NVNC/VncHost.cs

// NVNC - .NET VNC Server Library
// Copyright (C) 2014 T!T@N
//
// This file is a heavy modified version of RfbProtocol.cs from the 
// VncSharp project.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

using System;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Drawing;
using System.Collections.Generic;
using System.Net.Sockets;
using System.Security.Cryptography;
using NVNC.Encodings;
using NVNC.Readers;
using NVNC.Writers;
using NVNC.Utils;
using NVNC.Utils.ScreenTree;

namespace NVNC
{
    /// <summary>
    /// Contains methods and properties to handle all aspects of the RFB Protocol versions 3.3 - 3.8.
    /// </summary>
    public class VncHost
    {
        /// <summary>
        /// RFB Encoding constants.
        /// </summary>
        public enum Encoding
        {
            //encodings
            RawEncoding = 0,  //working
            CopyRectEncoding = 1,  //working
            RreEncoding = 2,  //working
            CoRreEncoding = 4,  //error
            HextileEncoding = 5,  //working
            ZrleEncoding = 16, //working

            //pseudo-encodings
            ZlibEncoding = 6, //working
        }
        /// <summary>
        /// Server to Client Message-Type constants.
        /// </summary>
        public enum ServerMessages
        {
            FramebufferUpdate = 0,
            SetColorMapEntries = 1,
            Bell = 2,
            ServerCutText = 3,
        }

        /// <summary>
        /// Client to Server Message-Type constants.
        /// </summary>
        public enum ClientMessages : byte
        {
            SetPixelFormat = 0,
            ReadColorMapEntries = 1,
            SetEncodings = 2,
            FramebufferUpdateRequest = 3,
            KeyEvent = 4,
            PointerEvent = 5,
            ClientCutText = 6,
        }

        //Version numbers
        protected int verMajor = 3;	// Major version of Protocol--probably 3
        protected int verMinor = 8;//8; // Minor version of Protocol--probably 3, 7, or 8

        //Shared flag
        public bool Shared { get; set; }

        public string CutText;

        public ScreenHandler screenHandler;
        //protected Socket localClient;		// Network object used to communicate with host
	protected TcpListener serverSocket;

	protected Stream stream;	// Stream object used to send/receive data
	protected BinaryReader reader;	// Integral rather than Byte values are typically
	protected BinaryWriter writer;	// sent and received, so these handle this.
	protected ZlibCompressedWriter zlibWriter; //The Zlib Stream Writer used for Zlib and ZRLE encodings

	public bool isRunning;

	//Port property
	//public int Port { get; set; }

	public string DisplayName;

/*
	private HashSet<Stream> clients = new HashSet<Stream>();
	public ICollection<Stream> Clients
	{
		get
		{
			return clients;
		}
	}
*/

	// Client supported encodings
	public uint[] Encodings { get; private set; }

	// Server preferred encoding
	private Encoding preferred_encoding = Encoding.ZrleEncoding;

	/// <summary>
	/// Gets the best encoding from the ones the client sent.
	/// </summary>
	/// <returns>Returns a enum representation of the encoding.</returns>
	public Encoding GetEncoding()
	{
		//TODO: If our preferred encoding is not found, use the best one the client sent
/*
		Encoding prefEnc = Encoding.ZrleEncoding;
		try
		{
*/
			for (int i = 0; i < Encodings.Length; i++) {
				if (((Encoding)Encodings[i]) == preferred_encoding) {
					return preferred_encoding;
				}
			}
			for (int i = 0; i < Encodings.Length; i++) {
				Encoding encoding = (Encoding)Encodings[i];
				if(Enum.IsDefined(typeof(Encoding), encoding)) {
					return encoding;
				}
			}
			//return null;
			throw new NotSupportedException("None of the client encodings are supported by server");
/*
		}
		catch
		{
			prefEnc = Encoding.ZlibEncoding;
		}
		return prefEnc;
*/
	}

	//public Encoding GetPreferredEncoding()

	public void SetPreferredEncoding(Encoding enc) {
		if(!Enum.IsDefined(typeof(Encoding), enc)) {
			throw new ArgumentException("invalid encoding");
		}
		preferred_encoding = enc;
	}

	public VncHost(String displayname, ScreenHandler sc)
	{
		DisplayName = displayname;
		screenHandler = sc;
	}

