Issue 1801 - Use URL objects to process URLs in the background page

lib/url.js

Index: lib/url.js
===================================================================
--- a/lib/url.js
+++ b/lib/url.js
@@ -45,3 +45,110 @@
 
   return URL;
 })();
+
+/**
+ * Gets the IDN-decoded hostname from a URL object.
+ *
+ * @param {URL} [url]
+ * @return {string}
+ */
+function getDecodedHostname(url)
+{
+  let hostname = url.hostname;
+
+  if (hostname.indexOf("xn--") == -1)
+    return hostname;
+
+  return punycode.toUnicode(hostname);
+}
+exports.getDecodedHostname = getDecodedHostname;
+
+/**
+ * Gets the IDN-decoded hostname from the URL of a frame.
+ * If the URL don't have host information (like "about:blank"
+ * and "data:" URLs) it falls back to the parent frame.
+ *
+ * @param {Frame} [frame]
+ * @return {string}
+ */
+function extractHostFromFrame(frame)
+{
+  for (; frame; frame = frame.parent)

[kzar, 2015/01/26 10:27:38]

Took me a second to grok this loop, wouldn't a while loop be clearer here?

while (frame)
{
  if (frame.url)
  {
    let hostname = getDecodedHostname(frame.url);
    if (hostname)
      return hostname;
  }

  frame = frame.parent;
}

return "";

[Sebastian Noack, 2015/01/26 10:38:39]

I think this a typical case for-lops exist for, to check for a condition and
advance the state in the header. This isn't necessarily limited to counters.

[kzar, 2015/01/26 17:19:05]

Hmm well I guess it's subjective which form is easier to read. I'll leave the
deciding vote to Wladimir :D

[Sebastian Noack, 2015/01/26 17:26:31]

As long as you don't consider for-loops generally less readable than while-loops
like below, there is objectively no reason why you shouldn't use for-loops here.

var i = 0;
while (i < 10)
{
  ...
  i++;
}

[Wladimir Palant, 2015/02/11 13:45:45]

I think I wrote the for loop in the original code, it went exactly like this one
:)

In general, I do like using for loops wherever it makes sense - meaning that the
increment doesn't have to be trivial. I would probably have concerns if it were
some complicated construct, but this one isn't.

+  {
+    let hostname = getDecodedHostname(frame.url);
+    if (hostname)
+      return hostname;
+  }
+
+  return "";
+}
+exports.extractHostFromFrame = extractHostFromFrame;
+
+/**
+ * Converts a URL object into a string. For HTTP(S) URLs the hash and
+ * auth crendetials are stripped, and the hostname gets IDN-decoded.
+ *
+ * @param {URL} [url]
+ * @return {string}
+ */
+function stringifyURL(url)
+{
+  let protocol = url.protocol;
+  if (protocol != "http:" && protocol != "https:")
+    return url.href;
+
+  let host = getDecodedHostname(url);
+  if (url.port)
+    host += ":" + url.port;
+  return protocol + "//" + host + url.pathname + url.search;
+}
+exports.stringifyURL = stringifyURL;
+
+function isDomain(hostname)
+{
+  return /[^\d.]/.test(hostname) && hostname.indexOf(":") == -1;

[Wladimir Palant, 2015/02/09 12:54:29]

new URL("http://0x5bec7a38/").hostname - gives you "0x5bec7a38" in Safari.
Chrome normalizes IPv4 addresses however. There is also
"http://0x5b.236.122.56/" by the way.

Also, please add a comment - it's not obvious what you are testing here.

[Sebastian Noack, 2015/02/11 10:55:51]

Done.

+}
+
+function getBaseDomain(hostname)
+{
+  let bits = hostname.split(".");
+  let cutoff = bits.length - 2;
+
+  for (let i = 0; i < bits.length; i++)
+  {
+    let offset = publicSuffixes[bits.slice(i).join(".")];
+
+    if (typeof offset != "undefined")
+    {
+      cutoff = i - offset;
+      break;
+    }
+  }
+
+  if (cutoff <= 0)
+    return hostname;
+
+  return bits.slice(cutoff).join(".");
+}
+
+/**
+ * Checks whether the request's origin is different from the document's origin.
+ *
+ * @param {URL}    [url]          The request URL
+ * @param {string} [documentHost] The IDN-decoded hostname of the document
+ * @return {Boolean}
+ */
+function isThirdParty(url, documentHost)
+{
+  let requestHost = getDecodedHostname(url).replace(/\.+$/, "");
+  documentHost = documentHost.replace(/\.+$/, "");
+
+  if (requestHost == documentHost)
+    return false;
+
+  if (!isDomain(requestHost) || !isDomain(documentHost))
+    return true;
+
+  return getBaseDomain(requestHost) != getBaseDomain(documentHost);
+}
+exports.isThirdParty = isThirdParty;