IMClientbyTCPinLAN

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

namespace IMClientbyTCPinLAN
{
    public partial class Form1 : Form
    {
        TcpClient tcpClient;
        private NetworkStream Stream;
        private static string CLOSED = "closed";
        private static string CONNECTED = "connected";
        private string state = CLOSED;
        private bool stopFlag;

        AesCryptoServiceProvider myAes;

        public Form1()
        {
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;
            txtHost.Text = getIPAddress();
            txtPort.Text = "9988";

            try
            {

                // Create a new instance of the AesCryptoServiceProvider class.
                // This generates a new key and initialization vector (IV).
                myAes = new AesCryptoServiceProvider();
                MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
                SHA256CryptoServiceProvider sha256 = new SHA256CryptoServiceProvider();
                myAes.Key = sha256.ComputeHash(Encoding.UTF8.GetBytes("Copyright(R) xiesir@gmail.com, 2015-2018, ;-)"));
                myAes.IV = md5.ComputeHash(Encoding.UTF8.GetBytes("Copyright 2015-2018"));
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }

        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            if (state == CONNECTED)
                return;

            if (txtUserName.Text.Length == 0)
            {
                MessageBox.Show("请输入您的呢称！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                txtUserName.Focus();
                return;
            }

            try
            {
                tcpClient = new TcpClient();
                tcpClient.Connect(IPAddress.Parse(txtHost.Text), Int32.Parse(txtPort.Text));
                Stream = tcpClient.GetStream();

                string cmd = "CONN|" + txtUserName.Text + "|";
                // Non-Encrypt
                byte[] outbytes = Encoding.Default.GetBytes(cmd.ToCharArray());
                // Encrypt
                //byte[] outbytes = EncryptStringToBytes_Aes(cmd, myAes.Key, myAes.IV);
                Stream.Write(outbytes, 0, outbytes.Length);

                Thread thread = new Thread(new ThreadStart(ServerResponse));
                thread.Start();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            if (state == CONNECTED)
            {
                string message = "EXIT|" + txtUserName.Text + "|";

                // Non-Encrypt
                Byte[] outbytes = Encoding.Default.GetBytes(message.ToCharArray());
                // Encrypt
                //byte[] outbytes = EncryptStringToBytes_Aes(message, myAes.Key, myAes.IV);
                Stream.Write(outbytes, 0, outbytes.Length);
                state = CLOSED;
                stopFlag = true;
                lstUsers.Items.Clear();
            }
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            try
            {
                if (!cbPrivate.Checked)
                {
                    string message = "CHAT|" + txtUserName.Text + ":" + this.tbSendContent.Text + "|";
                    this.tbSendContent.Text = "";
                    this.tbSendContent.Focus();

                    // Non-Encrypt
                    Byte[] outbytes = Encoding.Default.GetBytes(message.ToCharArray());
                    // Encrypt
                    //byte[] outbytes = EncryptStringToBytes_Aes(message, myAes.Key, myAes.IV);
                    Stream.Write(outbytes, 0, outbytes.Length);
                }
                else
                {
                    if (lstUsers.SelectedIndex == -1)
                    {
                        MessageBox.Show("请在列表中选择一个用户", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                        return;
                    }
                    string receiver = lstUsers.SelectedItem.ToString();
                    string message = "PRIV|" + txtUserName.Text + "|" + receiver + "|" + this.tbSendContent.Text + "|";
                    tbSendContent.Text = "";
                    tbSendContent.Focus();

                    // Non-Encrypt
                    byte[] outbytes = Encoding.Default.GetBytes(message.ToCharArray());
                    // Encrypt
                    //byte[] outbytes = EncryptStringToBytes_Aes(message, myAes.Key, myAes.IV);
                    Stream.Write(outbytes, 0, outbytes.Length);
                }
            }
            catch
            {
                tbMsg.AppendText("网络发生错误");
            }
        }

        private void ServerResponse()
        {
            byte[] buff = new byte[1024];
            string msg;
            int len;
            try
            {
                if (!Stream.CanRead)
                    return;

                stopFlag = false;
                while (!stopFlag)
                {
                    len = Stream.Read(buff, 0, buff.Length);
                    if (len < 1)
                    {
                        Thread.Sleep(200);
                        continue;
                    }

                    // Non-Decrypt
                    msg = Encoding.Default.GetString(buff, 0, len);
                    // Decrypt
                    //msg = DecryptStringFromBytes_Aes(buff, myAes.Key, myAes.IV);
                    msg.Trim();
                    string[] tokens = msg.Split(new Char[] { '|' });
                    //tokens[0]中保存了命令标志符（LIST或JOIN或QUIT）
                    if (tokens[0].ToUpper() == "OK")
                        add("成功进入");
                    else if (tokens[0].ToUpper() == "ERR")
                        add("命令执行错误：" + tokens[1]);
                    else if (tokens[0] == "LIST")
                    {
                        lstUsers.Items.Clear();
                        for (int i = 1; i < tokens.Length - 1; i++)
                            lstUsers.Items.Add(tokens[i].Trim());
                    }
                    else if (tokens[0] == "JOIN")
                    {
                        add("用户: " + tokens[1] + " 进入聊天室");
                        lstUsers.Items.Add(tokens[1]);
                        if (txtUserName.Text == tokens[1])
                            state = CONNECTED;
                    }
                    else if (tokens[0] == "QUIT")
                    {
                        if (lstUsers.Items.IndexOf(tokens[1]) > -1)
                            lstUsers.Items.Remove(tokens[1]);
                        add("用户： " + tokens[1] + " 已经离开");
                    }
                    else
                        add(msg);
                }
                //关闭连接
                tcpClient.Close();
            }
            catch
            {
                add("网络发生错误");
            }
        }

        delegate void addCallback(string text);
        private void add(string text)
        {
            if (tbMsg.InvokeRequired)
            {
                while (!tbMsg.IsHandleCreated)
                {
                    //解决窗体关闭时出现“访问已释放句柄“的异常
                    if (tbMsg.Disposing || tbMsg.IsDisposed)
                        return;
                }
                addCallback d = new addCallback(add);
                tbMsg.Invoke(d, new object[] { text });
            }
            else
            {
                tbMsg.AppendText(text + Environment.NewLine);
            }
        }

        private string getIPAddress()
        {
            //获得本机局域网IP地址
            IPAddress ip = null;
            IPAddress[] AddressList = Dns.GetHostEntry(Dns.GetHostName()).AddressList;
            if (AddressList.Length < 1)
                return "";
            for (int i = 0; i < AddressList.Length; i++)
                if (AddressList[i].AddressFamily == AddressFamily.InterNetwork)     // 获取 IPv4 地址
                {
                    ip = AddressList[i];
                    break;
                }
            return ip.ToString();
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            try
            {
                btnExit_Click(sender, e);
            }
            catch (Exception)
            {
                Application.Exit();
            }
        }

        static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("Key");
            byte[] encrypted;
            // Create an AesCryptoServiceProvider object
            // with the specified key and IV.
            using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                            swEncrypt.Flush();
                        }
                        encrypted = msEncrypt.ToArray();
                    }
                }
            }

            // Return the encrypted bytes from the memory stream.
            return encrypted;
        }

        static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");

            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;

            // Create an AesCryptoServiceProvider object
            // with the specified key and IV.
            using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for decryption.
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }

            }

            return plaintext;
        }

    }
}

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