Hardcode (noS1) PDU session ID to 10

Defacto, the PDU session ID for noS1 modes is already hardcoded, as
starting the nr-softmodem with --noS1 --default-pdu-id 1 leads to

    Assertion (entity != ((void *)0)) failed!
    In start_sdap_tun_gnb_first_ue_default_pdu_session() openair2/SDAP/nr_sdap/nr_sdap.c:163

Further, the --default-pdu-id parameter will be deactivated in a later
commit, and we cannot rely on it. Therefore:

- hardcode noS1 PDU ID (also used in --do-ra/--phy-test modes) to 10 and
  use in gNB&UE
- pass the PDU session ID used in SDAP entity initialization down to
  start_sdap_tun_gnb_first_ue_default_pdu_session() to always use the
  correct one

common/platform_constants.h

@@ -100,5 +100,8 @@
 // SDAP
 #define MAX_QOS_FLOWS 64
 
+// SDAP/5G NAS NOS1
+#define DEFAULT_NOS1_PDU_ID 10
+
 #define SPEED_OF_LIGHT 299792458 // in m/s
 #endif /* __PLATFORM_CONSTANTS_H__ */

openair2/RRC/NR/rrc_gNB_nsa.c

@@ -201,7 +201,7 @@ void rrc_add_nsa_user(gNB_RRC_INST *rrc, x2ap_ENDC_sgnb_addition_req_t *m, sctp_
   byte_array_t cgci = {0};
   if (get_softmodem_params()->phy_test == 1 || get_softmodem_params()->do_ra == 1) {
     DevAssert(m == NULL);
-    UE->rb_config = get_default_rbconfig(10 /* EPS bearer ID */, 1 /* drb ID */, NR_CipheringAlgorithm_nea0, NR_SecurityConfig__keyToUse_master, &rrc->pdcp_config);
+    UE->rb_config = get_default_rbconfig(DEFAULT_NOS1_PDU_ID, 1 /* drb ID */, NR_CipheringAlgorithm_nea0, NR_SecurityConfig__keyToUse_master, &rrc->pdcp_config);
     int len = cg_config_info_from_ue_cap_file(sizeof tmp, tmp);
     DevAssert(len > 0);
     cgci = create_byte_array(len, tmp);

openair2/SDAP/nr_sdap/nr_sdap.c

@@ -157,9 +157,9 @@ static void *sdap_tun_read_thread(void *arg)
   return NULL;
 }
 
-void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id)
+void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id, int pdu_session_id)
 {
-  nr_sdap_entity_t *entity = nr_sdap_get_entity(ue_id, get_softmodem_params()->default_pdu_session_id);
+  nr_sdap_entity_t *entity = nr_sdap_get_entity(ue_id, pdu_session_id);
   DevAssert(entity != NULL);
   DevAssert(entity->is_gnb);
   char *ifprefix = get_softmodem_params()->nsa ? "oaitun_gnb" : "oaitun_enb";

openair2/SDAP/nr_sdap/nr_sdap.h

@@ -60,7 +60,7 @@ void sdap_data_ind(int pdcp_entity,
                    char *buf,
                    int size);
 
-void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id);
+void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id, int pdu_session_id);
 void create_ue_ip_if(const char *ipv4, const char *ipv6, int ue_id, int pdu_session_id);
 
 #endif

openair2/SDAP/nr_sdap/nr_sdap_entity.c

@@ -534,7 +534,7 @@ static void nr_sdap_add_entity(const int is_gnb, const ue_id_t ue_id, const sdap
   if (IS_SOFTMODEM_NOS1 && is_gnb) {
     // In NOS1 mode, terminate SDAP for the first UE on the gNB. This allows injecting/receiving
     // PDCP SDUs to/from the TUN interface.
-    start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id);
+    start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id, sdap_entity->pdusession_id);
   }
 }
 

openair3/NAS/NR_UE/nr_nas_msg.c

@@ -2160,7 +2160,7 @@ void *nas_nrue(void *args_p)
       } break;
 
       case NAS_INIT_NOS1_IF: {
-        const int pdu_session_id = get_softmodem_params()->default_pdu_session_id;
+        const int pdu_session_id = DEFAULT_NOS1_PDU_ID;
         const char *ip = "10.0.1.2";
         const int qfi = 7;
         create_ue_ip_if(ip, NULL, nas->UE_id, pdu_session_id);