请大家帮忙看看这个socket收发文件。

Question

请大家帮忙看看。
很多问题.比如关闭连接等。很多ERROR。        Socket m_ListenSocket = null;
        Socket m_SendSocket = null;
        Socket socket = null;
        Thread thread = null;
        delegate void UIHandler(string msg);
        public frmComm()
        {
            InitializeComponent();
        }
        private void frmComm_Load(object sender, EventArgs e)
        {
            btnClose.Enabled = false;
            IPAddress[] ips = Dns.GetHostAddresses(Dns.GetHostName());
            foreach (IPAddress ip in ips)
            {
                if (ip.AddressFamily != AddressFamily.InterNetworkV6)
                {
                    txtLocalIP.Text = ip.ToString();
                    break;
                }
            }
        }
//display 略。
        private void btnBrowse_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter = "Text File|*.txt";
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                txtFile.Text = openFileDialog.FileName;
            }
        }
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (txtFile.Text == "")
            {
                MessageBox.Show("Please click \"Browse\" to select a file ...", "Information");
                return;
            }
            if (m_SendSocket == null || !m_SendSocket.Connected)
            {
                MessageBox.Show("Please Connect First ...", "Information");
                return;
            }
            string file = txtFile.Text;
            if (File.Exists(file))
            {
                string msg = File.ReadAllText(file, Encoding.Default);                byte[] buf = StringToByteArray(msg);
                if (buf != null)
                {
                    this.Invoke(new UIHandler(DisplayMe), msg);
                    SendMessage(buf);
                }
            }
            else
            {
                MessageBox.Show("File not exists ...", "Information");
            }
        }
        private byte[] StringToByteArray(string msg)
        {
            byte[] buf_msg = System.Text.UTF8Encoding.UTF8.GetBytes(msg);
            if (buf_msg.Length > 0xffff)
            {
                MessageBox.Show("Message Length : " + buf_msg.Length, "Information");
                return null;
            }
            byte[] buf = new byte[buf_msg.Length + 2];
            int index = 0;
            Array.Copy(BitConverter.GetBytes(buf_msg.Length), 0, buf, index, 2);
            index += 2;
            Array.Copy(buf_msg, 0, buf, index, buf_msg.Length);
            index += buf_msg.Length;            return buf;
        }
        private string ByteArrayToString(byte[] buf)
        {
            string msg = System.Text.UTF8Encoding.UTF8.GetString(buf);
            return msg;
        }
        private void SendMessage(byte[] buf)
        {
            if (m_SendSocket.Connected)
            {
                try
                {
                    m_SendSocket.Send(buf);
                }
                catch (Exception exp)
                {
                    MessageBox.Show(exp.Message);
                }
            }
            else
            {
                MessageBox.Show("Please connect first ...", "Information");
            }
        }
        private void btnConnect_Click(object sender, EventArgs e)
        {
            if (m_SendSocket != null && m_SendSocket.Connected)
            {
                MessageBox.Show("Already Connected!");
                return;
            }
            try
            {
                m_SendSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);            }
            catch (SocketException exp)
            {
                MessageBox.Show(exp.Message);
                return;
            }
            IPEndPoint ipep = GetIPEndPoint();
            try
            {
                m_SendSocket.Connect(ipep);
            }
            catch (Exception exp)
            {
                MessageBox.Show(exp.Message);
                return;
            }
            lblStatus.Text = "Connected!";
        }
        private void ReceiveMsg()
        {
            int receiveIndex = 0;
            int processIndex = 0;
            byte[] buf = new byte[4096];
            int len = 0;            try
            {
                lock(m_ListenSocket)
                    socket = m_ListenSocket.Accept();
            }
            catch
            {
                return;
            }
            if (socket == null)
            {
                return;
            }
            while (socket != null && socket.Connected)
            {
                try
                {                    len = socket.Receive(buf, receiveIndex, buf.Length - receiveIndex, SocketFlags.None);
                    if (len == 0)
                    {
                        MessageBox.Show("Disconnected by remote client.");
                        DisconnectSocket();
                        return;
                    }
                    receiveIndex += len;
                    if (receiveIndex - processIndex > 2)
                    {
                        len = BitConverter.ToUInt16(buf, processIndex);                        while (receiveIndex - processIndex >= len + 2)
                        {
                            byte[] buf_msg = new byte[len];
                            Array.Copy(buf, processIndex + 2, buf_msg, 0, len);
                            string msg = ByteArrayToString(buf_msg);
                            //rtbMsg.AppendText(msg);
                            this.Invoke(new UIHandler(Display), msg);                            processIndex += buf_msg.Length + 2;
                            if (!(receiveIndex - processIndex > 2))
                            {
                                break;
                            }
                            len = BitConverter.ToUInt16(buf, processIndex);
                        }
                        Array.Copy(buf, processIndex, buf, 0, receiveIndex - processIndex);
                        receiveIndex -= processIndex;
                        processIndex = 0;
                    }
                }
                catch (SocketException ex)
                {
                    MessageBox.Show("Disconnected");
                    DisconnectSocket();
                    this.Invoke(new Action<object>(EnableListenButton), new object[] { null });
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString(), "", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                finally
                {                }            }
        }
        private void DisconnectSocket()
        {
            if (socket != null && socket.Connected)
            {
                socket.Disconnect(false);
                socket.Shutdown(SocketShutdown.Both);
                socket.Close();
            }
        }
        private void EnableListenButton(object obj)
        {
            btnListen.Enabled = true;
        }
        private IPEndPoint GetIPEndPoint()
        {
            IPAddress ipAdd = null;
            bool success = IPAddress.TryParse(txtConnectIP.Text, out ipAdd);
            if (!success)
            {
                ipAdd = null;
                MessageBox.Show("Invalid IP Address ...", "Information");
                return null;
            }
            int port;
            success = int.TryParse(txtConnectPort.Text, out port);
            if (!success)
            {
                port = -1;
                MessageBox.Show("Invalid Port number ...", "Information");
                return null;
            }
            try
            {
                return new IPEndPoint(ipAdd, port);
            }
            catch (ArgumentOutOfRangeException exp)
            {
                MessageBox.Show(exp.Message);
                return null;
            }
        }
        private void btnListen_Click(object sender, EventArgs e)
        {
            int port;
            bool success = int.TryParse(txtListenPort.Text, out port);
            if (!success)
            {
                MessageBox.Show("Invalid Listening Post number ...", "Information");
                return;
            }
            try
            {
                m_ListenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                m_ListenSocket.Bind(new IPEndPoint(IPAddress.Any, port));
                m_ListenSocket.Listen(10);
            }
            catch (Exception exp)
            {
                MessageBox.Show(exp.Message);
            }
            thread = new Thread(new ThreadStart(ReceiveMsg));
            thread.Start();
            lblStatus.Text = "Start Listening";
            btnListen.Enabled = false;
            btnClose.Enabled = true;
        }
        private void btnClear_Click(object sender, EventArgs e)
        {
            rtbMsg.Clear();
        }
        private void btnClose_Click(object sender, EventArgs e)
        {
            DisconnectSocket();
            m_ListenSocket.Close();
            //thread.Abort();
            btnClose.Enabled = false;
            btnListen.Enabled = true;
        }
        private void frmComm_FormClosed(object sender, FormClosedEventArgs e)
        {
            Environment.Exit(0);
        }