RFC6455: simple echo test with websocket after handshake

websockets-echo-test.cs

/*       http://tools.ietf.org/html/rfc6455#section-5.2
	  0                   1                   2                   3
	  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	 +-+-+-+-+-------+-+-------------+-------------------------------+
	 |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
	 |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
	 |N|V|V|V|       |S|             |   (if payload len==126/127)   |
	 | |1|2|3|       |K|             |                               |
	 +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
	 |     Extended payload length continued, if payload len == 127  |
	 + - - - - - - - - - - - - - - - +-------------------------------+
	 |                               |Masking-key, if MASK set to 1  |
	 +-------------------------------+-------------------------------+
	 | Masking-key (continued)       |          Payload Data         |
	 +-------------------------------- - - - - - - - - - - - - - - - +
	 :                     Payload Data continued ...                :
	 + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
	 |                     Payload Data continued ...                |
	 +---------------------------------------------------------------+
*/
namespace websockets
{
	using System;
	using System.Collections.Generic;
	using System.Text;
	using System.IO;
	using System.Net.Sockets;

	public class WebSocketFrame : IDisposable
	{
		public enum Opcodes : byte
		{
			Continue    = 0x0, // =frrr-0000 : non-control   = continuation of fragment sequence
			Text        = 0x1, // =frrr-0001 : non-control   = data to be handled as utf-8
			Binary      = 0x2, // =frrr-0010 : non-control   = data to be handled as binary
			Close       = 0x8, // =frrr-1000 : control       = close connection
			Ping        = 0x9, // =frrr-1001 : control       = ping request
			Pong        = 0xA  // =frrr-1010 : control       = pong responce
		}

		public enum PayloadTypes : byte
		{
			Tall   = 0x00,  // =m000-0000 : frame[2]        = payload length; 0..125 bytes
			Grande = 0x7E,  // =m111-1110 : frame[3,4]      = payload length; 16-bit as unsigned integer (uShort)
			Venti  = 0x7D   // =m111-1111 : frame[3..11]    = payload length; 64-bit as unsigned integer (uLong)
		}
		public List<byte>   echo{get;set;}
		public UInt64       PayloadLength { get; set; }
		public Opcodes      Opcode { get; set; }
		public Byte[]       Mask { get; set; }
		public Boolean      isFinal  { get; set; }
		public Boolean      isMasked { get; set; }

		public void ProcessHeader(NetworkStream stream)
		{
			byte[] header   = new byte[2];
			byte[] mask     = new byte[4];
			echo = new List<byte>();
			stream.Read(header, 0, 2);
			echo.AddRange(header);

			this.isFinal        = (header[0] & 0x80) == 0x80;
			this.Opcode         = (Opcodes)(header[0] & 0x7F);
			this.isMasked       = (header[1] & 0x80) == 0x80;
			this.PayloadLength  = (ulong)(header[1] & 0x7F);


			if (PayloadLength == 126)
			{
				byte[] len = new byte[2];
				stream.Read(len, 0, 2);
				Array.Reverse(len);
				this.PayloadLength = (ulong)BitConverter.ToUInt16(len, 0);
			}
			else if (PayloadLength == 127)
			{
				byte[] len = new byte[8];
				stream.Read(len, 0, 8);
				Array.Reverse(len);
				this.PayloadLength = (ulong)BitConverter.ToUInt64(len, 0);
			}

			byte[] data = new byte[PayloadLength];
			stream.Read(mask, 0, 4);
			echo.AddRange(mask);
			stream.Read(data, 0, data.Length);
			echo.AddRange(data);
			
			if(isMasked)
			for (int i = 0; i < data.Length; i++)
				data[i] ^= mask[i % 4];

			Console.WriteLine("{0}: isFinal?{1}: Length:{2}", this.Opcode,this.isFinal,this.PayloadLength);
			if(Opcode == Opcodes.Text)
				Console.WriteLine(Encoding.UTF8.GetString(data));
			
			stream.Write(echo.ToArray(), 0, echo.Count);
			stream.Flush();

		}

		public void Dispose()
		{
			Console.WriteLine("Echo complete.");
		}
	}
}

those looking may find this snippet helpful when reading http://tools.ietf.org/html/rfc6455#section-5 and drinking some coffee