Issue 1498 - Look for iptables on the system first

src/org/adblockplus/android/configurators/IptablesProxyConfigurator.java

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 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
@@ skipping 40 matching lines @@
   @Override
   public boolean initialize()
   {
     try
     {
       if (!RootTools.isAccessGiven())
       {
         throw new IllegalStateException("No root access");
       }
 
-      final File ipt = this.context.getFileStreamPath("iptables");
-
-      if (!ipt.exists())
-      {
-        throw new FileNotFoundException("No iptables executable");
-      }
-
-      final String path = ipt.getAbsolutePath();
+      final String path = getIptablesExecutablePath();
 
       RootTools.sendShell("chmod 700 " + path, DEFAULT_TIMEOUT);
 
       boolean compatible = false;
       boolean version = false;
 
       final String command = path + " --version\n" + path + " -L -t nat -n\n";
 
       final List<String> result = RootTools.sendShell(command, DEFAULT_TIMEOUT);
 
@@ skipping 17 matching lines @@
       this.iptables = path;
 
       return true;
     }
     catch (final Exception e)
     {
       return false;
     }
   }
 
+  private String getIptablesExecutablePath() throws FileNotFoundException
+  {
+    File iptablesExecutable = new File("/system/bin/iptables");
+    if (!iptablesExecutable.exists())
+    {
+      Log.i(TAG, "iptables not found on the system, using embedded binary");
+      iptablesExecutable = context.getFileStreamPath("iptables");
+    }
+    if (!iptablesExecutable.exists())
+      throw new FileNotFoundException("No iptables executable");
+    return iptablesExecutable.getAbsolutePath();
+  }
+
   @Override
   public boolean registerProxy(final InetAddress address, final int port)
   {
     try
     {
       final int uid = this.context.getPackageManager().getPackageInfo(this.context.getPackageName(), 0).applicationInfo.uid;
 
       final StringBuilder cmd = new StringBuilder();
       cmd.append(this.iptables);
       cmd.append(IPTABLES_RETURN.replace("{{UID}}", String.valueOf(uid)));
@@ skipping 109 matching lines @@
   {
     return false;
   }
 
   @Override
   public String toString()
   {
     return "[ProxyConfigurator: " + this.getType() + "]";
   }
 }