From f69fda69e6f32ea215692f8d77fa9b17bfba52de Mon Sep 17 00:00:00 2001
From: ZorazeAli <zoraze.ali@cttc.es>
Date: Mon, 25 Mar 2019 14:22:05 +0100
Subject: [PATCH] lte: Extend EPC X2 interface to send handover cancel message

---
 src/lte/model/epc-x2-sap.h | 34 ++++++++++++++++++++++++++++
 src/lte/model/epc-x2.cc    | 46 ++++++++++++++++++++++++++++++++++++++
 src/lte/model/epc-x2.h     |  6 +++++
 3 files changed, 86 insertions(+)

diff --git a/src/lte/model/epc-x2-sap.h b/src/lte/model/epc-x2-sap.h
index 2201bd1a5..385eb2fd7 100644
--- a/src/lte/model/epc-x2-sap.h
+++ b/src/lte/model/epc-x2-sap.h
@@ -333,6 +333,21 @@ public:
     Ptr<Packet> ueData; ///< UE data
   };
 
+  /**
+   * \brief Parameters of the HANDOVER CANCEL message.
+   *
+   * See section 9.1.1.6 for further info about the parameters
+   *
+   */
+  struct HandoverCancelParams
+  {
+    uint16_t            oldEnbUeX2apId; ///< old ENB UE X2 AP ID
+    uint16_t            newEnbUeX2apId; ///< new ENB UE X2 AP ID
+    uint16_t            sourceCellId; ///< source cell ID
+    uint16_t            targetCellId; ///< target cell ID
+    uint16_t            cause; ///< cause
+  };
+
 };
 
 
@@ -396,6 +411,12 @@ public:
    * \param params the UE data parameters
    */
   virtual void SendUeData (UeDataParams params) = 0;
+
+  /**
+   * \brief Send handover Cancel to the target eNB
+   * \param params the handover cancel parameters
+   */
+  virtual void SendHandoverCancel (HandoverCancelParams params) = 0;
 };
 
 
@@ -529,6 +550,12 @@ public:
    */
   virtual void SendUeData (UeDataParams params);
 
+  /**
+   * \brief Send handover Cancel to the target eNB
+   * \param params the handover cancel parameters
+   */
+  virtual void SendHandoverCancel (HandoverCancelParams params);
+
 private:
   EpcX2SpecificEpcX2SapProvider ();
   C* m_x2; ///< owner class
@@ -601,6 +628,13 @@ EpcX2SpecificEpcX2SapProvider<C>::SendUeData (UeDataParams params)
   m_x2->DoSendUeData (params);
 }
 
+template <class C>
+void
+EpcX2SpecificEpcX2SapProvider<C>::SendHandoverCancel (HandoverCancelParams params)
+{
+  m_x2->DoSendHandoverCancel (params);
+}
+
 /**
  * EpcX2SpecificEpcX2SapUser
  */
diff --git a/src/lte/model/epc-x2.cc b/src/lte/model/epc-x2.cc
index dee3d7ff9..060164932 100644
--- a/src/lte/model/epc-x2.cc
+++ b/src/lte/model/epc-x2.cc
@@ -763,4 +763,50 @@ EpcX2::DoSendUeData (EpcX2SapProvider::UeDataParams params)
   sourceSocket->SendTo (packet, 0, InetSocketAddress (targetIpAddr, m_x2uUdpPort));
 }
 
+void
+EpcX2::DoSendHandoverCancel (EpcX2SapProvider::HandoverCancelParams params)
+{
+  NS_LOG_FUNCTION (this);
+
+  NS_LOG_LOGIC ("oldEnbUeX2apId = " << params.oldEnbUeX2apId);
+  NS_LOG_LOGIC ("newEnbUeX2apId = " << params.newEnbUeX2apId);
+  NS_LOG_LOGIC ("sourceCellId = " << params.sourceCellId);
+  NS_LOG_LOGIC ("targetCellId = " << params.targetCellId);
+
+  NS_ASSERT_MSG (m_x2InterfaceSockets.find (params.targetCellId) != m_x2InterfaceSockets.end (),
+                 "Socket infos not defined for targetCellId = " << params.targetCellId);
+
+  Ptr<Socket> localSocket = m_x2InterfaceSockets [params.targetCellId]->m_localCtrlPlaneSocket;
+  Ipv4Address remoteIpAddr = m_x2InterfaceSockets [params.targetCellId]->m_remoteIpAddr;
+
+  NS_LOG_LOGIC ("localSocket = " << localSocket);
+  NS_LOG_LOGIC ("remoteIpAddr = " << remoteIpAddr);
+
+  NS_LOG_INFO ("Send X2 message: HANDOVER CANCEL");
+
+  // Build the X2 message
+  EpcX2HandoverCancelHeader x2HandoverCancelHeader;
+  x2HandoverCancelHeader.SetOldEnbUeX2apId (params.oldEnbUeX2apId);
+  x2HandoverCancelHeader.SetNewEnbUeX2apId (params.newEnbUeX2apId);
+  x2HandoverCancelHeader.SetCause (params.cause);
+
+  EpcX2Header x2Header;
+  x2Header.SetMessageType (EpcX2Header::SuccessfulOutcome);
+  x2Header.SetProcedureCode (EpcX2Header::HandoverCancel);
+  x2Header.SetLengthOfIes (x2HandoverCancelHeader.GetLengthOfIes ());
+  x2Header.SetNumberOfIes (x2HandoverCancelHeader.GetNumberOfIes ());
+
+  NS_LOG_INFO ("X2 header: " << x2Header);
+  NS_LOG_INFO ("X2 UeContextRelease header: " << x2HandoverCancelHeader);
+
+  // Build the X2 packet
+  Ptr<Packet> packet = Create <Packet> ();
+  packet->AddHeader (x2HandoverCancelHeader);
+  packet->AddHeader (x2Header);
+  NS_LOG_INFO ("packetLen = " << packet->GetSize ());
+
+  // Send the X2 message through the socket
+  localSocket->SendTo (packet, 0, InetSocketAddress (remoteIpAddr, m_x2cUdpPort));
+}
+
 } // namespace ns3
diff --git a/src/lte/model/epc-x2.h b/src/lte/model/epc-x2.h
index c5f7bf80b..1f2149060 100644
--- a/src/lte/model/epc-x2.h
+++ b/src/lte/model/epc-x2.h
@@ -202,6 +202,12 @@ protected:
    * \param params EpcX2SapProvider::UeDataParams
    */
   virtual void DoSendUeData (EpcX2SapProvider::UeDataParams params);
+  /**
+   * \brief Send Handover Cancel function
+   * \param params the handover cancel parameters
+   *
+   */
+  virtual void DoSendHandoverCancel (EpcX2SapProvider::HandoverCancelParams params);
 
   EpcX2SapUser* m_x2SapUser; ///< X2 SAP user
   EpcX2SapProvider* m_x2SapProvider; ///< X2 SAP provider