Issue 3956 - Convert domain whitelisting filters

lib/abp2blocklist.js

Index: lib/abp2blocklist.js
diff --git a/lib/abp2blocklist.js b/lib/abp2blocklist.js
index 1bece259e455539c7aebdbf220479425f7eab0e3..0a1ec26e3e7907c5cd76357ba7887c5770c974a5 100644
--- a/lib/abp2blocklist.js
+++ b/lib/abp2blocklist.js
@@ -66,28 +66,38 @@ function convertElemHideFilter(filter, elemhideSelectorExceptions)
 }
 
 /**
- * Convert the given filter "regexpSource" string into a regular expression,
- * handling the conversion of unicode inside hostnames to punycode.
- * (Also deciding if the regular expression can be safely converted to and
- *  matched as lower case or not.)
+ * Parse the given filter "regexpSource" string. Producing a regular expression,
+ * extracting the hostname (if any), deciding if the regular expression is safe
+ * to be converted + matched as lower case and noting if the source contains
+ * anything after the hostname.)
  *
  * @param   {string} text regexpSource property of a filter
- * @returns {object} An object containing a regular expression string and a bool
+ * @returns {object} An object containing a regular expression string, a bool
  *                   indicating if the filter can be safely matched as lower
- *                   case: {regexp: "...", canSafelyMatchAsLowercase: true/false}
+ *                   case, a hostname string (or undefined) and a bool
+ *                   indicating if the source only contains a hostname or not:
+ *                     {regexp: "...",
+ *                      canSafelyMatchAsLowercase: true/false,
+ *                      hostname: "...",
+ *                      justHostname: true/false}
  */
-function toRegExp(text)
+function parseFilterRegexpSource(text)
 {
-  let result = [];
+  let regexp = [];
   let lastIndex = text.length - 1;
+  let hostname;
   let hostnameStart = null;
   let hostnameFinished = false;
+  let justHostname = false;
   let canSafelyMatchAsLowercase = false;
 
   for (let i = 0; i < text.length; i++)
   {
     let c = text[i];
 
+    if (hostnameFinished)
+      justHostname = false;
+
     // If we're currently inside the hostname we have to be careful not to
     // escape any characters until after we have converted it to punycode.
     if (hostnameStart != null && !hostnameFinished)
@@ -97,9 +107,11 @@ function toRegExp(text)
       if (!endingChar && i != lastIndex)
         continue;
 
-      let hostname = text.substring(hostnameStart, endingChar ? i : i + 1);
-      hostnameFinished = true;
-      result.push(escapeRegExp(punycode.toASCII(hostname)));
+      hostname = punycode.toASCII(
+        text.substring(hostnameStart, endingChar ? i : i + 1)
+      );
+      hostnameFinished = justHostname = true;
+      regexp.push(escapeRegExp(hostname));
       if (!endingChar)
         break;
     }
@@ -107,32 +119,32 @@ function toRegExp(text)
     switch (c)
     {
       case "*":
-        if (result.length > 0 && i < lastIndex && text[i + 1] != "*")
-          result.push(".*");
+        if (regexp.length > 0 && i < lastIndex && text[i + 1] != "*")
+          regexp.push(".*");
         break;
       case "^":
         if (i < lastIndex)
-          result.push(".");
+          regexp.push(".");
         break;
       case "|":
         if (i == 0)
         {
-          result.push("^");
+          regexp.push("^");
           break;
         }
         if (i == lastIndex)
         {
-          result.push("$");
+          regexp.push("$");
           break;
         }
         if (i == 1 && text[0] == "|")
         {
           hostnameStart = i + 1;
           canSafelyMatchAsLowercase = true;
-          result.push("https?://");
+          regexp.push("https?://");
           break;
         }
-        result.push("\\|");
+        regexp.push("\\|");
         break;
       case "/":
         if (!hostnameFinished &&
@@ -141,44 +153,27 @@ function toRegExp(text)
           hostnameStart = i + 1;
           canSafelyMatchAsLowercase = true;
         }
-        result.push("/");
+        regexp.push("/");
         break;
       case ".": case "+": case "$": case "?":
       case "{": case "}": case "(": case ")":
       case "[": case "]": case "\\":
-        result.push("\\", c);
+        regexp.push("\\", c);
         break;
       default:
         if (hostnameFinished && (c >= "a" && c <= "z" ||
                                  c >= "A" && c <= "Z"))
           canSafelyMatchAsLowercase = false;
-        result.push(c);
+        regexp.push(c);
     }
   }
 
