package gnu.crypto.sasl;

// ----------------------------------------------------------------------------
// $Id: ServerMechanism.java,v 1.4 2005/10/06 04:24:18 rsdio Exp $
//
// Copyright (C) 2003, 2005 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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, or (at your option)
// any later version.
//
// GNU Crypto 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 this program; see the file COPYING.  If not, write to the
//
//    Free Software Foundation Inc.,
//    51 Franklin Street, 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
// 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.
// ----------------------------------------------------------------------------

import gnu.crypto.Registry;

import java.util.HashMap;
import java.util.Map;

import javax.security.auth.callback.CallbackHandler;
import javax.security.sasl.Sasl;
import javax.security.sasl.SaslServer;
import javax.security.sasl.SaslException;

/**
 * <p>A base class to facilitate implementing SASL server-side mechanisms.</p>
 *
 * @version $Revision: 1.4 $
 */
public abstract class ServerMechanism implements SaslServer {

   // Constants and variables
   // -------------------------------------------------------------------------

   /** Name of this mechanism. */
   protected String mechanism;

   /** Name of protocol using this mechanism. */
   protected String protocol;

   /** Name of server to authenticate to. */
   protected String serverName;

   /** Properties of qualities desired for this mechanism. */
   protected Map properties;

   /** Callback handler to use with this mechanism instance. */
   protected CallbackHandler handler;

   /** Whether authentication phase is completed (true) or not (false). */
   protected boolean complete = false;

   /** The authorisation identity. */
   protected String authorizationID;

   /** Channel binding data to use with this mechanism instance. */
   protected byte[] channelBinding;

   /** The state of the authentication automaton. -1 means uninitialised. */
   protected int state = -1;

   /** The provider for authentication information. */
   protected IAuthInfoProvider authenticator;

   // Constructor(s)
   // -------------------------------------------------------------------------

   protected ServerMechanism(final String mechanism) {
      super();

      this.mechanism = mechanism;
      this.authenticator = AuthInfo.getProvider(mechanism);
      this.state = -1;
   }

   // Class methods
   // -------------------------------------------------------------------------

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

   // abstract methods to be implemented by concrete subclasses ---------------

   protected abstract void initMechanism() throws SaslException;
   protected abstract void resetMechanism() throws SaslException;

   // javax.security.sasl.SaslServer interface implementation -----------------

   public abstract byte[] evaluateResponse(byte[] response) throws SaslException;

   public boolean isComplete() {
      return complete;
   }

   public byte[] unwrap(final byte[] incoming, final int offset, final int len)
   throws SaslException {
      if (!isComplete()) {
         throw new IllegalMechanismStateException();
      }
      return this.engineUnwrap(incoming, offset, len);
   }

   public byte[] wrap(final byte[] outgoing, final int offset, final int len)
   throws SaslException {
      if (!isComplete()) {
         throw new IllegalMechanismStateException();
      }
      return this.engineWrap(outgoing, offset, len);
   }

   public String getMechanismName() {
      return this.mechanism;
   }

   public String getAuthorizationID() {
      return this.authorizationID;
   }

   public Object getNegotiatedProperty(final String propName) {
      if (!isComplete()) {
         throw new IllegalStateException();
      }
      if (Sasl.QOP.equals(propName)) {
         return getNegotiatedQOP();
      }
      if (Sasl.STRENGTH.equals(propName)) {
         return getNegotiatedStrength();
      }
      if (Sasl.SERVER_AUTH.equals(propName)) {
         return getNegotiatedServerAuth();
      }
      if (Sasl.MAX_BUFFER.equals(propName)) {
         return getNegotiatedMaxBuffer();
      }
      if (Sasl.RAW_SEND_SIZE.equals(propName)) {
         return getNegotiatedRawSendSize();
      }
      if (Sasl.POLICY_NOPLAINTEXT.equals(propName)) {
         return getNegotiatedPolicyNoPlainText();
      }
      if (Sasl.POLICY_NOACTIVE.equals(propName)) {
         return getNegotiatedPolicyNoActive();
      }
      if (Sasl.POLICY_NODICTIONARY.equals(propName)) {
         return getNegotiatedPolicyNoDictionary();
      }
      if (Sasl.POLICY_NOANONYMOUS.equals(propName)) {
         return getNegotiatedPolicyNoAnonymous();
      }
      if (Sasl.POLICY_FORWARD_SECRECY.equals(propName)) {
         return getNegotiatedPolicyForwardSecrecy();
      }
      if (Sasl.POLICY_PASS_CREDENTIALS.equals(propName)) {
         return getNegotiatedPolicyPassCredentials();
      }
      if (Sasl.REUSE.equals(propName)) {
         return getReuse();
      }
      return null;
   }

