Add NAS Service Request enc/dec functions

* FGMM enc/dec library files * Plain message encoding + logic for security protected message * added fill_fgstmsi function * add checks on length in 5G-S-TMSI encoder function * encoding of NAS Service Request and relevant mandatory IEs
2024-11-25 13:15:10 +01:00
parent c817c44ae9
commit 1c4e1029a8
7 changed files with 317 additions and 0 deletions
@@ -0,0 +1,90 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+#include "TLVEncoder.h"
+#include "TLVDecoder.h"
+#include "fgs_service_request.h"
+#include "FGSMobileIdentity.h"
+#include "NasKeySetIdentifier.h"
+#include "ServiceType.h"
+#include "NR_NAS_defs.h"
+
+#define LEN_FGS_MOBILE_ID_CONTENTS_SIZE 2 // octets
+#define MIN_LEN_FGS_SERVICE_REQUEST 10 // octets
+
+/**
+ * @brief Encode 5GMM NAS Service Request message (8.2.16 of 3GPP TS 24.501)
+ */
+int encode_fgs_service_request(uint8_t *buffer, fgs_service_request_msg_t *service_request, uint32_t len)
+{
+  // Return if buffer is shorter than min length
+  if (len < MIN_LEN_FGS_SERVICE_REQUEST)
+    return -1;
+
+  int encoded = 0;
+
+  // ngKSI + Service type (1 octet) (M)
+  *buffer = ((encode_nas_key_set_identifier(&service_request->naskeysetidentifier, IEI_NULL) & 0x0f) << 4)
+            | (service_request->serviceType & 0x0f);
+  encoded++;
+  len -= encoded;
+
+  // 5GS Mobile Identity (M) type 5G-S-TMSI (9 octets)
+  encoded += LEN_FGS_MOBILE_ID_CONTENTS_SIZE; // skip "Length of 5GS mobile identity contents" IE
+  len -= encoded;
+  encoded += encode_stmsi_5gs_mobile_identity(buffer + encoded, &service_request->fiveg_s_tmsi, len);
+  // encode length of 5GS mobile identity contents
+  uint16_t tmp = htons(encoded - LEN_FGS_MOBILE_ID_CONTENTS_SIZE - 1);
+  memcpy(buffer + 1, &tmp, sizeof(tmp));
+
+  return encoded;
+}
+
+/**
+ * @brief Decode 5GMM NAS Service Request message (8.2.16 of 3GPP TS 24.501)
+ */
+int decode_fgs_service_request(fgs_service_request_msg_t *sr, const uint8_t *buffer, uint32_t len)
+{
+  uint32_t decoded = 0;
+  int decoded_rc = 0;
+
+  // Service type (1/2 octet) (M)
+  sr->serviceType = *buffer & 0x0f;
+  // KSI (1/2 octet) (M)
+  if ((decoded_rc = decode_nas_key_set_identifier(&sr->naskeysetidentifier, IEI_NULL, *buffer >> 4)) < 0) {
+    return decoded_rc;
+  }
+  decoded++;
+
+  // 5GS Mobile Identity (M) type 5G-S-TMSI (9 octets) (M)
+  decoded += LEN_FGS_MOBILE_ID_CONTENTS_SIZE; // skip "Length of 5GS mobile identity contents" IE
+  if ((decoded_rc = decode_stmsi_5gs_mobile_identity(&sr->fiveg_s_tmsi, buffer + decoded, len - decoded)) < 0) {
+    return decoded_rc;
+  }
+  decoded += decoded_rc;
+
+  return decoded;
+}
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include "ProtocolDiscriminator.h"
+#include "SecurityHeaderType.h"
+#include "NasKeySetIdentifier.h"
+#include "ServiceType.h"
+#include "ExtendedProtocolDiscriminator.h"
+#include "FGCNasMessageContainer.h"
+//#include "PDUSessionStatus.h"
+#include "MessageType.h"
+#include "SpareHalfOctet.h"
+#include "FGSMobileIdentity.h"
+
+#ifndef FGS_SERVICE_REQUEST_H_
+#define FGS_SERVICE_REQUEST_H_
+
+/**
+ * Message name: Service request (8.2.16 of 3GPP TS 24.501)
+ * Description: The SERVICE REQUEST message is sent by the UE to the AMF
+ *              in order to request the establishment of an N1 NAS signalling
+ *              connection and/or to request the establishment of user-plane
+ *              resources for PDU sessions which are established without
+ *              user-plane resources
+ * Direction: UE to network
+ */
+
+typedef struct {
+  /* Mandatory fields */
+  NasKeySetIdentifier naskeysetidentifier;
+  ServiceType serviceType: 4;
+  Stmsi5GSMobileIdentity_t fiveg_s_tmsi;
+  /* Optional fields */
+  FGCNasMessageContainer *fgsnasmessagecontainer;
+} fgs_service_request_msg_t;
+
+int encode_fgs_service_request(uint8_t *buffer, fgs_service_request_msg_t *servicerequest, uint32_t len);
+int decode_fgs_service_request(fgs_service_request_msg_t *sr, const uint8_t *buffer, uint32_t len);
+
+#endif /* ! defined(FGS_SERVICE_REQUEST_H_) */
@@ -38,6 +38,7 @@
 #include "FGSMobileIdentity.h"

