1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.servlets;
20
21 import java.io.IOException;
22 import java.util.Map;
23 import java.util.concurrent.ConcurrentHashMap;
24 import java.util.regex.Matcher;
25 import java.util.regex.Pattern;
26
27 import javax.servlet.Filter;
28 import javax.servlet.FilterChain;
29 import javax.servlet.FilterConfig;
30 import javax.servlet.ServletException;
31 import javax.servlet.ServletRequest;
32 import javax.servlet.ServletResponse;
33 import javax.servlet.http.HttpServletRequest;
34
35 /* ------------------------------------------------------------ */
36 /** User Agent Filter.
37 * <p>
38 * This filter allows efficient matching of user agent strings for
39 * downstream or extended filters to use for browser specific logic.
40 * </p>
41 * <p>
42 * The filter is configured with the following init parameters:
43 * <dl>
44 * <dt>attribute</dt><dd>If set, then the request attribute of this name is set with the matched user agent string</dd>
45 * <dt>cacheSize</dt><dd>The size of the user-agent cache, used to avoid reparsing of user agent strings. The entire cache is flushed
46 * when this size is reached</dd>
47 * <dt>userAgent</dt><dd>A regex {@link Pattern} to extract the essential elements of the user agent.
48 * The concatenation of matched pattern groups is used as the user agent name</dd>
49 * <dl>
50 * An example value for pattern is <code>(?:Mozilla[^\(]*\(compatible;\s*+([^;]*);.*)|(?:.*?([^\s]+/[^\s]+).*)</code>. These two
51 * pattern match the common compatibility user-agent strings and extract the real user agent, failing that, the first
52 * element of the agent string is returned.
53 *
54 *
55 */
56 public class UserAgentFilter implements Filter
57 {
58 private static final String __defaultPattern = "(?:Mozilla[^\\(]*\\(compatible;\\s*+([^;]*);.*)|(?:.*?([^\\s]+/[^\\s]+).*)";
59 private Pattern _pattern = Pattern.compile(__defaultPattern);
60 private Map<String, String> _agentCache = new ConcurrentHashMap<String, String>();
61 private int _agentCacheSize=1024;
62 private String _attribute;
63
64 /* ------------------------------------------------------------ */
65 /* (non-Javadoc)
66 * @see javax.servlet.Filter#destroy()
67 */
68 public void destroy()
69 {
70 }
71
72 /* ------------------------------------------------------------ */
73 /* (non-Javadoc)
74 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
75 */
76 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException
77 {
78 if (_attribute!=null && _pattern!=null)
79 {
80 String ua=getUserAgent(request);
81 request.setAttribute(_attribute,ua);
82 }
83 chain.doFilter(request,response);
84 }
85
86 /* ------------------------------------------------------------ */
87 /* (non-Javadoc)
88 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
89 */
90 public void init(FilterConfig filterConfig) throws ServletException
91 {
92 _attribute=filterConfig.getInitParameter("attribute");
93
94 String p=filterConfig.getInitParameter("userAgent");
95 if (p!=null)
96 _pattern=Pattern.compile(p);
97
98 String size=filterConfig.getInitParameter("cacheSize");
99 if (size!=null)
100 _agentCacheSize=Integer.parseInt(size);
101 }
102
103 /* ------------------------------------------------------------ */
104 public String getUserAgent(ServletRequest request)
105 {
106 String ua=((HttpServletRequest)request).getHeader("User-Agent");
107 return getUserAgent(ua);
108 }
109
110 /* ------------------------------------------------------------ */
111 /** Get UserAgent.
112 * The configured agent patterns are used to match against the passed user agent string.
113 * If any patterns match, the concatenation of pattern groups is returned as the user agent
114 * string. Match results are cached.
115 * @param ua A user agent string
116 * @return The matched pattern groups or the original user agent string
117 */
118 public String getUserAgent(String ua)
119 {
120 if (ua == null)
121 return null;
122
123 String tag = _agentCache.get(ua);
124
125 if (tag == null)
126 {
127 if (_pattern != null)
128 {
129 Matcher matcher = _pattern.matcher(ua);
130 if (matcher.matches())
131 {
132 if (matcher.groupCount() > 0)
133 {
134 for (int g = 1; g <= matcher.groupCount(); g++)
135 {
136 String group = matcher.group(g);
137 if (group != null)
138 tag = tag == null ? group : tag + group;
139 }
140 }
141 else
142 {
143 tag = matcher.group();
144 }
145 }
146 }
147
148 if (tag == null)
149 tag = ua;
150
151 if (_agentCache.size() >= _agentCacheSize)
152 _agentCache.clear();
153 _agentCache.put(ua, tag);
154 }
155
156 return tag;
157 }
158 }