因为目标机器主动拒绝而无法建立连接（c＃套接字程序）

Question

我刚刚从msdn示例中复制代码，异步服务器和客户端套接字程序。但是我得到错误System.Net.SocketsException：无连接可以作出，因为目标机器积极地拒绝它127.0.0.1:11000

客户端程序：

using System; 
using System.Net; 
using System.Net.Sockets; 
using System.Threading; 
using System.Text; 

// State object for receiving data from remote device. 
public class StateObject 
{ 
// Client socket. 
public Socket workSocket = null; 
// Size of receive buffer. 
public const int BufferSize = 256; 
// Receive buffer. 
public byte[] buffer = new byte[BufferSize]; 
// Received data string. 
public StringBuilder sb = new StringBuilder(); 
} 

public class AsynchronousClient 
{ 
// The port number for the remote device. 
private const int port = 11000; 

// ManualResetEvent instances signal completion. 
private static ManualResetEvent connectDone = 
    new ManualResetEvent(false); 
private static ManualResetEvent sendDone = 
    new ManualResetEvent(false); 
private static ManualResetEvent receiveDone = 
    new ManualResetEvent(false); 

// The response from the remote device. 
private static String response = String.Empty; 

private static void StartClient() 
{ 
    // Connect to a remote device. 
    try 
    { 
     // Establish the remote endpoint for the socket. 
     // The name of the 
     // remote device is "host.contoso.com". 
     IPHostEntry ipHostInfo = Dns.Resolve("localhost"); 
     IPAddress ipAddress = ipHostInfo.AddressList[0]; 
     IPEndPoint remoteEP = new IPEndPoint(ipAddress, port); 

     // Create a TCP/IP socket. 
     Socket client = new Socket(AddressFamily.InterNetwork, 
      SocketType.Stream, ProtocolType.Tcp); 

     // Connect to the remote endpoint. 
     client.BeginConnect(remoteEP, 
      new AsyncCallback(ConnectCallback), client); 
     connectDone.WaitOne(); 

     // Send test data to the remote device. 
     Send(client, "This is a test<EOF>"); 
     sendDone.WaitOne(); 

     // Receive the response from the remote device. 
     Receive(client); 
     receiveDone.WaitOne(); 

     // Write the response to the console. 
     Console.WriteLine("Response received : {0}", response); 

     // Release the socket. 
     client.Shutdown(SocketShutdown.Both); 
     client.Close(); 

    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 

private static void ConnectCallback(IAsyncResult ar) 
{ 
    try 
    { 
     // Retrieve the socket from the state object. 
     Socket client = (Socket)ar.AsyncState; 

     // Complete the connection. 
     client.EndConnect(ar); 

     Console.WriteLine("Socket connected to {0}", 
      client.RemoteEndPoint.ToString()); 

     // Signal that the connection has been made. 
     connectDone.Set(); 
    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 

private static void Receive(Socket client) 
{ 
    try 
    { 
     // Create the state object. 
     StateObject state = new StateObject(); 
     state.workSocket = client; 

     // Begin receiving the data from the remote device. 
     client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, 
      new AsyncCallback(ReceiveCallback), state); 
    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 

private static void ReceiveCallback(IAsyncResult ar) 
{ 
    try 
    { 
     // Retrieve the state object and the client socket 
     // from the asynchronous state object. 
     StateObject state = (StateObject)ar.AsyncState; 
     Socket client = state.workSocket; 

     // Read data from the remote device. 
     int bytesRead = client.EndReceive(ar); 

     if (bytesRead > 0) 
     { 
      // There might be more data, so store the data received so far. 
      state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead)); 

      // Get the rest of the data. 
      client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, 
       new AsyncCallback(ReceiveCallback), state); 
     } 
     else 
     { 
      // All the data has arrived; put it in response. 
      if (state.sb.Length > 1) 
      { 
       response = state.sb.ToString(); 
      } 
      // Signal that all bytes have been received. 
      receiveDone.Set(); 
     } 
    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 

private static void Send(Socket client, String data) 
{ 
    // Convert the string data to byte data using ASCII encoding. 
    byte[] byteData = Encoding.ASCII.GetBytes(data); 

    // Begin sending the data to the remote device. 
    client.BeginSend(byteData, 0, byteData.Length, 0, 
     new AsyncCallback(SendCallback), client); 
} 

private static void SendCallback(IAsyncResult ar) 
{ 
    try 
    { 
     // Retrieve the socket from the state object. 
     Socket client = (Socket)ar.AsyncState; 

     // Complete sending the data to the remote device. 
     int bytesSent = client.EndSend(ar); 
     Console.WriteLine("Sent {0} bytes to server.", bytesSent); 

