/* JCESecurityParameters.java -- JCE-based security parameters.
   Copyright (C) 2004  Casey Marshall <csm@gnu.org>

This file is a part of Jessie.

Jessie is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

Jessie 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 General Public License
for more details.

You should have received a copy of the GNU General Public License along
with Jessie; if not, write to the

   Free Software Foundation, Inc.,
   59 Temple Place, Suite 330,
   Boston, MA  02111-1307
   USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under terms
of your choice, provided that you also meet, for each linked independent
module, the terms and conditions of the license of that module.  An
independent module is a module which is not derived from or based on
this library.  If you modify this library, you may extend this exception
to your version of the library, but you are not obligated to do so.  If
you do not wish to do so, delete this exception statement from your
version.  */


package org.metastatic.jessie.provider;

import java.io.ByteArrayOutputStream;

import java.util.Arrays;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.Mac;

import javax.net.ssl.SSLException;

class JCESecurityParameters implements SecurityParameters
{

  // Fields.
  // -------------------------------------------------------------------------

  private Cipher inCipher, outCipher;
  private Mac inMac, outMac;
  private Inflater inflater;
  private Deflater deflater;
  private int fragmentLength;
  private long inSequence, outSequence;
  private ProtocolVersion version;

  // Constructors.
  // -------------------------------------------------------------------------

  JCESecurityParameters ()
  {
    fragmentLength = 16384;
    inSequence = 0L;
    outSequence = 0L;
  }

  // Instance methods.
  // -------------------------------------------------------------------------

  public void reset()
  {
    inCipher = null;
    outCipher = null;
    inMac = null;
    outMac = null;
    deflater = null;
    inflater = null;
  }

  public void setInCipher (Object inCipher)
  {
    this.inCipher = (Cipher) inCipher;
  }

  public void setOutCipher (Object outCipher)
  {
    this.outCipher = (Cipher) outCipher;
  }

  public void setInMac (Object inMac)
  {
    this.inMac = (Mac) inMac;
    inSequence = 0L;
  }

  public void setOutMac (Object outMac)
  {
    this.outMac = (Mac) outMac;
    outSequence = 0L;
  }

  public void setDeflating (boolean deflate)
  {
    if (deflate)
      {
        if (deflater == null)
          deflater = new Deflater();
      }
    else
      deflater = null;
  }

  public void setInflating (boolean inflate)
  {
    if (inflate)
      {
        if (inflater == null)
          inflater = new Inflater();
      }
    else
      inflater = null;
  }

  public int getFragmentLength()
  {
    return fragmentLength;
  }

  public void setFragmentLength (int fragmentLength)
  {
    this.fragmentLength = fragmentLength;
  }

  public ProtocolVersion getVersion()
  {
    return version;
  }

  public void setVersion (ProtocolVersion version)
  {
    this.version = version;
  }

  public synchronized byte[] decrypt (byte[] fragment, ProtocolVersion version,
                                      ContentType type)
    throws MacException, OverflowException, SSLException
  {
    boolean badpad = false;
    if (inCipher != null)
      {
        // We imagine that the JCE would be used in cases where hardware
        // acceleration is available, since it isn't really that useful for
        // pure Java crypto. We decrypt (and encrypt, below) in one go
        // to minimize (potential) calls to native methods.
        try
          {
            fragment = inCipher.doFinal (fragment);
          }
        catch (BadPaddingException bpe)
          {
            badpad = true;
          }
        catch (IllegalBlockSizeException ibse)
          {
            badpad = true;
          }
      }

    if (inMac != null)
      {
        int macLen = inMac.getMacLength();
        int fragLen = fragment.length - macLen;
        byte[] mac = Util.trim (fragment, fragLen, macLen);
        fragment = Util.trim (fragment, fragLen);
        inMac.update ((byte) (inSequence >>> 56));
        inMac.update ((byte) (inSequence >>> 48));
        inMac.update ((byte) (inSequence >>> 40));
        inMac.update ((byte) (inSequence >>> 32));
        inMac.update ((byte) (inSequence >>> 24));
        inMac.update ((byte) (inSequence >>> 16));
        inMac.update ((byte) (inSequence >>>  8));
        inMac.update ((byte)  inSequence);
        inMac.update ((byte) type.getValue());
        if (version != ProtocolVersion.SSL_3)
          {
            inMac.update ((byte) version.getMajor());
            inMac.update ((byte) version.getMinor());
          }
        inMac.update ((byte) (fragLen >>> 8));
        inMac.update ((byte)  fragLen);
        inMac.update (fragment);
        if (!Arrays.equals (mac, inMac.doFinal()) || badpad)
          throw new MacException();
      }

    if (inflater != null)
      {
        byte[] buf = new byte[1024];
        ByteArrayOutputStream bout = new ByteArrayOutputStream (fragment.length << 1);
        inflater.setInput (fragment);
        int len;
        try
          {
            while ((len = inflater.inflate (buf)) > 0)
              {
                bout.write (buf, 0, len);
                if (bout.size() > fragmentLength + 1024)
                  throw new OverflowException ("inflated data too large");
              }
          }
        catch (DataFormatException dfe)
          {
            throw new SSLException (String.valueOf (dfe));
          }
        fragment = bout.toByteArray();
        inflater.reset();
      }

    inSequence++;
    return fragment;
  }

  public synchronized byte[] encrypt (byte[] fragment, int off, int len,
                                      ContentType type)
    throws OverflowException, SSLException
  {
    if (deflater != null)
      {
        byte[] buf = new byte[1024];
        ByteArrayOutputStream bout = new ByteArrayOutputStream (len >>> 1);
        deflater.setInput (fragment, off, len);
        deflater.finish();
        len = 0;
        while ((len = deflater.deflate (buf)) > 0)
          bout.write (buf, 0, len);
        // This should technically never happen for zlib.
        if (bout.size() > fragmentLength + 1024)
          throw new OverflowException ("deflated data too large");
        fragment = bout.toByteArray();
        off = 0;
        len = fragment.length;
        deflater.reset();
      }

    if (outMac != null)
      {
        outMac.update ((byte) (inSequence >>> 56));
        outMac.update ((byte) (inSequence >>> 48));
        outMac.update ((byte) (inSequence >>> 40));
        outMac.update ((byte) (inSequence >>> 32));
        outMac.update ((byte) (inSequence >>> 24));
        outMac.update ((byte) (inSequence >>> 16));
        outMac.update ((byte) (inSequence >>>  8));
        outMac.update ((byte)  inSequence);
        outMac.update ((byte) type.getValue());
        if (version != ProtocolVersion.SSL_3)
          {
            outMac.update ((byte) version.getMajor());
            outMac.update ((byte) version.getMinor());
          }
        outMac.update ((byte) (len >>> 8));
        outMac.update ((byte)  len);
        outMac.update (fragment, off, len);
        fragment = Util.concat (fragment, outMac.doFinal());
        off = 0;
        len = fragment.length;
      }

    if (outCipher != null)
      {
        try
          {
            fragment = outCipher.doFinal (fragment, off, len);
          }
        catch (BadPaddingException shouldNeverHappen)
          {
            // This is nonsensical. Don't even pretend that we can handle this.
            throw new RuntimeException ("bad padding thrown while encrypting");
          }
        catch (IllegalBlockSizeException ibse)
          {
            // Ditto.
            throw new RuntimeException ("illegal block size thrown while encrypting");
          }
        off = 0;
        len = fragment.length;
      }

    outSequence++;
    if (off == 0 && len == fragment.length)
      return fragment;
    else
      return Util.trim (fragment, off, len);
  }
}