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.mgt;
020
021import org.apache.shiro.session.Session;
022import org.apache.shiro.subject.PrincipalCollection;
023import org.apache.shiro.subject.Subject;
024import org.apache.shiro.subject.support.DefaultSubjectContext;
025import org.apache.shiro.subject.support.DelegatingSubject;
026import org.apache.shiro.util.CollectionUtils;
027import org.slf4j.Logger;
028import org.slf4j.LoggerFactory;
029
030import java.lang.reflect.Field;
031
032/**
033 * Default {@code SubjectDAO} implementation that stores Subject state in the Subject's Session by default (but this
034 * can be disabled - see below).  The Subject instance
035 * can be re-created at a later time by first acquiring the associated Session (typically from a
036 * {@link org.apache.shiro.session.mgt.SessionManager SessionManager}) via a session ID or session key and then
037 * building a {@code Subject} instance from {@code Session} attributes.
038 * <h2>Controlling how Sessions are used</h2>
039 * Whether or not a {@code Subject}'s {@code Session} is used or not to persist its own state is controlled on a
040 * <em>per-Subject</em> basis as determined by the configured
041 * {@link #setSessionStorageEvaluator(SessionStorageEvaluator) sessionStorageEvaluator}.
042 * The default {@code Evaluator} is a {@link DefaultSessionStorageEvaluator}, which supports enabling or disabling
043 * session usage for Subject persistence at a global level for all subjects (and defaults to allowing sessions to be
044 * used).
045 * <h3>Disabling Session Persistence Entirely</h3>
046 * Because the default {@code SessionStorageEvaluator} instance is a {@link DefaultSessionStorageEvaluator}, you
047 * can disable Session usage for Subject state entirely by configuring that instance directly, e.g.:
048 * <pre>
049 *     ((DefaultSessionStorageEvaluator)sessionDAO.getSessionStorageEvaluator()).setSessionStorageEnabled(false);
050 * </pre>
051 * or, for example, in {@code shiro.ini}:
052 * <pre>
053 *     securityManager.subjectDAO.sessionStorageEvaluator.sessionStorageEnabled = false
054 * </pre>
055 * but <b>note:</b> ONLY do this your
056 * application is 100% stateless and you <em>DO NOT</em> need subjects to be remembered across remote
057 * invocations, or in a web environment across HTTP requests.
058 * <h3>Supporting Both Stateful and Stateless Subject paradigms</h3>
059 * Perhaps your application needs to support a hybrid approach of both stateful and stateless Subjects:
060 * <ul>
061 * <li>Stateful: Stateful subjects might represent web end-users that need their identity and authentication
062 * state to be remembered from page to page.</li>
063 * <li>Stateless: Stateless subjects might represent API clients (e.g. REST clients) that authenticate on every
064 * request, and therefore don't need authentication state to be stored across requests in a session.</li>
065 * </ul>
066 * To support the hybrid <em>per-Subject</em> approach, you will need to create your own implementation of the
067 * {@link SessionStorageEvaluator} interface and configure it via the
068 * {@link #setSessionStorageEvaluator(SessionStorageEvaluator)} method, or, with {@code shiro.ini}:
069 * <pre>
070 *     myEvaluator = com.my.CustomSessionStorageEvaluator
071 *     securityManager.subjectDAO.sessionStorageEvaluator = $myEvaluator
072 * </pre>
073 * <p/>
074 * Unless overridden, the default evaluator is a {@link DefaultSessionStorageEvaluator}, which enables session usage for
075 * Subject state by default.
076 *
077 * @see #isSessionStorageEnabled(org.apache.shiro.subject.Subject)
078 * @see SessionStorageEvaluator
079 * @see DefaultSessionStorageEvaluator
080 * @since 1.2
081 */
082public class DefaultSubjectDAO implements SubjectDAO {
083
084    private static final Logger log = LoggerFactory.getLogger(DefaultSubjectDAO.class);
085
086    /**
087     * Evaluator that determines if a Subject's session may be used to store the Subject's own state.
