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 */
019package org.apache.shiro.authc.pam;
020
021import org.apache.shiro.authc.AuthenticationException;
022import org.apache.shiro.authc.AuthenticationInfo;
023import org.apache.shiro.authc.AuthenticationToken;
024import org.apache.shiro.realm.Realm;
025import org.apache.shiro.subject.PrincipalCollection;
026
027import java.util.Collection;
028
029/**
030 * {@link AuthenticationStrategy} implementation that only accepts the account data from
031 * the first successfully consulted Realm and ignores all subsequent realms.  This is slightly
032 * different behavior than {@link AtLeastOneSuccessfulStrategy}, so please review both to see
033 * which one meets your needs better.
034 *
035 * @see AtLeastOneSuccessfulStrategy AtLeastOneSuccessfulAuthenticationStrategy
036 * @since 0.9
037 */
038public class FirstSuccessfulStrategy extends AbstractAuthenticationStrategy {
039
040    private boolean stopAfterFirstSuccess;
041
042    public void setStopAfterFirstSuccess(boolean stopAfterFirstSuccess) {
043        this.stopAfterFirstSuccess = stopAfterFirstSuccess;
044    }
045
046    public boolean getStopAfterFirstSuccess() {
047        return stopAfterFirstSuccess;
048    }
049
050    /**
051     * Returns {@code null} immediately, relying on this class's {@link #merge merge} implementation to return
052     * only the first {@code info} object it encounters, ignoring all subsequent ones.
053     */
054    public AuthenticationInfo beforeAllAttempts(Collection<? extends Realm> realms, AuthenticationToken token)
055            throws AuthenticationException {
056        return null;
057    }
058
059    /**
060     * Throws ShortCircuitIterationException if stopAfterFirstSuccess is set and authentication is
061     * successful with a previously consulted realm.
062     * Returns the <code>aggregate</code> method argument, without modification
063     * otherwise.
064     */
065    public AuthenticationInfo beforeAttempt(Realm realm, AuthenticationToken token, AuthenticationInfo aggregate)
066            throws AuthenticationException {
067        if (getStopAfterFirstSuccess() && aggregate != null && !isEmpty(aggregate.getPrincipals())) {
068            throw new ShortCircuitIterationException();
069        }
070        return aggregate;
071    }
072
073    private static boolean isEmpty(PrincipalCollection pc) {
074        return pc == null || pc.isEmpty();
075    }
076
077    /**
078     * Returns the specified {@code aggregate} instance if is non null and valid (that is, has principals and they are
079     * not empty) immediately, or, if it is null or not valid, the {@code info} argument is returned instead.
080     * <p/>
081     * This logic ensures that the first valid info encountered is the one retained and all subsequent ones are ignored,
082     * since this strategy mandates that only the info from the first successfully authenticated realm be used.
083     */
084    protected AuthenticationInfo merge(AuthenticationInfo info, AuthenticationInfo aggregate) {
085        if (aggregate != null && !isEmpty(aggregate.getPrincipals())) {
086            return aggregate;
087        }
088        return info != null ? info : aggregate;
089    }
090}