	/// <summary>
	/// Gets the Protocol Version of the remote VNC Host--probably 3.3, 3.7, or 3.8.
	/// </summary>
	/// <returns>Returns a float representation of the protocol version that the server is using.</returns>
	public float ServerVersion
	{
		get
		{
			return verMajor + (verMinor * 0.1f);
		}
	}

	public ZlibCompressedWriter ZlibWriter
	{
		get
		{
			return zlibWriter;
		}
	}

	/// <summary>
	/// The main server loop. Listening on the selected port occurs here, and accepting incoming connections
	/// </summary>
	public void StartListen(int port)
	{
		isRunning = true;
		try
		{
			serverSocket = new TcpListener(IPAddress.Any, port);
			serverSocket.Server.NoDelay = true;
			serverSocket.Start();
		}
		//The port is being used, and serverSocket cannot start
		catch (Exception ex)
		{
			/*
			   Console.WriteLine(ex.ToString());
			//Close();
			return;
			 */
			isRunning = false;
			throw;
		}
	}

	public void ConnectStream(Stream s) {
		isRunning = true;
		stream = s;
		reader = new BigEndianBinaryReader(stream);
		writer = new BigEndianBinaryWriter(stream);
		zlibWriter = new ZlibCompressedWriter(stream);
		//clients.Add(stream);
	}

	public void Accept() {
		try
		{
			//SocketError error = SocketError.AccessDenied;

			Socket s = serverSocket.AcceptSocket();
			s.NoDelay = true; //Disable the Naggle algorithm

			IPAddress addr = IPAddress.Parse(((IPEndPoint)s.RemoteEndPoint).Address.ToString());
			Console.Error.WriteLine(addr);

			ConnectStream(new NetworkStream(s, true));
		}
		catch (Exception ex) { Console.Error.WriteLine(ex.ToString()); }

	}

	public void ReverseConnect(String host, int port) {
		IPHostEntry e = Dns.GetHostEntry(host);
		foreach(IPAddress a in e.AddressList) {
			IPEndPoint endpoint = new IPEndPoint(a, port);
			Socket s = new Socket(endpoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
			s.Connect(endpoint);
			if(s.Connected) {
				s.NoDelay = true;
				ConnectStream(new NetworkStream(s, true));
				return;
			}
		}
		throw new IOException(String.Format("Can't connect to {0} port {1}", host, port));
	}

	/// <summary>
	/// Reads VNC Protocol Version message (see RFB Doc v. 3.8 section 6.1.1)
	/// </summary>
	/// <exception cref="NotSupportedException">Thrown if the version of the protocol is not known or supported.</exception>
	public void ReadProtocolVersion()
	{
		try
		{
			byte[] b = reader.ReadBytes(12);
			if(b.Length < 12) {
				Console.Error.WriteLine("ReadProtocolVersion: short read");
				return;
			}

			// As of the time of writing, the only supported versions are 3.3, 3.7, and 3.8.
			if (b[0] == 0x52 &&					// R
					b[1] == 0x46 &&					// F
					b[2] == 0x42 &&					// B
					b[3] == 0x20 &&					// (space)
					b[4] == 0x30 &&					// 0
					b[5] == 0x30 &&					// 0
					b[6] == 0x33 &&					// 3
					b[7] == 0x2e &&					// .
					(b[8] == 0x30 ||                 // 0
					 b[8] == 0x38) &&				// BUG FIX: Apple reports 8 
					(b[9] == 0x30 ||                 // 0
					 b[9] == 0x38) &&				// BUG FIX: Apple reports 8 
					(b[10] == 0x33 ||				// 3, 7, OR 8 are all valid and possible
					 b[10] == 0x36 ||				// BUG FIX: UltraVNC reports protocol version 3.6!
					 b[10] == 0x37 ||
					 b[10] == 0x38 ||
					 b[10] == 0x39) &&               // BUG FIX: Apple reports 9					
					b[11] == 0x0a)					// \n
			{
				// Since we only currently support the 3.x protocols, this can be assumed here.
				// If and when 4.x comes out, this will need to be fixed--however, the entire 
				// protocol will need to be updated then anyway :)
				verMajor = 3;

