PB Packet.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq;


class Packet
{
    private UInt16 header;
    private UInt16 length;
    private byte[] data;

    public Packet(byte[] data)
    {
        this.data = data;
    }

    public void Parse()
    {
        Console.WriteLine("Raw Data: " + TcpEchoServer.nicePacketString(this.data));
        bool encrypted = false;

        if (this.data.Length < 4)
            return;

        if (BitConverter.IsLittleEndian)
        {
            this.length = BitConverter.ToUInt16(data, 0);
        }
        else
            throw new NotImplementedException();

        if (this.length > 8908)
        {
            this.length = Convert.ToUInt16(this.length & 0x7FFF);
            encrypted = true;
        }

        if(this.data.Length - 2 < this.length + 2)
        {
            Console.WriteLine("Invalid Length:" + (this.data.Length - 2) + "/" + (this.length + 2));
            return;
        }

        byte[] content = this.data.Skip(2).Take(this.length).ToArray();
        if (encrypted)
        {
            content = this.Decrypt(content);
        }

        this.Read(content);

    }
    public byte[] Decrypt(byte[] data)
    {
        //Console.WriteLine("Decrypting Data (Length: " + this.length + ")");

        byte lastElement = data[data.Length - 1];
        for (int i = data.Length - 1; i > 0; i--)
        {
            data[i] = (byte)(((data[i - 1] & 0xFF) << (8 - GetShift())) | ((data[i] & 0xFF) >> GetShift()));
        }
        data[0] = (byte)((lastElement << (8 - GetShift())) | ((data[0] & 0xFF) >> GetShift()));

        return data;
    }

    public void Read(byte[] data)
    {
        this.header = BitConverter.ToUInt16(data.Take(2).ToArray(), 0);
        Console.WriteLine("ID: " + this.header + " => " + TcpEchoServer.nicePacketString(data));
        TcpEchoServer.writePacketToFile(data);
    }

    private int GetShift()
    {
        return ((29891) % 7) + 1;
    }
}