Merge remote-tracking branch 'origin/ue_nas_simulator' into integration_2026_w13 (!3973)

Introduce UE NAS Simulator

This MR introduces a simple standalone tester for 5G UE NAS signaling and NGAP
messages. It connects to the AMF to perform NGAP and NAS encoding/decoding and
validates the UE Registration and PDU Session Establishment processes without
the overhead of a full Radio Access Network (PHY/MAC/RLC).

The motivation for this tester is as follows,
- This tester is a lightweight, deterministic tool to test the UE NAS layer
directly.
- Developers can easily inject specific NAS messages depending on the use-case.
- Developers can validate custom NAS/NGAP messages without the need to implement
complete RRC/MAC etc procedures.

Start the 5G Core network to test the UE NAS simulator. The compiling and
testing procedure is described below.
To compile:
mkdir build && cd build && cmake .. -GNinja && ninja nr-ue-nas-simulator-test

To run:
  LD_LIBRARY_PATH=. ./tests/nr-ue-nas-simulator/nr-ue-nas-simulator-test -O ../tests/nr-ue-nas-simulator/test.conf

doc/README.md

@@ -124,6 +124,7 @@ The other SDRs (AW2S, LimeSDR, ...) have no READMEs.
 - Component tests are under `tests/`. Currently, the following component tests are supported
   - A simple CU-UP tester, see the corresponding [README.md](../tests/nr-cuup/README.md).
   - A CU-NRPPA tester, see the corresponding [README.md](../tests/nr-cu-nrppa/README.md).
+  - A UE NAS tester, see the corresponding [README.md](../tests/nr-ue-nas-simulator/README.md).
 - [TESTBenches.md](./TESTBenches.md) lists the CI setup and links to pipelines
 - The CI setup uses a [custom framework](../ci-scripts/README.md) to run
   end-to-end tests.

openair3/NAS/NR_UE/nr_nas_msg.c

@@ -78,6 +78,12 @@
 
 static nr_ue_nas_t nr_ue_nas[MAX_NUM_NR_UE_INST] = {0};
 
+nr_ue_nas_t *get_nr_ue_nas_info(uint8_t ue_inst)
+{
+  AssertFatal(ue_inst >= 0 && ue_inst < MAX_NUM_NR_UE_INST, "Invalid UE instance\n");
+  return &nr_ue_nas[ue_inst];
+}
+
 #define FOREACH_STATE(TYPE_DEF)                  \
   TYPE_DEF(NAS_SECURITY_NO_SECURITY_CONTEXT, 0)  \
   TYPE_DEF(NAS_SECURITY_UNPROTECTED, 1)          \
@@ -1166,6 +1172,10 @@ static void generateSecurityModeComplete(nr_ue_nas_t *nas, as_nas_info_t *initia
       security_header_len
       + mm_msg_encode(plain, (uint8_t *)(initialNasMsg->nas_data + security_header_len), size - security_header_len);
 
+  if (rr.nas_data) {
+    free(rr.nas_data);
+  }
+
   /* ciphering */
   uint8_t buf[initialNasMsg->length - 7];
   stream_cipher.context = nas->security_container->ciphering_context;

openair3/NAS/NR_UE/nr_nas_msg.h

@@ -113,5 +113,6 @@ void *nas_nrue(void *args_p);
 void nas_init_nrue(int num_ues);
 void nr_ue_create_ip_if(const char *ifnameprefix, const char *ipv4, const char *ipv6, int ue_id, int pdu_session_id);
 void request_pdusession(nr_ue_nas_t *nas, const pdu_session_config_t *pdu);
+nr_ue_nas_t *get_nr_ue_nas_info(uint8_t ue_inst);
 
 #endif /* __NR_NAS_MSG_SIM_H__*/

tests/CMakeLists.txt

 add_subdirectory(nr-cuup)
 add_subdirectory(nr-cu-nrppa)
+add_subdirectory(nr-ue-nas-simulator)

tests/nr-ue-nas-simulator/CMakeLists.txt

+add_executable(nr-ue-nas-simulator-test nr-ue-nas-simulator.c
+               ${OPENAIR2_DIR}/GNB_APP/gnb_config_common.c
+               ${OPENAIR2_DIR}/GNB_APP/gnb_config_ng.c)
+
+target_link_libraries(nr-ue-nas-simulator-test PRIVATE nr_nas nr_common lib_uicc usim_lib)
+target_link_libraries(nr-ue-nas-simulator-test PRIVATE
+                      CONFIG_LIB ITTI SCTP_CLIENT
+                      f1ap ngap SECURITY GTPV1U
+                      UTIL softmodem_common)
+target_link_libraries(nr-ue-nas-simulator-test PRIVATE asn1_lte_rrc_hdrs asn1_nr_rrc_hdrs)
+add_dependencies(nr-ue-nas-simulator-test params_libconfig)

