NNSF my MME code: respect selected PLMN ID

openair3/S1AP/s1ap_eNB_nas_procedures.c

@@ -89,6 +89,7 @@ int s1ap_eNB_handle_nas_first_req(
       mme_desc_p = s1ap_eNB_nnsf_select_mme_by_mme_code(
                      instance_p,
                      s1ap_nas_first_req_p->establishment_cause,
+                     s1ap_nas_first_req_p->selected_plmn_identity,
                      s1ap_nas_first_req_p->ue_identity.s_tmsi.mme_code);
     }
   }

openair3/S1AP/s1ap_eNB_nnsf.c

@@ -92,11 +92,10 @@ s1ap_eNB_nnsf_select_mme(s1ap_eNB_instance_t       *instance_p,
 struct s1ap_eNB_mme_data_s *
 s1ap_eNB_nnsf_select_mme_by_mme_code(s1ap_eNB_instance_t       *instance_p,
                                      rrc_establishment_cause_t  cause,
+                                     int                        selected_plmn_identity,
                                      uint8_t                    mme_code)
 {
   struct s1ap_eNB_mme_data_s *mme_data_p = NULL;
-  struct s1ap_eNB_mme_data_s *mme_highest_capacity_p = NULL;
-  uint8_t current_capacity = 0;
 
   RB_FOREACH(mme_data_p, s1ap_mme_map, &instance_p->s1ap_mme_head) {
     struct served_gummei_s *gummei_p = NULL;
@@ -135,30 +134,37 @@ s1ap_eNB_nnsf_select_mme_by_mme_code(s1ap_eNB_instance_t       *instance_p,
       }
     }
 
-    if (current_capacity < mme_data_p->relative_mme_capacity) {
-      /* We find a better MME, keep a reference to it */
-      current_capacity = mme_data_p->relative_mme_capacity;
-      mme_highest_capacity_p = mme_data_p;
-    }
-
     /* Looking for MME code matching the one provided by NAS */
     STAILQ_FOREACH(gummei_p, &mme_data_p->served_gummei, next) {
       struct mme_code_s *mme_code_p = NULL;
+      struct plmn_identity_s   *served_plmn_p = NULL;
 
+      STAILQ_FOREACH(served_plmn_p, &gummei_p->served_plmns, next) {
+        if ((served_plmn_p->mcc == instance_p->mcc[selected_plmn_identity]) &&
+            (served_plmn_p->mnc == instance_p->mnc[selected_plmn_identity])) {
+          break;
+        }
+      }
       STAILQ_FOREACH(mme_code_p, &gummei_p->mme_codes, next) {
         if (mme_code_p->mme_code == mme_code) {
-          return mme_data_p;
+          break;
         }
       }
+
+      /* The MME matches the parameters provided by the NAS layer ->
+      * the MME is knwown and the association is ready.
+      * Return the reference to the MME to use it for this UE.
+      */
+      if (mme_code_p && served_plmn_p) {
+        return mme_data_p;
+      }
     }
   }
 
-  /* At this point no MME matches the provided GUMMEI. Select the one with the
-   * highest relative capacity.
-   * In case the list of known MME is empty, simply return NULL, that way the RRC
-   * layer should know about it and reject RRC connectivity.
-   */
-  return mme_highest_capacity_p;
+  /* At this point no MME matches the selected PLMN and MME code. In this case,
+   * return NULL. That way the RRC layer should know about it and reject RRC
+   * connectivity. */
+  return NULL;
 }
 
 struct s1ap_eNB_mme_data_s *

openair3/S1AP/s1ap_eNB_nnsf.h

@@ -29,6 +29,7 @@ s1ap_eNB_nnsf_select_mme(s1ap_eNB_instance_t       *instance_p,
 struct s1ap_eNB_mme_data_s*
 s1ap_eNB_nnsf_select_mme_by_mme_code(s1ap_eNB_instance_t       *instance_p,
                                      rrc_establishment_cause_t  cause,
+                                     int                        selected_plmn_identity,
                                      uint8_t                    mme_code);
 
 struct s1ap_eNB_mme_data_s*