Starting to add the ability to handle UE context release complete.

srsepc/hdr/mme/s1ap_common.h

@@ -140,6 +140,7 @@ typedef struct{
     emm_state_t state;
     uint32_t mme_ue_s1ap_id;
     uint8_t attach_type;
+    struct in_addr ue_ip;
     srslte::gtpc_f_teid_ie sgw_ctrl_fteid;
 } ue_emm_ctx_t;
 

srsepc/hdr/mme/s1ap_ctx_mngmt_proc.h

@@ -52,6 +52,7 @@ public:
   bool handle_initial_context_setup_response(LIBLTE_S1AP_MESSAGE_INITIALCONTEXTSETUPRESPONSE_STRUCT *in_ctxt_resp);
   bool handle_ue_context_release_request(LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASEREQUEST_STRUCT *ue_rel, struct sctp_sndrcvinfo *enb_sri, srslte::byte_buffer_t *reply_buffer, bool *reply_flag);
   bool send_ue_context_release_command(ue_ecm_ctx_t *ecm_ctx, srslte::byte_buffer_t *reply_buffer);
+  bool handle_ue_context_release_complete(LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASECOMPLETE_STRUCT *rel_comp);
 
 private:
   s1ap_ctx_mngmt_proc();

srsepc/src/mme/s1ap.cc

@@ -283,6 +283,9 @@ s1ap::handle_successful_outcome(LIBLTE_S1AP_SUCCESSFULOUTCOME_STRUCT *msg)
   case LIBLTE_S1AP_SUCCESSFULOUTCOME_CHOICE_INITIALCONTEXTSETUPRESPONSE:
     m_s1ap_log->info("Received Initial Context Setup Response.\n");
     return m_s1ap_ctx_mngmt_proc->handle_initial_context_setup_response(&msg->choice.InitialContextSetupResponse);
+  case  LIBLTE_S1AP_SUCCESSFULOUTCOME_CHOICE_UECONTEXTRELEASECOMPLETE:
+    m_s1ap_log->info("Received UE Context Release Complete\n");
+    return m_s1ap_ctx_mngmt_proc->handle_ue_context_release_complete(&msg->choice.UEContextReleaseComplete);
   default:
     m_s1ap_log->error("Unhandled successful outcome message: %s\n", liblte_s1ap_successfuloutcome_choice_text[msg->choice_type]);
   }

srsepc/src/mme/s1ap_ctx_mngmt_proc.cc

@@ -349,5 +349,62 @@ s1ap_ctx_mngmt_proc::send_ue_context_release_command(ue_ecm_ctx_t *ecm_ctx, srsl
   return true;
 }
 
