jspwiki-main/src/main/java/org/apache/wiki/api/core/Session.java

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    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
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       http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.wiki.api.core;

import org.apache.wiki.event.WikiEventListener;

import javax.security.auth.Subject;
import java.security.AccessControlException;
import java.security.Principal;
import java.security.PrivilegedAction;
import java.util.Locale;


/**
 * <p>Represents a long-running wiki session, with an associated user Principal, user Subject, and authentication status. The sesion
 * is initialized with minimal, default-deny values: authentication is set to <code>false</code>, and the user principal is set to
 * <code>null</code>.</p>
 * <p>The Session allows callers to:</p>
 * <ul>
 *   <li>Obtain the authentication status of the user via
 *     {@link #isAnonymous()} and {@link #isAuthenticated()}</li>
 *   <li>Query the session for Principals representing the
 *     user's identity via {@link #getLoginPrincipal()},
 *     {@link #getUserPrincipal()} and {@link #getPrincipals()}</li>
 *   <li>Store, retrieve and clear UI messages via
 *     {@link #addMessage(String)}, {@link #getMessages(String)}
 *     and {@link #clearMessages(String)}</li>
 * </ul>
 * <p>To keep track of the Principals each user posseses, each Session stores a JAAS Subject. Various login processes add or
 * remove Principals when users authenticate or log out.</p>
 * <p>Session extends the {@link org.apache.wiki.event.WikiEventListener} interface and listens for group add/change/delete
 * events fired by event sources the Session is registered with: {@link org.apache.wiki.auth.AuthenticationManager},
 * {@link org.apache.wiki.auth.UserManager} and {@link org.apache.wiki.auth.authorize.GroupManager}, so it can catch group events. Thus,
 * when a user is added to a {@link org.apache.wiki.auth.authorize.Group}, a corresponding {@link org.apache.wiki.auth.GroupPrincipal} is
 * injected into the Subject's Principal set. Likewise, when the user is removed from the Group or the Group is deleted, the
 * GroupPrincipal is removed from the Subject. The effect that this strategy produces is extremely beneficial: when someone adds a user
 * to a wiki group, that user <em>immediately</em> gains the privileges associated with that group; he or she does not need to
 * re-authenticate.
 * </p>
 * <p>In addition to methods for examining individual <code>Session</code> objects, this class also contains a number of static
 * methods for managing Sessions for an entire wiki. These methods allow callers to find, query and remove Session objects, and
 * to obtain a list of the current wiki session users.</p>
 */
public interface Session extends WikiEventListener {

    /** An anonymous user's session status. */
    String  ANONYMOUS = "anonymous";

    /** An asserted user's session status. */
    String  ASSERTED = "asserted";

    /** An authenticated user's session status. */
    String  AUTHENTICATED = "authenticated";

    /**
     * Returns <code>true</code> if the user is considered asserted via a session cookie; that is, the Subject contains the Principal
     * Role.ASSERTED.
     *
     * @return Returns <code>true</code> if the user is asserted
     */
    boolean isAsserted();

    /**
     * Returns the authentication status of the user's session. The user is considered authenticated if the Subject contains the
     * Principal Role.AUTHENTICATED. If this method determines that an earlier LoginModule did not inject Role.AUTHENTICATED, it
     * will inject one if the user is not anonymous <em>and</em> not asserted.
     *
     * @return Returns <code>true</code> if the user is authenticated
     */
    boolean isAuthenticated();

    /**
     * <p>Determines whether the current session is anonymous. This will be true if any of these conditions are true:</p>
     * <ul>
     *   <li>The session's Principal set contains {@link org.apache.wiki.auth.authorize.Role#ANONYMOUS}</li>
     *   <li>The session's Principal set contains {@link org.apache.wiki.auth.WikiPrincipal#GUEST}</li>
     *   <li>The Principal returned by {@link #getUserPrincipal()} evaluates to an IP address.</li>
     * </ul>
     * <p>The criteria above are listed in the order in which they are evaluated.</p>
     * @return whether the current user's identity is equivalent to an IP address
     */
    boolean isAnonymous();

    /**
     * <p> Returns the Principal used to log in to an authenticated session. The login principal is determined by examining the
     * Subject's Principal set for PrincipalWrappers or WikiPrincipals with type designator <code>LOGIN_NAME</code>; the first one
     * found is the login principal. If one is not found, this method returns the first principal that isn't of type Role or
     * GroupPrincipal. If neither of these conditions hold, this method returns
     * {@link org.apache.wiki.auth.WikiPrincipal#GUEST}.
     *
     * @return the login Principal. If it is a PrincipalWrapper containing an externally-provided Principal, the object returned is the
     * Principal, not the wrapper around it.
     */
    Principal getLoginPrincipal();

