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Read ISO in larger chunks

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Deterous
2024-02-18 16:59:04 +09:00
parent 6e529f0050
commit f74220efea
1 changed files with 82 additions and 48 deletions
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LibIRD/IRD.cs
+82 -48
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@@ -715,7 +715,6 @@ namespace LibIRD
HashFiles(fs, reader, rootDir); HashFiles(fs, reader, rootDir);
if (FileCount != fileCount) if (FileCount != fileCount)
{ {
//Console.WriteLine($"{isoPath} contains split files: detected {FileCount} out of {fileCount} expected files");
long[] tempFileKeys = FileKeys; long[] tempFileKeys = FileKeys;
Array.Resize(ref tempFileKeys, (int)FileCount); Array.Resize(ref tempFileKeys, (int)FileCount);
FileKeys = tempFileKeys; FileKeys = tempFileKeys;
@@ -891,8 +890,8 @@ namespace LibIRD
RegionEnd[^1] = (UpdateEnd / SectorSize) - 1; RegionEnd[^1] = (UpdateEnd / SectorSize) - 1;
// Determine MD5 hashes for each region // Determine MD5 hashes for each region
using MD5 md5 = MD5.Create(); int bufSectors = 1024;
byte[] buf = new byte[SectorSize]; byte[] buf = new byte[bufSectors * SectorSize];
for (int i = 0; i < RegionCount; i++) for (int i = 0; i < RegionCount; i++)
{ {
// Start reading data from first sector of region // Start reading data from first sector of region
@@ -900,19 +899,32 @@ namespace LibIRD
// Compute MD5 hash for just the region portion of the ISO file // Compute MD5 hash for just the region portion of the ISO file
int numBytes; int numBytes;
for (long j = RegionStart[i]; j <= RegionEnd[i]; j++) using MD5 md5 = MD5.Create();
int regionSectors = (int)(RegionEnd[i] - RegionStart[i]) + 1;
for (int j = bufSectors; j <= regionSectors; j += bufSectors)
{ {
// Read one sector at a time // Read into buffer
numBytes = fs.Read(buf, 0, buf.Length); numBytes = fs.Read(buf, 0, buf.Length);
// Check that an entire sector was read // TODO: Process partial buffer if non-zero is returned
if (numBytes < buf.Length) if (numBytes < buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly"); throw new InvalidFileSystemException("Disc region ended unexpectedly");
// Process MD5 sum one sector at a time
// Process MD5 sum
md5.TransformBlock(buf, 0, buf.Length, null, 0); md5.TransformBlock(buf, 0, buf.Length, null, 0);
} }
// Read any remaining sectors
int bufRemainder = (int)(SectorSize * (regionSectors % bufSectors));
if (bufRemainder != 0)
{
numBytes = fs.Read(buf, 0, bufRemainder);
// TODO: Process partial buffer if non-zero is returned
if (numBytes < bufRemainder)
throw new InvalidFileSystemException("Disc region ended unexpectedly");
}
// Compute and store MD5 hash of region // Compute and store MD5 hash of region
md5.TransformFinalBlock(buf, 0, 0); md5.TransformFinalBlock(buf, 0, bufRemainder);
RegionHashes[i] = md5.Hash; RegionHashes[i] = md5.Hash;
} }
} }
@@ -938,13 +950,14 @@ namespace LibIRD
// Determine smallest file offset as first sector // Determine smallest file offset as first sector
long smallestOffset = fileClusters[0].Offset; long smallestOffset = fileClusters[0].Offset;
bool nonContiguous = false;
for (int i = 1; i < fileClusters.Length; i++) for (int i = 1; i < fileClusters.Length; i++)
{ {
if (fileClusters[i] == null) if (fileClusters[i] == null)
throw new InvalidFileSystemException($"Unexpected file extents for {filePath}"); throw new InvalidFileSystemException($"Unexpected file extents for {filePath}");
if (fileClusters[i].Offset * SectorSize != fileClusters[i - 1].Offset * SectorSize + fileClusters[i - 1].Count) if (fileClusters[i].Offset * SectorSize != fileClusters[i - 1].Offset * SectorSize + fileClusters[i - 1].Count)
Console.WriteLine($"Non-contiguous file found: {filePath}"); nonContiguous = true;
if (fileClusters[i].Offset < smallestOffset) if (fileClusters[i].Offset < smallestOffset)
smallestOffset = fileClusters[i].Offset; smallestOffset = fileClusters[i].Offset;
@@ -953,6 +966,8 @@ namespace LibIRD
// If already encountered file offset, skip this file // If already encountered file offset, skip this file
if (Array.Exists(FileKeys, element => element == smallestOffset)) if (Array.Exists(FileKeys, element => element == smallestOffset))
continue; continue;
else if (nonContiguous)
Console.WriteLine($"Non-contiguous file found: {filePath}");
// Add file offset to keys // Add file offset to keys
FileKeys[FileCount] = smallestOffset; FileKeys[FileCount] = smallestOffset;
@@ -968,39 +983,47 @@ namespace LibIRD
} }
} }
// Hash each non-contiguous portion of the ISO file // Read one sector at a time for small files
byte[] buf = new byte[SectorSize]; int bufSectors = (fileClusters[0].Count < 1024 * SectorSize) ? 1 : 1024;
MD5 md5 = MD5.Create(); byte[] buf = new byte[bufSectors * SectorSize];
// Hash each non-contiguous portion of the file
