如何识别和区分客户端-服务器套接字应用程序中连接的客户端？

Question

In the scenario where there is a SINGLE asynchronous socket server, and n-number of clients connected, on the server side how can I differentiate the clients? I need to know which client the data is coming from. Note - It may not be possible to append an identifier to requests.

Clients are created at runtime:

public void CreateSockets()
        {
             Parallel.For(1, Convert.ToInt32(numericUpDown1.Value) + 1, i =>
            {
                new Thread(() => Connect(i)).Start();
            });
        }

Abbreviated client creation loop:

public void Connect(int i)
{
    ClientSocket[i] = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

        try
        {
            ClientSocket[i].Connect(ip, port);
        }
        catch (SocketException sex)
        {
            Console.WriteLine(sex);
        }

     RequestLoop();
}

The sockets are being created, connect, and are sending data to the server. The server is directly from the MS site examples of Asynchronous Socket Server.

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
{
    // 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();

    // Client socket.
    public Socket workSocket = null;
}  
  
public class AsynchronousSocketListener
{
    // Thread signal.  
    public static ManualResetEvent allDone = new ManualResetEvent(false);

    public AsynchronousSocketListener()
    {
    }

    public static void StartListening()
    {
        // Establish the local endpoint for the socket.  
        // The DNS name of the computer  
        // running the listener is "host.contoso.com".  
        IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());  
        IPAddress ipAddress = ipHostInfo.AddressList[0];  
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);  
  
        // Create a TCP/IP socket.  
        Socket listener = new Socket(ipAddress.AddressFamily,  
            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

The combination of srcip:srcport:dstip:dstport is a unique value.

Use that Value to identify your client. When a client connects, have the client send an identifier. Maintain state in your server mapping that combination to your client.

You will never have two identical values of this on any socket on your.network. (Except in the case of private.networks with identical ip addresses).