uint GetContentKey(ArcView file, List<Entry> dir, EncryptionScheme scheme)
{
if (null != scheme.ContentKey)
return scheme.ContentKey.Value;
if ("system.arc".Equals (Path.GetFileName (file.Name), StringComparison.InvariantCultureIgnoreCase))
{
return ReadSysenvSeed (file, dir, scheme.IndexKey);
}
else
{
var system_arc = VFS.CombinePath (VFS.GetDirectoryName (file.Name), "system.arc");
using (var arc = VFS.OpenView (system_arc))
{
var header = arc.View.ReadBytes (0, 0x30);
Decrypt (header, 0, scheme.IndexKey);
using (var arc_file = ReadIndex (arc, header, scheme))
{
return ReadSysenvSeed (arc, arc_file.Dir, scheme.IndexKey);
}
}
}
}
AzArchive ReadIndex(ArcView file, byte[] header, EncryptionScheme scheme)
{
int ext_count = LittleEndian.ToInt32 (header, 4);
int count = LittleEndian.ToInt32 (header, 8);
uint index_length = LittleEndian.ToUInt32 (header, 12);
if (ext_count < 1 || ext_count > 8 || !IsSaneCount (count) || index_length >= file.MaxOffset)
return null;
var packed_index = file.View.ReadBytes (header.Length, index_length);
if (packed_index.Length != index_length)
return null;
Decrypt (packed_index, header.Length, scheme.IndexKey);
uint checksum = LittleEndian.ToUInt32 (packed_index, 0);
if (checksum != Adler32.Compute (packed_index, 4, packed_index.Length-4))
{
if (checksum != Crc32.Compute (packed_index, 4, packed_index.Length-4))
throw new InvalidFormatException ("Index checksum mismatch");
}
using (var input = new MemoryStream (packed_index, 4, packed_index.Length-4))
{
var dir = ParseIndex (input, count, header.Length + index_length, file.MaxOffset);
if (null == dir)
return null;
uint content_key = GetContentKey (file, dir, scheme);
return new AzArchive (file, this, dir, scheme.IndexKey, content_key);
}
}
public override ArcFile TryOpen(ArcView file)
{
byte[] header_encrypted = file.View.ReadBytes (0, 0x30);
if (header_encrypted.Length < 0x30)
return null;
byte[] header = new byte[header_encrypted.Length];
if (CurrentScheme != null)
{
try
{
Buffer.BlockCopy (header_encrypted, 0, header, 0, header.Length);
Decrypt (header, 0, CurrentScheme.IndexKey);
if (Binary.AsciiEqual (header, 0, "ARC\0"))
{
var arc = ReadIndex (file, header, CurrentScheme);
if (null != arc)
return arc;
}
}
catch { /* ignore parse errors */ }
}
foreach (var scheme in KnownSchemes.Values)
{
Buffer.BlockCopy (header_encrypted, 0, header, 0, header.Length);
Decrypt (header, 0, scheme.IndexKey);
if (Binary.AsciiEqual (header, 0, "ARC\0"))
{
var arc = ReadIndex (file, header, scheme);
if (null != arc)
CurrentScheme = new EncryptionScheme (arc.SysenvKey, arc.RegularKey);
return arc;
}
}
return null;
}
