1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.shiro.web.filter.authz;
20
21 import org.apache.shiro.subject.Subject;
22 import org.apache.shiro.util.StringUtils;
23 import org.apache.shiro.web.filter.AccessControlFilter;
24 import org.apache.shiro.web.util.WebUtils;
25
26 import javax.servlet.ServletRequest;
27 import javax.servlet.ServletResponse;
28 import javax.servlet.http.HttpServletResponse;
29 import java.io.IOException;
30
31 /**
32 * Superclass for authorization-related filters. If an request is unauthorized, response handling is delegated to the
33 * {@link #onAccessDenied(javax.servlet.ServletRequest, javax.servlet.ServletResponse) onAccessDenied} method, which
34 * provides reasonable handling for most applications.
35 *
36 * @see #onAccessDenied(javax.servlet.ServletRequest, javax.servlet.ServletResponse)
37 * @since 0.9
38 */
39 public abstract class AuthorizationFilter extends AccessControlFilter {
40
41 /**
42 * The URL to which users should be redirected if they are denied access to an underlying path or resource,
43 * {@code null} by default which will issue a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response
44 * (401 Unauthorized).
45 */
46 private String unauthorizedUrl;
47
48 /**
49 * Returns the URL to which users should be redirected if they are denied access to an underlying path or resource,
50 * or {@code null} if a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response should be issued (401 Unauthorized).
51 * <p/>
52 * The default is {@code null}, ensuring default web server behavior. Override this default by calling the
53 * {@link #setUnauthorizedUrl(String) setUnauthorizedUrl} method with a meaningful path within your application
54 * if you would like to show the user a 'nice' page in the event of unauthorized access.
55 *
56 * @return the URL to which users should be redirected if they are denied access to an underlying path or resource,
57 * or {@code null} if a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response should be issued (401 Unauthorized).
58 */
59 public String getUnauthorizedUrl() {
60 return unauthorizedUrl;
61 }
62
63 /**
64 * Sets the URL to which users should be redirected if they are denied access to an underlying path or resource.
65 * <p/>
66 * If the value is {@code null} a raw {@link HttpServletResponse#SC_UNAUTHORIZED} response will
67 * be issued (401 Unauthorized), retaining default web server behavior.
68 * <p/>
69 * Unless overridden by calling this method, the default value is {@code null}. If desired, you can specify a
70 * meaningful path within your application if you would like to show the user a 'nice' page in the event of
71 * unauthorized access.
72 *
73 * @param unauthorizedUrl the URL to which users should be redirected if they are denied access to an underlying
74 * path or resource, or {@code null} to a ensure raw {@link HttpServletResponse#SC_UNAUTHORIZED} response is
75 * issued (401 Unauthorized).
76 */
77 public void setUnauthorizedUrl(String unauthorizedUrl) {
78 this.unauthorizedUrl = unauthorizedUrl;
79 }
80
81 /**
82 * Handles the response when access has been denied. It behaves as follows:
83 * <ul>
84 * <li>If the {@code Subject} is unknown<sup><a href="#known">[1]</a></sup>:
85 * <ol><li>The incoming request will be saved and they will be redirected to the login page for authentication
86 * (via the {@link #saveRequestAndRedirectToLogin(javax.servlet.ServletRequest, javax.servlet.ServletResponse)}
87 * method).</li>
88 * <li>Once successfully authenticated, they will be redirected back to the originally attempted page.</li></ol>
89 * </li>
90 * <li>If the Subject is known:</li>
91 * <ol>
92 * <li>The HTTP {@link HttpServletResponse#SC_UNAUTHORIZED} header will be set (401 Unauthorized)</li>
93 * <li>If the {@link #getUnauthorizedUrl() unauthorizedUrl} has been configured, a redirect will be issued to that
94 * URL. Otherwise the 401 response is rendered normally</li>
95 * </ul>
96 * <code><a name="known">[1]</a></code>: A {@code Subject} is 'known' when
97 * <code>subject.{@link org.apache.shiro.subject.Subject#getPrincipal() getPrincipal()}</code> is not {@code null},
98 * which implicitly means that the subject is either currently authenticated or they have been remembered via
99 * '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 }