Reset CU-UP E1 UE contexts after E1 Setup Response

38.463 sec. 8.2.3 says

> This procedure also re-initialises the E1AP UE-related contexts (if
> any) and erases all related signalling connections in the two nodes like
> a Reset procedure would do.

Hence, delete all contexts after reception of E1 Setup Response. This
minimizes a risk of receiving an E1 bearer setup req for an existing UE,
which currently leads to an assert [we trust the CU-CP does not send the
same UE ID twice, as we only "mirror" the existing UE ID].

openair2/E1AP/e1ap.c

@@ -219,6 +219,8 @@ int e1apCUUP_handle_SETUP_RESPONSE(sctp_assoc_t assoc_id, e1ap_upcp_inst_t *inst
     return -1;
   }
   free_e1ap_cuup_setup_response(&out);
+
+  e1_reset(); // reset all UE contexts, if any: see 38.463 sec 8.2.3
   return 0;
 }
 

openair2/LAYER2/nr_pdcp/cucp_cuup_handler.c

@@ -330,3 +330,15 @@ void e1_bearer_release_cmd(const e1ap_bearer_release_cmd_t *cmd)
 
   get_e1_if()->bearer_release_complete(&cplt);
 }
+
+void e1_reset(void)
+{
+  /* we get the list of all UEs from the PDCP, which maintains a list */
+  ue_id_t ue_ids[MAX_MOBILES_PER_GNB];
+  int num = nr_pdcp_get_num_ues(ue_ids, MAX_MOBILES_PER_GNB);
+  for (uint32_t i = 0; i < num; ++i) {
+    ue_id_t ue_id = ue_ids[i];
+    LOG_W(E1AP, "releasing UE %ld\n", ue_id);
+    remove_ue_e1(ue_id);
+  }
+}

openair2/LAYER2/nr_pdcp/cucp_cuup_handler.h

@@ -31,5 +31,6 @@ struct e1ap_bearer_release_cmd_s;
 void e1_bearer_context_setup(const struct e1ap_bearer_setup_req_s *req);
 void e1_bearer_context_modif(const struct e1ap_bearer_setup_req_s *req);
 void e1_bearer_release_cmd(const struct e1ap_bearer_release_cmd_s *cmd);
+void e1_reset(void);
 
 #endif /* CUCP_CUUP_HANDLER_H */