088     */
089    private SessionStorageEvaluator sessionStorageEvaluator;
090
091    public DefaultSubjectDAO() {
092        //default implementation allows enabling/disabling session usages at a global level for all subjects:
093        this.sessionStorageEvaluator = new DefaultSessionStorageEvaluator();
094    }
095
096    /**
097     * Determines if the subject's session will be used to persist subject state or not.  This implementation
098     * merely delegates to the internal {@link SessionStorageEvaluator} (a
099     * {@code DefaultSessionStorageEvaluator} by default).
100     *
101     * @param subject the subject to inspect to determine if the subject's session will be used to persist subject
102     *                state or not.
103     * @return {@code true} if the subject's session will be used to persist subject state, {@code false} otherwise.
104     * @see #setSessionStorageEvaluator(SessionStorageEvaluator)
105     * @see DefaultSessionStorageEvaluator
106     */
107    protected boolean isSessionStorageEnabled(Subject subject) {
108        return getSessionStorageEvaluator().isSessionStorageEnabled(subject);
109    }
110
111    /**
112     * Returns the {@code SessionStorageEvaluator} that will determine if a {@code Subject}'s state may be persisted in
113     * the Subject's session.  The default instance is a {@link DefaultSessionStorageEvaluator}.
114     *
115     * @return the {@code SessionStorageEvaluator} that will determine if a {@code Subject}'s state may be persisted in
116     *         the Subject's session.
117     * @see DefaultSessionStorageEvaluator
118     */
119    public SessionStorageEvaluator getSessionStorageEvaluator() {
120        return sessionStorageEvaluator;
121    }
122
123    /**
124     * Sets the {@code SessionStorageEvaluator} that will determine if a {@code Subject}'s state may be persisted in
125     * the Subject's session. The default instance is a {@link DefaultSessionStorageEvaluator}.
126     *
127     * @param sessionStorageEvaluator the {@code SessionStorageEvaluator} that will determine if a {@code Subject}'s
128     *                                state may be persisted in the Subject's session.
129     * @see DefaultSessionStorageEvaluator
130     */
131    public void setSessionStorageEvaluator(SessionStorageEvaluator sessionStorageEvaluator) {
132        this.sessionStorageEvaluator = sessionStorageEvaluator;
133    }
134
135    /**
136     * Saves the subject's state to the subject's {@link org.apache.shiro.subject.Subject#getSession() session} only
137     * if {@link #isSessionStorageEnabled(Subject) sessionStorageEnabled(subject)}.  If session storage is not enabled
138     * for the specific {@code Subject}, this method does nothing.
139     * <p/>
140     * In either case, the argument {@code Subject} is returned directly (a new Subject instance is not created).
141     *
142     * @param subject the Subject instance for which its state will be created or updated.
143     * @return the same {@code Subject} passed in (a new Subject instance is not created).
144     */
145    public Subject save(Subject subject) {
146        if (isSessionStorageEnabled(subject)) {
147            saveToSession(subject);
148        } else {
149            log.trace("Session storage of subject state for Subject [{}] has been disabled: identity and " +
150                    "authentication state are expected to be initialized on every request or invocation.", subject);
151        }
152
153        return subject;
154    }
155
156    /**
157     * Saves the subject's state (it's principals and authentication state) to its
158     * {@link org.apache.shiro.subject.Subject#getSession() session}.  The session can be retrieved at a later time
159     * (typically from a {@link org.apache.shiro.session.mgt.SessionManager SessionManager} to be used to recreate
160     * the {@code Subject} instance.
161     *
162     * @param subject the subject for which state will be persisted to its session.
163     */
164    protected void saveToSession(Subject subject) {
165        //performs merge logic, only updating the Subject's session if it does not match the current state:
166        mergePrincipals(subject);
167        mergeAuthenticationState(subject);
168    }
169
170    /**
171     * Merges the Subject's current {@link org.apache.shiro.subject.Subject#getPrincipals()} with whatever may be in
172     * any available session.  Only updates the Subject's session if the session does not match the current principals
173     * state.
174     *
175     * @param subject the Subject for which principals will potentially be merged into the Subject's session.
