Fix PDCP re-establishment of SRB1 and SRB2

- SRB1 shall be re-established at the time of RRCReestablishmentRequest
  according to 5.3.7.4 of 3GPP TS 38.331
- SRB2 shall be re-established when creating srb-ToAddModList
  according to 5.3.5.6.3 of 3GPP TS 38.331

openair2/RRC/NR/rrc_gNB.c

@@ -370,6 +370,9 @@ unsigned int rrc_gNB_get_next_transaction_identifier(module_id_t gnb_mod_idP)
   return tmp;
 }
 
+/**
+ * @brief Create srb-ToAddModList for RRCSetup and RRCReconfiguration messages
+*/
 static NR_SRB_ToAddModList_t *createSRBlist(gNB_RRC_UE_t *ue, bool reestablish)
 {
   if (!ue->Srb[1].Active) {
@@ -381,6 +384,7 @@ static NR_SRB_ToAddModList_t *createSRBlist(gNB_RRC_UE_t *ue, bool reestablish)
     if (ue->Srb[i].Active) {
       asn1cSequenceAdd(list->list, NR_SRB_ToAddMod_t, srb);
       srb->srb_Identity = i;
+      /* Set reestablishPDCP only for SRB2 */
       if (reestablish && i == 2) {
         asn1cCallocOne(srb->reestablishPDCP, NR_SRB_ToAddMod__reestablishPDCP_true);
       }
@@ -1021,11 +1025,11 @@ static void rrc_gNB_generate_RRCReestablishment(rrc_gNB_ue_context_t *ue_context
 
   /* SRBs */
   for (int srb_id = 1; srb_id < NR_NUM_SRB; srb_id++) {
-    if (ue_p->Srb[srb_id].Active) {
+    if (ue_p->Srb[srb_id].Active)
       nr_pdcp_config_set_security(ue_p->rrc_ue_id, srb_id, security_mode, kRRCenc, kRRCint, kUPenc);
-      nr_pdcp_reestablishment(ue_p->rrc_ue_id, srb_id, true);
-    }
   }
+  /* Re-establish PDCP for SRB1, according to 5.3.7.4 of 3GPP TS 38.331 */
+  nr_pdcp_reestablishment(ue_p->rrc_ue_id, 1, true);
   /* PDCP Reestablishment over E1 */
   cuup_notify_reestablishment(rrc, ue_p);
   /* F1AP DL RRC Message Transfer */
@@ -1083,7 +1087,17 @@ static void rrc_gNB_process_RRCReestablishmentComplete(const protocol_ctxt_t *co
                    NR_RLC_BearerConfig__reestablishRLC_true);
   }
 
+  /* Re-establish SRB2 according to clause 5.3.5.6.3 of 3GPP TS 38.331
+   * (SRB1 is re-established with RRCReestablishment message)
+   */
+  int srb_id = 2;
+  if (ue_p->Srb[srb_id].Active) {
+      nr_pdcp_reestablishment(ue_p->rrc_ue_id, srb_id, true);
+  }
+
+  /* Create srb-ToAddModList */
   NR_SRB_ToAddModList_t *SRBs = createSRBlist(ue_p, true);
+  /* Create drb-ToAddModList */
   NR_DRB_ToAddModList_t *DRBs = createDRBlist(ue_p, true);
 
   uint8_t new_xid = rrc_gNB_get_next_transaction_identifier(ctxt_pP->module_id);