     // Signal that all bytes have been sent. 
     sendDone.Set(); 
    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 

public static int Main(String[] args) 
{ 
    StartClient(); 
    return 0; 
} 
} 

服务器程序：

using System; 
using System.Net; 
using System.Net.Sockets; 
using System.Text; 
using System.Threading; 

// State object for reading client data asynchronously 
public class StateObject 
{ 
// Client socket. 
public Socket workSocket = null; 
// Size of receive buffer. 
public const int BufferSize = 1024; 
// Receive buffer. 
public byte[] buffer = new byte[BufferSize]; 
// Received data string. 
public StringBuilder sb = new StringBuilder(); 
} 

public class AsynchronousSocketListener 
{ 
// Thread signal. 
public static ManualResetEvent allDone = new ManualResetEvent(false); 

public AsynchronousSocketListener() 
{ 
} 

public static void StartListening() 
{ 
    // Data buffer for incoming data. 
    byte[] bytes = new Byte[1024]; 

    // Establish the local endpoint for the socket. 
    // The DNS name of the computer 
    // running the listener is "host.contoso.com". 
    IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName()); 
    IPAddress ipAddress = ipHostInfo.AddressList[0]; 
    IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000); 

    // Create a TCP/IP socket. 
    Socket listener = new Socket(AddressFamily.InterNetwork, 
     SocketType.Stream, ProtocolType.Tcp); 

    // Bind the socket to the local endpoint and listen for incoming connections. 
    try 
    { 
     listener.Bind(localEndPoint); 
     listener.Listen(100); 

     while (true) 
     { 
      // Set the event to nonsignaled state. 
      allDone.Reset(); 

      // Start an asynchronous socket to listen for connections. 
      Console.WriteLine("Waiting for a connection..."); 
      listener.BeginAccept(
       new AsyncCallback(AcceptCallback), 
       listener); 

      // Wait until a connection is made before continuing. 
      allDone.WaitOne(); 
     } 

    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 

    Console.WriteLine("\nPress ENTER to continue..."); 
    Console.Read(); 

} 

public static void AcceptCallback(IAsyncResult ar) 
{ 
    // Signal the main thread to continue. 
    allDone.Set(); 

    // Get the socket that handles the client request. 
    Socket listener = (Socket)ar.AsyncState; 
    Socket handler = listener.EndAccept(ar); 

    // Create the state object. 
    StateObject state = new StateObject(); 
    state.workSocket = handler; 
    handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, 
     new AsyncCallback(ReadCallback), state); 
} 

public static void ReadCallback(IAsyncResult ar) 
{ 
    String content = String.Empty; 

    // Retrieve the state object and the handler socket 
    // from the asynchronous state object. 
    StateObject state = (StateObject)ar.AsyncState; 
    Socket handler = state.workSocket; 

    // Read data from the client socket. 
    int bytesRead = handler.EndReceive(ar); 

    if (bytesRead > 0) 
    { 
     // There might be more data, so store the data received so far. 
     state.sb.Append(Encoding.ASCII.GetString(
      state.buffer, 0, bytesRead)); 

     // Check for end-of-file tag. If it is not there, read 
     // more data. 
     content = state.sb.ToString(); 
     if (content.IndexOf("<EOF>") > -1) 
     { 
      // All the data has been read from the 
      // client. Display it on the console. 
      Console.WriteLine("Read {0} bytes from socket. \n Data : {1}", 
       content.Length, content); 
      // Echo the data back to the client. 
      Send(handler, content); 
     } 
     else 
     { 
      // Not all data received. Get more. 
      handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, 
      new AsyncCallback(ReadCallback), state); 
     } 
    } 
} 

private static void Send(Socket handler, String data) 
{ 
    // Convert the string data to byte data using ASCII encoding. 
    byte[] byteData = Encoding.ASCII.GetBytes(data); 

    // Begin sending the data to the remote device. 
    handler.BeginSend(byteData, 0, byteData.Length, 0, 
     new AsyncCallback(SendCallback), handler); 
} 

private static void SendCallback(IAsyncResult ar) 
{ 
    try 
    { 
     // Retrieve the socket from the state object. 
     Socket handler = (Socket)ar.AsyncState; 

     // Complete sending the data to the remote device. 
     int bytesSent = handler.EndSend(ar); 
     Console.WriteLine("Sent {0} bytes to client.", bytesSent); 

     handler.Shutdown(SocketShutdown.Both); 
     handler.Close(); 

    } 
    catch (Exception e) 
    { 
     Console.WriteLine(e.ToString()); 
    } 
} 


public static int Main(String[] args) 
{ 
    StartListening(); 
    return 0; 
} 
} 

Answer 1

变化

IPAddress ipAddress = ipHostInfo.AddressList[0]; 

到

IPAddress ipAddress = IPAddress.Any; 

在StartListening方法....