/*
 * Copyright (c) 2001-2004 Caucho Technology, Inc.  All rights reserved.
 *
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Caucho Technology (http://www.caucho.com/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "Hessian", "Resin", and "Caucho" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    info@caucho.com.
 *
 * 5. Products derived from this software may not be called "Resin"
 *    nor may "Resin" appear in their names without prior written
 *    permission of Caucho Technology.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CAUCHO TECHNOLOGY OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author Scott Ferguson
 */

package com.caucho.hessian.security;

import java.security.*;
import java.security.cert.*;
import java.util.*;
import javax.crypto.*;

import java.io.*;

import com.caucho.hessian.io.*;

public class X509Signature extends HessianEnvelope {
  private String _algorithm = "HmacSHA256";
  private X509Certificate _cert;
  private PrivateKey _privateKey;
  private SecureRandom _secureRandom;
  
  public X509Signature()
  {
  }

  /**
   * Sets the encryption algorithm for the content.
   */
  public void setAlgorithm(String algorithm)
  {
    if (algorithm == null)
      throw new NullPointerException();
    
    _algorithm = algorithm;
  }

  /**
   * Gets the encryption algorithm for the content.
   */
  public String getAlgorithm()
  {
    return _algorithm;
  }

  /**
   * The X509 certificate to obtain the public key of the recipient.
   */
  public X509Certificate getCertificate()
  {
    return _cert;
  }

  /**
   * The X509 certificate to obtain the public key of the recipient.
   */
  public void setCertificate(X509Certificate cert)
  {
    _cert = cert;
  }

  /**
   * The key to obtain the private key of the recipient.
   */
  public PrivateKey getPrivateKey()
  {
    return _privateKey;
  }

  /**
   * The private key.
   */
  public void setPrivateKey(PrivateKey key)
  {
    _privateKey = key;
  }

  /**
   * The random number generator for the shared secrets.
   */
  public SecureRandom getSecureRandom()
  {
    return _secureRandom;
  }

  /**
   * The random number generator for the shared secrets.
   */
  public void setSecureRandom(SecureRandom random)
  {
    _secureRandom = random;
  }

  public Hessian2Output wrap(Hessian2Output out)
    throws IOException
  {
    if (_privateKey == null)
      throw new IOException("X509Signature.wrap requires a private key");
    
    if (_cert == null)
      throw new IOException("X509Signature.wrap requires a certificate");
    
    OutputStream os = new SignatureOutputStream(out);
    
    Hessian2Output filterOut = new Hessian2Output(os);

    filterOut.setCloseStreamOnClose(true);
    
    return filterOut;
  }

  public Hessian2Input unwrap(Hessian2Input in)
    throws IOException
  {
    if (_cert == null)
      throw new IOException("X509Signature.unwrap requires a certificate");
    
    int version = in.readEnvelope();

    String method = in.readMethod();

    if (! method.equals(getClass().getName()))
      throw new IOException("expected hessian Envelope method '" +
                            getClass().getName() + "' at '" + method + "'");

    return unwrapHeaders(in);
  }

  public Hessian2Input unwrapHeaders(Hessian2Input in)
    throws IOException
  {
    if (_cert == null)
      throw new IOException("X509Signature.unwrap requires a certificate");
    
    InputStream is = new SignatureInputStream(in);

    Hessian2Input filter = new Hessian2Input(is);

    filter.setCloseStreamOnClose(true);
    
    return filter;
  }

  class SignatureOutputStream extends OutputStream {
    private Hessian2Output _out;
    private OutputStream _bodyOut;
    private Mac _mac;
    
    SignatureOutputStream(Hessian2Output out)
      throws IOException
    {
      try {
        KeyGenerator keyGen = KeyGenerator.getInstance(_algorithm);

        if (_secureRandom != null)
          keyGen.init(_secureRandom);

        SecretKey sharedKey = keyGen.generateKey();
    
        _out = out;

        _out.startEnvelope(X509Signature.class.getName());
      
        PublicKey publicKey = _cert.getPublicKey();

        byte []encoded = publicKey.getEncoded();
        MessageDigest md = MessageDigest.getInstance("SHA1");
        md.update(encoded);
        byte []fingerprint = md.digest();

