Issue 7236 - Handle sub properties in abort-on-property snippets

lib/content/snippets.js

 /*
  * 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 680 matching lines @@
 function randomId()
 {
   // 2176782336 is 36^6 which mean 6 chars [a-z0-9]
   // 60466176 is 36^5
   // 2176782336 - 60466176 = 2116316160. This ensure to always have 6
   // chars even if Math.random() returns its minimum value 0.0
   //
   return Math.floor(Math.random() * 2116316160 + 60466176).toString(36);
 }
 
-function wrapPropertyAccess(object, property, descriptor, magic)
-{
-  let dot = property.indexOf(".");
-  if (dot == -1)
+function wrapPropertyAccess(object, property, descriptor)
+{
+  let dotIndex = property.indexOf(".");
+  if (dotIndex == -1)
   {
     // simple property case.
     let currentDescriptor = Object.getOwnPropertyDescriptor(object, property);
     if (currentDescriptor && !currentDescriptor.configurable)
-      return false;
+      return;
 
     Object.defineProperty(object, property, descriptor);
-    return true;
+    return;
   }
-  let name = property.slice(0, dot);
-  property = property.slice(dot + 1);
+
+  let name = property.slice(0, dotIndex);
+  property = property.slice(dotIndex + 1);
   let value = object[name];
   if (value && typeof value == "object")
-    return wrapPropertyAccess(value, property, descriptor, magic);
+    wrapPropertyAccess(value, property, descriptor);
 
   let currentDescriptor = Object.getOwnPropertyDescriptor(object, name);
-  if (currentDescriptor)
-  {
-    if (currentDescriptor.set && currentDescriptor.set.hasOwnProperty(magic))
-      return true;
-    if (!currentDescriptor.configurable)
-      return false;
-  }
-
-  let v;
-  let setter = a =>
-  {
-    v = a;
-    if (a && typeof a == "object")
-      wrapPropertyAccess(a, property, descriptor, magic);
+  if (currentDescriptor && !currentDescriptor.configurable)
+    return;
+
+  let setter = newValue =>
+  {
+    value = newValue;
+    if (newValue && typeof newValue == "object")
+      wrapPropertyAccess(newValue, property, descriptor);
   };
-  setter[magic] = undefined;

[Manish Jethani, 2019/02/08 10:49:48]

I do not quite understand why this tag is necessary. Can you give an example of
a case where this would help?

[hub, 2019/02/08 14:14:03]

See above line 723 where we check if it's here and in that case move on.

[Manish Jethani, 2019/02/12 16:12:38]

Yes, but my question is more about why we need the tag at all. i.e. what if we
didn't tag it? Would it break something?

[hub, 2019/02/12 18:11:28]

so we don't try to set it again if it has already been, in case of recursion.
better be safe than sorry.

[Manish Jethani, 2019/02/15 14:45:24]

Well in any case it's redundant because configurable will be false for our own
descriptor. There's no need to set the magic property, nor to check for it.

[hub, 2019/02/19 15:36:48]

How do we know we are the one who set it?

[Manish Jethani, 2019/02/19 18:13:07]

We don't know, but if it's not configurable we can't set it anyway. (The code
will never reach the point where we check for the magic property.)

[hub, 2019/02/19 20:54:52]

Done.

-  Object.defineProperty(object, name, {get: () => v, set: setter});
-  return true;
+
+  Object.defineProperty(object, name, {get: () => value, set: setter});
 }
 
 /**
  * Overrides the <code>onerror</code> handler to discard tagged error messages
  * from our property wrapping.
  *
  * @param {string} magic The magic string that tags the error message.
  */
 function overrideOnError(magic)
 {
@@ skipping 23 matching lines @@
   if (!property)
     return;
 
   let rid = randomId();
 
   function abort()
   {
     throw new ReferenceError(rid);
   }
 
-  if (wrapPropertyAccess(window, property, {get: abort, set() {}}, rid))
-    overrideOnError(rid);
+  wrapPropertyAccess(window, property, {get: abort, set() {}});
+  overrideOnError(rid);
 }
 
 exports["abort-on-property-read"] = makeInjector(abortOnPropertyRead,
                                                  wrapPropertyAccess,
                                                  overrideOnError,
                                                  randomId);
 
 /**
  * Patches a property on the window object to abort execution when the
  * property is written.
@@ skipping 10 matching lines @@
   if (!property)
     return;
 
   let rid = randomId();
 
   function abort()
   {
     throw new ReferenceError(rid);
   }
 
-  if (wrapPropertyAccess(window, property, {set: abort}, rid))
-    overrideOnError(rid);
+  wrapPropertyAccess(window, property, {set: abort});
+  overrideOnError(rid);
 }
 
 exports["abort-on-property-write"] = makeInjector(abortOnPropertyWrite,
                                                   wrapPropertyAccess,
                                                   overrideOnError,
                                                   randomId);
 
 /**
  * Aborts the execution of an inline script.
  *
@@ skipping 12 matching lines @@
 
 
   let object = window;
   let path = api.split(".");
   let name = path.pop();
 
   for (let node of path)
   {
     object = object[node];
 
-    if (!object || typeof object != "object")
+    if (!object || !(typeof object == "object" || typeof object == "function"))
       return;
   }
 
   let currentValue = object[name];
 
   let abort = () =>
   {
     let element = document.currentScript;
     if (element instanceof HTMLScriptElement && element.src == "" &&
         element != us && (!re || re.test(element.textContent)))
     {
       throw new ReferenceError(rid);
     }
   };
 
   let descriptor = {
     get()
     {
       abort();
       return currentValue;
     },
     set(value)
     {
       abort();
       currentValue = value;
     }
   };
 
-  if (wrapPropertyAccess(object, name, descriptor, rid))
-    overrideOnError(rid);
+  wrapPropertyAccess(object, name, descriptor);
+  overrideOnError(rid);
 }
 
 exports["abort-current-inline-script"] =
   makeInjector(abortCurrentInlineScript, wrapPropertyAccess, toRegExp,
                overrideOnError, regexEscape, randomId);
+
+/**
+ * Strips a query string parameter from <code>fetch()</code> calls.
+ *
+ * @param {string} name The name of the parameter.
+ * @param {?string} [urlPattern] An optional pattern that the URL must match.
+ */
+function stripFetchQueryParameter(name, urlPattern = null)
+{
+  let fetch_ = window.fetch;
+  if (typeof fetch_ != "function")
+    return;
+
+  let urlRegExp = urlPattern ? toRegExp(urlPattern) : null;
+  window.fetch = function fetch(...args)
+  {
+    let [source] = args;
+    if (typeof source == "string" &&
+        (!urlRegExp || urlRegExp.test(source)))
+    {
+      let url = new URL(source);
+      url.searchParams.delete(name);
+      args[0] = url.href;
+    }
+    return fetch_.apply(this, args);
+  };
+}
+
+exports["strip-fetch-query-parameter"] = makeInjector(stripFetchQueryParameter,
+                                                      toRegExp, regexEscape);