				// Figure out which version of the protocol this is:
				switch (b[10])
				{
					case 0x33:
					case 0x36:	// BUG FIX: pass 3.3 for 3.6 to allow UltraVNC to work, thanks to Steve Bostedor.
						verMinor = 3;
						break;
					case 0x37:
						verMinor = 7;
						break;
					case 0x38:
						verMinor = 8;
						break;
					case 0x39:  // BUG FIX: Apple reports 3.889
						// According to the RealVNC mailing list, Apple is really using 3.3 
						// (see http://www.mail-archive.com/vnc-list@realvnc.com/msg23615.html).  I've tested with
						// both 3.3 and 3.8, and they both seem to work (I obviously haven't hit the issues others have).
						// Because 3.8 seems to work, I'm leaving that, but it might be necessary to use 3.3 in future.
						verMinor = 8;
						break;
				}
			}
			else
			{
				throw new NotSupportedException("Only versions 3.3, 3.7, and 3.8 of the RFB Protocol are supported.");
			}
		}
		catch (IOException ex)
		{
			Console.WriteLine(ex.Message);
			Close();
		}
	}

	/// <summary>
	/// Sends the Protocol Version supported by the server.  Will be highest supported by client (see RFB Doc v. 3.8 section 6.1.1).
	/// </summary>
	public void WriteProtocolVersion()
	{
		try
		{
			// We will use which ever version the server understands, be it 3.3, 3.7, or 3.8.
			Debug.Assert(verMinor == 3 || verMinor == 7 || verMinor == 8, "Wrong Protocol Version!",
					string.Format("Protocol Version should be 3.3, 3.7, or 3.8 but is {0}.{1}", verMajor.ToString(), verMinor.ToString()));

			writer.Write(GetBytes(string.Format("RFB 003.00{0}\n", verMinor.ToString())));
			writer.Flush();
		}
		catch (IOException ex)
		{
			Console.Error.WriteLine(ex.Message);
			Close();

		}
	}

	/// <summary>
	/// Closes the active connection and stops the VNC Server.
	/// </summary>
	public void Close()
	{
		isRunning = false;
		if(serverSocket != null) serverSocket.Stop();
		//foreach(Stream s in clients) s.Close();
		//clients.Clear();
		if(stream != null) {
			stream.Close();
			stream = null;
		}
        }

        /// <summary>
        /// Converts the VNC password to a byte array.
        /// </summary>
        /// <param name="password">The VNC password as a String, to be converted to bytes.</param>
        /// <returns>Returns a byte array of the password.</returns>
        private byte[] PasswordToKey(string password)
        {
            byte[] key = new byte[8];
            // Key limited to 8 bytes max.
            if (password.Length >= 8)
            {
                System.Text.Encoding.ASCII.GetBytes(password, 0, 8, key, 0);
            }
            else
            {
                System.Text.Encoding.ASCII.GetBytes(password, 0, password.Length, key, 0);
            }
            // VNC uses reverse byte order in key
            for (int i = 0; i < 8; i++)
                key[i] = (byte)(((key[i] & 0x01) << 7) |
                                 ((key[i] & 0x02) << 5) |
                                 ((key[i] & 0x04) << 3) |
                                 ((key[i] & 0x08) << 1) |
                                 ((key[i] & 0x10) >> 1) |
                                 ((key[i] & 0x20) >> 3) |
                                 ((key[i] & 0x40) >> 5) |
                                 ((key[i] & 0x80) >> 7));
            return key;
        }

