public bool TestAesKey(byte[] bytes, byte[] key)
{
BinaryReader IndexReader = new BinaryReader(new MemoryStream(AESDecryptor.DecryptAES(bytes, key)));
int stringLen = IndexReader.ReadInt32();
if (stringLen > 128 || stringLen < -128)
{
return(false);
}
if (stringLen == 0)
{
return(IndexReader.ReadUInt16() == 0);
}
if (stringLen < 0)
{
int nullTerminatedPos = 4 - (stringLen - 1) * 2;
IndexReader.BaseStream.Seek(nullTerminatedPos, SeekOrigin.Begin);
return(IndexReader.ReadInt16() == 0);
}
else
{
int nullTerminatedPos = 4 + stringLen - 1;
IndexReader.BaseStream.Seek(nullTerminatedPos, SeekOrigin.Begin);
return(IndexReader.ReadSByte() == 0);
}
}
public ArraySegment <byte> GetData(Stream stream, byte[] key, string[] compressionMethods)
{
lock (stream)
{
if (CompressionMethodIndex == 0U)
{
stream.Position = Offset + StructSize;
if (Encrypted)
{
var data = new byte[(Size & 15) == 0 ? Size : (Size / 16 + 1) * 16];
stream.Read(data, 0, data.Length);
return(new ArraySegment <byte>(AESDecryptor.DecryptAES(data, key), 0, (int)UncompressedSize));
}
else
{
var data = new byte[UncompressedSize];
stream.Read(data, 0, data.Length);
return(new ArraySegment <byte>(data));
}
}
else
{
var data = new byte[UncompressedSize];
Decompress(stream, key, compressionMethods, data);
return(new ArraySegment <byte>(data));
}
}
throw new NotImplementedException("Decompression not yet implemented");
}
bool DecryptAndValidateIndex(ref byte[] IndexData, byte[] aesKey, FSHAHash ExpectedHash, out FSHAHash OutHash)
{
if (Info.bEncryptedIndex)
{
IndexData = AESDecryptor.DecryptAES(IndexData, aesKey);
}
OutHash = ExpectedHash; // too lazy to actually check against the hash
// https://github.com/EpicGames/UnrealEngine/blob/79a64829237ae339118bb50b61d84e4599c14e8a/Engine/Source/Runtime/PakFile/Private/IPlatformFilePak.cpp#L5371
return(true);
}
private void Decompress(Stream stream, byte[] key, string[] compressionMethods, byte[] outData)
{
if (compressionMethods == null || compressionMethods.Length == 0)
{
throw new ArgumentOutOfRangeException(nameof(compressionMethods), "CompressionMethods are null or empty");
}
string compressionMethod = compressionMethods[CompressionMethodIndex - 1]; // -1 because we dont have 'NAME_None' in the array
int bytesRead = 0;
for (int i = 0; i < CompressionBlocks.Length; i++)
{
stream.Position = Offset + CompressionBlocks[i].CompressedStart;
int uncompressedSize = (int)Math.Min(CompressionBlockSize, outData.Length - bytesRead);
byte[] blockBbuffer;
if (Encrypted)
{
blockBbuffer = new byte[BinaryHelper.Align(CompressionBlocks[i].Size, AESDecryptor.BLOCK_SIZE)];
stream.Read(blockBbuffer, 0, blockBbuffer.Length);
blockBbuffer = AESDecryptor.DecryptAES(blockBbuffer, key);
}
else
{
blockBbuffer = new byte[CompressionBlocks[i].Size];
stream.Read(blockBbuffer, 0, blockBbuffer.Length);
}
using var blockMs = new MemoryStream(blockBbuffer, false);
using Stream compressionStream = compressionMethod switch
{
"Zlib" => new ZlibStream(blockMs, CompressionMode.Decompress),
"Gzip" => new GZipStream(blockMs, CompressionMode.Decompress),
"Oodle" => new OodleStream(blockBbuffer, uncompressedSize),
_ => throw new NotImplementedException($"Decompression not yet implemented ({compressionMethod})")
};
bytesRead += compressionStream.Read(outData, bytesRead, uncompressedSize);
}
}
void ReadIndexInternal(byte[] key, PakFilter filter, out Exception exc)
{
if (Initialized)
{
exc = new InvalidOperationException("Index is already initialized");
return;
}
if (Info.bEncryptedIndex && key == null)
{
exc = new ArgumentException("Index is encrypted but no key was provided", nameof(key));
return;
}
Stream.Position = Info.IndexOffset;
BinaryReader IndexReader;
if (Info.bEncryptedIndex)
{
IndexReader = new BinaryReader(new MemoryStream(AESDecryptor.DecryptAES(Reader.ReadBytes((int)Info.IndexSize), key)));
int stringLen = IndexReader.ReadInt32();
if (stringLen > 512 || stringLen < -512)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
if (stringLen < 0)
{
IndexReader.BaseStream.Position += (stringLen - 1) * 2;
if (IndexReader.ReadUInt16() != 0)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
}
else
{
IndexReader.BaseStream.Position += stringLen - 1;
if (IndexReader.ReadByte() != 0)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
}
IndexReader.BaseStream.Position = 0;
}
else
{
IndexReader = Reader;
}
Dictionary <string, FPakEntry> tempFiles;
if (Info.Version >= EPakVersion.PATH_HASH_INDEX)
{
ReadIndexUpdated(IndexReader, key, out tempFiles, filter);
}
else
{
// https://github.com/EpicGames/UnrealEngine/blob/bf95c2cbc703123e08ab54e3ceccdd47e48d224a/Engine/Source/Runtime/PakFile/Private/IPlatformFilePak.cpp#L4509
MountPoint = IndexReader.ReadFString();
if (MountPoint.StartsWith("../../.."))
