[c#] Creating a "Hello World" WebSocket example

I couldnt find a simple working example anywhere (as of Jan 19), so here is an updated version. I have chrome version 71.0.3578.98.

C# Websocket server :

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;

namespace WebSocketServer
{
    class Program
    {
    static Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
    static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

    static void Main(string[] args)
    {
        serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
        serverSocket.Listen(1); //just one socket
        serverSocket.BeginAccept(null, 0, OnAccept, null);
        Console.Read();
    }

    private static void OnAccept(IAsyncResult result)
    {
        byte[] buffer = new byte[1024];
        try
        {
            Socket client = null;
            string headerResponse = "";
            if (serverSocket != null && serverSocket.IsBound)
            {
                client = serverSocket.EndAccept(result);
                var i = client.Receive(buffer);
                headerResponse = (System.Text.Encoding.UTF8.GetString(buffer)).Substring(0, i);
                // write received data to the console
                Console.WriteLine(headerResponse);
                Console.WriteLine("=====================");
            }
            if (client != null)
            {
                /* Handshaking and managing ClientSocket */
                var key = headerResponse.Replace("ey:", "`")
                          .Split('`')[1]                     // dGhlIHNhbXBsZSBub25jZQ== \r\n .......
                          .Replace("\r", "").Split('\n')[0]  // dGhlIHNhbXBsZSBub25jZQ==
                          .Trim();

                // key should now equal dGhlIHNhbXBsZSBub25jZQ==
                var test1 = AcceptKey(ref key);

                var newLine = "\r\n";

                var response = "HTTP/1.1 101 Switching Protocols" + newLine
                     + "Upgrade: websocket" + newLine
                     + "Connection: Upgrade" + newLine
                     + "Sec-WebSocket-Accept: " + test1 + newLine + newLine
                     //+ "Sec-WebSocket-Protocol: chat, superchat" + newLine
                     //+ "Sec-WebSocket-Version: 13" + newLine
                     ;

                client.Send(System.Text.Encoding.UTF8.GetBytes(response));
                var i = client.Receive(buffer); // wait for client to send a message
                string browserSent = GetDecodedData(buffer, i);
                Console.WriteLine("BrowserSent: " + browserSent);

                Console.WriteLine("=====================");
                //now send message to client
                client.Send(GetFrameFromString("This is message from server to client."));
                System.Threading.Thread.Sleep(10000);//wait for message to be sent
            }
        }
        catch (SocketException exception)
        {
            throw exception;
        }
        finally
        {
            if (serverSocket != null && serverSocket.IsBound)
            {
                serverSocket.BeginAccept(null, 0, OnAccept, null);
            }
        }
    }

    public static T[] SubArray<T>(T[] data, int index, int length)
    {
        T[] result = new T[length];
        Array.Copy(data, index, result, 0, length);
        return result;
    }

    private static string AcceptKey(ref string key)
    {
        string longKey = key + guid;
        byte[] hashBytes = ComputeHash(longKey);
        return Convert.ToBase64String(hashBytes);
    }

    static SHA1 sha1 = SHA1CryptoServiceProvider.Create();
    private static byte[] ComputeHash(string str)
    {
        return sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(str));
    }

    //Needed to decode frame
    public static string GetDecodedData(byte[] buffer, int length)
    {
        byte b = buffer[1];
        int dataLength = 0;
        int totalLength = 0;
        int keyIndex = 0;

        if (b - 128 <= 125)
        {
            dataLength = b - 128;
            keyIndex = 2;
            totalLength = dataLength + 6;
        }

        if (b - 128 == 126)
        {
            dataLength = BitConverter.ToInt16(new byte[] { buffer[3], buffer[2] }, 0);
            keyIndex = 4;
            totalLength = dataLength + 8;
        }

