c# - 接收对 UDP 广播的应答 (C#)

Question

我正在尝试发送一个 udp 广播，并在 c# 中接收一个答案。虽然发送广播效果很好，但我在 c# 中没有收到任何答复。但是当我用 wireshark 查看时，我可以看到已经发送了一个答案:

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(这就是答案)

Wireshark 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

那是我的 C# 代码:

    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 );
        }
    }

程序在调用 udpClient.Receive 时停止。谁能帮我吗？ :)

Answer 1

由于您使用相同的进程来发送和接收，因此您需要在发送消息之前打开接收器，并且您需要使用 udpClient.ReceiveAsync() 并在允许您的程序关闭之前等待应答.