Reworked cuup_notify_reestablishment

- to fetch PDU session to setup in E1 following logic as in e1_send_bearer_updates
- fill bearer context modification request with stored F1-U tunnel information
  during E1 reestablishment, otherwise it would initialized to 0 by default
- update GTP tunnel with the stored configuration after E1 reestablishment

openair2/RRC/NR/rrc_gNB.c

@@ -930,31 +930,44 @@ static pdu_session_to_mod_t *find_or_next_pdu_session(e1ap_bearer_mod_req_t *bea
 
 static void cuup_notify_reestablishment(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue_p)
 {
-  e1ap_bearer_mod_req_t req = {0};
+  e1ap_bearer_mod_req_t req = {
+      .gNB_cu_cp_ue_id = ue_p->rrc_ue_id,
+      .gNB_cu_up_ue_id = ue_p->rrc_ue_id,
+  };
   if (!ue_associated_to_cuup(rrc, ue_p))
     return;
-  req.numPDUSessionsMod = ue_p->nb_of_pdusessions;
-  req.gNB_cu_cp_ue_id = ue_p->rrc_ue_id;
-  req.gNB_cu_up_ue_id = ue_p->rrc_ue_id;
-  for (int i = 0; i < req.numPDUSessionsMod; i++) {
-    for (int drb_id = 1; drb_id <= MAX_DRBS_PER_UE; drb_id++) {
-      if (ue_p->established_drbs[drb_id - 1].status == DRB_INACTIVE)
-        continue;
-      rrc_pdu_session_param_t *pdu = find_pduSession_from_drbId(ue_p, drb_id);
-      if (pdu == NULL) {
-        LOG_E(RRC, "UE %d: E1 Bearer Context Modification: no PDU session for DRB ID %d\n", ue_p->rrc_ue_id, drb_id);
-        continue;
-      }
-      /* E1 Bearear Context Modification Request */
-      req.pduSessionMod[i].numDRB2Modify += 1;
-      req.pduSessionMod[i].sessionId = ue_p->pduSession[i].param.pdusession_id;
-      req.pduSessionMod[i].DRBnGRanModList[drb_id - 1].id = drb_id;
-      /* PDCP configuration */
-      bearer_context_pdcp_config_t *pdcp_config = &req.pduSessionMod[i].DRBnGRanModList[drb_id - 1].pdcp_config;
-      drb_t *rrc_drb = get_drb(ue_p, drb_id);
-      set_bearer_context_pdcp_config(pdcp_config, rrc_drb, rrc->configuration.um_on_default_drb);
-      pdcp_config->pDCP_Reestablishment = true;
+  /* loop through active DRBs */
+  for (int drb_id = 1; drb_id <= MAX_DRBS_PER_UE; drb_id++) {
+    if (ue_p->established_drbs[drb_id - 1].status == DRB_INACTIVE)
+      continue;
+    /* fetch an existing PDU session for this DRB */
+    rrc_pdu_session_param_t *pdu = find_pduSession_from_drbId(ue_p, drb_id);
+    if (pdu == NULL) {
+      LOG_E(RRC, "UE %d: E1 Bearer Context Modification: no PDU session for DRB ID %d\n", ue_p->rrc_ue_id, drb_id);
+      continue;
     }
+    /* Get pointer to existing (or new one) PDU session to modify in E1 */
+    pdu_session_to_mod_t *pdu_e1 = find_or_next_pdu_session(&req, pdu->param.pdusession_id);
+    AssertError(pdu != NULL,
+                continue,
+                "UE %d: E1 Bearer Context Modification: PDU session %d to setup is null\n",
+                ue_p->rrc_ue_id,
+                pdu->param.pdusession_id);
+    /* Prepare PDU for E1 Bearear Context Modification Request */
+    pdu_e1->sessionId = pdu->param.pdusession_id;
+    /* Fill DRB to setup with ID, DL TL and DL TEID */
+    DRB_nGRAN_to_mod_t *drb_e1 = &pdu_e1->DRBnGRanModList[pdu_e1->numDRB2Modify];
+    drb_e1->id = drb_id;
+    drb_e1->numDlUpParam = 1;
+    memcpy(&drb_e1->DlUpParamList[0].tlAddress, &pdu->param.cuup_addr_f1u.buffer, sizeof(uint8_t) * 4);
+    drb_e1->DlUpParamList[0].teId = pdu->param.cuup_teid_f1u[drb_id];
+    /* PDCP configuration */
+    bearer_context_pdcp_config_t *pdcp_config = &drb_e1->pdcp_config;
+    drb_t *rrc_drb = get_drb(ue_p, drb_id);
+    set_bearer_context_pdcp_config(pdcp_config, rrc_drb, rrc->configuration.um_on_default_drb);
+    pdcp_config->pDCP_Reestablishment = true;
+    /* increase DRB to modify counter */
+    pdu_e1->numDRB2Modify += 1;
   }
   /* Send E1 Bearer Context Modification Request (3GPP TS 38.463) */
   sctp_assoc_t assoc_id = get_existing_cuup_for_ue(rrc, ue_p);