Issue 5175 - Reject element hiding filter with empty domain names

compiled/filter/ElemHideBase.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 124 matching lines @@
                   (length - end) * sizeof(String::value_type));
       offset += (length - end) * sizeof(String::value_type);
 
       return converted;
     }
 
     return OwnedString(text);
   }
 }
 
-ElemHideBase::ElemHideBase(Type type, const String& text, const ElemHideData& data)
+ElemHideBase::ElemHideBase(Type type, const String& text,
+    const ElemHideData& data, const ParsedDomains& parsedDomains)
     : ActiveFilter(type, ConvertFilter(text, data.mSelectorStart), false),
       mData(data)
 {
   if (mData.HasDomains())
-    ParseDomains(mData.GetDomainsSource(mText), u',');
+    FillDomains(mData.GetDomainsSource(mText), parsedDomains);
 }
 
-Filter::Type ElemHideBase::Parse(DependentString& text, ElemHideData& data)
+Filter::Type ElemHideBase::Parse(DependentString& text, DependentString& error,
+    ElemHideData& data, ParsedDomains& parsedDomains)
 {
   StringScanner scanner(text);
 
   // Domains part
   bool seenSpaces = false;
   while (!scanner.done())
   {
     String::value_type next = scanner.next();
     if (next == u'#')
     {
@@ skipping 44 matching lines @@
       case u'}':
         return Type::UNKNOWN;
     }
   }
 
   // We are done validating, now we can normalize whitespace and the domain part
   if (seenSpaces)
     NormalizeWhitespace(text, data.mDomainsEnd, data.mSelectorStart);
   DependentString(text, 0, data.mDomainsEnd).toLower();
 
+  parsedDomains =
+    ParseDomainsInternal(data.GetDomainsSource(text), u',', false);
+  if (parsedDomains.hasEmpty)
+  {
+    error = u"filter_invalid_domain"_str;
+    return Type::INVALID;
+  }
+
   if (exception)
     return Type::ELEMHIDEEXCEPTION;
 
   if (emulation)
     return Type::ELEMHIDEEMULATION;
 
   return Type::ELEMHIDE;
 }
 
 OwnedString ElemHideBase::GetSelectorDomain() const
 {
   /* TODO this is inefficient */
   OwnedString result;
   if (mDomains)
   {
     for (const auto& item : *mDomains)
     {
       if (item.second && !item.first.empty())
       {
         if (!result.empty())
           result.append(u',');
         result.append(item.first);
       }
     }
   }
   return result;
 }