fix: UE Context Request IE handling (#771)

src/amf/nas-path.c

@@ -66,6 +66,7 @@ int nas_5gs_send_to_downlink_nas_transport(amf_ue_t *amf_ue, ogs_pkbuf_t *pkbuf)
 void nas_5gs_send_registration_accept(amf_ue_t *amf_ue)
 {
     int rv;
+    bool transfer_needed = false;
 
     ran_ue_t *ran_ue = NULL;
 
@@ -79,8 +80,28 @@ void nas_5gs_send_registration_accept(amf_ue_t *amf_ue)
     gmmbuf = gmm_build_registration_accept(amf_ue);
     ogs_expect_or_return(gmmbuf);
 
-    if (ran_ue->ue_context_requested == true &&
-        ran_ue->initial_context_setup_request_sent == false) {
+    /*
+     * Previously, AMF would sends PDUSessionResourceSetupRequest
+     * when the following conditions were met:
+     * - gNB didn't send UE Context Request IE of InitialUEMessage
+     * - AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
+     *   to the gNB
+     *
+     * However, in issues #771, the gNB did not accept
+     * PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
+     * that if gNB needs to send data traffic to the UE, AMF should send
+     * an InitialContextSetupRequest regardless of UE Context Request IE.
+     * This is because gNB requires the kgNB security context
+     * for data connection.
+     *
+     * So, in this case, Open5GS-AMF decided to send
+     * an InitialContexSetupRequest regardless of
+     * whether it received UE Context Request IE of InitialUEMessage.
+     */
+    transfer_needed = PDU_RES_SETUP_REQ_TRANSFER_NEEDED(amf_ue);
+
+    if (ran_ue->initial_context_setup_request_sent == false &&
+        (ran_ue->ue_context_requested == true || transfer_needed == true)) {
         ngapbuf = ngap_ue_build_initial_context_setup_request(amf_ue, gmmbuf);
         ogs_expect_or_return(ngapbuf);
 
@@ -89,32 +110,9 @@ void nas_5gs_send_registration_accept(amf_ue_t *amf_ue)
 
         ran_ue->initial_context_setup_request_sent = true;
     } else {
-        if (PDU_RES_SETUP_REQ_TRANSFER_NEEDED(amf_ue)) {
-        /*
-         * Previously, AMF would sends PDUSessionResourceSetupRequest
-         * when the following conditions were met:
-         * - gNB didn't send UE Context Request IE of InitialUEMessage
-         * - AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
-         *   to the gNB
-         *
-         * However, in issues #771, the gNB did not accept
-         * PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
-         * that if gNB needs to send data traffic to the UE, AMF should send
-         * an InitialContextSetupRequest regardless of UE Context Request IE.
-         * This is because gNB requires the kgNB security context
-         * for data connection.
-         *
-         * So, in this case, Open5GS-AMF decided to send
-         * an InitialContexSetupRequest regardless of
-         * whether it received UE Context Request IE of InitialUEMessage.
-         */
-#if WILL_BE_REMOVED
+        if (transfer_needed == true) {
             ngapbuf = ngap_ue_build_pdu_session_resource_setup_request(
                     amf_ue, gmmbuf);
-#else
-            ngapbuf = ngap_ue_build_initial_context_setup_request(
-                    amf_ue, gmmbuf);
-#endif
             ogs_expect_or_return(ngapbuf);
 
             rv = nas_5gs_send_to_gnb(amf_ue, ngapbuf);
@@ -150,6 +148,7 @@ void nas_5gs_send_registration_reject(
 void nas_5gs_send_service_accept(amf_ue_t *amf_ue)
 {
     int rv;
+    bool transfer_needed = false;
     ran_ue_t *ran_ue = NULL;
 
     ogs_pkbuf_t *gmmbuf = NULL;
@@ -162,8 +161,28 @@ void nas_5gs_send_service_accept(amf_ue_t *amf_ue)
     gmmbuf = gmm_build_service_accept(amf_ue);
     ogs_expect_or_return(gmmbuf);
 
