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.authz.aop;
020
021import org.apache.shiro.authz.AuthorizationException;
022import org.apache.shiro.authz.UnauthenticatedException;
023import org.apache.shiro.authz.annotation.RequiresGuest;
024
025import java.lang.annotation.Annotation;
026
027/**
028 * Checks to see if a @{@link org.apache.shiro.authz.annotation.RequiresGuest RequiresGuest} annotation
029 * is declared, and if so, ensures the calling <code>Subject</code> does <em>not</em>
030 * have an {@link org.apache.shiro.subject.Subject#getPrincipal() identity} before invoking the method.
031 * <p>
032 * This annotation essentially ensures that <code>subject.
033 * {@link org.apache.shiro.subject.Subject#getPrincipal() getPrincipal()} == null</code>.
034 *
035 * @since 0.9.0
036 */
037public class GuestAnnotationHandler extends AuthorizingAnnotationHandler {
038
039    /**
040     * Default no-argument constructor that ensures this interceptor looks for
041     * <p>
042     * {@link org.apache.shiro.authz.annotation.RequiresGuest RequiresGuest} annotations in a method
043     * declaration.
044     */
045    public GuestAnnotationHandler() {
046        super(RequiresGuest.class);
047    }
048
049    /**
050     * Ensures that the calling <code>Subject</code> is NOT a <em>user</em>, that is, they do not
051     * have an {@link org.apache.shiro.subject.Subject#getPrincipal() identity} before continuing.  If they are
052     * a user ({@link org.apache.shiro.subject.Subject#getPrincipal() Subject.getPrincipal()} != null), an
053     * <code>AuthorizingException</code> will be thrown indicating that execution is not allowed to continue.
054     *
055     * @param a the annotation to check for one or more roles
056     * @throws org.apache.shiro.authz.AuthorizationException if the calling <code>Subject</code> is not a &quot;guest&quot;.
057     */
058    public void assertAuthorized(Annotation a) throws AuthorizationException {
059        if (a instanceof RequiresGuest && getSubject().getPrincipal() != null) {
060            throw new UnauthenticatedException("Attempting to perform a guest-only operation.  The current Subject is "
061                    + "not a guest (they have been authenticated or remembered from a previous login).  Access "
062                    + "denied.");
063        }
064    }
065}