176     */
177    protected void mergePrincipals(Subject subject) {
178        //merge PrincipalCollection state:
179
180        PrincipalCollection currentPrincipals = null;
181
182        //SHIRO-380: added if/else block - need to retain original (source) principals
183        //This technique (reflection) is only temporary - a proper long term solution needs to be found,
184        //but this technique allowed an immediate fix that is API point-version forwards and backwards compatible
185        //
186        //A more comprehensive review / cleaning of runAs should be performed for Shiro 1.3 / 2.0 +
187        if (subject.isRunAs() && subject instanceof DelegatingSubject) {
188            try {
189                Field field = DelegatingSubject.class.getDeclaredField("principals");
190                field.setAccessible(true);
191                currentPrincipals = (PrincipalCollection)field.get(subject);
192            } catch (Exception e) {
193                throw new IllegalStateException("Unable to access DelegatingSubject principals property.", e);
194            }
195        }
196        if (currentPrincipals == null || currentPrincipals.isEmpty()) {
197            currentPrincipals = subject.getPrincipals();
198        }
199
200        Session session = subject.getSession(false);
201
202        if (session == null) {
203            if (!CollectionUtils.isEmpty(currentPrincipals)) {
204                session = subject.getSession();
205                session.setAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY, currentPrincipals);
206            }
207            //otherwise no session and no principals - nothing to save
208        } else {
209            PrincipalCollection existingPrincipals =
210                    (PrincipalCollection) session.getAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
211
212            if (CollectionUtils.isEmpty(currentPrincipals)) {
213                if (!CollectionUtils.isEmpty(existingPrincipals)) {
214                    session.removeAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
215                }
216                //otherwise both are null or empty - no need to update the session
217            } else {
218                if (!currentPrincipals.equals(existingPrincipals)) {
219                    session.setAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY, currentPrincipals);
220                }
221                //otherwise they're the same - no need to update the session
222            }
223        }
224    }
225
226    /**
227     * Merges the Subject's current authentication state with whatever may be in
228     * any available session.  Only updates the Subject's session if the session does not match the current
229     * authentication state.
230     *
231     * @param subject the Subject for which principals will potentially be merged into the Subject's session.
232     */
233    protected void mergeAuthenticationState(Subject subject) {
234
235        Session session = subject.getSession(false);
236
237        if (session == null) {
238            if (subject.isAuthenticated()) {
239                session = subject.getSession();
240                session.setAttribute(DefaultSubjectContext.AUTHENTICATED_SESSION_KEY, Boolean.TRUE);
241            }
242            //otherwise no session and not authenticated - nothing to save
243        } else {
244            Boolean existingAuthc = (Boolean) session.getAttribute(DefaultSubjectContext.AUTHENTICATED_SESSION_KEY);
245
246            if (subject.isAuthenticated()) {
247                if (existingAuthc == null || !existingAuthc) {
248                    session.setAttribute(DefaultSubjectContext.AUTHENTICATED_SESSION_KEY, Boolean.TRUE);
249                }
250                //otherwise authc state matches - no need to update the session
251            } else {
252                if (existingAuthc != null) {
253                    //existing doesn't match the current state - remove it:
254                    session.removeAttribute(DefaultSubjectContext.AUTHENTICATED_SESSION_KEY);
255                }
256                //otherwise not in the session and not authenticated - no need to update the session
257            }
258        }
259    }
260
261    /**
262     * Removes any existing subject state from the Subject's session (if the session exists).  If the session
263     * does not exist, this method does not do anything.
264     *
265     * @param subject the subject for which any existing subject state will be removed from its session.
266     */
267    protected void removeFromSession(Subject subject) {
268        Session session = subject.getSession(false);
269        if (session != null) {
270            session.removeAttribute(DefaultSubjectContext.AUTHENTICATED_SESSION_KEY);
271            session.removeAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
272        }
273    }
274
275    /**
276     * Removes any existing subject state from the subject's session (if the session exists).
277     *
278     * @param subject the Subject instance for which any persistent state should be deleted.
279     */
280    public void delete(Subject subject) {
281        removeFromSession(subject);
282    }
283}