        /// <summary>
        /// If the password is not empty, perform VNC Authentication with it.
        /// </summary>
        /// <param name="password">The current VNC Password</param>
        /// <returns>Returns a boolean value representing successful authentication or not.</returns>
        public bool WriteAuthentication(string password)
        {
            // Indicate to the client which type of authentication will be used.
            //The type of Authentication to be used, 1 (None) or 2 (VNC Authentication).
            if (String.IsNullOrEmpty(password))
            {
                // Protocol Version 3.7 onward supports multiple security types, while 3.3 only 1
                if (verMinor == 3)
                {
                    WriteUint32(1);
                }
                else
                {
                    byte[] types = { 1 };
                    writer.Write((byte)types.Length);

                    for (int i = 0; i < types.Length; i++)
                        writer.Write(types[i]);
                }
                if (verMinor >= 7)
                    reader.ReadByte();
                if (verMinor == 8)
                    WriteSecurityResult(0);
                return true;
            }
            if (verMinor == 3)
            {
                WriteUint32(2);
            }
            else
            {
                byte[] types = { 2 };
                writer.Write((byte)types.Length);

                for (int i = 0; i < types.Length; i++)
                    writer.Write(types[i]);
            }
            if (verMinor >= 7)
                reader.ReadByte();

            //A random 16 byte challenge
            byte[] bChallenge = new byte[16];
            Random rand = new Random(DateTime.Now.Millisecond);
            rand.NextBytes(bChallenge);

            // send the bytes to the client and wait for the response
            writer.Write(bChallenge);
            writer.Flush();

            byte[] receivedBytes = reader.ReadBytes(16);
            byte[] key = PasswordToKey(password);
		bool authOK;

		if(receivedBytes.Length == 16) {
            DES des = new DESCryptoServiceProvider();
            des.Padding = PaddingMode.None;
            des.Mode = CipherMode.ECB;
            ICryptoTransform enc = des.CreateEncryptor(key, null);
            byte[] ourBytes = new byte[16];
            enc.TransformBlock(bChallenge, 0, bChallenge.Length, ourBytes, 0);

                Console.WriteLine("Us: " + System.Text.Encoding.ASCII.GetString(ourBytes));
                Console.WriteLine("Client sent us: " + System.Text.Encoding.ASCII.GetString(receivedBytes));
			Console.Error.WriteLine(receivedBytes.Length);
            authOK = true;
            for (int i = 0; i < ourBytes.Length; i++) {
                if (receivedBytes[i] != ourBytes[i])
                    authOK = false;
			}
		} else {
			authOK = false;
		}

            if (authOK)
            {
                WriteSecurityResult(0);
                return true;
            }
            WriteSecurityResult(1);
            if (verMinor != 8) return false;
            string ErrorMsg = "Wrong password, sorry";
            WriteUint32((uint)ErrorMsg.Length);
            writer.Write(GetBytes(ErrorMsg));
            return false;
        }

        /// <summary>
        /// When the client uses VNC Authentication, after the Challege/Response, a status code is sent to indicate whether authentication worked.
        /// </summary>
        /// <param name="sr">An unsigned integer indicating the status of authentication: 0 = OK; 1 = Failed; 2 = Too Many (deprecated).</param>
        public void WriteSecurityResult(uint sr)
        {
            writer.Write(sr);
        }

        /// <summary>
        /// Receives an Initialisation message from the client.
        /// </summary>
        /// <returns>True if the server allows other clients to connect, otherwise False.</returns>
        public bool ReadClientInit()
        {
            bool sh = false;
            try
            {
                Shared = (reader.ReadByte() == 1);
                sh = Shared;
                return Shared;
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();
            }
            return sh;
        }

        /// <summary>
        /// Writes the server's Initialization message, specifically the Framebuffer's properties.
        /// </summary>
        /// <param name="fb">The framebuffer that is sent.</param>
        public void WriteServerInit(Framebuffer fb)
        {
            try
            {
                writer.Write(Convert.ToUInt16(fb.Width));
                writer.Write(Convert.ToUInt16(fb.Height));
                writer.Write(fb.ToPixelFormat());

                writer.Write(Convert.ToUInt32(fb.DesktopName.Length));
                writer.Write(GetBytes(fb.DesktopName));
                writer.Flush();
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Receives the format to be used when sending Framebuffer Updates.
        /// </summary>
        /// <returns>A Framebuffer telling the server how to encode pixel data. Typically this will be the same one sent by the server during initialization.</returns>
        public Framebuffer ReadSetPixelFormat(int w, int h)
        {
            Framebuffer ret = null;
            try
            {
                ReadPadding(3);
                byte[] pf = ReadBytes(16);
                ret = Framebuffer.FromPixelFormat(pf, w, h);
                return ret;
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();
            }
            return ret;
        }

