Issue 3710 - Unify hostname logic

lib/abp2blocklist.js

Index: lib/abp2blocklist.js
diff --git a/lib/abp2blocklist.js b/lib/abp2blocklist.js
index 1c1ff6cf57607e7344359dc9109a616c793df721..069d5153cea8d02a37076bd0b8509c9136f20aee 100644
--- a/lib/abp2blocklist.js
+++ b/lib/abp2blocklist.js
@@ -66,38 +66,49 @@ function convertElemHideFilter(filter, elemhideSelectorExceptions)
 }
 
 /**
- * Convert the given filter "regexpSource" string into a regular expression.
+ * 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.)
  *
  * @param   {string} text regexpSource property of a filter
  * @returns {object} An object containing a regular expression string and a bool
  *                   indicating if the filter can be safely matched as lower
- *                   case: {regexp: "...", caseSenstive: true/false}
+ *                   case: {regexp: "...", canSafelyMatchAsLowercase: true/false}
  */
 function toRegExp(text)
 {
   let result = [];
   let lastIndex = text.length - 1;
-  let hostnameStarted = false;
+  let hostnameStart = null;
   let hostnameFinished = false;
-  let caseSensitive = false;
+  let canSafelyMatchAsLowercase = false;
 
   for (let i = 0; i < text.length; i++)
   {
     let c = text[i];
 
+    // 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)
+    {
+      if (c == "*" || c == "^" || c == "?" || c == "/" || i == lastIndex)

[Sebastian Noack, 2016/02/27 20:30:38]

If you turn the logic here the other way around, you don't need an else block.

  if (c != "*" && c != "^" && c != "?" && c != "/" && i < lastIndex)
    continue;

[Sebastian Noack, 2016/02/27 20:30:38]

I'm not entirely sure if the case of last index is handled correctly. So if I
get the logic right you'd consider just "example.co" part of the hostname in
"||example.com".

[kzar, 2016/02/27 21:28:53]

Done.

[kzar, 2016/02/27 21:28:53]

Good point but it's even more complicated, what if we're at the last index but
also the current character is one that would have ended a hostname?! I've done
my best to keep the logic simple, but complexity crept in a bit.

+      {
+        hostnameFinished = true;
+        let hostname = text.substring(hostnameStart, i);
+        result.push(escapeRegExp(punycode.toASCII(hostname)));
+      }
+      else
+        continue;
+    }
+
     switch (c)
     {
       case "*":
-        if (hostnameStarted)
-          hostnameFinished = true;
         if (result.length > 0 && i < lastIndex && text[i + 1] != "*")
           result.push(".*");
         break;
       case "^":
-        if (hostnameStarted)
-          hostnameFinished = true;
         if (i < lastIndex)
           result.push(".");
         break;
@@ -114,45 +125,41 @@ function toRegExp(text)
         }
         if (i == 1 && text[0] == "|")
         {
-          hostnameStarted = caseSensitive = true;
           result.push("https?://");

[Sebastian Noack, 2016/02/27 20:30:38]

Nit: Mind moving that line to just above the break, for consistency?

[kzar, 2016/02/27 21:28:53]

Done.

+          hostnameStart = i + 1;
+          canSafelyMatchAsLowercase = true;
           break;
         }
-        result.push("\\", c);
+        result.push("\\|");
         break;
-      case "?":
-        if (hostnameStarted)
-          hostnameFinished = true;
-      case ".": case "+": case "$": case "{": case "}":
+      case "/":
+        result.push("/");

[Sebastian Noack, 2016/02/27 20:30:38]

Nit: Mind moving that line to just above the break, for consistency?

[kzar, 2016/02/27 21:28:53]

Done.

+        if (!hostnameFinished &&

[Sebastian Noack, 2016/02/27 20:30:38]

Nit: It doesn't matter, but I personally find that it reads slightly better if
you have similar code aligned when wrapping:

  if (!hostnameFinished && text.charAt(i-2) == ":"
                        && text.charAt(i-1) == "/")

[kzar, 2016/02/27 21:28:53]

I'd rather leave this one as it is.

+            text.charAt(i-2) == ":" && text.charAt(i-1) == "/")
+        {
+          hostnameStart = i + 1;
+          canSafelyMatchAsLowercase = true;
+        }
+        break;
+      case ".": case "+": case "$": case "{": case "}": case "?":

[Sebastian Noack, 2016/02/27 20:30:38]

Nit: I think the way this block was originally wrapped was a little nicer:

  case ".": case "+": case "$": case "?":
  case "{": case "}": case "(": case ")":
  case "[": case "]": case "\\":

But I guess it's personal preference, so I leave it up you.

[kzar, 2016/02/27 21:28:53]

Done.

       case "(": case ")": case "[": case "]": case "\\":
         result.push("\\", c);
         break;
-      case "/":
-        if (hostnameStarted)
-          hostnameFinished = true;
-        else if (text.charAt(i-2) == ":" && text.charAt(i-1) == "/")
-          hostnameStarted = caseSensitive = true;

[kzar, 2016/02/27 14:29:34]

(I've switched this around as I decided that sneaky fall-throughs in this big
switch were making things more confusing.)

       default:
         if (hostnameFinished && (c >= "a" && c <= "z" ||
                                  c >= "A" && c <= "Z"))
-          caseSensitive = false;
+          canSafelyMatchAsLowercase = false;
         result.push(c);
     }
   }
 
-  return {regexp: result.join(""), caseSensitive: caseSensitive};
+  return {regexp: result.join(""),
+          canSafelyMatchAsLowercase: canSafelyMatchAsLowercase};
 }
 
 function getRegExpTrigger(filter)
 {
-  let result = toRegExp(filter.regexpSource.replace(
-    // Safari expects punycode, filter lists use unicode
-    /^(\|\||\|?https?:\/\/)([\w\-.*\u0080-\uFFFF]+)/i,
-    function (match, prefix, domain)
-    {
-      return prefix + punycode.toASCII(domain);
-    }
-  ));
+  let result = toRegExp(filter.regexpSource);
 
   let trigger = {"url-filter": result.regexp};
 
@@ -162,10 +169,10 @@ function getRegExpTrigger(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.caseSensitive && !filter.matchCase)
+  if (result.canSafelyMatchAsLowercase && !filter.matchCase)
     trigger["url-filter"] = trigger["url-filter"].toLowerCase();
 
-  if (result.caseSensitive || filter.matchCase)
+  if (result.canSafelyMatchAsLowercase || filter.matchCase)
     trigger["url-filter-is-case-sensitive"] = true;
 
   return trigger;