   public void dispose() throws SaslException {
      reset();
   }

   // other Instance methods --------------------------------------------------

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

   protected String getNegotiatedStrength() {
      return Registry.STRENGTH_LOW;
   }

   protected String getNegotiatedServerAuth() {
      return Registry.SERVER_AUTH_FALSE;
   }

   protected String getNegotiatedMaxBuffer() {
      return null;
   }

   protected String getNegotiatedPolicyNoPlainText() {
      return null;
   }

   protected String getNegotiatedPolicyNoActive() {
      return null;
   }

   protected String getNegotiatedPolicyNoDictionary() {
      return null;
   }

   protected String getNegotiatedPolicyNoAnonymous() {
      return null;
   }

   protected String getNegotiatedPolicyForwardSecrecy() {
      return null;
   }

   protected String getNegotiatedPolicyPassCredentials() {
      return null;
   }

   protected String getNegotiatedRawSendSize() {
      return String.valueOf(Registry.SASL_BUFFER_MAX_LIMIT);
   }

   protected String getReuse() {
      return Registry.REUSE_FALSE;
   }

   protected byte[]
   engineUnwrap(final byte[] incoming, final int offset, final int len)
   throws SaslException {
      final byte[] result = new byte[len];
      System.arraycopy(incoming, offset, result, 0, len);
      return result;
   }

   protected byte[]
   engineWrap(final byte[] outgoing, final int offset, final int len)
   throws SaslException {
      final byte[] result = new byte[len];
      System.arraycopy(outgoing, offset, result, 0, len);
      return result;
   }

   /**
    * <p>Initialises the mechanism with designated attributes. Permissible names
    * and values are mechanism specific.</p>
    *
    * @param attributes a set of name-value pairs that describes the desired
    * future behaviour of this instance.
    * @throws IllegalMechanismStateException if the instance is already
    * initialised.
    * @throws SaslException if an exception occurs during the process.
    */
   public void init(final Map attributes) throws SaslException {
      if (state != -1) {
         throw new IllegalMechanismStateException("init()");
      }

      if (properties == null) {
         properties = new HashMap();
      } else {
         properties.clear();
      }
      if (attributes != null) {
         protocol = (String) attributes.get(Registry.SASL_PROTOCOL);
         serverName = (String) attributes.get(Registry.SASL_SERVER_NAME);
         handler = (CallbackHandler) attributes.get(Registry.SASL_CALLBACK_HANDLER);
         channelBinding = (byte[]) attributes.get(Registry.SASL_CHANNEL_BINDING);
         properties.putAll(attributes);
      } else {
         handler = null;
      }

      if (protocol == null) {
         protocol = "";
      }
      if (serverName == null) {
         serverName = "";
      }
      if (authenticator != null) {
         authenticator.activate(properties);
      }
      if (channelBinding == null) {
         channelBinding = new byte[0];
      }
      initMechanism();
      complete = false;
      state = 0;
   }

   /**
    * <p>Resets the mechanism instance for re-initialisation and use with other
    * characteristics.</p>
    *
    * @throws SaslException if an exception occurs during the process.
    */
   public void reset() throws SaslException {
      resetMechanism();
      properties.clear();
      if (authenticator != null) {
         authenticator.passivate();
      }
      protocol = serverName = null;
      channelBinding = null;
      complete = false;
      state = -1;
   }
}
