Fixed bug when GUTI is unknown but EMM context was previously present. Added function to delete EMM context.

srsepc/hdr/mme/s1ap.h

@@ -87,7 +87,7 @@ public:
   void add_new_ue_ecm_ctx(const ue_ecm_ctx_t &ue_ecm_ctx);
   ue_emm_ctx_t* find_ue_emm_ctx_from_imsi(uint64_t imsi);
   ue_ecm_ctx_t* find_ue_ecm_ctx_from_mme_ue_s1ap_id(uint32_t mme_ue_s1ap_id);
-  bool delete_ue_emm_ctx(ue_emm_ctx_t *ue_emm_ctx);
+  bool delete_ue_emm_ctx(uint64_t imsi);
   bool delete_ue_ecm_ctx(uint32_t mme_ue_s1ap_id);
   void delete_ues_ecm_ctx_in_enb(uint16_t enb_id);
 

srsepc/src/mme/s1ap.cc

@@ -419,6 +419,22 @@ s1ap::find_ue_ecm_ctx_from_mme_ue_s1ap_id(uint32_t mme_ue_s1ap_id)
     return it->second;
   }
 }
+bool
+s1ap::delete_ue_emm_ctx(uint64_t imsi)
+{
+  std::map<uint64_t, ue_emm_ctx_t*>::iterator ue_emm_ctx_it = m_imsi_to_ue_emm_ctx.find(imsi);
+  if(ue_emm_ctx_it == m_imsi_to_ue_emm_ctx.end()) 
+  {
+    m_s1ap_log->info("Cannot delete UE EMM context, UE not found. IMSI: %d\n", imsi);
+    return false;
+  }
+
+  //Delete UE context
+  m_imsi_to_ue_emm_ctx.erase(ue_emm_ctx_it);
+  delete ue_emm_ctx_it->second;
+  m_s1ap_log->info("Deleted UE EMM Context.\n");
+  return true;
+}
 
 bool
 s1ap::delete_ue_ecm_ctx(uint32_t mme_ue_s1ap_id)
@@ -450,7 +466,7 @@ s1ap::delete_ue_ecm_ctx(uint32_t mme_ue_s1ap_id)
   //Delete UE context
   m_mme_ue_s1ap_id_to_ue_ecm_ctx.erase(ue_ecm_ctx_it);
   delete ue_ecm_ctx;
-  m_s1ap_log->info("Deleted UE Context.\n");
+  m_s1ap_log->info("Deleted UE ECM Context.\n");
 
   return true;
 }

srsepc/src/mme/s1ap_nas_transport.cc

@@ -619,6 +619,16 @@ s1ap_nas_transport::handle_identity_response(srslte::byte_buffer_t *nas_msg, ue_
   for(int i=0;i<=14;i++){
     imsi  += id_resp.mobile_id.imsi[i]*std::pow(10,14-i);
   }
+
+  //Check if EMM context already exists
+  ue_emm_ctx_t *ue_tmp_ptr = m_s1ap->find_ue_emm_ctx_from_imsi(imsi);
+  if(ue_tmp_ptr != NULL)
+  {
+    m_s1ap_log->warning("Unkonw GUTI, but UE's EMM context present.\n");
+    m_s1ap->delete_ue_emm_ctx(imsi);
+  }
+
+
   m_s1ap_log->info("Id Response -- IMSI: %015lu\n", imsi);
   m_s1ap_log->console("Id Response -- IMSI: %015lu\n", imsi);
   ue_ecm_ctx->imsi = imsi;