        String keyAlgorithm = _privateKey.getAlgorithm();
        Cipher keyCipher = Cipher.getInstance(keyAlgorithm);
        keyCipher.init(Cipher.WRAP_MODE, _privateKey);

        byte []encKey = keyCipher.wrap(sharedKey);
    
        _out.writeInt(4);
        _out.writeString("algorithm");
        _out.writeString(_algorithm);
        _out.writeString("fingerprint");
        _out.writeBytes(fingerprint);
        _out.writeString("key-algorithm");
        _out.writeString(keyAlgorithm);
        _out.writeString("key");
        _out.writeBytes(encKey);

        _mac = Mac.getInstance(_algorithm);
        _mac.init(sharedKey);

        _bodyOut = _out.getBytesOutputStream();
      } catch (RuntimeException e) {
        throw e;
      } catch (IOException e) {
        throw e;
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }

    public void write(int ch)
      throws IOException
    {
      _bodyOut.write(ch);
      _mac.update((byte) ch);
    }

    public void write(byte []buffer, int offset, int length)
      throws IOException
    {
      _bodyOut.write(buffer, offset, length);
      _mac.update(buffer, offset, length);
    }

    public void close()
      throws IOException
    {
      Hessian2Output out = _out;
      _out = null;

      if (out == null)
        return;
      
      _bodyOut.close();

      byte []sig = _mac.doFinal();

      out.writeInt(1);
      out.writeString("signature");
      out.writeBytes(sig);

      out.completeEnvelope();
      out.close();
    }
  }
  
  class SignatureInputStream extends InputStream {
    private Hessian2Input _in;
    
    private Mac _mac;
    private InputStream _bodyIn;
    private CipherInputStream _cipherIn;
    
    SignatureInputStream(Hessian2Input in)
      throws IOException
    {
      try {
        _in = in;

        byte []fingerprint = null;
        String keyAlgorithm = null;
        String algorithm = null;
        byte []encKey = null;

        int len = in.readInt();

        for (int i = 0; i < len; i++) {
          String header = in.readString();

          if ("fingerprint".equals(header))
            fingerprint = in.readBytes();
          else if ("key-algorithm".equals(header))
            keyAlgorithm = in.readString();
          else if ("algorithm".equals(header))
            algorithm = in.readString();
          else if ("key".equals(header))
            encKey = in.readBytes();
          else
            throw new IOException("'" + header + "' is an unexpected header");
        }

        Cipher keyCipher = Cipher.getInstance(keyAlgorithm);
        keyCipher.init(Cipher.UNWRAP_MODE, _cert);

        Key key = keyCipher.unwrap(encKey, algorithm, Cipher.SECRET_KEY);
        _bodyIn = _in.readInputStream();

        _mac = Mac.getInstance(algorithm);
        _mac.init(key);
      } catch (RuntimeException e) {
        throw e;
      } catch (IOException e) {
        throw e;
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    
    public int read()
      throws IOException
    {
      int ch = _bodyIn.read();

      if (ch < 0)
        return ch;

      _mac.update((byte) ch);

      return ch;
    }
    
    public int read(byte []buffer, int offset, int length)
      throws IOException
    {
      int len = _bodyIn.read(buffer, offset, length);

      if (len < 0)
        return len;

      _mac.update(buffer, offset, len);

      return len;
    }

    public void close()
      throws IOException
    {
      Hessian2Input in = _in;
      _in = null;

      if (in != null) {
        _bodyIn.close();

        int len = in.readInt();
        byte []signature = null;

        for (int i = 0; i < len; i++) {
          String header = in.readString();

          if ("signature".equals(header))
            signature = in.readBytes();
        }

        in.completeEnvelope();
        in.close();
          

        if (signature == null)
          throw new IOException("Expected signature");

        byte []sig = _mac.doFinal();

        if (sig.length != signature.length)
          throw new IOException("mismatched signature");

        for (int i = 0; i < sig.length; i++) {
          if (signature[i] != sig[i])
            throw new IOException("mismatched signature");
        }

        // XXX: save principal
      }
    }
  }
}
