Hack: Prevent CU-UP UE ID management if integrated CU

This is a workaround for a problem described in #706. In short, we
cannot reuse the cu_add/remove_f1_ue_data() functions if we are in an
integrated CU-UP/CP ("CU"), but then we can also not reliably use
different UE IDs in CU-UP and CU-CP (except if using even more hacks).

openair2/LAYER2/nr_pdcp/cucp_cuup_handler.c

@@ -134,11 +134,15 @@ static instance_t get_f1_gtp_instance(void)
 
 void e1_bearer_context_setup(const e1ap_bearer_setup_req_t *req)
 {
+  bool need_ue_id_mgmt = e1_used();
+
   /* mirror the CU-CP UE ID for CU-UP */
   uint32_t cu_up_ue_id = req->gNB_cu_cp_ue_id;
   f1_ue_data_t ued = {.secondary_ue = req->gNB_cu_cp_ue_id};
+  if (need_ue_id_mgmt) {
     cu_add_f1_ue_data(cu_up_ue_id, &ued);
     LOG_I(E1AP, "adding UE with CU-CP UE ID %d and CU-UP UE ID %d\n", req->gNB_cu_cp_ue_id, cu_up_ue_id);
+  }
 
   instance_t n3inst = get_n3_gtp_instance();
   instance_t f1inst = get_f1_gtp_instance();
@@ -260,6 +264,8 @@ void e1_bearer_context_modif(const e1ap_bearer_setup_req_t *req)
 
 void e1_bearer_release_cmd(const e1ap_bearer_release_cmd_t *cmd)
 {
+  bool need_ue_id_mgmt = e1_used();
+
   instance_t n3inst = get_n3_gtp_instance();
   instance_t f1inst = get_f1_gtp_instance();
 
@@ -269,7 +275,9 @@ void e1_bearer_release_cmd(const e1ap_bearer_release_cmd_t *cmd)
   if (f1inst >= 0)  // is there F1-U?
     newGtpuDeleteAllTunnels(f1inst, cmd->gNB_cu_up_ue_id);
   nr_pdcp_remove_UE(cmd->gNB_cu_up_ue_id);
+  if (need_ue_id_mgmt) {
     cu_remove_f1_ue_data(cmd->gNB_cu_up_ue_id);
+  }
 
   e1ap_bearer_release_cplt_t cplt = {
     .gNB_cu_cp_ue_id = cmd->gNB_cu_cp_ue_id,

openair2/LAYER2/nr_pdcp/cuup_cucp_if.c

@@ -22,14 +22,22 @@
 #include "cuup_cucp_if.h"
 
 static e1_if_t e1_if;
+static bool g_uses_e1;
 
 e1_if_t *get_e1_if(void)
 {
   return &e1_if;
 }
 
+bool e1_used(void)
+{
+  return g_uses_e1;
+}
+
 void nr_pdcp_e1_if_init(bool uses_e1)
 {
+  g_uses_e1 = uses_e1;
+
   if (uses_e1)
     cuup_cucp_init_e1ap(&e1_if);
   else

openair2/LAYER2/nr_pdcp/cuup_cucp_if.h

@@ -38,6 +38,7 @@ typedef struct e1_if_t {
 } e1_if_t;
 
 e1_if_t *get_e1_if(void);
+bool e1_used(void);
 void nr_pdcp_e1_if_init(bool uses_e1);
 
 void cuup_cucp_init_direct(e1_if_t *iface);