Pass to RRC the 5G-S-TMSI extracted from NAS Registration Accept

* NAS -> RRC: RRC receives an ITTI message with NAS 5GMM indication message
  containing the 5G-S-TMSI derived from NAS GUTI
* 5G-S-TMSI is stored in the RRC instance and to be later encoded in the RRCSetup

openair2/RRC/NR_UE/rrc_UE.c

@@ -601,6 +601,8 @@ NR_UE_RRC_INST_t* nr_rrc_init_ue(char* uecap_file, int nb_inst, int num_ant_tx)
     rrc->as_security_activated = false;
     rrc->detach_after_release = false;
     rrc->reconfig_after_reestab = false;
+    /* 5G-S-TMSI */
+    rrc->fiveG_S_TMSI = UINT64_MAX;
 
     FILE *f = NULL;
     if (uecap_file)
@@ -2098,6 +2100,12 @@ void *rrc_nrue(void *notUsed)
     break;
   }
 
+  case NAS_5GMM_IND: {
+    nas_5gmm_ind_t *req = &NAS_5GMM_IND(msg_p);
+    rrc->fiveG_S_TMSI = req->fiveG_STMSI;
+    break;
+  }
+
   default:
     LOG_E(NR_RRC, "[UE %ld] Received unexpected message %s\n", rrc->ue_id, ITTI_MSG_NAME(msg_p));
     break;

openair2/RRC/NR_UE/rrc_defs.h

@@ -239,6 +239,9 @@ typedef struct NR_UE_RRC_INST_s {
   Rrc_State_NR_t nrRrcState;
   // flag to identify 1st reconfiguration after reestablishment
   bool reconfig_after_reestab;
+  // 5G-S-TMSI
+  uint64_t fiveG_S_TMSI;
+
   //Sidelink params
   NR_SL_PreconfigurationNR_r16_t *sl_preconfig;
   // NTN params