C＃UDP服务器与客户端对话

Question

I've tried multiple methods of doing this, and non seem to work out. But there must be a way.

What I'm trying to do (in C#) is create a server. I want the server to listen on a IP and port, and when it connects to a client, I want it to read what the client says, and send a reply. For the client, I want to connect to a server and send data, and receive the reply from the server.

How can I go about doing this?

I've used Microsoft examples and examples found on MSDN. They have Client > data > Server but it doesn't ever seem to include the server reply.

I know this can be done, obviously, because we have multiplayer games.

Thanks for the help.

EDIT - Code snippets

SERVER

 static void Main(string[] args) { int recv; byte[] data = new byte[1024]; IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, 904); Socket newSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); newSocket.Bind(endPoint); Console.WriteLine("Listening for connections..."); //LISTEN FOR CLIENT IPEndPoint sender = new IPEndPoint(IPAddress.Any, 904); EndPoint tmpRemote = (EndPoint)sender; //READ MESSAGE FROM CLIENT recv = newSocket.ReceiveFrom(data, ref tmpRemote); Console.WriteLine("Messaged received from: " + tmpRemote.ToString()); Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv)); string welcome = "Welcome to server!"; data = Encoding.ASCII.GetBytes(welcome); //SEND WELCOME REPLY TO CLIENT Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); sock.Bind(tmpRemote); sock.SendTo(data, tmpRemote); Console.WriteLine("Reply sent to client"); while (true) { if(!newSocket.Connected) { Console.WriteLine("Client disconnected."); break; } data = new byte[1024]; recv = newSocket.ReceiveFrom(data, ref tmpRemote); if (recv == 0) break; Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv)); } newSocket.Close(); Console.WriteLine("Server disconnected."); Console.ReadLine(); } } 

CLIENT

  static void Main(string[] args) { Console.WriteLine("Message [127.0.0.1:904]: "); string msg = Console.ReadLine(); byte[] packetData = ASCIIEncoding.ASCII.GetBytes(msg); string IP = "127.0.0.1"; int port = 904; IPEndPoint ep = new IPEndPoint(IPAddress.Parse(IP), port); Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); client.SendTo(packetData, ep); Console.WriteLine("Data sent!"); int recv; byte[] data = new byte[1024]; EndPoint tmpRemote = (EndPoint)ep; while(true) { //READ MESSAGE FROM SERVER recv = client.ReceiveFrom(data, ref tmpRemote); Console.WriteLine("Messaged received from: " + tmpRemote.ToString()); Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv)); } client.Close(); Console.WriteLine("Client disconnected."); Console.ReadLine(); } 

I can't get the server to talk back to the client and have the client read/display the server's reply.

Answer 1

change this sentence

sock.SendTo(data, tmpRemote);

to

newSocket.SendTo(data, tmpRemote);

and remove these sentences, you have bind local EndPoint twice.

Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
sock.Bind(tmpRemote);

In Net, you can use UdpClient instead of Socket .

If you want a demo, look at this demo .