        /// <summary>
        /// Reads the supported encodings from the client.
        /// </summary>
        public void ReadSetEncodings()
        {
            try
            {
                ReadPadding(1);
                ushort len = reader.ReadUInt16();
                uint[] enc = new uint[len];

			Console.Error.Write("Remote encodings:");
                for (int i = 0; i < (Int32)len; i++) {
				enc[i] = reader.ReadUInt32();
				Console.Error.Write(" {0}", (Encoding)enc[i]);
			}

			Console.Error.WriteLine();

                Encodings = enc;
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Reads a request for an update of the area specified by (x, y, w, h).
        /// <param name="fb">The server's current Framebuffer.</param>
        /// </summary>
        public void ReadFrameBufferUpdateRequest(Framebuffer fb)
        {
            try
            {
                bool incremental = Convert.ToBoolean((int)(reader.ReadByte()));
                ushort x = reader.ReadUInt16();
                ushort y = reader.ReadUInt16();
                ushort width = reader.ReadUInt16();
                ushort height = reader.ReadUInt16();

                //Console.WriteLine("FrameBufferUpdateRequest on x: " + x + " y: " + y + " w: " + width + " h:" + height);

                /*new Thread(delegate() { */
                DoFrameBufferUpdate(fb, incremental, x, y, width, height);
                /*}).Start();*/
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Creates the encoded pixel data in a form of an EncodedRectangle with the preferred encoding.
        /// </summary>
        private void DoFrameBufferUpdate(Framebuffer fb, bool incremental, int x, int y, int width, int height)
        {
            //if (incremental)
            //    return;
            Trace.WriteLine("X: " + x + " Y: " + y + " W: " + fb.Width + " H: " + fb.Height);
            int w = fb.Width;
            int h = fb.Height;
            if ((x < 0) || (y < 0) || (width <= 0) || (height <= 0))
            {
                Trace.WriteLine("Neg:" + x + ":" + y + ":" + width + ":" + height);
                return;
            }
            if (x + width > w)
            {
                Trace.WriteLine("Too wide");
                Console.Error.WriteLine("Too wide");
                return;
            }
            if (y + height > h)
            {
                Trace.WriteLine("Too high");
                Console.Error.WriteLine("Too high");
                return;
            }
            Trace.WriteLine("Bounds OK!");

            HashSet<EncodedRectangle> rectangles = new HashSet<EncodedRectangle>();
            try
            {
                Stopwatch tip = Stopwatch.StartNew();
                EncodedRectangleFactory factory = new EncodedRectangleFactory(this, fb);
#if USE_SCREEN_DIFF
                ICollection<QuadNode> list = screenHandler.GetChange();
                
                Trace.WriteLine(list.Count + " rectangles to encode");
			Console.Error.WriteLine("{0} rectangles to encode", list.Count);
                foreach (QuadNode iter in list)
                {
                    Trace.WriteLine(iter.ToString());
                    EncodedRectangle localRect = factory.Build(iter, GetEncoding());
                    localRect.Encode();

                    rectangles.Add(localRect);
                }
#else
			EncodedRectangle localRect = factory.Build(new Rectangle2(x,y,width, height), GetEncoding());
			localRect.Encode();
			rectangles.Add(localRect);
#endif
			tip.Stop();
                Trace.WriteLine("Encoding took: " + tip.Elapsed);
            }
            catch (IOException e)
            {
			Console.Error.WriteLine(e);
			Close();
			return;
            }
            if (rectangles.Count != 0)
                WriteFrameBufferUpdate(rectangles);

