340 lines
11 KiB
C#

//! \file ArcEAGLS.cs
//! \date Fri May 15 02:52:04 2015
//! \brief EAGLS system resource archives.
//
// Copyright (C) 2015-2016 by morkt
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.IO;
using System.Text;
using GameRes.Formats.Strings;
using GameRes.Utility;
namespace GameRes.Formats.Eagls
{
[Export(typeof(ArchiveFormat))]
public class PakOpener : ArchiveFormat
{
public override string Tag { get { return "PAK/EAGLS"; } }
public override string Description { get { return "EAGLS engine resource archive"; } }
public override uint Signature { get { return 0; } }
public override bool IsHierarchic { get { return false; } }
public override bool CanWrite { get { return false; } }
public PakOpener ()
{
Extensions = new string[] { "pak" };
}
internal static readonly string IndexKey = "1qaz2wsx3edc4rfv5tgb6yhn7ujm8ik,9ol.0p;/-@:^[]";
internal static readonly byte[] EaglsKey = Encoding.ASCII.GetBytes ("EAGLS_SYSTEM");
internal static readonly byte[] AdvSysKey = Encoding.ASCII.GetBytes ("ADVSYS");
public override ArcFile TryOpen (ArcView file)
{
if (file.Name.HasExtension (".idx"))
return null;
string idx_name = Path.ChangeExtension (file.Name, ".idx");
if (!VFS.FileExists (idx_name))
return null;
var idx_entry = VFS.FindFile (idx_name);
if (idx_entry.Size > 0xfffff || idx_entry.Size < 10000)
return null;
byte[] index;
using (var idx = VFS.OpenView (idx_entry))
index = DecryptIndex (idx);
int index_offset = 0;
int entry_size = index.Length / 10000;
if (entry_size > 40)
entry_size = 40;
bool long_offsets = 40 == entry_size;
int name_size = long_offsets ? 0x18 : 0x14;
long first_offset = LittleEndian.ToUInt32 (index, name_size);
bool has_scripts = false;
var dir = new List<Entry>();
while (index_offset < index.Length)
{
if (0 == index[index_offset])
break;
var name = Binary.GetCString (index, index_offset, name_size);
index_offset += name_size;
var entry = FormatCatalog.Instance.Create<Entry> (name);
if (name.HasExtension ("dat"))
{
entry.Type = "script";
has_scripts = true;
}
if (long_offsets)
{
entry.Offset = LittleEndian.ToInt64 (index, index_offset) - first_offset;
entry.Size = LittleEndian.ToUInt32 (index, index_offset+8);
index_offset += 0x10;
}
else
{
entry.Offset = LittleEndian.ToUInt32 (index, index_offset) - first_offset;
entry.Size = LittleEndian.ToUInt32 (index, index_offset+4);
index_offset += 8;
}
if (!entry.CheckPlacement (file.MaxOffset))
return null;
dir.Add (entry);
}
if (0 == dir.Count)
return null;
if (dir[0].Name.HasExtension ("gr")) // CG archive
{
var rng = DetectEncryptionScheme (file, dir[0]);
return new EaglsArchive (file, this, dir, new CgEncryption (rng));
}
else if (has_scripts)
{
var enc = QueryEncryption();
if (enc != null)
return new EaglsArchive (file, this, dir, enc);
}
return new ArcFile (file, this, dir);
}
public override Stream OpenEntry (ArcFile arc, Entry entry)
{
var earc = arc as EaglsArchive;
if (null == earc || !entry.Name.HasAnyOfExtensions ("dat", "gr"))
return arc.File.CreateStream (entry.Offset, entry.Size);
return earc.DecryptEntry (entry);
}
byte[] DecryptIndex (ArcView idx)
{
int idx_size = (int)idx.MaxOffset-4;
byte[] output = new byte[idx_size];
using (var view = idx.CreateViewAccessor (0, (uint)idx.MaxOffset))
unsafe
{
var rng = new CRuntimeRandomGenerator();
rng.SRand (view.ReadInt32 (idx_size));
byte* ptr = view.GetPointer (0);
try
{
for (int i = 0; i < idx_size; ++i)
{
output[i] = (byte)(ptr[i] ^ IndexKey[rng.Rand() % IndexKey.Length]);
}
return output;
}
finally
{
view.SafeMemoryMappedViewHandle.ReleasePointer();
}
}
}
IRandomGenerator DetectEncryptionScheme (ArcView file, Entry first_entry)
{
int signature = (file.View.ReadInt32 (first_entry.Offset) >> 8) & 0xFFFF;
