AdamuSw/src/Network/PacketTwister/PacketTwister42.cs

// <copyright file="PacketTwister42.cs" company="MUnique">
// Licensed under the MIT License. See LICENSE file in the project root for full license information.
// </copyright>

namespace MUnique.OpenMU.Network.PacketTwister;

/// <summary>
/// PacketTwister implementation for packets of an unknown type.
/// </summary>
internal class PacketTwister42 : IPacketTwister
{
    /// <inheritdoc/>
    public void Twist(Span<byte> data)
    {
        if (data.Length >= 4)
        {
            if (data.Length >= 8)
            {
                if (data.Length >= 16)
                {
                    if (data.Length >= 32)
                    {
                        var v8 = (byte)(data[8] >> 7);
                        data[8] *= 2;
                        data[8] |= v8;
                        var v9 = (byte)(data[10] >> 2);
                        data[10] <<= 6;
                        data[10] |= v9;
                        data[28] ^= 0xAE;
                    }
                    else
                    {
                        var v2 = (byte)((data[14] >> 2) & 1);
                        if (((data[14] >> 1) & 1) != 0)
                        {
                            data[14] |= 4;
                        }
                        else
                        {
                            data[14] &= 0xFB;
                        }

                        if (v2 != 0)
                        {
                            data[14] |= 2;
                        }
                        else
                        {
                            data[14] &= 0xFD;
                        }

                        data[4] ^= 0x40;
                        var v10 = (byte)((data[3] >> 2) & 1);
                        if (((data[3] >> 3) & 1) != 0)
                        {
                            data[3] |= 4;
                        }
                        else
                        {
                            data[3] &= 0xFB;
                        }

                        if (v10 != 0)
                        {
                            data[3] |= 8;
                        }
                        else
                        {
                            data[3] &= 0xF7;
                        }

                        data[0] ^= 0xC7;
                        var v7 = (byte)(data[4] >> 4);
                        data[4] *= 16;
                        data[4] |= v7;
                    }
                }
                else
                {
                    var v4 = data[4];
                    data[4] = data[1];
                    data[1] = v4;
                    data[1] ^= 0x64;
                    var v5 = data[4];
                    data[4] = data[1];
                    data[1] = v5;
                    var v6 = (byte)(data[1] >> 5);
                    data[1] *= 8;
                    data[1] |= v6;
                }
            }
            else
            {
                data[1] ^= 0x3C;
                data[2] ^= 0x96;
                var v3 = data[1];
                data[1] = data[2];
                data[2] = v3;
            }
        }
    }

    /// <inheritdoc/>
    public void Correct(Span<byte> data)
    {
        if (data.Length >= 4)
        {
            if (data.Length >= 8)
            {
                if (data.Length >= 16)
                {
                    if (data.Length >= 32)
                    {
                        data[28] ^= 0xAE;
                        var v8 = (byte)(data[10] >> 6);
                        data[10] *= 4;
                        data[10] |= v8;
                        var v9 = (byte)(data[8] >> 1);
                        data[8] <<= 7;
                        data[8] |= v9;
                    }
                    else
                    {
                        var v7 = (byte)(data[4] >> 4);
                        data[4] *= 16;
                        data[4] |= v7;
                        data[0] ^= 0xC7;
                        var v2 = (byte)((data[3] >> 2) & 1);
                        if (((data[3] >> 3) & 1) != 0)
                        {
                            data[3] |= 4;
                        }
                        else
                        {
                            data[3] &= 0xFB;
                        }

                        if (v2 != 0)
                        {
                            data[3] |= 8;
                        }
                        else
                        {
                            data[3] &= 0xF7;
                        }

                        data[4] ^= 0x40;
                        var v10 = (byte)((data[14] >> 2) & 1);
                        if (((data[14] >> 1) & 1) != 0)
                        {
                            data[14] |= 4;
                        }
                        else
                        {
                            data[14] &= 0xFB;
                        }

                        if (v10 != 0)
                        {
                            data[14] |= 2;
                        }
                        else
                        {
                            data[14] &= 0xFD;
                        }
                    }
                }
                else
                {
                    var v4 = (byte)(data[1] >> 3);
                    data[1] *= 32;
                    data[1] |= v4;
                    var v5 = data[4];
                    data[4] = data[1];
                    data[1] = v5;
                    data[1] ^= 0x64;
                    var v6 = data[4];
                    data[4] = data[1];
                    data[1] = v6;
                }
            }
            else
            {
                var v3 = data[1];
                data[1] = data[2];
                data[2] = v3;
                data[2] ^= 0x96;
                data[1] ^= 0x3C;
            }
        }
    }
}