        }

        /// <summary>
        /// Writes the number of update rectangles being sent to the client.
        /// After that, for each rectangle, the encoded data is sent.
        /// </summary>
        public void WriteFrameBufferUpdate(ICollection<EncodedRectangle> rectangles)
        {
		//Console.Error.WriteLine("method: WriteFrameBufferUpdate({0})", rectangles);
            Stopwatch watch = Stopwatch.StartNew();
            try
            {
                WriteServerMessageType(ServerMessages.FramebufferUpdate);
                WritePadding(1);
                writer.Write(Convert.ToUInt16(rectangles.Count));

                foreach (EncodedRectangle e in rectangles)
                    e.WriteData();
                writer.Flush();

                watch.Stop();
                Trace.WriteLine("Sending took: " + watch.Elapsed);
            }
            catch (IOException ex)
            {
                Console.Error.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Receives a key press or release event from the client.
        /// </summary>
        public void ReadKeyEvent()
        {
            try
            {
                bool pressed = (reader.ReadByte() == 1);
                ReadPadding(2);
                uint keysym = reader.ReadUInt32();

                //Do KeyEvent
                //new Thread(delegate() { 
                Robot.KeyEvent(pressed, Convert.ToInt32(keysym));
                //}).Start();
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Receives a mouse movement or button press/release from the client.
        /// </summary>
        public void ReadPointerEvent()
        {
            try
            {
                byte buttonMask = reader.ReadByte();
                ushort X = reader.ReadUInt16();
                ushort Y = reader.ReadUInt16();
                /*new Thread(delegate() { */
                Robot.PointerEvent(buttonMask, X, Y);
                /*}).Start();*/
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Receives the clipboard data from the client.
        /// </summary>
        public void ReadClientCutText()
        {
            try
            {
                ReadPadding(3);

                int len = Convert.ToInt32(reader.ReadUInt32());
                string text = GetString(reader.ReadBytes(len));
                CutText = text;
                System.Windows.Forms.Clipboard.SetDataObject(text.Replace("\n", Environment.NewLine), true);
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Reads the type of message being sent by the client--all messages are prefixed with a message type.
        /// </summary>
        /// <returns>Returns the message type as an integer.</returns>
        public ClientMessages ReadServerMessageType()
        {
            byte x = 0;
            try
            {
                x = Convert.ToByte((int)reader.ReadByte());
                return (ClientMessages)x;
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();
            }
            return (ClientMessages)x;
        }

        /// <summary>
        /// Writes the type of message being sent to the client--all messages are prefixed with a message type.
        /// </summary>
        private void WriteServerMessageType(ServerMessages message)
        {
            try { writer.Write(Convert.ToByte(message)); }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        // TODO: this color map code should probably go in Framebuffer.cs
        private ushort[,] mapEntries = new ushort[256, 3];
        public ushort[,] MapEntries
        {
            get
            {
                return mapEntries;
            }
        }

        /// <summary>
        /// Reads 8-bit RGB color values (or updated values) into the color map.
        /// </summary>
        public void ReadColorMapEntry()
        {
            ReadPadding(1);
            ushort firstColor = ReadUInt16();
            ushort nbColors = ReadUInt16();

            for (int i = 0; i < nbColors; i++, firstColor++)
            {
                mapEntries[firstColor, 0] = (byte)(ReadUInt16() * byte.MaxValue / ushort.MaxValue);    // R
                mapEntries[firstColor, 1] = (byte)(ReadUInt16() * byte.MaxValue / ushort.MaxValue);    // G
                mapEntries[firstColor, 2] = (byte)(ReadUInt16() * byte.MaxValue / ushort.MaxValue);    // B
            }
        }

        /// <summary>
        /// Writes 8-bit RGB color values (or updated values) from the color map.
        /// </summary>
        public void WriteColorMapEntry(ushort firstColor, Color[] colors)
        {
            try
            {
                WriteServerMessageType(ServerMessages.SetColorMapEntries);

                WritePadding(1);
                writer.Write(firstColor);
                writer.Write((ushort)colors.Length);

                for (int i = 0; i < colors.Length; i++)
                {
                    writer.Write((ushort)colors[i].R);
                    writer.Write((ushort)colors[i].G);
                    writer.Write((ushort)colors[i].B);
                }
                writer.Flush();
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        /// <summary>
        /// Writes the text from the Cut Buffer on the server.
        /// </summary>
        public void WriteServerCutText(string text)
        {
            try
            {
                WriteServerMessageType(ServerMessages.ServerCutText);
                WritePadding(3);

                writer.Write((uint)text.Length);
                writer.Write(GetBytes(text));
                writer.Flush();
            }
            catch (IOException ex)
            {
                Console.WriteLine(ex.Message);
                Close();

