Server Connection C# - System.Net.SocketException(10022)

Question

Hi I want create a server connection between two computers with C#.
Here is the source code I've tried:

  Socket sks;  
        EndPoint epLocal, epRemote;  
        byte[] buffer;  
  
        private void Form2_Load(object sender, EventArgs e)  
        {  
            sks = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);  
  
            sks.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);  
            textLocalIp.Text = GetLocalIP();  
  
            textFriendsIp.Text = GetLocalIP();  
        }  
        private string GetLocalIP()  
  
        {  
  
            IPHostEntry host;  
  
            host = Dns.GetHostEntry(Dns.GetHostName());  
  
            foreach (IPAddress ip in host.AddressList)  
  
            {  
  
                if (ip.AddressFamily == AddressFamily.InterNetwork)  
  
                {  
  
                    return ip.ToString();  
  
                }  
  
            }  
  
            return "127.0.0.1";  
  
        }  
  
        private void button2_Click(object sender, EventArgs e)  
        {  
            try  
  
            { // binding socket  
  
                epLocal = new IPEndPoint(IPAddress.Parse(textLocalIp.Text), Convert.ToInt32(textLocalPort.Text));  
  
                sks.Bind(epLocal);  
  
  
  
                // connect to remote IP and port  
  
                epRemote = new IPEndPoint(IPAddress.Parse(textFriendsIp.Text), Convert.ToInt32(textFriendsPort.Text));  
  
                sks.Connect(epRemote);  
                buffer = new byte[1500];  
  
                sks.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new  
                AsyncCallback(MessageCallBack), buffer);  
  
  
  
                // release button to send message  
  
  
                button2.Text = "Connected";  
  
  
  
  
            }  
            catch (Exception ex)  
  
            {  
  
                MessageBox.Show(ex.ToString());  
  
            }  
        }  
  
        private void button1_Click(object sender, EventArgs e)  
        {  
            textBox5.Text = "Rock";  
            try  
  
            { // converts from string to byte[]  
  
                System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();  
  
                byte[] msg = new byte[1500];  
  
                msg = enc.GetBytes(textBox5.Text);  
  
  
  
                // sending the message  
  
                sks.Send(msg);  
  
  
  
                // add to listbox  
  
                listBox1.Items.Add("You:+ " + textBox5.Text);  
  
  
  
                // clear txtMessage  
  
                textBox5.Clear();  
  
            }  
  
            catch (Exception ex)  
  
            {  
  
                MessageBox.Show(ex.ToString());  
  
            }  
        }  
 private void MessageCallBack(IAsyncResult aResult)  
        {  
  
          
            try  
  
            {  
  
                int size = sks.EndReceiveFrom(aResult, ref epRemote);  
  
  
  
                // check if theres actually information if (size > 0) { // used to help us on getting the data  
  
                byte[] receivedData = new byte[1464];  
  
  
  
                // getting the message data  
  
                receivedData = (byte[])aResult.AsyncState;  
  
  
  
                // converts message data byte array to string  
  
                ASCIIEncoding eEncoding = new ASCIIEncoding();  
  
                string receivedMessage = eEncoding.GetString(receivedData);  
  
  
  
                // adding Message to the listbox  
  
                listBox1.Items.Add("Friend: " + receivedMessage);  
  
            }  
            catch (Exception exp)  
  
            {  
  
                MessageBox.Show(exp.ToString());  
  
            }  
  
  
            // starts to listen the socket again  
  
            buffer = new byte[1500];  
  
            sks.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new AsyncCallback(MessageCallBack), buffer);  
  
          
  
  
}  
    }  

But when I try this out entering my IP and port and the other device's IP and port, it throws this exception::

Answer 1

Hi HemanthB-9452,
You are binding same socket to mutiple Endpoint objects , that's why you are getting an InvalidArgument exception.
You need to connect to remote IP and port on client side and bind socket on server side.
Here is a code example about how to create a client application that will send message to the listener server and read it.
Client:

static void Main(string[] args)  
{  
    StartClient();  
              
}  
public static void StartClient()  
{  
    byte[] bytes = new byte[1024];  
  
    try  
    {  
        // Connect to a Remote server    
        // Get Host IP Address that is used to establish a connection    
        // If a host has multiple addresses, you will get a list of addresses    
        IPHostEntry host = Dns.GetHostEntry("localhost");  
        IPAddress ipAddress = host.AddressList[0];  
        IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);  
  
        // Create a TCP/IP  socket.      
        Socket sender = new Socket(ipAddress.AddressFamily,  
            SocketType.Stream, ProtocolType.Tcp);  
  
        // Connect the socket to the remote endpoint. Catch any errors.      
        try  
        {  
            // Connect to Remote EndPoint    
            sender.Connect(remoteEP);  
  
            Console.WriteLine("Socket connected to {0}",  
                sender.RemoteEndPoint.ToString());  
  
            // Encode the data string into a byte array.      
            byte[] msg = Encoding.ASCII.GetBytes("This is a test<EOF>");  
  
            // Send the data through the socket.      
            int bytesSent = sender.Send(msg);  
  
            // Receive the response from the remote device.      
            int bytesRec = sender.Receive(bytes);  
            Console.WriteLine("Echoed test = {0}",  
                Encoding.ASCII.GetString(bytes, 0, bytesRec));  
  
            // Release the socket.      
            sender.Shutdown(SocketShutdown.Both);  
            sender.Close();  
  
        }  
        catch (ArgumentNullException ane)  
        {  
            Console.WriteLine("ArgumentNullException : {0}", ane.ToString());  
        }  
        catch (SocketException se)  
        {  
            Console.WriteLine("SocketException : {0}", se.ToString());  
        }  
        catch (Exception e)  
        {  
            Console.WriteLine("Unexpected exception : {0}", e.ToString());  
        }  
  
    }  
    catch (Exception e)  
    {  
        Console.WriteLine(e.ToString());  
    }  
}  

Server:

static void Main(string[] args)  
{  
  
    StartServer();  
}  
public static void StartServer()  
{  
    // Get Host IP Address that is used to establish a connection    
    // If a host has multiple addresses, you will get a list of addresses    
    IPHostEntry host = Dns.GetHostEntry("localhost");  
    IPAddress ipAddress = host.AddressList[0];  
    IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);  
  
  
    try  
    {  
  
        // Create a Socket that will use Tcp protocol        
        Socket listener = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);  
        // A Socket must be associated with an endpoint using the Bind method    
        listener.Bind(localEndPoint);  
        // Specify how many requests a Socket can listen before it gives Server busy response.    
        // We will listen 10 requests at a time    
        listener.Listen(10);  
  
        Console.WriteLine("Waiting for a connection...");  
        Socket handler = listener.Accept();  
  
        // Incoming data from the client.      
        string data = null;  
        byte[] bytes = null;  
  
        while (true)  
        {  
            bytes = new byte[1024];  
            int bytesRec = handler.Receive(bytes);  
            data += Encoding.ASCII.GetString(bytes, 0, bytesRec);  
            if (data.IndexOf("<EOF>") > -1)  
            {  
                break;  
            }  
        }  
  
        Console.WriteLine("Text received : {0}", data);  
  
        byte[] msg = Encoding.ASCII.GetBytes(data);  
        handler.Send(msg);  
        handler.Shutdown(SocketShutdown.Both);  
        handler.Close();  
    }  
    catch (Exception e)  
    {  
        Console.WriteLine(e.ToString());  
    }  
  
    Console.WriteLine("\n Press any key to continue...");  
    Console.ReadKey();  
}  

Best Regards,
Daniel Zhang

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