using MD5 md5 = MD5.Create();
for (int i = 0; i < fileClusters.Length; i++) for (int i = 0; i < fileClusters.Length; i++)
{ {
// Start reading data from the beginning of the ISO file // Start reading data from the beginning of the current extent
fs.Seek(fileClusters[i].Offset * SectorSize, SeekOrigin.Begin); fs.Seek(fileClusters[i].Offset * SectorSize, SeekOrigin.Begin);
int numBytes; int numBytes;
// Read all data before the first data sector // Read file in buffers
for (int j = 0; j < (fileClusters[i].Count / SectorSize); j++) long fileSectors = fileClusters[i].Count / SectorSize;
for (int j = 0; j <= fileSectors - bufSectors; j += bufSectors)
{ {
numBytes = fs.Read(buf, 0, buf.Length); numBytes = fs.Read(buf, 0, buf.Length);
// Check that an entire sector was read // TODO: Process partial buffer if non-zero is returned
if (numBytes < buf.Length) if (numBytes != buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly"); throw new InvalidFileSystemException("Disc region ended unexpectedly");
// Decrypt sector if necessary
// Decrypt buffer if necessary
if (encrypted) if (encrypted)
buf = DecryptSector(buf, (int)fileClusters[i].Offset + j); DecryptSectors(ref buf, (int)fileClusters[i].Offset + j);
// Hash sector // Hash sector
md5.TransformBlock(buf, 0, numBytes, null, 0); md5.TransformBlock(buf, 0, buf.Length, null, 0);
} }
// Read remaining partial sector // Read remaining partial buffer
if (fileClusters[i].Count % SectorSize != 0) if ((fileClusters[i].Count % buf.Length) > 0)
{ {
numBytes = fs.Read(buf, 0, buf.Length); numBytes = fs.Read(buf, 0, buf.Length);
// Check that an entire sector was read // TODO: Process partial buffer if non-zero is returned
if (numBytes < buf.Length) if (numBytes != buf.Length)
throw new InvalidFileSystemException("Disc region ended unexpectedly"); throw new InvalidFileSystemException("Disc region ended unexpectedly");
// Decrypt partial sector if necessary
// Decrypt buffer if necessary
if (encrypted) if (encrypted)
buf = DecryptSector(buf, (int)fileClusters[i].Offset + (int)(fileClusters[i].Count / SectorSize)); DecryptSectors(ref buf, (int)fileClusters[i].Offset + bufSectors * (int)(fileClusters[i].Count / buf.Length));
// Hash partial sector
md5.TransformBlock(buf, 0, (int)(fileClusters[i].Count % SectorSize), null, 0); // Hash partial buffer
md5.TransformBlock(buf, 0, (int)(fileClusters[i].Count % buf.Length), null, 0);
} }
} }
@@ -1018,38 +1041,49 @@ namespace LibIRD
} }
/// <summary> /// <summary>
/// Decrypts a given sector byte array /// Decrypts a given byte array of sector(s)
/// </summary> /// </summary>
/// <param name="sector">Byte array to be decrypted</param> /// <param name="buffer">Byte array to be decrypted</param>
/// <param name="offset">Number of bytes to decrypt</param>
/// <exception cref="InvalidOperationException"></exception> /// <exception cref="InvalidOperationException"></exception>
private protected byte[] DecryptSector(byte[] sector, int sectorNumber) private protected void DecryptSectors(ref byte[] buffer, int sectorNumber)
{ {
ArgumentNullException.ThrowIfNull(buffer);
if (buffer.Length == 0 || buffer.Length % SectorSize != 0)
throw new ArgumentException("Encrypted buffer must be multiple of SectorSize");
// Setup AES decryption // Setup AES decryption
using Aes aes = Aes.Create() ?? throw new InvalidOperationException("AES not available. Change your system settings"); using Aes aes = Aes.Create() ?? throw new InvalidOperationException("AES not available. Change your system settings");
// Set AES settings // Set AES settings
aes.Key = DiscKey; aes.Key = DiscKey;
aes.Padding = PaddingMode.None; aes.Padding = PaddingMode.None;
aes.Mode = CipherMode.CBC; aes.Mode = CipherMode.CBC;
// Determine Initial Value based on sector number // Decrypt buffer one sector at a time
byte[] iv = new byte[16]; for (int i = 0; i < buffer.Length; i += (int)SectorSize)
for (int i = 0; i < 16; i++)
{ {
byte a = (byte)(sectorNumber & 0xFF); // Determine AES Initial Value based on sector number
iv[16 - i - 1] = (byte)(sectorNumber & 0xFF); byte[] iv = new byte[16];
sectorNumber >>= 8; int tempNum = sectorNumber;
for (int j = 0; j < 16; j++)
{
iv[16 - j - 1] = (byte)(tempNum & 0xFF);
tempNum >>= 8;
}
aes.IV = iv;
// Perform AES decryption
using MemoryStream stream = new();
using CryptoStream cs = new(stream, aes.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(buffer, i, (int)SectorSize);
cs.FlushFinalBlock();
// Write decrypted sector to output
stream.ToArray().CopyTo(buffer, i);
sectorNumber++;
} }
aes.IV = iv; return;
// Perform AES decryption
using MemoryStream stream = new();
using ICryptoTransform dec = aes.CreateDecryptor();
using CryptoStream cs = new(stream, dec, CryptoStreamMode.Write);
cs.Write(sector, 0, sector.Length);
cs.FlushFinalBlock();
return stream.ToArray();
} }
/// <summary> /// <summary>