private byte[] LoadBlock(int blockIndex, int expectedLength)
{
uint offset;
int toread;
uint encryptionseed;
if (_entry.IsCompressed)
{
offset = _blockPositions[blockIndex];
toread = (int)(_blockPositions[blockIndex + 1] - offset);
}
else
{
offset = (uint)(blockIndex * _blockSize);
toread = expectedLength;
}
offset += _entry.FilePos;
var data = new byte[toread];
lock (_stream)
{
_stream.Seek(offset, SeekOrigin.Begin);
var read = _stream.Read(data, 0, toread);
if (read != toread)
{
throw new MpqParserException("Insufficient data or invalid data length");
}
}
if (_entry.IsEncrypted && _entry.FileSize > 3)
{
if (_entry.EncryptionSeed == 0)
{
throw new MpqParserException("Unable to determine encryption key");
}
encryptionseed = (uint)(blockIndex + _entry.EncryptionSeed);
StormBuffer.DecryptBlock(data, encryptionseed);
}
if (_entry.IsCompressed && (toread != expectedLength))
{
data = (_entry.Flags & MpqFileFlags.CompressedMulti) != 0
? DecompressMulti(data, expectedLength)
: PKDecompress(new MemoryStream(data), expectedLength);
}
return(data);
}
/// <summary>
/// Decrypts the contents of the <see cref="MpqTable"/>.
/// </summary>
/// <param name="data">The encrypted entries in the table.</param>
internal void Decrypt(byte[] data)
{
StormBuffer.DecryptBlock(data, StormBuffer.HashString(Key, 0x300));
}
/// <summary>
/// Initializes a new instance of the <see cref="MpqStream"/> class.
/// </summary>
/// <param name="entry">The file's entry in the <see cref="BlockTable"/>.</param>
/// <param name="baseStream">The <see cref="MpqArchive"/>'s stream.</param>
/// <param name="blockSize">The <see cref="MpqArchive.BlockSize"/>.</param>
internal MpqStream(MpqEntry entry, Stream baseStream, int blockSize)
{
_mode = MpqStreamMode.Read;
_isStreamOwner = false;
_filePosition = entry.FilePosition;
_fileSize = entry.FileSize;
_compressedSize = entry.CompressedSize;
_flags = entry.Flags;
_isCompressed = (_flags & MpqFileFlags.Compressed) != 0;
_isEncrypted = _flags.HasFlag(MpqFileFlags.Encrypted);
_isSingleUnit = _flags.HasFlag(MpqFileFlags.SingleUnit);
_encryptionSeed = entry.EncryptionSeed;
_baseEncryptionSeed = entry.BaseEncryptionSeed;
_stream = baseStream;
_blockSize = blockSize;
if (_isSingleUnit)
{
// Read the entire file into memory
var filedata = new byte[_compressedSize];
lock (_stream)
{
_stream.Seek(_filePosition, SeekOrigin.Begin);
var read = _stream.Read(filedata, 0, filedata.Length);
if (read != filedata.Length)
{
throw new MpqParserException("Insufficient data or invalid data length");
}
}
if (_isEncrypted && _fileSize > 3)
{
if (_encryptionSeed == 0)
{
throw new MpqParserException("Unable to determine encryption key");
}
StormBuffer.DecryptBlock(filedata, _encryptionSeed);
}
_currentData = _flags.HasFlag(MpqFileFlags.CompressedMulti) && _compressedSize > 0
? DecompressMulti(filedata, _fileSize)
: filedata;
}
else
{
_currentBlockIndex = -1;
// Compressed files start with an array of offsets to make seeking possible
if (_isCompressed)
{
var blockposcount = (int)((_fileSize + _blockSize - 1) / _blockSize) + 1;
// Files with metadata have an extra block containing block checksums
if ((_flags & MpqFileFlags.FileHasMetadata) != 0)
{
blockposcount++;
}
_blockPositions = new uint[blockposcount];
lock (_stream)
{
_stream.Seek(_filePosition, SeekOrigin.Begin);
using (var br = new BinaryReader(_stream, new UTF8Encoding(), true))
{
for (var i = 0; i < blockposcount; i++)
{
_blockPositions[i] = br.ReadUInt32();
}
}
}
var blockpossize = (uint)blockposcount * 4;
/*
* if (_blockPositions[0] != blockpossize)
* {
* // _entry.Flags |= MpqFileFlags.Encrypted;
* throw new MpqParserException();
* }
*/
if (_isEncrypted && blockposcount > 1)
{
var maxOffset1 = (uint)_blockSize + blockpossize;
if (_encryptionSeed == 0)
{
// This should only happen when the file name is not known.
if (!entry.TryUpdateEncryptionSeed(_blockPositions[0], _blockPositions[1], blockpossize, maxOffset1))
{
throw new MpqParserException("Unable to determine encyption seed");
}
}
_encryptionSeed = entry.EncryptionSeed;
_baseEncryptionSeed = entry.BaseEncryptionSeed;
StormBuffer.DecryptBlock(_blockPositions, _encryptionSeed - 1);
if (_blockPositions[0] != blockpossize)
{
throw new MpqParserException($"Decryption failed{(string.IsNullOrEmpty(entry.FileName) ? string.Empty : $" for '{entry.FileName}'")} (block position 0).");
}
if (_blockPositions[1] > maxOffset1)
{
throw new MpqParserException($"Decryption failed{(string.IsNullOrEmpty(entry.FileName) ? string.Empty : $" for '{entry.FileName}'")} (block position 1).");
}
}
}