tests/nr-ue-nas-simulator/README.md

+This is a simple standalone tester for 5G UE NAS signaling and NGAP messages. It connects to the AMF to perform NGAP and NAS encoding/decoding and validates the UE Registration and PDU Session Establishment processes without the overhead of a full Radio Access Network (PHY/MAC/RLC).
+
+[[_TOC_]]
+
+# Motivation
+- This tester is a lightweight, deterministic tool to **test the UE NAS layer directly**. 
+- Developers can easily inject specific NAS messages depending on the use-case.
+- Developers can validate custom NAS/NGAP messages without the need to implement complete RRC/MAC etc procedures.
+
+# Overview
+From a schematic point of view, the tester and Core Network interaction looks like this:
+```
+        +-------+
+        |  AMF  |
+        +-------+
+            |
+ NGAP/NAS   | (N1/N2)
+            |
+        +-------+
+        |tester | (nr-ue-nas-simulator-test)
+        +-------+
+
+```
+
+The tester is designed to validate the integration of NAS and NGAP messages required for a 5G Standalone (SA) UE to attach to the network. It acts as a simulated gNB and a UE, bridging NAS messages directly into NGAP payloads and connecting to the 5G Core Network's AMF.
+
+The following messages are integrated and tested:
+
+* **NGAP:** NG Setup Request/Response, Initial UE Message, Downlink NAS Transport, Uplink NAS Transport, Initial Context Setup Request/Response, PDU Session Resource Setup Request/Response, UE Context Release Command/Complete.
+
+* **NAS (5GMM/5GSM):** Registration Request/Accept/Complete, Authentication Request/Response, Security Mode Command/Complete, PDU Session Establishment Request/Accept, Deregistration Request/Accept.
+
+* **RRC (Custom):** Forwards the uplink/downlink NAS messages directly between UE and AMF.
+
+A test scenario is fixed to these steps:
+1. The 5G Core Network is deployed via Docker.
+2. The tester connects to the AMF and establishes the NGAP connection (NG Setup).
+3. The tester automatically triggers an Initial UE Registration Request.
+4. Authentication and NAS Security Mode procedures are completed.
+5. The tester requests and successfully establishes an IPv4 PDU Session.
+6. The tester finally initiates deregistration request and exits succesfully.
+
+# Usage
+To run this test, you need to set up the Core Network and build the tester.
+
+**1. Core Network Deployment**
+
+Pull the required Docker images for the OAI 5G Core:
+
+    docker pull oaisoftwarealliance/ims:latest
+    docker pull oaisoftwarealliance/oai-amf:develop
+    docker pull oaisoftwarealliance/oai-nrf:develop
+    docker pull oaisoftwarealliance/oai-smf:develop
+    docker pull oaisoftwarealliance/oai-udr:develop
+    docker pull oaisoftwarealliance/oai-upf:develop
+    docker pull oaisoftwarealliance/oai-udm:develop
+    docker pull oaisoftwarealliance/oai-ausf:develop
+
+Deploy the network using the docker compose file:
+
+    cd doc/tutorial_resources/oai-cn5g
+    docker compose -f docker-compose.yaml up -d
+
+At the end of all experiments, you can also undeploy the network with:
+    docker compose -f docker-compose.yaml down -t 0
+
+**2. Building the Tester**
+
+You can build the tester as follows:
+
+    cd ~/openairinterface5g
+    mkdir build && cd build && cmake .. -GNinja && ninja nr-ue-nas-simulator-test
+
+**3. Running the Tester**
+
+Start the tester with the dedicated configuration file:
+
+    openairinterface5g/build$ LD_LIBRARY_PATH=. ./tests/nr-ue-nas-simulator/nr-ue-nas-simulator-test -O ../tests/nr-ue-nas-simulator/test.conf
+
+# Limitations
+- The tester is limited to a fixed flow: Initial Attach -> PDU Session -> Deregistration.
+- The tester doesnt create a GTP tunnel after PDU session and uses a harcoded teid.
+
+# Future Enhancements
+- A real GTP tunnel can be created to test various data related functionalities like QoS.
+- Simulate the actual UE RRC layer, i.e., forwarding the CellGroupConfig, have the UE apply that (without actually using it).
+- Make it scriptable to test custom message implementations.

tests/nr-ue-nas-simulator/test.conf

+Active_gNBs = ( "gNB-OAI");
+# Asn1_verbosity, choice in: none, info, annoying
+Asn1_verbosity = "none";
+
+gNBs =
+(
+ {
+    ////////// Identification parameters:
+    gNB_ID    =  0xe00;
+    gNB_name  =  "gNB-OAI";
+
+    // Tracking area code, 0x0000 and 0xfffe are reserved values
+    tracking_area_code  =  1;
+    plmn_list = ({ mcc = 001; mnc = 01; mnc_length = 2; snssaiList = ({ sst = 1; }) });
+
+    nr_cellid = 12345678L;
+
+    # ------- SCTP definitions
+    SCTP :
+    {
+        # Number of streams to use in input/output
+        SCTP_INSTREAMS  = 2;
+        SCTP_OUTSTREAMS = 2;
+    };
+
+
+    ////////// AMF parameters:
+    amf_ip_address = ({ ipv4 = "192.168.70.132"; });
+
+
+    NETWORK_INTERFACES :
+    {
+        GNB_IPV4_ADDRESS_FOR_NG_AMF              = "192.168.70.129/24";
+        GNB_IPV4_ADDRESS_FOR_NGU                 = "192.168.70.129/24";
+        GNB_PORT_FOR_S1U                         = 2152; # Spec 2152
+    };
+
+  }
+);
+
+uicc0 = {
+  imsi = "001010000000001";
+  key = "fec86ba6eb707ed08905757b1bb44b8f";
+  opc = "C42449363BBAD02B66D16BC975D77CC1";
+  pdu_sessions = ({ dnn = "oai"; nssai_sst = 1; });
+}
+
+log_config :
+{
+  global_log_level                      ="info";
+  hw_log_level                          ="info";
+  phy_log_level                         ="info";
+  mac_log_level                         ="info";
+  rlc_log_level                         ="info";
+  pdcp_log_level                        ="info";
+  rrc_log_level                         ="info";
+  ngap_log_level                        ="debug";
+  f1ap_log_level                        ="debug";
+};