byte seed = file.View.ReadByte (first_entry.Offset+first_entry.Size-1);
IRandomGenerator[] rng_list = {
new LehmerRandomGenerator(),
new CRuntimeRandomGenerator(),
};
foreach (var rng in rng_list)
{
rng.SRand (seed);
rng.Rand(); // skip LZSS control byte
int test = signature;
test ^= EaglsKey[rng.Rand() % EaglsKey.Length];
test ^= EaglsKey[rng.Rand() % EaglsKey.Length] << 8;
// FIXME
// as key is rather short, this detection could produce false results sometimes
if (0x4D42 == test) // 'BM'
return rng;
}
throw new UnknownEncryptionScheme();
}
public override ResourceOptions GetDefaultOptions ()
{
IEntryEncryption enc = null;
if (!string.IsNullOrEmpty (Properties.Settings.Default.EAGLSEncryption))
KnownSchemes.TryGetValue (Properties.Settings.Default.EAGLSEncryption, out enc);
return new EaglsOptions { Encryption = enc };
}
public override object GetAccessWidget ()
{
return new GUI.WidgetEAGLS();
}
IEntryEncryption QueryEncryption ()
{
var options = Query<EaglsOptions> (arcStrings.ArcEncryptedNotice);
return options.Encryption;
}
internal static Dictionary<string, IEntryEncryption> KnownSchemes = new Dictionary<string, IEntryEncryption>
{
{ "EAGLS", new EaglsEncryption() },
{ "AdvSys", new AdvSysEncryption() },
};
}
public class EaglsOptions : ResourceOptions
{
public IEntryEncryption Encryption;
}
public interface IRandomGenerator
{
void SRand (int seed);
int Rand ();
}
[Serializable]
public class CRuntimeRandomGenerator : IRandomGenerator
{
uint m_seed;
public void SRand (int seed)
{
m_seed = (uint)seed;
}
public int Rand ()
{
m_seed = m_seed * 214013u + 2531011u;
return (int)(m_seed >> 16) & 0x7FFF;
}
}
[Serializable]
public class LehmerRandomGenerator : IRandomGenerator
{
int m_seed;
const int A = 48271;
const int Q = 44488;
const int R = 3399;
const int M = 2147483647;
public void SRand (int seed)
{
m_seed = seed ^ 123459876;
}
public int Rand ()
{
m_seed = A * (m_seed % Q) - R * (m_seed / Q);
if (m_seed < 0)
m_seed += M;
return (int)(m_seed * 4.656612875245797e-10 * 256);
}
}
public interface IEntryEncryption
{
void Decrypt (byte[] data);
}
[Serializable]
public class CgEncryption : IEntryEncryption
{
readonly byte[] Key = PakOpener.EaglsKey;
readonly IRandomGenerator m_rng;
public CgEncryption (IRandomGenerator rng)
{
m_rng = rng;
}
public void Decrypt (byte[] data)
{
m_rng.SRand (data[data.Length-1]);
int limit = Math.Min (data.Length-1, 0x174b);
for (int i = 0; i < limit; ++i)
{
data[i] ^= (byte)Key[m_rng.Rand() % Key.Length];
}
}
}
[Serializable]
public class EaglsEncryption : IEntryEncryption
{
readonly byte[] Key = PakOpener.EaglsKey;
readonly IRandomGenerator m_rng;
public EaglsEncryption ()
{
m_rng = new CRuntimeRandomGenerator();
}
public void Decrypt (byte[] data)
{
int text_offset = 3600;
int text_length = data.Length - text_offset - 2;
m_rng.SRand ((sbyte)data[data.Length-1]);
for (int i = 0; i < text_length; i += 2)
{
data[text_offset + i] ^= Key[m_rng.Rand() % Key.Length];
}
}
}
[Serializable]
public class AdvSysEncryption : IEntryEncryption
{
readonly byte[] Key = PakOpener.AdvSysKey;
public void Decrypt (byte[] data)
{
int text_offset = 136000;
int text_length = data.Length - text_offset;
for (int i = 0; i < text_length; ++i)
{
data[text_offset + i] ^= Key[i % Key.Length];
}
}
}
internal class EaglsArchive : ArcFile
{
readonly IEntryEncryption Encryption;
public EaglsArchive (ArcView arc, ArchiveFormat impl, ICollection<Entry> dir, IEntryEncryption enc)
: base (arc, impl, dir)
{
Encryption = enc;
}
public Stream DecryptEntry (Entry entry)
{
byte[] input = File.View.ReadBytes (entry.Offset, entry.Size);
Encryption.Decrypt (input);
return new BinMemoryStream (input, entry.Name);
}
}
}