/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.security.Principal;
import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.util.StringManager;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.digester.Digester;


/**
 * Simple implementation of <b>Realm</b> that reads an XML file to configure
 * the valid users, passwords, and roles.  The file format (and default file
 * location) are identical to those currently supported by Tomcat 3.X.
 * <p>
 * <strong>IMPLEMENTATION NOTE</strong>: It is assumed that the in-memory
 * collection representing our defined users (and their roles) is initialized
 * at application startup and never modified again.  Therefore, no thread
 * synchronization is performed around accesses to the principals collection.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 543691 $ $Date: 2007-06-02 03:37:08 +0200 (Sat, 02 Jun 2007) $
 */

public class MemoryRealm  extends RealmBase {

    /**
     * Return the Principal associated with the specified username and
     * credentials, if there is one; otherwise return <code>null</code>.
     *
     * @param username Username of the Principal to look up
     * @param credentials Password or other credentials to use in
     *  authenticating this username
     */
    public Principal authenticate(String username, String credentials) {
        GenericPrincipal principal = (GenericPrincipal) principals.get(username);

        if (principal != null) {
			validated = (digest(credentials).equalsIgnoreCase(principal.getPassword())); 
        }

        if (validated) {
			log.debug(sm.getString("memoryRealm.authenticateSuccess", username));
            return (principal);
        } 
    }

    /**
     * Return a short name for this Realm implementation.
     */
      /**
     * Digest the password using the specified algorithm and
     * convert the result to a corresponding hexadecimal string.
     * If exception, the plain credentials string is returned.
     *
     * @param credentials Password or other credentials to use in
     *  authenticating this username
     */
    protected String digest(String credentials)  {
        synchronized (this) {
            try {
                byte[] bytes = null;
                if(getDigestEncoding() == null) {
                    bytes = credentials.getBytes();
                } else {
                    try {
                        bytes = credentials.getBytes(getDigestEncoding());
					}
                }
                md.update(bytes);
                return (HexUtils.convert(md.digest()));
           }
		}
    }
}