{
MountPoint = MountPoint.Substring(8);
}
else
{
// Weird mount point location...
MountPoint = "/";
}
if (!CaseSensitive)
{
MountPoint = MountPoint.ToLowerInvariant();
}
var NumEntries = IndexReader.ReadInt32();
tempFiles = new Dictionary <string, FPakEntry>(NumEntries);
for (int i = 0; i < NumEntries; i++)
{
var entry = new FPakEntry(IndexReader, Info.Version, CaseSensitive, FileName);
// if there is no filter OR the filter passes
if (filter == null || filter.CheckFilter(MountPoint + entry.Name, CaseSensitive))
{
// Filename is without the MountPoint concatenated to save memory
tempFiles[entry.Name] = entry;
}
}
}
Paks.Merge(tempFiles, out var files, MountPoint);
Entries = files;
DebugHelper.WriteLine("{0} {1} {2} {3}", "[FModel]", "[PakFileReader]", "[ReadIndexInternal]", $"{FileName} contains {Entries.Count} files, mount point: \"{this.MountPoint}\", version: {(int)this.Info.Version}");
if (Info.bEncryptedIndex)
{
// underlying stream is a MemoryStream of the decrypted index, might improve performance with a crypto stream of some sort
IndexReader.Dispose();
}
Reader.Dispose();
Initialized = true;
exc = null;
}
void ReadIndexInternal(byte[] key, PakFilter filter, out Exception exc)
{
if (Initialized)
{
exc = new InvalidOperationException("Index is already initialized");
return;
}
if (Info.bEncryptedIndex && key == null)
{
exc = new ArgumentException("Index is encrypted but no key was provided", nameof(key));
return;
}
Stream.Position = Info.IndexOffset;
BinaryReader IndexReader;
if (Info.bEncryptedIndex)
{
IndexReader = new BinaryReader(new MemoryStream(AESDecryptor.DecryptAES(Reader.ReadBytes((int)Info.IndexSize), key)));
int stringLen = IndexReader.ReadInt32();
if (stringLen > 512 || stringLen < -512)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
if (stringLen < 0)
{
IndexReader.BaseStream.Position += (stringLen - 1) * 2;
if (IndexReader.ReadUInt16() != 0)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
}
else
{
IndexReader.BaseStream.Position += stringLen - 1;
if (IndexReader.ReadByte() != 0)
{
exc = new ArgumentException("The provided key is invalid", nameof(key));
return;
}
}
IndexReader.BaseStream.Position = 0;
}
else
{
IndexReader = Reader;
}
Dictionary <string, FPakEntry> tempFiles;
if (Info.Version >= EPakVersion.PATH_HASH_INDEX)
{
ReadIndexUpdated(IndexReader, key, out tempFiles, filter);
}
else
{
// https://github.com/EpicGames/UnrealEngine/blob/bf95c2cbc703123e08ab54e3ceccdd47e48d224a/Engine/Source/Runtime/PakFile/Private/IPlatformFilePak.cpp#L4509
MountPoint = IndexReader.ReadFString() ?? "";
if (MountPoint.StartsWith("../../.."))
{
MountPoint = MountPoint[8..];