Question

So I’m trying to make a client for my server in C#, that accepts messages as commands so I can control the client remotely. I’ve had problem after problem with my masterServer.Connect taking FOREVER to load, and almost every time I close my application I have to wait 10 seconds for it to completely stop. I’ve tried EVERYTHING to stop this… no luck. So i’ve given up on that, and now to fix another issue i’m using a masterServer = new TcpClient() which seems to work pretty well inside the CreateConnection() thread. But when the thread is done, I call the SendClientInfo() somewhere down the line and it results in this runtime error:

Cannot access a disposed object, System.Net.Sockets.TcpClient

So i’ve tried my best to figure out a way from saving the object before it disposes or anything but I just can’t find out how to do it. So here are my questions:

1. How do I prevent the mainServer = new TcpClient() from disposing so I can use that on my SendClientInfo()?
2. Can ANYONE rework my CreateConnection() method so I can see how to do that correct? I’ve rewrote that thing a thousand times, and still it looks extremely buggy and the masterServer.connect() takes FOREVER to do if it hasn’t connected to a server yet.
3. Any other changes or fixes you can see here. I’ve been in and out this for hours and hours just trying to teach myself how to use Sockets by reading like a hundred tutorials. Anything you show me that i’m doing wrong I will always remember and do it correctly next time.

Let me know if you need anymore information… I really appreciate it.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;

namespace RemoteClient
{
    public partial class Form1 : Form
    {
        private int MyPort = 56789;
        private IPAddress myIp = IPAddress.Parse("210.232.115.79");
        private IPAddress serverIp = IPAddress.Parse("72.216.18.77"); // Master Server's IP Address
        public static TcpClient masterServer = new TcpClient();

        private StreamWriter responseWriter;
        private StreamReader commandReader;

        private Thread connectionThread;
        private Thread commandsThread;

        private bool RequestExitConnectionThread { get; set; }

        private delegate void AddMessageDelegate(string message, int category);
        private delegate void ConnectedDelegate();

        private bool isConnected { get; set; }

        public Form1()
        {
            InitializeComponent();
            isConnected = false;
        }

        private void LogMessage(string message, int category)
        {
            if (category == 1)
            {
                ListViewItem item = new ListViewItem(message);
                item.BackColor = Color.LightGreen;
                item.UseItemStyleForSubItems = true;
                Log.Items.Add(item).SubItems.Add(DateTime.Now.ToString());
            }
            if (category == 2)
            {
                ListViewItem item = new ListViewItem(message);
                item.BackColor = Color.Orange;
                item.UseItemStyleForSubItems = true;
                Log.Items.Add(item).SubItems.Add(DateTime.Now.ToString());
            }
            if (category == 3)
            {
                ListViewItem item = new ListViewItem(message);
                item.BackColor = Color.Yellow;
                item.UseItemStyleForSubItems = true;
                Log.Items.Add(item).SubItems.Add(DateTime.Now.ToString());
            }
            if (category == 0)
            {
                Log.Items.Add(message).SubItems.Add(DateTime.Now.ToString());
            }
        }

        private void Connected()
        {
            LogMessage("Found and Accepted Master Server's connection. Waiting for reply...",1);
            Status.Text = "Connected!";
            Status.ForeColor = Color.Green;

            commandsThread = new Thread(new ThreadStart(RecieveCommands));

            sendClientInfo();
        }

        private void exitButton_Click(object sender, EventArgs e)
        {
            Disconnect();
            exitButton.Enabled = false;
            exitButton.Text = "Closing...";

            if (connectionThread != null)
            {
                while (connectionThread.IsAlive)
                {
                    Application.DoEvents();
                }
            }

            this.Close();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Connect();
        }

        private void Disconnect()
        {
            RequestExitConnectionThread = true;

            if (masterServer != null)
                masterServer.Close();

            if (connectionThread != null)
                connectionThread.Abort();

            LogMessage("Closing Client. Please wait while Program threads end.", 2);
        }

        private void Disconnected()
        {
            Status.Text = "Disconnected";
            Status.ForeColor = Color.Red;
            Connect();
        }

        private void Connect()
        {
            LogMessage("Attempting to connect to Master Server...", 1);

            connectionThread = new Thread(new ThreadStart(CreateConnection));
            connectionThread.Start();
        }

        private void CreateConnection()
        {
            int i = 1;
            bool success = false;

            while (!success)
            {
                try
                {
                    using (masterServer = new TcpClient())
                    {
                        IAsyncResult result = masterServer.BeginConnect(serverIp, MyPort, null, null);
                        success = result.AsyncWaitHandle.WaitOne(1000, false);
                    }

                    if (success)
                    {
                        BeginInvoke(new ConnectedDelegate(this.Connected), new object[] {});
                        break;
                    }
                    else
                    {
                        Thread.Sleep(2000);
                        BeginInvoke(new AddMessageDelegate(LogMessage), new object[] { "Connection Retry # " + i.ToString() + ". Master Server hasn't been started yet.", 3 });
                    }
                }
                catch
                {
                    MessageBox.Show("Error!");
                }
                i++;
            }

        }

        private void RecieveCommands()
        {
            MessageBox.Show("Hello!");
            commandReader = new StreamReader(masterServer.GetStream());

            string CommandResponse = commandReader.ReadLine();
            string Command = null;

            if (CommandResponse != null)
                MessageBox.Show("Recieved Command that was NOT null!");

            if (CommandResponse != null)
            {
                MessageBox.Show("Recieved null response!");
                BeginInvoke(new AddMessageDelegate(LogMessage), new object[] { "Disconnected From Master Server. Reason: Recieved Null response.", 1 });
                Disconnected();
            }
            else if (CommandResponse.StartsWith("0"))
            {
                MessageBox.Show("Recieved 0 as a response!");
                Command = CommandResponse.Substring(2).Trim();

                isConnected = false;
                BeginInvoke(new AddMessageDelegate(LogMessage), new object[] { "Disconnected From Master Server. Reason: " + Command, 1 });
            }
            else if (CommandResponse.StartsWith("1"))
            {
                MessageBox.Show("Recieved 1 as a response!");
                isConnected = true;
                BeginInvoke(new AddMessageDelegate(LogMessage), new object[] { "Connected to Master Server Successfully.", 1 });
            }
        }


        //************************** RESPONSE'S BELOW HERE ************************* \\

        private void sendClientInfo()
        {
            responseWriter = new StreamWriter(masterServer.GetStream());

            responseWriter.WriteLine(myIp.ToString());
            responseWriter.Flush();
        }

    }
}

Answer 1

In this case you should not be using a using block. In fact, unless there are some wild scenarios that don’t come to mind, never use a using block on a variable that is declared outside of that scope. The using block calls the Dispose() method at the completion of the block, which is why your server is being disposed. Just change your code to remove the block and you should be all set. Like this:

masterServer = new TcpClient();

IAsyncResult result = masterServer.BeginConnect(serverIp, MyPort, null, null);
success = result.AsyncWaitHandle.WaitOne(1000, false);