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;
025
026import java.util.Collection;
027
028
029/**
030 * A {@code AuthenticationStrategy} implementation assists the {@link ModularRealmAuthenticator} during the
031 * log-in process in a pluggable realm (PAM) environment.
032 *
033 * <p>The {@code ModularRealmAuthenticator} will consult implementations of this interface on what to do during each
034 * interaction with the configured Realms.  This allows a pluggable strategy of whether or not an authentication
035 * attempt must be successful for all realms, only 1 or more realms, no realms, etc.
036 *
037 * @see AllSuccessfulStrategy
038 * @see AtLeastOneSuccessfulStrategy
039 * @see FirstSuccessfulStrategy
040 * @since 0.2
041 */
042public interface AuthenticationStrategy {
043
044    /**
045     * Method invoked by the ModularAuthenticator signifying that the authentication process is about to begin for the
046     * specified {@code token} - called before any {@code Realm} is actually invoked.
047     *
048     * <p>The {@code AuthenticationInfo} object returned from this method is essentially an empty place holder for
049     * aggregating account data across multiple realms.  It should be populated by the strategy implementation over the
050     * course of authentication attempts across the multiple realms.  It will be passed into the
051     * {@link #beforeAttempt} calls, allowing inspection of the aggregated account data up to that point in the
052     * multi-realm authentication, allowing any logic to be executed accordingly.
053     *
054     * @param realms the Realms that will be consulted during the authentication process for the specified token.
055     * @param token  the Principal/Credential representation to be used during authentication for a corresponding subject.
056     * @return an empty AuthenticationInfo object that will populated with data from multiple realms.
057     * @throws AuthenticationException if the strategy implementation does not wish the Authentication attempt to execute.
058     */
059    AuthenticationInfo beforeAllAttempts(Collection<? extends Realm> realms, AuthenticationToken token) throws AuthenticationException;
060
061    /**
062     * Method invoked by the ModularAuthenticator just prior to the realm being consulted for account data,
063     * allowing pre-authentication-attempt logic for that realm only.
064     *
065     * <p>This method returns an {@code AuthenticationInfo} object that will be used for further interaction with realms.  Most
066     * implementations will merely return the {@code aggregate} method argument if they don't have a need to
067     * manipulate it.
068     *
069     * @param realm     the realm that will be consulted for {@code AuthenticationInfo} for the specified {@code token}.
070     * @param token     the {@code AuthenticationToken} submitted for the subject attempting system log-in.
071     * @param aggregate the aggregated AuthenticationInfo object being used across the multi-realm authentication attempt
072     * @return the AuthenticationInfo object that will be presented to further realms in the authentication process - returning
073     *         the {@code aggregate} method argument is the normal case if no special action needs to be taken.
074     * @throws org.apache.shiro.authc.AuthenticationException
075     *          an exception thrown by the Strategy implementation if it wishes the login
076     *          process for the associated subject (user) to stop immediately.
077     */
078    AuthenticationInfo beforeAttempt(Realm realm, AuthenticationToken token, AuthenticationInfo aggregate) throws AuthenticationException;
079
080    /**
081     * Method invoked by the ModularAuthenticator just after the given realm has been consulted for authentication,
082     * allowing post-authentication-attempt logic for that realm only.
083     *
084     * <p>This method returns an {@code AuthenticationInfo} object that will be used for further interaction with realms.  Most
085     * implementations will merge the {@code singleRealmInfo} into the {@code aggregateInfo} and
086     * just return the {@code aggregateInfo} for continued use throughout the authentication process.</p>
087     *
088     * @param realm           the realm that was just consulted for {@code AuthenticationInfo} for the given {@code token}.
089     * @param token           the {@code AuthenticationToken} submitted for the subject attempting system log-in.
090     * @param singleRealmInfo the info returned from a single realm.
091     * @param aggregateInfo   the aggregate info representing all realms in a multi-realm environment.
092     * @param t               the Throwable thrown by the Realm during the attempt, or {@code null} if the method returned normally.
093     * @return the AuthenticationInfo object that will be presented to further realms in the authentication process - returning
094     *         the {@code aggregateAccount} method argument is the normal case if no special action needs to be taken.
095     * @throws AuthenticationException an exception thrown by the Strategy implementation if it wishes the login process
096     *                                 for the associated subject (user) to stop immediately.
097     */
098    AuthenticationInfo afterAttempt(Realm realm, AuthenticationToken token, AuthenticationInfo singleRealmInfo, AuthenticationInfo aggregateInfo, Throwable t)
099            throws AuthenticationException;
100
101    /**
102     * Method invoked by the ModularAuthenticator signifying that all of its configured Realms have been consulted
103     * for account data, allowing post-proccessing after all realms have completed.
104     *
105     * <p>Returns the final AuthenticationInfo object that will be returned from the Authenticator to the authenticate() caller.
106     * This is most likely the aggregate AuthenticationInfo object that has been populated by many realms, but the actual return value is
107     * always up to the implementation.
108     *
109     * @param token     the {@code AuthenticationToken} submitted for the subject attempting system log-in.
110     * @param aggregate the aggregate {@code AuthenticationInfo} instance populated by all realms during the log-in attempt.
111     * @return the final {@code AuthenticationInfo} object to return to the Authenticator.authenticate() caller.
112     * @throws AuthenticationException if the Strategy implementation wishes to fail the authentication attempt.
113     */
114    AuthenticationInfo afterAllAttempts(AuthenticationToken token, AuthenticationInfo aggregate) throws AuthenticationException;
115}