    /**
     * <p>Returns the primary user Principal associated with this session. The primary user principal is determined as follows:</p>
     * <ol>
     *     <li>If the Subject's Principal set contains WikiPrincipals, the first WikiPrincipal with type designator
     *         <code>WIKI_NAME</code> or (alternatively) <code>FULL_NAME</code> is the primary Principal.</li>
     *     <li>For all other cases, the first Principal in the Subject's principal collection that that isn't of type Role or
     *         GroupPrincipal is the primary.</li>
     * </ol>
     * If no primary user Principal is found, this method returns {@link org.apache.wiki.auth.WikiPrincipal#GUEST}.
     *
     * @return the primary user Principal
     */
    Principal getUserPrincipal();

    /**
     *  Returns a cached Locale object for this user.  It's better to use WikiContext's corresponding getBundle() method, since that
     *  will actually react if the user changes the locale in the middle, but if that's not available (or, for some reason, you need
     *  the speed), this method can also be used.  The Locale expires when the Session expires, and currently there is no way to
     *  reset the Locale.
     *
     *  @return A cached Locale object
     *  @since 2.5.96
     */
    Locale getLocale();

    /**
     * Adds a message to the generic list of messages associated with the session. These messages retain their order of insertion and
     * remain until the {@link #clearMessages()} method is called.
     *
     * @param message the message to add; if <code>null</code> it is ignored.
     */
    void addMessage( String message );

    /**
     * Adds a message to the specific set of messages associated with the session. These messages retain their order of insertion and
     * remain until the {@link #clearMessages()} method is called.
     *
     * @param topic the topic to associate the message to;
     * @param message the message to add
     */
    void addMessage( String topic, String message );

    /**
     * Clears all messages associated with this session.
     */
    void clearMessages();

    /**
     * Clears all messages associated with a session topic.
     *
     * @param topic the topic whose messages should be cleared.
     */
    void clearMessages( String topic );

    /**
     * Returns all generic messages associated with this session. The messages stored with the session persist throughout the
     * session unless they have been reset with {@link #clearMessages()}.
     *
     * @return the current messages.
     */
    String[] getMessages();

    /**
     * Returns all messages associated with a session topic. The messages stored with the session persist throughout the
     * session unless they have been reset with {@link #clearMessages(String)}.
     *
     * @return the current messages.
     * @param topic The topic
     */
    String[] getMessages( String topic );

    /**
     * Returns all user Principals associated with this session. User principals are those in the Subject's principal collection that
     * aren't of type Role or of type GroupPrincipal. This is a defensive copy.
     *
     * @return Returns the user principal
     * @see org.apache.wiki.auth.AuthenticationManager#isUserPrincipal(Principal)
     */
    Principal[] getPrincipals();

    /**
     * Returns an array of Principal objects that represents the groups and roles that the user associated with a Session possesses.
     * The array is built by iterating through the Subject's Principal set and extracting all Role and GroupPrincipal objects into a
     * list. The list is returned as an array sorted in the natural order implied by each Principal's <code>getName</code> method. Note
     * that this method does <em>not</em> consult the external Authorizer or GroupManager; it relies on the Principals that have been
     * injected into the user's Subject at login time, or after group creation/modification/deletion.
     *
     * @return an array of Principal objects corresponding to the roles the Subject possesses
     */
    Principal[] getRoles();

    /**
     * Returns <code>true</code> if the Session's Subject possess a supplied Principal. This method eliminates the need to externally
     * request and inspect the JAAS subject.
     *
     * @param principal the Principal to test
     * @return the result
     */
    boolean hasPrincipal( Principal principal );

    /** Invalidates the Session and resets its Subject's Principals to the equivalent of a "guest session". */
    void invalidate();

    /**
     * <p>Returns the status of the wiki session as a text string. Valid values are:</p>
     * <ul>
     *   <li>{@link #AUTHENTICATED}</li>
     *   <li>{@link #ASSERTED}</li>
     *   <li>{@link #ANONYMOUS}</li>
     * </ul>
     *
     * @return the user's session status
     */
    String getStatus();

    /**
     * Returns the {@link Subject} associated to the session.
     *
     * @return {@link Subject} associated to the session.
     */
    Subject getSubject();

    /**
     * Wrapper for {@link Subject#doAsPrivileged(Subject, PrivilegedAction, java.security.AccessControlContext)}
     * that executes an action with the privileges posssessed by a Session's Subject. The action executes with a <code>null</code>
     * AccessControlContext, which has the effect of running it "cleanly" without the AccessControlContexts of the caller.
     *
     * @param session the wiki session
     * @param action the privileged action
     * @return the result of the privileged action; may be <code>null</code>
     * @throws java.security.AccessControlException if the action is not permitted by the security policy
     */
    static Object doPrivileged( final Session session, final PrivilegedAction<?> action ) throws AccessControlException {
        return Subject.doAsPrivileged( session.getSubject(), action, null );
    }

}