getting Socket Exception 10054 when trying to socket.Connect

Question

1- I have a GHIElectronics FEZ Spider 3 device

2- I have connected the device to my laptop via an Ethernet cable and configured the network settings

3- I can ping the FEZ device from my laptop using cmd : ping 172.16.43.193

4- I have wriiten a windows forms application to run on my laptop and act as a TCP Receiver

5- I want to send TCP Packets from FEZ device to the win app on my laptop

the following is the win app code :

            string[] dnsAddresses = { "172.16.40.2", "172.16.40.5" };
        const Int32 c_port = 12250;
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            try
            {
                System.Threading.Thread t = new Thread(new ThreadStart(SendTCPMessage));
                txtStatus.Text = txtStatus.Text + "TCP listening established successfully\r\n";
            }
            catch (Exception ex)
            {
                txtStatus.Text = txtStatus.Text + "An error occured while trying to establish TCP listening : \r\n" + ex.Message + "\r\n";
                if (ex.InnerException != null)
                    txtStatus.Text = txtStatus.Text + ex.InnerException + "\r\n";
            }
        }

        private void SendTCPMessage()
        {

            Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, c_port);
            server.Bind(localEndPoint);
            server.Listen(1);
            while (true)
            {
                // Wait for a client to connect.
                Socket clientSocket = server.Accept();
                // Process the client request. true means asynchronous.
                new ProcessClientRequest(clientSocket, true);
            }
        }

internal sealed class ProcessClientRequest
        {

            private Socket m_clientSocket;
            /// <summary>
            /// The constructor calls another method to handle the request, but can
            /// optionally do so in a new thread.
            /// </summary>
            /// /// <param name="clientSocket"></param>
            /// <param name="asynchronously"></param>
            public ProcessClientRequest(Socket clientSocket, Boolean asynchronously)
            {
                m_clientSocket = clientSocket;
                if (asynchronously)
                    // Spawn a new thread to handle the request.
                    new Thread(ProcessRequest).Start();
                else ProcessRequest();
            }
            /// <summary>
            /// Processes the request.
            /// </summary>

            private void ProcessRequest()
            {
                const Int32 c_microsecondsPerSecond = 1000000;
                // 'using' ensures that the client's socket gets closed.
                using (m_clientSocket)
                {
                    // Wait for the client request to start to arrive.
                    Byte[] buffer = new Byte[1024];
                    if (m_clientSocket.Poll(5 * c_microsecondsPerSecond,
                    SelectMode.SelectRead))
                    {
                        // If 0 bytes in buffer, then the connection has been closed,
                        // reset, or terminated.
                        if (m_clientSocket.Available == 0)
                            return;
                        // Read the first chunk of the request (we don't actually do
                        // anything with it).
                        Int32 bytesRead = m_clientSocket.Receive(buffer,
                        m_clientSocket.Available, SocketFlags.None);
                        String result = "";
                        string FileContent = new string(Encoding.UTF8.GetChars(buffer));
                        MessageBox.Show("Text file with following content received :\r\n" + FileContent);
                        if (SaveFile(FileContent))
                        {
                            result = "1";
                        }
                        else
                        {
                            result = "0";
                        }

                        // Return a static string to the client.        
                        byte[] buf = Encoding.UTF8.GetBytes(result);
                        int offset = 0;
                        int ret = 0;
                        int len = buf.Length;
                        while (len > 0)
                        {
                            ret = m_clientSocket.Send(buf, offset, len, SocketFlags.None);
                            len -= ret;
                            offset += ret;
                        }
                        m_clientSocket.Close();
                    }
                }
            }

            private bool SaveFile(string FileContent)
            {
                bool returnValue = false;
                try
                {
                    string RootSaveDirectory = ConfigurationManager.AppSettings["FileSaveRootDirectory"].ToString();
                    string SaveDirectoryName = DateTime.Now.Year.ToString() + "." + DateTime.Now.Month.ToString() + "." + DateTime.Now.Day.ToString() + "   " + DateTime.Now.Hour.ToString() + "." + DateTime.Now.Minute.ToString() + "." + DateTime.Now.Second.ToString() + "." + DateTime.Now.Millisecond.ToString();
                    string SaveDirectory = Path.Combine(RootSaveDirectory, SaveDirectoryName);
                    if (!Directory.Exists(SaveDirectory))
                    {
                        Directory.CreateDirectory(SaveDirectory);
                    }
                    string FileName = ConfigurationManager.AppSettings["FileName"].ToString();
                    File.WriteAllText(Path.Combine(SaveDirectory, FileName), FileContent);
                    returnValue = true;
                }
                catch { }
                return returnValue;
            }
        }

and the following is the code which I use on the FEZ device to send TCP Packets to the win app on my laptop :

public bool SendFile()
    {
        bool returnValue = false;
        try
        {
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPAddress ServerIP = new IPAddress(new byte[] { 172, 16, 43, 193 });
            IPEndPoint ServerEndPoint = new IPEndPoint(ServerIP, 12250);
            byte[] buf = Encoding.UTF8.GetBytes(FileContentText);
            socket.Connect(ServerEndPoint);
            socket.Send(buf);
            if (socket.Poll(5 * 1000000, SelectMode.SelectRead)) // wait for data from the server
            {
                byte[] inbuf = new byte[socket.Available];
                socket.Receive(inbuf);
                //string m = new string(Encoding.UTF8.GetChars(inbuf));

            }
            socket.Close();
        }
        catch (SocketException ex)
        {
            string s = ex.Message;
            if (ex.InnerException != null)
                s = s + ex.InnerException.Message;
            if (ex.StackTrace != null)
                s = s + ex.StackTrace;
        }
        return returnValue;
    }

The issue is that on FEZ device when I try to send tcp packets at the following line of code

socket.Connect(ServerEndPoint);

A SocketException with the following Id is thrown :

10054

Answer 1

I got what the issue was !

in the

page_load

event after :

System.Threading.Thread t = new Thread(new ThreadStart(SendTCPMessage));

I have forgotten to write :

t.Start();

Answer 2

I assume in your case socket.Poll() immediately returns false before the data has arrived, closing the socket when it leaves the scope of the using block.

If my assumption is correct, I would rewrite the ProcessRequest method - skip the Poll() and the Socket.Available check, and just use socket.Receive().

socket.Receive() will block (your worker thread) until it receives response, and returns 0 if the remote party has disconnected.

Something like:

using (m_clientSocket)
{
    int bytes;
    while ((bytes = m_clientSocket.Receive(...)) > 0)
    {
        // process "bytes" bytes from the buffer
    }

    // other side has disconnected
}

And don't forget to catch SocketExceptions in that routine.