byte[] CalculateHash(Stream stream, bool create)
{
long pos = stream.Position;
if (create)
{
_bodyLength = StreamLength(stream);
}
using (HashAlgorithm hasher = (_snk != null) ? _snk.CreateHasher() : QQnCryptoHelpers.CreateHashAlgorithm(_hashType))
{
long newPos = _hashPosition;
if (stream.Position != newPos)
{
stream.Position = newPos;
}
byte[] buffer;
using (MemoryStream ms = new MemoryStream()) // Use memorystream and writer to resolve endian-issues
using (QQnBinaryWriter bw = new QQnBinaryWriter(ms))
{
bw.Write(_guid.ToByteArray());
bw.Write(_bodyLength);
buffer = ms.ToArray();
}
hasher.TransformBlock(buffer, 0, buffer.Length, null, 0);
buffer = new byte[8192];
int nRead;
while (0 != (nRead = stream.Read(buffer, 0, buffer.Length)))
{
hasher.TransformBlock(buffer, 0, nRead, null, 0);
}
hasher.TransformFinalBlock(buffer, 0, 0);
if (stream.CanSeek)
{
stream.Position = pos;
}
return(hasher.Hash);
}
}
