RefererFilter


1   package org.roller.presentation.filters;
2   
3   import org.apache.commons.logging.Log;
4   import org.apache.commons.logging.LogFactory;
5   import org.roller.model.RefererManager;
6   import org.roller.presentation.RollerContext;
7   import org.roller.presentation.RollerRequest;
8   
9   import java.io.IOException  ;
10  
11  import javax.servlet.Filter  ;
12  import javax.servlet.FilterChain  ;
13  import javax.servlet.FilterConfig  ;
14  import javax.servlet.ServletException  ;
15  import javax.servlet.ServletRequest  ;
16  import javax.servlet.ServletResponse  ;
17  import javax.servlet.http.HttpServletRequest  ;
18  import javax.servlet.http.HttpServletResponse  ;
19  
20  
21  
22  /**
23   * Keep track of referers.
24   * 
25   * @web.filter name="RefererFilter"
26   * *web.filter-mapping url-pattern="/page/*"
27   * 
28   * @author David M. Johnson
29   */
30  public class RefererFilter implements Filter  
31  {
32      private FilterConfig     mFilterConfig = null;
33      private static Log mLogger = 
34          LogFactory.getFactory().getInstance(RefererFilter.class);
35     
36      /**
37       * destroy
38       */
39      public void destroy()
40      {
41      }
42  
43      /**
44       * doFilter
45       */
46      public void doFilter(
47          ServletRequest   req, ServletResponse   res, FilterChain   chain)
48          throws IOException  , ServletException  
49      {
50          HttpServletRequest   request = (HttpServletRequest  )req;
51          boolean isRefSpammer = false;       
52          try
53          {
54              RollerRequest rreq = RollerRequest.getRollerRequest(request);
55              RollerContext rctx = RollerContext.getRollerContext(
56                  mFilterConfig.getServletContext());
57              
58              if ( rreq.getUser() != null )
59              {
60                  String   userName = rreq.getUser().getUserName();                
61                  
62                  // Base page URLs, with and without www.
63                  String   basePageUrlWWW = 
64                      rctx.getAbsoluteContextUrl(request)+"/page/"+userName;                        
65                  String   basePageUrl = basePageUrlWWW;          
66                  if ( basePageUrlWWW.startsWith("http://www.") )
67                  {
68                      // chop off the http://www.
69                      basePageUrl = "http://"+basePageUrlWWW.substring(11);
70                  }
71                                   
72                  // Base comment URLs, with and without www.  
73                  String   baseCommentsUrlWWW = 
74                      rctx.getAbsoluteContextUrl(request)+"/comments/"+userName;   
75                  String   baseCommentsUrl = baseCommentsUrlWWW;          
76                  if ( baseCommentsUrlWWW.startsWith("http://www.") )
77                  {
78                      // chop off the http://www.
79                      baseCommentsUrl= "http://"+baseCommentsUrlWWW.substring(11);
80                  }
81                  
82                  // Don't process hits from same user's blogs as referers by
83                  // ignoring Don't process referer from pages that start with base URLs. 
84                  String   referer = request.getHeader("Referer");               
85                  if (  referer==null ||
86                        ( 
87                           !referer.startsWith( basePageUrl ) 
88                        && !referer.startsWith( basePageUrlWWW )
89                        && !referer.startsWith( baseCommentsUrl )
90                        && !referer.startsWith( baseCommentsUrlWWW )
91                        )
92                     )
93                  {
94                      RefererManager refMgr = 
95                          rreq.getRoller().getRefererManager();
96                      isRefSpammer = refMgr.processRequest(rreq);
97                  }
98                  else
99                  {
100                     if (mLogger.isDebugEnabled())
101                     {
102                         mLogger.debug("Ignoring referer="+referer);
103                     }
104                 }
105             }
106         }
107         catch (Exception   e)
108         {
109             mLogger.error("Processing referer",e);
110         }
111         
112         if (isRefSpammer)
113         {
114             HttpServletResponse   response = (HttpServletResponse  )res;
115             response.sendError(HttpServletResponse.SC_FORBIDDEN);            
116         }
117         else
118         {
119             chain.doFilter(req, res);
120         }
121     }
122 
123     /**
124      * init
125      */
126     public void init(FilterConfig   filterConfig) throws ServletException  
127     {
128         mFilterConfig = filterConfig;
129     }
130 }
131
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