-    if (ran_ue->ue_context_requested == true &&
-        ran_ue->initial_context_setup_request_sent == false) {
+    /*
+     * Previously, AMF would sends PDUSessionResourceSetupRequest
+     * when the following conditions were met:
+     * - gNB didn't send UE Context Request IE of InitialUEMessage
+     * - AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
+     *   to the gNB
+     *
+     * However, in issues #771, the gNB did not accept
+     * PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
+     * that if gNB needs to send data traffic to the UE, AMF should send
+     * an InitialContextSetupRequest regardless of UE Context Request IE.
+     * This is because gNB requires the kgNB security context
+     * for data connection.
+     *
+     * So, in this case, Open5GS-AMF decided to send
+     * an InitialContexSetupRequest regardless of
+     * whether it received UE Context Request IE of InitialUEMessage.
+     */
+    transfer_needed = PDU_RES_SETUP_REQ_TRANSFER_NEEDED(amf_ue);
+
+    if (ran_ue->initial_context_setup_request_sent == false &&
+        (ran_ue->ue_context_requested == true || transfer_needed == true)) {
         ngapbuf = ngap_ue_build_initial_context_setup_request(amf_ue, gmmbuf);
         ogs_expect_or_return(ngapbuf);
 
@@ -172,32 +191,9 @@ void nas_5gs_send_service_accept(amf_ue_t *amf_ue)
 
         ran_ue->initial_context_setup_request_sent = true;
     } else {
-        if (PDU_RES_SETUP_REQ_TRANSFER_NEEDED(amf_ue)) {
-        /*
-         * Previously, AMF would sends PDUSessionResourceSetupRequest
-         * when the following conditions were met:
-         * - gNB didn't send UE Context Request IE of InitialUEMessage
-         * - AMF should send SMF generated TRANSFER message(PDU_RES_SETUP_REQ)
-         *   to the gNB
-         *
-         * However, in issues #771, the gNB did not accept
-         * PDUSessionResourceSetupRequest. Perhaps the gNB engineer thought
-         * that if gNB needs to send data traffic to the UE, AMF should send
-         * an InitialContextSetupRequest regardless of UE Context Request IE.
-         * This is because gNB requires the kgNB security context
-         * for data connection.
-         *
-         * So, in this case, Open5GS-AMF decided to send
-         * an InitialContexSetupRequest regardless of
-         * whether it received UE Context Request IE of InitialUEMessage.
-         */
-#if WILL_BE_REMOVED
+        if (transfer_needed == true) {
             ngapbuf = ngap_ue_build_pdu_session_resource_setup_request(
                     amf_ue, gmmbuf);
-#else
-            ngapbuf = ngap_ue_build_initial_context_setup_request(
-                    amf_ue, gmmbuf);
-#endif
             ogs_expect_or_return(ngapbuf);
 
             rv = nas_5gs_send_to_gnb(amf_ue, ngapbuf);

tests/registration/idle-test.c

@@ -1153,18 +1153,18 @@ static void test3_func(abts_case *tc, void *data)
     rv = testgnb_ngap_send(ngap, sendbuf);
     ABTS_INT_EQUAL(tc, OGS_OK, rv);
 
-    /* Receive InitialContextSetupRequest +
+    /* Receive PDUSessionResourceSetupRequest +
      * Service accept */
     recvbuf = testgnb_ngap_read(ngap);
     ABTS_PTR_NOTNULL(tc, recvbuf);
     testngap_recv(test_ue, recvbuf);
     ABTS_INT_EQUAL(tc,
-            NGAP_ProcedureCode_id_InitialContextSetup,
+            NGAP_ProcedureCode_id_PDUSessionResourceSetup,
             test_ue->ngap_procedure_code);
     ABTS_INT_EQUAL(tc, 0x0000, test_ue->pdu_session_reactivation_result);
 
-    /* Send InitialContextSetupResponse */
-    sendbuf = testngap_build_initial_context_setup_response(test_ue, true);
+    /* Send PDUSessionResourceSetupResponse */
+    sendbuf = testngap_ue_build_pdu_session_resource_setup_response(test_ue);
     ABTS_PTR_NOTNULL(tc, sendbuf);
     rv = testgnb_ngap_send(ngap, sendbuf);
     ABTS_INT_EQUAL(tc, OGS_OK, rv);