001/*
002 * oauth2-oidc-sdk
003 *
004 * Copyright 2012-2016, Connect2id Ltd and contributors.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.oauth2.sdk.id;
019
020
021import com.nimbusds.oauth2.sdk.util.StringUtils;
022import net.jcip.annotations.Immutable;
023
024
025/**
026 * Opaque value used to maintain state between a request and a callback. Also
027 * serves as a protection against XSRF attacks, among other uses.
028 */
029@Immutable
030public final class State extends Identifier {
031        
032        
033        private static final long serialVersionUID = 5357710275974915335L;
034        
035        
036        /**
037         * Creates a new state with the specified value.
038         *
039         * @param value The state value. Must not be {@code null} or empty 
040         *              string.
041         */
042        public State(final String value) {
043        
044                super(value);
045        }
046
047
048        /**
049         * Creates a new state with a randomly generated value of the specified
050         * byte length, Base64URL-encoded.
051         *
052         * @param byteLength The byte length of the value to generate. Must be
053         *                   greater than one.
054         */
055        public State(final int byteLength) {
056        
057                super(byteLength);
058        }
059        
060        
061        /**
062         * Creates a new state with a randomly generated 256-bit (32-byte) 
063         * value, Base64URL-encoded.
064         */
065        public State() {
066
067                super();
068        }
069        
070        
071        @Override
072        public boolean equals(final Object object) {
073        
074                return object instanceof State &&
075                       this.toString().equals(object.toString());
076        }
077        
078        
079        /**
080         * Parses a state from the specified string.
081         *
082         * @param s The string to parse, {@code null} or empty if no state is
083         *          specified.
084         *
085         * @return The state, {@code null} if the parsed string was 
086         *         {@code null} or empty.
087         */
088        public static State parse(final String s) {
089        
090                if (StringUtils.isBlank(s))
091                        return null;
092                
093                return new State(s);
094        }
095}