+bool
+s1ap_ctx_mngmt_proc::handle_ue_context_release_complete(LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASECOMPLETE_STRUCT *rel_comp)
+{
+  /*
+    typedef struct{
+    bool                                                         ext;
+    LIBLTE_S1AP_MME_UE_S1AP_ID_STRUCT                            MME_UE_S1AP_ID;
+    LIBLTE_S1AP_ENB_UE_S1AP_ID_STRUCT                            eNB_UE_S1AP_ID;
+    LIBLTE_S1AP_CRITICALITYDIAGNOSTICS_STRUCT                    CriticalityDiagnostics;
+    bool                                                         CriticalityDiagnostics_present;
+    LIBLTE_S1AP_USERLOCATIONINFORMATION_STRUCT                   UserLocationInformation;
+    bool                                                         UserLocationInformation_present;
+    }LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASECOMPLETE_STRUCT;
+   */
+
+  uint32_t mme_ue_s1ap_id = rel_comp->MME_UE_S1AP_ID.MME_UE_S1AP_ID;
+  m_s1ap_log->info("Received UE Context Release Complete. MME-UE S1AP Id: %d\n", mme_ue_s1ap_id);
+  m_s1ap_log->console("Received UE Context Release Complete. MME-UE S1AP Id %d\n", mme_ue_s1ap_id);
+
+  ue_ctx_t * ue_ctx = m_s1ap->find_ue_ctx_from_mme_ue_s1ap_id(mme_ue_s1ap_id);
+  if(ue_ctx == NULL)
+  {
+    m_s1ap_log->info("No UE context to release found. MME-UE S1AP Id: %d\n", mme_ue_s1ap_id);
+    m_s1ap_log->console("No UE context to release found. MME-UE S1AP Id: %d\n", mme_ue_s1ap_id);
+    return false;
+  }
+  ue_ecm_ctx_t *ecm_ctx = &ue_ctx->ecm_ctx; 
+
+  //Delete user plane context at the SPGW (but keep GTP-C connection).
+  if (ecm_ctx->state == ECM_STATE_CONNECTED)
+  {
+    //There are active E-RABs, send release access mearers request
+    m_s1ap_log->console("There are active E-RABs, send release access mearers request");
+    m_s1ap_log->info("There are active E-RABs, send release access mearers request");
+    m_mme_gtpc->send_release_access_bearers_request(ecm_ctx->imsi);
+    //The handle_releease_access_bearers_response function will make sure to mark E-RABS DEACTIVATED
+    //It will release the UEs downstream S1-u and keep the upstream S1-U connection active.
+  }
+  else
+  {
+    //No ECM Context to release
+    m_s1ap_log->info("UE is not ECM connected. No need to release S1-U. MME UE S1AP Id %d\n", mme_ue_s1ap_id);
+    m_s1ap_log->console("UE is not ECM connected. No need to release S1-U. MME UE S1AP Id %d\n", mme_ue_s1ap_id);
+    //Make sure E-RABS are merked as DEACTIVATED.
+    for(int i=0;i<MAX_ERABS_PER_UE;i++)
+    {
+      ecm_ctx->erabs_ctx[i].state = ERAB_DEACTIVATED;
+    }
+  }
+
+  //Delete UE context
+  m_s1ap->release_ue_ecm_ctx(ue_ctx->ecm_ctx.mme_ue_s1ap_id);
+  m_s1ap_log->info("UE Context Release Completed.\n");
+  m_s1ap_log->console("UE Context Release Completed.\n");
+  return true;
+}
+
 
 } //namespace srsepc

srsepc/src/mme/s1ap_nas_transport.cc

@@ -699,12 +699,14 @@ s1ap_nas_transport::handle_nas_service_request(uint32_t m_tmsi,
       //Save whether secure ESM information transfer is necessary
       ecm_ctx->eit = false;
 
-      //Initialize E-RABs
+      //Get UE IP, and uplink F-TEID
-      for(uint i = 0 ; i< MAX_ERABS_PER_UE; i++)
+      if(emm_ctx->ue_ip.s_addr == 0 )
       {
-        ecm_ctx->erabs_ctx[i].state = ERAB_DEACTIVATED;
+        m_s1ap_log->error("UE has no valid IP assigned upon reception of service request");
-        ecm_ctx->erabs_ctx[i].erab_id = i;
       }
+      
+      m_s1ap_log->console("UE previously assigned IP: %s",inet_ntoa(emm_ctx->ue_ip));
+      //Mark E-RABs as setup, but not active yet 
 
       //Re-generate K_eNB
       liblte_security_generate_k_enb(emm_ctx->security_ctxt.k_asme, emm_ctx->security_ctxt.ul_nas_count, emm_ctx->security_ctxt.k_enb);
@@ -932,16 +934,11 @@ s1ap_nas_transport::handle_identity_response(srslte::byte_buffer_t *nas_msg, ue_
 
   m_s1ap_log->info("Id Response -- IMSI: %015lu\n", imsi);
   m_s1ap_log->console("Id Response -- IMSI: %015lu\n", imsi);
-  ecm_ctx->imsi = imsi;
 
-  //Get UE EMM context
+  //Set UE's context IMSI
-  //if(m_s1ap->get_tmp_ue_emm_ctx(ue_ecm_ctx->mme_ue_s1ap_id, &ue_emm_ctx) == false)
-  //{
-  //  m_s1ap_log->error("Could not find UE's temporary EMM context. MME UE S1AP Id: %d\n",ue_ecm_ctx->mme_ue_s1ap_id);
-  //  return false;
-  //}
   emm_ctx->imsi=imsi;
-  
+  ecm_ctx->imsi = imsi;
+
   //Get Authentication Vectors from HSS
   if(!m_hss->gen_auth_info_answer(imsi, emm_ctx->security_ctxt.k_asme, autn, rand, emm_ctx->security_ctxt.xres))
   {