Determine the frame structure

src/org/adblockplus/android/AdblockPlus.java

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 package org.adblockplus.android;
 
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.util.ArrayList;
 import java.util.Calendar;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.TimeZone;
 import java.util.regex.Pattern;
 
 import org.adblockplus.android.updater.AlarmReceiver;
 
 import android.app.ActivityManager;
 import android.app.ActivityManager.RunningServiceInfo;
 import android.app.AlarmManager;
 import android.app.Application;
 import android.app.PendingIntent;
@@ skipping 40 matching lines @@
   private Subscription[] subscriptions;
 
   /**
    * Indicates whether filtering is enabled or not.
    */
   private boolean filteringEnabled = false;
 
   private ABPEngine abpEngine;
   
   private static AdblockPlus instance;
+  
+  private static class ReferrerMappingCache extends LinkedHashMap<String, String>
+  {
+    private static final long serialVersionUID = 1L;
+    private static final int MAX_SIZE = 5000;
+
+    public ReferrerMappingCache()
+    {
+      super(MAX_SIZE + 1, 0.75f, true);
+    }
+
+    @Override
+    protected boolean removeEldestEntry(Map.Entry<String, String> eldest)
+    {
+      return size() > MAX_SIZE;
+    }
+  };
+
+  private ReferrerMappingCache referrerMapping = new ReferrerMappingCache();
 
   /**
    * Returns pointer to itself (singleton pattern).
    */
   public static AdblockPlus getApplication()
   {
     return instance;
   }
 
   public int getBuildNumber()
@@ skipping 234 matching lines @@
    *          Request query string
    * @param referrer
    *          Request referrer header
    * @param accept
    *          Request accept header
    * @return true if matched filter was found
    * @throws Exception
    */
   public boolean matches(String url, String query, String referrer, String accept)
   {
+    if (referrer != null)
+      referrerMapping.put(url, referrer);
+
     if (!filteringEnabled)
       return false;
     
     String contentType = null;
 
     if (accept != null)
     {
       if (accept.contains("text/css"))
         contentType = "STYLESHEET";
       else if (accept.contains("image/*"))
@@ skipping 10 matching lines @@
         contentType = "IMAGE";
       else if (RE_FONT.matcher(url).matches())
         contentType = "FONT";
     }
     if (contentType == null)
       contentType = "OTHER";
 
     if (!"".equals(query))
       url = url + "?" + query;
 
-    return abpEngine.matches(url, contentType, referrer);
+    final List<String> referrerChain = buildReferrerChain(referrer);
+    Log.d("Referrer chain", url + ": " + referrerChain.toString());
+    String[] referrerChainArray = referrerChain.toArray(new String[referrerChain.size()]);
+    return abpEngine.matches(url, contentType, referrerChainArray);
+  }
+
+  private List<String> buildReferrerChain(String url)
+  {
+    final List<String> referrerChain = new ArrayList<String>();
+    // We need to limit the chain length to ensure we don't block indefinitely if there's
+    // a referrer loop.
+    final int maxChainLength = 10;
+    for (int i = 0; i < maxChainLength && url != null; i++)
+    {
+      referrerChain.add(url);
+      url = referrerMapping.get(url);
+    }
+    return referrerChain;
   }
 
   /**
    * Checks if filtering is enabled.
    */
   public boolean isFilteringEnabled()
   {
     return filteringEnabled;
   }
 
@@ skipping 114 matching lines @@
       Log.e(TAG, e.getMessage(), e);
     }
 
     // Set crash handler
     Thread.setDefaultUncaughtExceptionHandler(new CrashHandler(this));
 
     // Initiate update check
     scheduleUpdater(0);
   }
 }