-  return {regexp: result.join(""),
-          canSafelyMatchAsLowercase: canSafelyMatchAsLowercase};
-}
-
-function getRegExpTrigger(filter)
-{
-  let result = toRegExp(filter.regexpSource);
-
-  let trigger = {"url-filter": result.regexp};
-
-  // Limit rules to to HTTP(S) URLs
-  if (!/^(\^|http)/i.test(trigger["url-filter"]))
-    trigger["url-filter"] = "^https?://.*" + trigger["url-filter"];
-
-  // For rules containing only a hostname we know that we're matching against
-  // a lowercase string unless the matchCase option was passed.
-  if (result.canSafelyMatchAsLowercase && !filter.matchCase)
-    trigger["url-filter"] = trigger["url-filter"].toLowerCase();
-
-  if (result.canSafelyMatchAsLowercase || filter.matchCase)
-    trigger["url-filter-is-case-sensitive"] = true;
-
-  return trigger;
+  return {
+    regexp: regexp.join(""),
+    canSafelyMatchAsLowercase: canSafelyMatchAsLowercase,
+    hostname: hostname,
+    justHostname: justHostname
+  };
 }
 
 function getResourceTypes(filter)
@@ -225,7 +220,29 @@ function addDomainPrefix(domains)
 
 function convertFilter(filter, action, withResourceTypes)
 {
-  let trigger = getRegExpTrigger(filter);
+  let parsed = parseFilterRegexpSource(filter.regexpSource);
+
+  // For the special case of $document whitelisting filters with just a domain
+  // we can generate an equivalent blocking rule exception using if-domain.
+  if (filter.contentType == typeMap.DOCUMENT && parsed.justHostname)

[Sebastian Noack, 2016/05/12 12:12:25]

For filters like example.com$document,image we would have to generate both, one
rule with if-domain and one with url-filter.

[kzar, 2016/05/16 16:22:36]

Done.

+    return {trigger: {"url-filter": ".*",

[Sebastian Noack, 2016/05/12 12:12:26]

Nit: Mind wrapping the nested object for better readability?

[Sebastian Noack, 2016/05/12 12:12:26]

Wouldn't an empty string be sufficient as url-filter to match all URLs?

[kzar, 2016/05/16 16:22:36]

Done.

[kzar, 2016/05/16 16:22:36]

Unfortunately this causes a "Extension compilation failed: Invalid url-filter
object." exception.

+            "if-domain": addDomainPrefix([parsed.hostname])},
+            action: {type: "ignore-previous-rules"}};
+
+  let trigger = {"url-filter": parsed.regexp};
+
+  // Limit rules to to HTTP(S) URLs

[Sebastian Noack, 2016/05/12 12:12:26]

Typo: to to

[kzar, 2016/05/16 16:22:36]

Done.

+  if (!/^(\^|http)/i.test(trigger["url-filter"]))
+    trigger["url-filter"] = "^https?://.*" + trigger["url-filter"];
+
+  // For rules containing only a hostname we know that we're matching against
+  // a lowercase string unless the matchCase option was passed.
+  if (parsed.canSafelyMatchAsLowercase && !filter.matchCase)
+    trigger["url-filter"] = trigger["url-filter"].toLowerCase();
+
+  if (parsed.canSafelyMatchAsLowercase || filter.matchCase)
+    trigger["url-filter-is-case-sensitive"] = true;
+
   let included = [];
   let excluded = [];
 
@@ -352,7 +369,8 @@ ContentBlockerList.prototype.addFilter = function(filter)
 
   if (filter instanceof filterClasses.WhitelistFilter)
   {
-    if (filter.contentType & (typeMap.IMAGE
+    if (filter.contentType & (typeMap.DOCUMENT
+                              | typeMap.IMAGE
                               | typeMap.STYLESHEET
                               | typeMap.SCRIPT
                               | typeMap.FONT