/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.catalina.realm;


import java.io.IOException;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;

import org.apache.catalina.util.StringManager;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * <p>Implementation of the JAAS <code>CallbackHandler</code> interface,
 * used to negotiate delivery of the username and credentials that were
 * specified to our constructor.  No interaction with the user is required
 * (or possible).</p>
 *
 * <p>This <code>CallbackHandler</code> will pre-digest the supplied
 * password, if required by the <code>&lt;Realm&gt;</code> element in 
 * <code>server.xml</code>.</p>
 * <p>At present, <code>JAASCallbackHandler</code> knows how to handle callbacks of
 * type <code>javax.security.auth.callback.NameCallback</code> and
 * <code>javax.security.auth.callback.PasswordCallback</code>.</p>
 *
 * @author Craig R. McClanahan
 * @author Andrew R. Jaquith
 * @version $Revision$ $Date$
 */

public class JAASCallbackHandler implements CallbackHandler {
    private static Log log = LogFactory.getLog(JAASCallbackHandler.class);

    // ------------------------------------------------------------ Constructor


    /**
     * Construct a callback handler configured with the specified values.
     * Note that if the <code>JAASRealm</code> instance specifies digested passwords,
     * the <code>password</code> parameter will be pre-digested here.
     *
     * @param realm Our associated JAASRealm instance
     * @param username Username to be authenticated with
     * @param password Password to be authenticated with
     */
    public JAASCallbackHandler(JAASRealm realm, String username,
                               String password) {

        super();
        this.realm = realm;
        this.username = username;

        if (realm.hasMessageDigest()) {
            this.password = realm.digest(password);
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("jaasCallback.digestpassword", password, this.password));
            }
        }
        else {
            this.password = password;
        }
    }


    // ----------------------------------------------------- Instance Variables

    /**
     * The string manager for this package.
     */
    protected static final StringManager sm =
        StringManager.getManager(Constants.Package);

    /**
     * The password to be authenticated with.
     */
    protected String password = null;


    /**
     * The associated <code>JAASRealm</code> instance.
     */
    protected JAASRealm realm = null;


    /**
     * The username to be authenticated with.
     */
    protected String username = null;


    // --------------------------------------------------------- Public Methods


    /**
     * Retrieve the information requested in the provided <code>Callbacks</code>.
     * This implementation only recognizes <code>NameCallback</code> and
     * <code>PasswordCallback</code> instances.
     *
     * @param callbacks The set of <code>Callback</code>s to be processed
     *
     * @exception IOException if an input/output error occurs
     * @exception UnsupportedCallbackException if the login method requests
     *  an unsupported callback type
     */
    public void handle(Callback callbacks[])
        throws IOException, UnsupportedCallbackException {

        for (int i = 0; i < callbacks.length; i++) {

            if (callbacks[i] instanceof NameCallback) {
                if (realm.getContainer().getLogger().isTraceEnabled())
                    realm.getContainer().getLogger().trace(sm.getString("jaasCallback.username", username));
                ((NameCallback) callbacks[i]).setName(username);
            } else if (callbacks[i] instanceof PasswordCallback) {
                if (realm.getContainer().getLogger().isTraceEnabled())
                    realm.getContainer().getLogger().trace(sm.getString("jaasCallback.password", password));
                final char[] passwordcontents;
                if (password != null) {
                    passwordcontents = password.toCharArray();
                } else {
                    passwordcontents = new char[0];
                }
                ((PasswordCallback) callbacks[i]).setPassword
                    (passwordcontents);
            } else {
                throw new UnsupportedCallbackException(callbacks[i]);
            }
        }
    }
}