/* CramMD5Client.java -- 
   Copyright (C) 2003, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath 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.

GNU Classpath 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.

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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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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
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package gnu.javax.crypto.sasl.crammd5;

import gnu.java.security.Registry;
import gnu.java.security.util.Util;
import gnu.javax.crypto.sasl.ClientMechanism;

import java.io.IOException;
import java.security.InvalidKeyException;

import javax.security.auth.callback.Callback;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
import javax.security.sasl.AuthenticationException;
import javax.security.sasl.SaslClient;
import javax.security.sasl.SaslException;

/**
 * The CRAM-MD5 SASL client-side mechanism.
 */
public class CramMD5Client
    extends ClientMechanism
    implements SaslClient
{
  public CramMD5Client()
  {
    super(Registry.SASL_CRAM_MD5_MECHANISM);
  }

  protected void initMechanism() throws SaslException
  {
  }

  protected void resetMechanism() throws SaslException
  {
  }

  public boolean hasInitialResponse()
  {
    return false;
  }

  public byte[] evaluateChallenge(final byte[] challenge) throws SaslException
  {
    if (challenge == null)
      throw new SaslException("null challenge");
    try
      {
        final String username;
        final char[] password;
        Callback[] callbacks;
        if ((! properties.containsKey(Registry.SASL_USERNAME))
            && (! properties.containsKey(Registry.SASL_PASSWORD)))
          {
            callbacks = new Callback[2];
            final NameCallback nameCB;
            final String defaultName = System.getProperty("user.name");
            if (defaultName == null)
              nameCB = new NameCallback("username: ");
            else
              nameCB = new NameCallback("username: ", defaultName);
            final PasswordCallback pwdCB = new PasswordCallback("password: ",
                                                                false);
            callbacks[0] = nameCB;
            callbacks[1] = pwdCB;
            this.handler.handle(callbacks);
            username = nameCB.getName();
            password = pwdCB.getPassword();
          }
        else
          {
            if (properties.containsKey(Registry.SASL_USERNAME))
              username = (String) properties.get(Registry.SASL_USERNAME);
            else
              {
                callbacks = new Callback[1];
                final NameCallback nameCB;
                final String defaultName = System.getProperty("user.name");
                if (defaultName == null)
                  nameCB = new NameCallback("username: ");
                else
                  nameCB = new NameCallback("username: ", defaultName);
                callbacks[0] = nameCB;
                this.handler.handle(callbacks);
                username = nameCB.getName();
              }

            if (properties.containsKey(Registry.SASL_PASSWORD))
              password = ((String) properties.get(Registry.SASL_PASSWORD)).toCharArray();
            else
              {
                callbacks = new Callback[1];
                final PasswordCallback pwdCB = new PasswordCallback("password: ",
                                                                    false);
                callbacks[0] = pwdCB;
                this.handler.handle(callbacks);
                password = pwdCB.getPassword();
              }
          }
        if (password == null)
          throw new SaslException("null password supplied");
        final byte[] digest;
        try
          {
            digest = CramMD5Util.createHMac(password, challenge);
          }
        catch (InvalidKeyException x)
          {
            throw new AuthenticationException("evaluateChallenge()", x);
          }
        final String response = username + " "
                                + Util.toString(digest).toLowerCase();
        this.complete = true;
        return response.getBytes("UTF-8");
      }
    catch (UnsupportedCallbackException x)
      {
        throw new AuthenticationException("evaluateChallenge()", x);
      }
    catch (IOException x)
      {
        throw new AuthenticationException("evaluateChallenge()", x);
      }
  }

  protected String getNegotiatedQOP()
  {
    return Registry.QOP_AUTH;
  }
}