#region Disclaimer / License
// Copyright (C) 2015, The Duplicati Team
// http://www.duplicati.com, info@duplicati.com
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
#endregion
using System;
using System.Collections.Generic;
using System.Text;
namespace Duplicati.Library.Utility
{
///
/// A special stream that does on-the-fly MD5 calculations
///
public class MD5CalculatingStream : HashCalculatingStream
{
public MD5CalculatingStream(System.IO.Stream basestream)
: base(basestream, "MD5")
{
}
}
///
/// A special stream that does on-the-fly hash calculations
///
public class HashCalculatingStream : OverrideableStream
{
private System.Security.Cryptography.HashAlgorithm m_hash;
private byte[] m_finalHash = null;
bool m_hasRead = false;
bool m_hasWritten = false;
private byte[] m_hashbuffer = null;
private int m_hashbufferLength = 0;
public HashCalculatingStream(System.IO.Stream basestream, string hashalgorithm)
: this(basestream, HashAlgorithmHelper.Create(hashalgorithm))
{
}
public HashCalculatingStream(System.IO.Stream basestream, System.Security.Cryptography.HashAlgorithm algorithm)
: base(basestream)
{
m_hash = algorithm;
m_hash.Initialize();
m_hashbuffer = new byte[m_hash.InputBlockSize];
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
if (m_hash != null)
{
m_hash.Clear();
m_hash = null;
m_hashbuffer = null;
m_hashbufferLength = 0;
}
}
public override int Read(byte[] buffer, int offset, int count)
{
if (m_hasWritten)
throw new InvalidOperationException(Strings.MD5CalculatingStream.IncorrectUsageError);
m_hasRead = true;
int tmp = base.Read(buffer, offset, count);
UpdateHash(buffer, offset, tmp);
return tmp;
}
public override void Write(byte[] buffer, int offset, int count)
{
if (m_hasRead)
throw new InvalidOperationException(Strings.MD5CalculatingStream.IncorrectUsageError);
m_hasWritten = true;
UpdateHash(buffer, offset, count);
base.Write(buffer, offset, count);
}
private void UpdateHash(byte[] buffer, int offset, int count)
{
if (m_finalHash != null)
throw new Exception("Cannot read/write after hash is read");
//If we have a fragment from the last block, fill up
if (m_hashbufferLength > 0 && count + m_hashbufferLength > m_hashbuffer.Length)
{
int bytesToUse = m_hashbuffer.Length - m_hashbufferLength;
Array.Copy(buffer, m_hashbuffer, bytesToUse);
m_hash.TransformBlock(m_hashbuffer, 0, m_hashbuffer.Length, m_hashbuffer, 0);
count -= bytesToUse;
offset += bytesToUse;
m_hashbufferLength = 0;
}
//Take full blocks directly
int fullBlocks = count / m_hashbuffer.Length;
if (fullBlocks > 0)
{
int bytesToUse = fullBlocks * m_hashbuffer.Length;
m_hash.TransformBlock(buffer, offset, bytesToUse, buffer, offset);
count -= bytesToUse;
offset += bytesToUse;
}
//Keep trailing bytes
if (count > 0)
{
Array.Copy(buffer, offset, m_hashbuffer, 0, count);
m_hashbufferLength = count;
}
}
public string GetFinalHashString()
{
return Utility.ByteArrayAsHexString(this.GetFinalHash());
}
public byte[] GetFinalHash()
{
if (m_finalHash == null)
{
m_hash.TransformFinalBlock(m_hashbuffer, 0, m_hashbufferLength);
m_finalHash = m_hash.Hash;
}
return m_finalHash;
}
}
}