/// <summary>
/// Read the header from a stream. This method advances the stream by
/// the length of the header but doesn't close the stream.
/// </summary>
/// <param name="stream">The stream to read the header from</param>
/// <returns>Sii file header information</returns>
public static SiiHeader FromStream(Stream stream)
{
SiiHeader header = new SiiHeader();
using (BinaryReader br = new BinaryReader(stream, Encoding.UTF8, true)) {
header.Signature = br.ReadUInt32();
header.Hmac = br.ReadBytes(32);
header.InitializationVector = br.ReadBytes(16);
header.DecompressedUnitSize = br.ReadUInt32();
}
return(header);
}
/// <summary>
/// Read a Sii binary file.
/// </summary>
/// <param name="stream">Stream containing the sii binary data</param>
/// <returns>The root Sii object representing the unit</returns>
public async Task <Object> ReadFromBinary(Stream stream)
{
SiiHeader header = SiiHeader.FromStream(stream);
using (MemoryStream plainStream = new MemoryStream()) {
if (header.Signature != SII_CRYPTO_UNIT_SIGNATURE) // Not a valid encrypted unit
{
throw new InvalidSiiFileException();
}
await SiiEncryption.Decrypt(stream, plainStream, header.InitializationVector);
plainStream.Position = 0;
byte[] plainSig = new byte[SII_TEXT_UNIT_SIGNATURE.Length];
byte[] txtSig = Encoding.UTF8.GetBytes(SII_TEXT_UNIT_SIGNATURE);
bool compressed = false;
plainStream.Read(plainSig, 0, plainSig.Length);
plainStream.Position = 0;
for (int i = 0; i < txtSig.Length; i++)
{
if (txtSig[i] != plainSig[i])
{
compressed = true;
break;
}
}
Stream decompressedStream;
if (compressed)
{
decompressedStream = new MemoryStream();
await SiiCompression.Decompress(plainStream, decompressedStream);
decompressedStream.Position = 0;
}
else
{
decompressedStream = plainStream;
}
return(await ReadFromText(decompressedStream));
}
}