            }
        }

        // ---------------------------------------------------------------------------------------
        // Here's all the "low-level" protocol stuff so user objects can access the data directly

        /// <summary>
        /// Reads a single UInt32 value from the server, taking care of Big- to Little-Endian conversion.
        /// </summary>
        /// <returns>Returns a UInt32 value.</returns>
        public uint ReadUint32()
        {
            return reader.ReadUInt32();
        }

        /// <summary>
        /// Reads a single UInt16 value from the server, taking care of Big- to Little-Endian conversion.
        /// </summary>
        /// <returns>Returns a UInt16 value.</returns>
        public ushort ReadUInt16()
        {
            return reader.ReadUInt16();
        }

        /// <summary>
        /// Reads a single Byte value from the server.
        /// </summary>
        /// <returns>Returns a Byte value.</returns>
        public byte ReadByte()
        {
            return reader.ReadByte();
        }

        /// <summary>
        /// Reads the specified number of bytes from the server, taking care of Big- to Little-Endian conversion.
        /// </summary>
        /// <param name="count">The number of bytes to be read.</param>
        /// <returns>Returns a Byte Array containing the values read.</returns>
        public byte[] ReadBytes(int count)
        {
            return reader.ReadBytes(count);
        }

        /// <summary>
        /// Writes a single UInt32 value to the server, taking care of Little- to Big-Endian conversion.
        /// </summary>
        /// <param name="value">The UInt32 value to be written.</param>
        public void WriteUint32(uint value)
        {
            writer.Write(value);
        }

        /// <summary>
        /// Writes a single unsigned short value to the server, taking care of Little- to Big-Endian conversion.
        /// </summary>
        /// <param name="value">The UInt16 value to be written.</param>
        public void WriteUInt16(ushort value)
        {
            writer.Write(value);
        }

        /// <summary>
        /// Writes a single unsigned integer value to the server, taking care of Little-to Big-Endian conversion.
        /// </summary>
        /// <param name="value">The UInt32 value to be written.</param>
        public void WriteUInt32(uint value)
        {
            writer.Write(value);
        }
        /// <summary>
        /// Writes a single Byte value to the server.
        /// </summary>
        /// <param name="value">The UInt32 value to be written.</param>
        public void WriteByte(byte value)
        {
            writer.Write(value);
        }

        /// <summary>
        /// Writes a byte array to the server.
        /// </summary>
        /// <param name="buffer">The byte array to be written.</param>
        public void Write(byte[] buffer)
        {
            writer.Write(buffer);
        }

        /// <summary>
        /// Reads the specified number of bytes of padding (i.e., garbage bytes) from the server.
        /// </summary>
        /// <param name="length">The number of bytes of padding to read.</param>
        public void ReadPadding(int length)
        {
            ReadBytes(length);
        }

        /// <summary>
        /// Writes the specified number of bytes of padding (i.e., garbage bytes) to the server.
        /// </summary>
        /// <param name="length">The number of bytes of padding to write.</param>
        public void WritePadding(int length)
        {
            byte[] padding = new byte[length];
            writer.Write(padding, 0, padding.Length);
        }

        /// <summary>
        /// Converts a string to bytes for transfer to the server.
        /// </summary>
        /// <param name="text">The text to be converted to bytes.</param>
        /// <returns>Returns a Byte Array containing the text as bytes.</returns>
        protected static byte[] GetBytes(string text)
        {
            return System.Text.Encoding.ASCII.GetBytes(text);
        }

        /// <summary>
        /// Converts a series of bytes to a string.
        /// </summary>
        /// <param name="bytes">The Array of Bytes to be converted to a string.</param>
        /// <returns>Returns a String representation of bytes.</returns>
        protected static string GetString(byte[] bytes)
        {
            return System.Text.Encoding.UTF8.GetString(bytes, 0, bytes.Length);
        }
    }
}