1 // ======================================================================== 2 // Copyright (c) 2006-2009 Mort Bay Consulting Pty. Ltd. 3 // ------------------------------------------------------------------------ 4 // All rights reserved. This program and the accompanying materials 5 // are made available under the terms of the Eclipse Public License v1.0 6 // and Apache License v2.0 which accompanies this distribution. 7 // The Eclipse Public License is available at 8 // http://www.eclipse.org/legal/epl-v10.html 9 // The Apache License v2.0 is available at 10 // http://www.opensource.org/licenses/apache2.0.php 11 // You may elect to redistribute this code under either of these licenses. 12 // ======================================================================== 13 14 package org.eclipse.jetty.servlets; 15 16 import java.io.IOException; 17 import java.util.Map; 18 import java.util.concurrent.ConcurrentHashMap; 19 import java.util.regex.Matcher; 20 import java.util.regex.Pattern; 21 22 import javax.servlet.Filter; 23 import javax.servlet.FilterChain; 24 import javax.servlet.FilterConfig; 25 import javax.servlet.ServletException; 26 import javax.servlet.ServletRequest; 27 import javax.servlet.ServletResponse; 28 import javax.servlet.http.HttpServletRequest; 29 30 /* ------------------------------------------------------------ */ 31 /** User Agent Filter. 32 * <p> 33 * This filter allows efficient matching of user agent strings for 34 * downstream or extended filters to use for browser specific logic. 35 * </p> 36 * <p> 37 * The filter is configured with the following init parameters: 38 * <dl> 39 * <dt>attribute</dt><dd>If set, then the request attribute of this name is set with the matched user agent string</dd> 40 * <dt>cacheSize</dt><dd>The size of the user-agent cache, used to avoid reparsing of user agent strings. The entire cache is flushed 41 * when this size is reached</dd> 42 * <dt>userAgent</dt><dd>A regex {@link Pattern} to extract the essential elements of the user agent. 43 * The concatenation of matched pattern groups is used as the user agent name</dd> 44 * <dl> 45 * An example value for pattern is <code>(?:Mozilla[^\(]*\(compatible;\s*+([^;]*);.*)|(?:.*?([^\s]+/[^\s]+).*)</code>. These two 46 * pattern match the common compatibility user-agent strings and extract the real user agent, failing that, the first 47 * element of the agent string is returned. 48 * 49 * 50 */ 51 public class UserAgentFilter implements Filter 52 { 53 private Pattern _pattern; 54 private Map _agentCache = new ConcurrentHashMap(); 55 private int _agentCacheSize=1024; 56 private String _attribute; 57 58 /* ------------------------------------------------------------ */ 59 /* (non-Javadoc) 60 * @see javax.servlet.Filter#destroy() 61 */ 62 public void destroy() 63 { 64 } 65 66 /* ------------------------------------------------------------ */ 67 /* (non-Javadoc) 68 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) 69 */ 70 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException 71 { 72 if (_attribute!=null && _pattern!=null) 73 { 74 String ua=getUserAgent(request); 75 request.setAttribute(_attribute,ua); 76 } 77 chain.doFilter(request,response); 78 } 79 80 /* ------------------------------------------------------------ */ 81 /* (non-Javadoc) 82 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig) 83 */ 84 public void init(FilterConfig filterConfig) throws ServletException 85 { 86 _attribute=filterConfig.getInitParameter("attribute"); 87 88 String p=filterConfig.getInitParameter("userAgent"); 89 if (p!=null) 90 _pattern=Pattern.compile(p); 91 92 String size=filterConfig.getInitParameter("cacheSize"); 93 if (size!=null) 94 _agentCacheSize=Integer.parseInt(size); 95 } 96 97 /* ------------------------------------------------------------ */ 98 public String getUserAgent(ServletRequest request) 99 { 100 String ua=((HttpServletRequest)request).getHeader("User-Agent"); 101 return getUserAgent(ua); 102 } 103 104 /* ------------------------------------------------------------ */ 105 /** Get UserAgent. 106 * The configured agent patterns are used to match against the passed user agent string. 107 * If any patterns match, the concatenation of pattern groups is returned as the user agent 108 * string. Match results are cached. 109 * @param ua A user agent string 110 * @return The matched pattern groups or the original user agent string 111 */ 112 public String getUserAgent(String ua) 113 { 114 if (ua==null) 115 return null; 116 117 String tag = (String)_agentCache.get(ua); 118 119 120 if (tag==null) 121 { 122 Matcher matcher=_pattern.matcher(ua); 123 if (matcher.matches()) 124 { 125 if(matcher.groupCount()>0) 126 { 127 for (int g=1;g<=matcher.groupCount();g++) 128 { 129 String group=matcher.group(g); 130 if (group!=null) 131 tag=tag==null?group:(tag+group); 132 } 133 } 134 else 135 tag=matcher.group(); 136 } 137 else 138 tag=ua; 139 140 if (_agentCache.size()>=_agentCacheSize) 141 _agentCache.clear(); 142 _agentCache.put(ua,tag); 143 144 } 145 return tag; 146 } 147 }