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