        if (b - 128 == 127)
        {
            dataLength = (int)BitConverter.ToInt64(new byte[] { buffer[9], buffer[8], buffer[7], buffer[6], buffer[5], buffer[4], buffer[3], buffer[2] }, 0);
            keyIndex = 10;
            totalLength = dataLength + 14;
        }

        if (totalLength > length)
            throw new Exception("The buffer length is small than the data length");

        byte[] key = new byte[] { buffer[keyIndex], buffer[keyIndex + 1], buffer[keyIndex + 2], buffer[keyIndex + 3] };

        int dataIndex = keyIndex + 4;
        int count = 0;
        for (int i = dataIndex; i < totalLength; i++)
        {
            buffer[i] = (byte)(buffer[i] ^ key[count % 4]);
            count++;
        }

        return Encoding.ASCII.GetString(buffer, dataIndex, dataLength);
    }

    //function to create  frames to send to client 
    /// <summary>
    /// Enum for opcode types
    /// </summary>
    public enum EOpcodeType
    {
        /* Denotes a continuation code */
        Fragment = 0,

        /* Denotes a text code */
        Text = 1,

        /* Denotes a binary code */
        Binary = 2,

        /* Denotes a closed connection */
        ClosedConnection = 8,

        /* Denotes a ping*/
        Ping = 9,

        /* Denotes a pong */
        Pong = 10
    }

    /// <summary>Gets an encoded websocket frame to send to a client from a string</summary>
    /// <param name="Message">The message to encode into the frame</param>
    /// <param name="Opcode">The opcode of the frame</param>
    /// <returns>Byte array in form of a websocket frame</returns>
    public static byte[] GetFrameFromString(string Message, EOpcodeType Opcode = EOpcodeType.Text)
    {
        byte[] response;
        byte[] bytesRaw = Encoding.Default.GetBytes(Message);
        byte[] frame = new byte[10];

        int indexStartRawData = -1;
        int length = bytesRaw.Length;

        frame[0] = (byte)(128 + (int)Opcode);
        if (length <= 125)
        {
            frame[1] = (byte)length;
            indexStartRawData = 2;
        }
        else if (length >= 126 && length <= 65535)
        {
            frame[1] = (byte)126;
            frame[2] = (byte)((length >> 8) & 255);
            frame[3] = (byte)(length & 255);
            indexStartRawData = 4;
        }
        else
        {
            frame[1] = (byte)127;
            frame[2] = (byte)((length >> 56) & 255);
            frame[3] = (byte)((length >> 48) & 255);
            frame[4] = (byte)((length >> 40) & 255);
            frame[5] = (byte)((length >> 32) & 255);
            frame[6] = (byte)((length >> 24) & 255);
            frame[7] = (byte)((length >> 16) & 255);
            frame[8] = (byte)((length >> 8) & 255);
            frame[9] = (byte)(length & 255);

            indexStartRawData = 10;
        }

        response = new byte[indexStartRawData + length];

        int i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
        {
            response[reponseIdx] = frame[i];
            reponseIdx++;
        }

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
        {
            response[reponseIdx] = bytesRaw[i];
            reponseIdx++;
        }

        return response;
    }
}
}

Client html and javascript:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"_x000D_
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">_x000D_
<html xmlns="http://www.w3.org/1999/xhtml">_x000D_
<head>_x000D_
    <script type="text/javascript">_x000D_
        var socket = new WebSocket('ws://localhost:8080/websession');_x000D_
        socket.onopen = function() {_x000D_
           // alert('handshake successfully established. May send data now...');_x000D_
     socket.send("Hi there from browser.");_x000D_
        };_x000D_
  socket.onmessage = function (evt) {_x000D_
                //alert("About to receive data");_x000D_
                var received_msg = evt.data;_x000D_
                alert("Message received = "+received_msg);_x000D_
            };_x000D_
        socket.onclose = function() {_x000D_
            alert('connection closed');_x000D_
        };_x000D_
    </script>_x000D_
</head>_x000D_
<body>_x000D_
</body>_x000D_
</html>