 #define MIN_LEN_FGS_MOBILE_ID_IE 3 // type of identity "No identity"
+#define LEN_5G_FGS_TMSI_IE 9

 static int decode_guti_5gs_mobile_identity(Guti5GSMobileIdentity_t *guti, const uint8_t *buffer);

@@ -45,6 +46,56 @@ static int encode_guti_5gs_mobile_identity(Guti5GSMobileIdentity_t *guti, uint8_
 static int encode_suci_5gs_mobile_identity(Suci5GSMobileIdentity_t *suci, uint8_t *buffer);
 static int encode_imeisv_5gs_mobile_identity(Imeisv5GSMobileIdentity_t *imeisv, uint8_t *buffer);

+int encode_stmsi_5gs_mobile_identity(uint8_t *buffer, Stmsi5GSMobileIdentity_t *stmsi, uint32_t len)
+{
+  // Return if buffer is shorter than min length
+  if (len < LEN_5G_FGS_TMSI_IE)
+    return -1;
+
+  uint32_t encoded = 0;
+  // octet 4
+  *(buffer + encoded) = (DIGIT1 << 4) | ((stmsi->spare & 0x1) << 3) | (stmsi->typeofidentity & 0x7);
+  encoded++;
+  // octet 5-6
+  uint16_t temp = 0x00 | ((stmsi->amfsetid) << 6) | (stmsi->amfpointer & 0x3f);
+  IES_ENCODE_U16(buffer, encoded, temp);
+  // octet 7
+  IES_ENCODE_U32(buffer, encoded, stmsi->tmsi);
+  return encoded;
+}
+
+int decode_stmsi_5gs_mobile_identity(Stmsi5GSMobileIdentity_t *stmsi, const uint8_t *buffer, uint32_t len)
+{
+  int decoded = 0;
+  uint16_t temp;
+
+  // Return if buffer is shorter than min length
+  if (len < LEN_5G_FGS_TMSI_IE)
+    return -1;
+
+  // Octet 4: spare (bit 3) and type of identity (bits 0-2)
+  stmsi->digit1 = DIGIT1;
+  stmsi->spare = (*(buffer + decoded) >> 3) & 0x1;
+  stmsi->typeofidentity = *(buffer + decoded) & 0x7;
+
+  // Validate type of identity
+  if (stmsi->typeofidentity != FGS_MOBILE_IDENTITY_5GS_TMSI) {
+    return -1;
+  }
+
+  decoded++;
+
+  // Octet 5-6: AMF Set ID (bits 6-15) and AMF Pointer (bits 0-5)
+  IES_DECODE_U16(buffer, decoded, temp);
+  stmsi->amfsetid = (temp >> 6) & 0x03ff;
+  stmsi->amfpointer = temp & 0x3f;
+
+  // Octet 7-10: 32-bit TMSI
+  IES_DECODE_U32(buffer, decoded, stmsi->tmsi);
+
+  return decoded;
+}
+
 int decode_5gs_mobile_identity(FGSMobileIdentity *fgsmobileidentity, uint8_t iei, const uint8_t *buffer, uint32_t len)
 {
  int decoded_rc = TLV_DECODE_VALUE_DOESNT_MATCH;
@@ -109,6 +160,10 @@ int encode_5gs_mobile_identity(FGSMobileIdentity *fgsmobileidentity, uint8_t iei
                 buffer + encoded);
  }

+  if (fgsmobileidentity->stmsi.typeofidentity == FGS_MOBILE_IDENTITY_5GS_TMSI) {
+    encoded_rc = encode_stmsi_5gs_mobile_identity(buffer + encoded, &fgsmobileidentity->stmsi, len);
+  }
+
  if (encoded_rc < 0) {
    return encoded_rc;
  }
@@ -37,6 +37,8 @@
 #ifndef FGS_MOBILE_IDENTITY_H_
 #define FGS_MOBILE_IDENTITY_H_

+// 4x 1bit according to 9.11.3.4 5GS mobile identity (type 5G-S-TMSI)
+#define DIGIT1 0xF

 typedef struct {
  uint8_t  spare:5;
@@ -151,5 +153,8 @@ int encode_5gs_mobile_identity(FGSMobileIdentity *fgsmobileidentity, uint8_t iei

 int decode_5gs_mobile_identity(FGSMobileIdentity *fgsmobileidentity, uint8_t iei, const uint8_t *buffer, uint32_t len);

+int encode_stmsi_5gs_mobile_identity(uint8_t *buffer, Stmsi5GSMobileIdentity_t *stmsi, uint32_t len);
+int decode_stmsi_5gs_mobile_identity(Stmsi5GSMobileIdentity_t *stmsi, const uint8_t *buffer, uint32_t len);
+
 #endif /* FGS MOBILE IDENTITY_H_ */