接收UDP广播（C＃）的答案

Question

我试图发送一个udp广播，并在c＃中收到答案。虽然发送广播的作品完美，我没有收到任何答案在C＃中。但是，当我把使用Wireshark一看，我可以看到一个答案已发出：

1. 从192.168.0.141发送到192.168.0.255
2. 从192.168.0.105发送到255.255.255.255（这将是答案）

Wireshark的日志：

1 0.000000 192.168.0.141 192.168.0.255 UDP Source port: 55487 Destination port: 17784 
2 0.000851 192.168.0.105 255.255.255.255 UDP Source port: 17784 Destination port: 55487 

这就是我的C＃代码：调用udpClient.Receive时

private static byte[] SendBuffer = new byte[] { 1, 2, 3 }; 

    public static void SendAndReceiveBroadcast(byte[] data, IPEndPoint broadcastEndpoint) 
    { 

     using(Socket broadcastSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)) 
     { 
      broadcastSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1); 
      broadcastSocket.SendTo(data, broadcastEndpoint); 
      receivePort = broadcastSocket.LocalEndPoint.ToString().Split(':')[1]; 
      Console.WriteLine("Sent {0} from Port {1}", CollectionsHelper.ItemsToString(data, "{0:X2}"), broadcastSocket.LocalEndPoint.ToString()); 
      broadcastSocket.Close(); 
     } 

     using(Socket receiveSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp)) 
     { 
      IPEndPoint broadcastAddress = new IPEndPoint(IPAddress.Any, Convert.ToInt32(receivePort)); 
      UdpClient udpClient = new UdpClient(); 
      udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true); 
      udpClient.Client.Bind(broadcastAddress); 
      IPEndPoint remoteIP = new IPEndPoint(IPAddress.Any, Convert.ToInt32(receivePort)); 
      byte[] answer = udpClient.Receive(ref remoteIP); 
     } 
    } 

程序停止。任何人都可以帮助我吗？ :)

Answer 1

1. 您应该使用ReceiveFrom。 Receive用于TCP。
2. 如果我没有弄错，广播消息不排队。广播前拨打BeginReceiveFrom，之后拨打EndReceiveFrom。

Answer 2

由于您使用相同的过程发送和接收，您需要在发送消息之前打开接收器，并且您需要使用udpClient.ReceiveAsync（）并等待答案，然后再允许您的程序去关机。