Merge remote-tracking branch 'origin/fixes-initial-context-setup' into integration_2026_w09 (!3952)

Fixes for Initial UE Context Setup

This MR fixes DRB aggregation from E1 so DRBs from multiple PDU sessions
are appended correctly into the F1 DRB array instead of overwriting
existing entries. It also makes NGAP Initial Context Setup skip PDU
sessions that are already established for the UE, only setting up new
sessions.

DRB aggregation from E1: Adjust fill_drb_to_be_setup_from_e1_resp to
pass &drbs[nb_drb] into fill_f1_drbs_from_e1, ensuring DRBs from later
PDU sessions are appended after the current count.

Duplicate PDU sessions in NGAP Initial Context Setup: In
rrc_gNB_process_NGAP_INITIAL_CONTEXT_SETUP_REQ, detect requested PDU
session IDs that already exist with PDU_SESSION_STATUS_ESTABLISHED, log
a warning, and skip them so they are not added to UE->initial_pdus.

openair2/RRC/NR/rrc_gNB.c

@@ -3050,7 +3050,7 @@ static int fill_drb_to_be_setup_from_e1_resp(const gNB_RRC_INST *rrc,
     const pdu_session_setup_t *session = &pduSession[p];
     rrc_pdu_session_param_t *pdu = find_pduSession(&UE->pduSessions, session->id);
     DevAssert(pdu);
-    nb_drb += fill_f1_drbs_from_e1(rrc, UE, pdu, session->DRBnGRanList, session->numDRBSetup, drbs);
+    nb_drb += fill_f1_drbs_from_e1(rrc, UE, pdu, session->DRBnGRanList, session->numDRBSetup, &drbs[nb_drb]);
   }
   DevAssert(nb_drb < MAX_DRBS_PER_UE);
   return nb_drb;

openair2/RRC/NR/rrc_gNB_NGAP.c

@@ -506,14 +506,38 @@ int rrc_gNB_process_NGAP_INITIAL_CONTEXT_SETUP_REQ(MessageDef *msg_p, instance_t
 
   if (req->nb_of_pdusessions > 0) {
     AssertFatal(req->has_ue_ambr, "UE aggregate maximum bitrate is required when there are PDU sessions to setup");
-    /* if there are PDU sessions to setup, store them to be created once
+
-     * security (and UE capabilities) are received */
+    /* Build the list of PDU sessions to actually set up, filtering out those
-    UE->n_initial_pdu = req->nb_of_pdusessions;
+     * whose PDU Session ID already identifies an active PDU session for this UE.
-    UE->initial_pdus = calloc_or_fail(UE->n_initial_pdu, sizeof(*UE->initial_pdus));
+     * According to TS 38.413, establishment of such a PDU session shall be
-    for (int i = 0; i < UE->n_initial_pdu; ++i)
+     * reported as failed in the response. */
-      cp_pdusession_resource_item_to_pdusession(&UE->initial_pdus[i], &req->pdusession[i]);
+    int ps_count = 0;
-    UE->ambr.dl_br = req->ue_ambr.br_dl;
+    pdusession_t psessions[NGAP_MAX_PDU_SESSION] = {0};
-    UE->ambr.ul_br = req->ue_ambr.br_ul;
+
+    for (int i = 0; i < req->nb_of_pdusessions; ++i) {
+      const pdusession_resource_item_t *src = &req->pdusession[i];
+
+      rrc_pdu_session_param_t *existing = find_pduSession(&UE->pduSessions, src->pdusession_id);
+      if (existing != NULL && existing->status == PDU_SESSION_STATUS_ESTABLISHED) {
+        LOG_W(NR_RRC, "UE %d: InitialContextSetup contains already active PDU session ID %d\n", UE->rrc_ue_id, src->pdusession_id);
+        continue;
+      }
+
+      /* This is a PDU session that is not yet active for this UE: add it to the list */
+      DevAssert(ps_count < req->nb_of_pdusessions);
+      cp_pdusession_resource_item_to_pdusession(&psessions[ps_count++], src);
+    }
+
+    UE->n_initial_pdu = 0;
+    if (ps_count > 0) {
+      UE->initial_pdus = calloc_or_fail(ps_count, sizeof(*UE->initial_pdus));
+      memcpy(UE->initial_pdus, psessions, ps_count * sizeof(*UE->initial_pdus));
+      UE->n_initial_pdu = ps_count;
+
+      /* If we have at least one session to set up, store AMBR */
+      UE->ambr.dl_br = req->ue_ambr.br_dl;
+      UE->ambr.ul_br = req->ue_ambr.br_ul;
+    }
   }
 
   /* security */