Issue 4450 - Prevent ElemHide filters with empty domains

lib/filterClasses.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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/>.
  */
 
 /**
  * @fileOverview Definition of Filter class and its subclasses.
  */
 
 let {FilterNotifier} = require("filterNotifier");
 let {extend} = require("coreUtils");
 
+// Helper function used to determine if a filter has any empty domains or not.
+function emptyDomains(domains, separator)
+{
+  let emptySoFar = true;
+  for (let i = 0; i < domains.length; i++)
+  {
+    switch (domains[i])
+    {
+      case separator:
+        if (emptySoFar)
+          return true;
+        emptySoFar = true;
+      break;
+      case "~":
+      break;
+      default:
+        emptySoFar = false;
+    }
+  }
+  return emptySoFar;
+}
+
 /**
  * Abstract base class for filters
  *
  * @param {String} text   string representation of the filter
  * @constructor
  */
 function Filter(text)
 {
   this.text = text;
   this.subscriptions = [];
@@ skipping 882 matching lines @@
     }
 
     if (id)
       selector = tagName + "." + id + additional + "," + tagName + "#" + id + additional;
     else if (tagName || additional)
       selector = tagName + additional;
     else
       return new InvalidFilter(text, "filter_elemhide_nocriteria");
   }
 
+  if (domain && emptyDomains(domain, ElemHideBase.prototype.domainSeparator))

[Wladimir Palant, 2016/10/06 08:06:14]

Why have this function rather than /(^|,)~?(,|$)/.test(domain)? Yes, you would
duplicate the separator character but the result would be considerably faster.

[kzar, 2016/10/06 08:53:55]

Done.

+    return new InvalidFilter(text, "filter_empty_domain");

[Wladimir Palant, 2016/10/06 08:06:14]

filter_invalid_domain? We allow empty domains, but here the domain is invalid.

[kzar, 2016/10/06 08:53:56]

Done.

+
   if (isException)
     return new ElemHideException(text, domain, selector);
 
   let match = Filter.csspropertyRegExp.exec(selector);
   if (match)
   {
     // CSS property filters are inefficient so we need to make sure that
     // they're only applied if they specify active domains
     if (!/,[^~][^,.]*\.[^,]/.test("," + domain))
       return new InvalidFilter(text, "filter_cssproperty_nodomain");
@@ skipping 97 matching lines @@
     // several times on Safari, due to WebKit bug 132872
     let prop = Object.getOwnPropertyDescriptor(this, "regexpString");
     if (prop)
       return prop.value;
 
     let regexp = Filter.toRegExp(this.regexpSource);
     Object.defineProperty(this, "regexpString", {value: regexp});
     return regexp;
   }
 });