Revert "Send RRC UECapabilityEnquiry after reconfig, trigger UE update if necessary"

This reverts commit 4a7d7975ce.

Trigger the UE capability right after security mode complete, as
specified in O-RAN WG5.C.1-v11. Also, there is no "need" for the
"default" RRC Reconfiguration (it will come once PDU sessions are
requested), so remove this as well.

openair2/RRC/NR/rrc_gNB.c

@@ -567,20 +567,7 @@ void rrc_gNB_generate_dedicatedRRCReconfiguration(const protocol_ctxt_t *const c
 
   uint8_t xid = rrc_gNB_get_next_transaction_identifier(ctxt_pP->module_id);
   gNB_RRC_UE_t *ue_p = &ue_context_pP->ue_context;
-  /* hack: in many cases, we want to send a PDU session resource setup response
+  ue_p->xids[xid] = RRC_PDUSESSION_ESTABLISH;
-   * after this dedicated RRC Reconfiguration (e.g., new PDU session). However,
-   * this is not always the case, e.g., when the PDU sessions came through the
-   * NG initial UE context setup, in which case all PDU sessions are
-   * established, and we end up here after a UE Capability Enquiry. So below,
-   * check if we are currently setting up any PDU sessions, and only then, set
-   * the xid to trigger a PDU session setup response. */
-  ue_p->xids[xid] = RRC_DEDICATED_RECONF;
-  for (int i = 0; i < ue_p->nb_of_pdusessions; ++i) {
-    if (ue_p->pduSession[i].status < PDU_SESSION_STATUS_ESTABLISHED) {
-      ue_p->xids[xid] = RRC_PDUSESSION_ESTABLISH;
-      break;
-    }
-  }
   struct NR_RRCReconfiguration_v1530_IEs__dedicatedNAS_MessageList *dedicatedNAS_MessageList = CALLOC(1, sizeof(*dedicatedNAS_MessageList));
 
   for (int i = 0; i < ue_p->nb_of_pdusessions; i++) {
@@ -1389,35 +1376,6 @@ static int handle_ueCapabilityInformation(const protocol_ctxt_t *const ctxt_pP,
 
   rrc_gNB_send_NGAP_UE_CAPABILITIES_IND(ctxt_pP, ue_context_p, ue_cap_info);
 
-  /* if we already have DRBs setup (SRB2 exists if there is at least one DRB),
-   * there might not be a further reconfiguration on which we can rely, so send
-   * the UE capabilities to the DU to have it trigger a reconfiguration. */
-  if (UE->Srb[2].Active && UE->ue_cap_buffer.len > 0 && UE->ue_cap_buffer.buf != NULL) {
-    cu_to_du_rrc_information_t cu2du = {0};
-    if (UE->ue_cap_buffer.len > 0 && UE->ue_cap_buffer.buf != NULL) {
-      cu2du.uE_CapabilityRAT_ContainerList = UE->ue_cap_buffer.buf;
-      cu2du.uE_CapabilityRAT_ContainerList_length = UE->ue_cap_buffer.len;
-    }
-
-    f1_ue_data_t ue_data = cu_get_f1_ue_data(UE->rrc_ue_id);
-    if (ue_data.du_assoc_id == 0) {
-      LOG_E(NR_RRC, "cannot send data: invalid assoc_id 0, DU offline\n");
-      return -1;
-    }
-    gNB_RRC_INST *rrc = RC.nrrrc[0];
-    f1ap_ue_context_modif_req_t ue_context_modif_req = {
-        .gNB_CU_ue_id = UE->rrc_ue_id,
-        .gNB_DU_ue_id = ue_data.secondary_ue,
-        .plmn.mcc = rrc->configuration.mcc[0],
-        .plmn.mnc = rrc->configuration.mnc[0],
-        .plmn.mnc_digit_length = rrc->configuration.mnc_digit_length[0],
-        .nr_cellid = rrc->nr_cellid,
-        .servCellId = 0, /* TODO: correct value? */
-        .cu_to_du_rrc_information = &cu2du,
-    };
-    rrc->mac_rrc.ue_context_modification_request(ue_data.du_assoc_id, &ue_context_modif_req);
-  }
-
   return 0;
 }
 
@@ -1535,14 +1493,6 @@ static void handle_rrcReconfigurationComplete(const protocol_ctxt_t *const ctxt_
       LOG_I(RRC, "UE %d: transaction %d still ongoing for action %d\n", UE->rrc_ue_id, i, UE->xids[i]);
     }
   }
-
-  /* if we did not receive any UE Capabilities, let's do that now. It should
-   * only happen on the first time a reconfiguration arrives. Afterwards, we
-   * should have them. If the UE does not give us anything, we will re-request
-   * the capabilities after each reconfiguration, which is a finite number */
-  if (UE->ue_cap_buffer.len == 0) {
-    rrc_gNB_generate_UECapabilityEnquiry(ctxt_pP, ue_context_p);
-  }
 }
 //-----------------------------------------------------------------------------
 int rrc_gNB_decode_dcch(const protocol_ctxt_t *const ctxt_pP,
@@ -1650,7 +1600,9 @@ int rrc_gNB_decode_dcch(const protocol_ctxt_t *const ctxt_pP,
         nr_rrc_pdcp_config_security(ctxt_pP, ue_context_p, 1);
         ue_context_p->ue_context.as_security_active = true;
 
-        rrc_gNB_generate_defaultRRCReconfiguration(ctxt_pP, ue_context_p);
+        /* trigger UE capability enquiry if we don't have them yet */
+        if (ue_context_p->ue_context.ue_cap_buffer.len == 0)
+          rrc_gNB_generate_UECapabilityEnquiry(ctxt_pP, ue_context_p);
         break;
 
       case NR_UL_DCCH_MessageType__c1_PR_securityModeFailure: