, ran_id, resources)));
+		NGAP.send(m_ngap_succMsg(m_n2_PDUSessionResourceReleaseResponse(g_pars.ue_pars.amf_id,
+										g_pars.ue_pars.ran_id,
+										resources)));
    }
 }
diff --git a/library/NGAP_Emulation.ttcn b/library/NGAP_Emulation.ttcn
index aa4b485..3034fab 100644
--- a/library/NGAP_Emulation.ttcn
+++ b/library/NGAP_Emulation.ttcn
@@ -116,11 +116,13 @@
signature NGAPEM_register(in AMF_UE_NGAP_ID amf_id, in RAN_UE_NGAP_ID ran_id, in NGAP_ConnHdlr hdlr);
 signature NGAPEM_register_proc(in integer procedureCode, in NGAP_ConnHdlr hdlr);
+signature NGAPEM_obtain_amf_id() return AMF_UE_NGAP_ID;
 //signature NGAPEM_derive_nas_token(in octetstring kasme, in NGAP_ConnHdlr hdlr, out OCT32 nas_token);
type port NGAPEM_PROC_PT procedure {
    inout NGAPEM_register;
    inout NGAPEM_register_proc;
+	inout NGAPEM_obtain_amf_id;
    //inout NGAPEM_derive_nas_token;
 } with { extension "internal" };
@@ -605,6 +607,11 @@
    		f_create_expect_proc(procedureCode, vc_conn);
    		NGAP_PROC.reply(NGAPEM_register_proc:{procedureCode, vc_conn}) to vc_conn;
    		}
+		[] NGAP_PROC.getcall(NGAPEM_obtain_amf_id:{}) -> sender vc_conn {
+			var integer i := f_assoc_id_by_comp(vc_conn);
+			amf_id := NGapAssociationTable[i].amf_ue_ngap_id;
+			NGAP_PROC.reply(NGAPEM_obtain_amf_id:{} value amf_id) to vc_conn;
+			}
 //		[] NGAP_PROC.getcall(NGAPEM_derive_nas_token:{?, ?, -}) -> param(kasme, vc_conn) {
 //			var integer assoc_id := f_assoc_id_by_comp(vc_conn);
 //			var OCT32 nas_token := f_kdf_nas_token(kasme, NGapAssociationTable[assoc_id].nus.tx_count)
@@ -701,4 +708,17 @@
    }
 }
+/* ConnHdlr function to obtain AMF_ID internally stored in association table.
+ * This is needed because we don't receive NGAP layer of DownlinkNasTransport in
+ * ConnHdlr from Emulation, so there's no direct way to obtain it early during
+ * registration procedure. */
+function f_ngap_obtain_amf_id() runs on NGAP_ConnHdlr return AMF_UE_NGAP_ID {
+	var AMF_UE_NGAP_ID amf_id;
+	NGAP_PROC.call(NGAPEM_obtain_amf_id:{}) {
+		[] NGAP_PROC.getreply(NGAPEM_obtain_amf_id:{}) -> value amf_id {
+			return amf_id;
+		}
+	}
+}
+
 }
-- 
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Gerrit-MessageType: merged
Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Change-Id: I49cb6d7fe9f18734c49bb49ecceb671e8122ce88
Gerrit-Change-Number: 40891
Gerrit-PatchSet: 1
Gerrit-Owner: pespin pespin@sysmocom.de
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria vyanitskiy@sysmocom.de
Gerrit-Reviewer: laforge laforge@osmocom.org
Gerrit-Reviewer: pespin pespin@sysmocom.de



    