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 */
019 package org.apache.shiro.web.filter.authz;
020
021 import org.apache.shiro.subject.Subject;
022 import org.apache.shiro.util.StringUtils;
023 import org.apache.shiro.web.filter.AccessControlFilter;
024 import org.apache.shiro.web.util.WebUtils;
025
026 import javax.servlet.ServletRequest;
027 import javax.servlet.ServletResponse;
028 import javax.servlet.http.HttpServletResponse;
029 import java.io.IOException;
030
031 /**
032 * Superclass for authorization-related filters. If an request is unauthorized, response handling is delegated to the
033 * {@link #onAccessDenied(javax.servlet.ServletRequest, javax.servlet.ServletResponse) onAccessDenied} method, which
034 * provides reasonable handling for most applications.
035 *
036 * @see #onAccessDenied(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
037 * @since 0.9
038 */
039 public abstract class AuthorizationFilter extends AccessControlFilter {
040
041 /**
042 * The URL to which users should be redirected if they are denied access to an underlying path or resource,
043 * {@code null} by default which will issue a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response
044 * (401 Unauthorized).
045 */
046 private String unauthorizedUrl;
047
048 /**
049 * Returns the URL to which users should be redirected if they are denied access to an underlying path or resource,
050 * or {@code null} if a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response should be issued (401 Unauthorized).
051 * <p/>
052 * The default is {@code null}, ensuring default web server behavior. Override this default by calling the
053 * {@link #setUnauthorizedUrl(String) setUnauthorizedUrl} method with a meaningful path within your application
054 * if you would like to show the user a 'nice' page in the event of unauthorized access.
055 *
056 * @return the URL to which users should be redirected if they are denied access to an underlying path or resource,
057 * or {@code null} if a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response should be issued (401 Unauthorized).
058 */
059 public String getUnauthorizedUrl() {
060 return unauthorizedUrl;
061 }
062
063 /**
064 * Sets the URL to which users should be redirected if they are denied access to an underlying path or resource.
065 * <p/>
066 * If the value is {@code null} a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response will
067 * be issued (401 Unauthorized), retaining default web server behavior.
068 * <p/>
069 * Unless overridden by calling this method, the default value is {@code null}. If desired, you can specify a
070 * meaningful path within your application if you would like to show the user a 'nice' page in the event of
071 * unauthorized access.
072 *
073 * @param unauthorizedUrl the URL to which users should be redirected if they are denied access to an underlying
074 * path or resource, or {@code null} to a ensure raw {@link HttpServletResponse#SC_UNAUTHORIZED} response is
075 * issued (401 Unauthorized).
076 */
077 public void setUnauthorizedUrl(String unauthorizedUrl) {
078 this.unauthorizedUrl = unauthorizedUrl;
079 }
080
081 /**
082 * Handles the response when access has been denied. It behaves as follows:
083 * <ul>
084 * <li>If the {@code Subject} is unknown<sup><a href="#known">[1]</a></sup>:
085 * <ol><li>The incoming request will be saved and they will be redirected to the login page for authentication
086 * (via the {@link #saveRequestAndRedirectToLogin(javax.servlet.ServletRequest, javax.servlet.ServletResponse)}
087 * method).</li>
088 * <li>Once successfully authenticated, they will be redirected back to the originally attempted page.</li></ol>
089 * </li>
090 * <li>If the Subject is known:</li>
091 * <ol>
092 * <li>The HTTP {@link HttpServletResponse#SC_UNAUTHORIZED} header will be set (401 Unauthorized)</li>
093 * <li>If the {@link #getUnauthorizedUrl() unauthorizedUrl} has been configured, a redirect will be issued to that
094 * URL. Otherwise the 401 response is rendered normally</li>
095 * </ul>
096 * <code><a name="known">[1]</a></code>: A {@code Subject} is 'known' when
097 * <code>subject.{@link org.apache.shiro.subject.Subject#getPrincipal() getPrincipal()}</code> is not {@code null},
098 * which implicitly means that the subject is either currently authenticated or they have been remembered via
099 * 'remember me' services.
100 *
101 * @param request the incoming <code>ServletRequest</code>
102 * @param response the outgoing <code>ServletResponse</code>
103 * @return {@code false} always for this implementation.
104 * @throws IOException if there is any servlet error.
105 */
106 protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws IOException {
107
108 Subject subject = getSubject(request, response);
109 // If the subject isn't identified, redirect to login URL
110 if (subject.getPrincipal() == null) {
111 saveRequestAndRedirectToLogin(request, response);
112 } else {
113 // If subject is known but not authorized, redirect to the unauthorized URL if there is one
114 // If no unauthorized URL is specified, just return an unauthorized HTTP status code
115 String unauthorizedUrl = getUnauthorizedUrl();
116 //SHIRO-142 - ensure that redirect _or_ error code occurs - both cannot happen due to response commit:
117 if (StringUtils.hasText(unauthorizedUrl)) {
118 WebUtils.issueRedirect(request, response, unauthorizedUrl);
119 } else {
120 WebUtils.toHttp(response).sendError(HttpServletResponse.SC_UNAUTHORIZED);
121 }
122 }
123 return false;
124 }
125
126 }