001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.shiro.session.mgt.eis;
020    
021    import org.apache.shiro.session.Session;
022    import org.slf4j.Logger;
023    import org.slf4j.LoggerFactory;
024    
025    import java.io.Serializable;
026    import java.util.Random;
027    
028    /**
029     * Generates session IDs by using a {@link Random} instance to generate random IDs. The default {@code Random}
030     * implementation is a {@link java.security.SecureRandom SecureRandom} with the {@code SHA1PRNG} algorithm.
031     *
032     * @since 1.0
033     */
034    public class RandomSessionIdGenerator implements SessionIdGenerator {
035    
036        private static final Logger log = LoggerFactory.getLogger(RandomSessionIdGenerator.class);
037    
038        private static final String RANDOM_NUM_GENERATOR_ALGORITHM_NAME = "SHA1PRNG";
039        private Random random;
040    
041        public RandomSessionIdGenerator() {
042            try {
043                this.random = java.security.SecureRandom.getInstance(RANDOM_NUM_GENERATOR_ALGORITHM_NAME);
044            } catch (java.security.NoSuchAlgorithmException e) {
045                log.debug("The SecureRandom SHA1PRNG algorithm is not available on the current platform.  Using the " +
046                        "platform's default SecureRandom algorithm.", e);
047                this.random = new java.security.SecureRandom();
048            }
049        }
050    
051        public Random getRandom() {
052            return this.random;
053        }
054    
055        public void setRandom(Random random) {
056            this.random = random;
057        }
058    
059        /**
060         * Returns the String value of the configured {@link Random}'s {@link Random#nextLong() nextLong()} invocation.
061         *
062         * @param session the {@link Session} instance to which the ID will be applied.
063         * @return the String value of the configured {@link Random}'s {@link Random#nextLong()} invocation.
064         */
065        public Serializable generateId(Session session) {
066            //ignore the argument - just call the Random:
067            return Long.toString(getRandom().nextLong());
068        }
069    }