Reestablishment hack: free reconfigurationWithSync

After handover, the last CellGroupConfig received is the one for
handover, containing a reconfigurationWithSync. Resending this
CellGroupConfig to the UE after reestablishment would trigger a
handover. Free the reconfigurationWithSync to have the UE complete
reestablishment at the current cell.

The CU implementation of reestablishment modifies the CellGroupConfig.
It should not do this, but does as of now. The specification (38.473 Sec
8.7) foresees an optional F1 UE context modification procedure (which
can be used to receive the CellGroupConfig). This should be done instead
to retrieve the correct CellGroupConfig.

Note that the F1 UE context setup procedure, similar to the UE context
modification procedure, would also allow to perform reestablishment on a
DU that is not the original one.

openair2/RRC/NR/rrc_gNB.c

@@ -909,6 +909,17 @@ static void rrc_gNB_process_RRCReestablishmentComplete(gNB_RRC_INST *rrc, gNB_RR
                    NR_RLC_BearerConfig__reestablishRLC_true);
   }
 
+  /* TODO: remove a reconfigurationWithSync, we don't need it for
+   * reestablishment. The whole reason why this might be here is that we store
+   * the CellGroupConfig (after handover), and simply reuse it for
+   * reestablishment, instead of re-requesting the CellGroupConfig from the DU.
+   * Hence, add below hack; the solution would be to request the
+   * CellGroupConfig from the DU when doing reestablishment. */
+  if (cellGroupConfig->spCellConfig->reconfigurationWithSync != NULL) {
+    ASN_STRUCT_FREE(asn_DEF_NR_ReconfigurationWithSync, cellGroupConfig->spCellConfig->reconfigurationWithSync);
+    cellGroupConfig->spCellConfig->reconfigurationWithSync = NULL;
+  }
+
   /* Re-establish SRB2 according to clause 5.3.5.6.3 of 3GPP TS 38.331
    * (SRB1 is re-established with RRCReestablishment message)
    */