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Unified Diff: lib/content/snippets.js

Issue 29886700: Issue 6969 - Implement abort-on-property-read snippet (Closed) Base URL: https://hg.adblockplus.org/adblockpluscore/
Patch Set: Fix wrap property Created Oct. 29, 2018, 8:01 p.m.
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Index: lib/content/snippets.js
===================================================================
--- a/lib/content/snippets.js
+++ b/lib/content/snippets.js
@@ -486,8 +486,74 @@
{
event.preventDefault();
}
},
true);
}
exports["prevent-inline-scripts"] = preventInlineScripts;
+
+/**
+ * Generates a random alphanumeric ID consisting of 6 base-36 digits
+ * from the range 100000..zzzzzz (both inclusive).
+ *
+ * @returns {string} The random ID.
+ */
+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)
+{
+ let currentDescriptor = Object.getOwnPropertyDescriptor(object, property);
+ if (!currentDescriptor)
+ {
Manish Jethani 2018/10/30 22:57:28 OK, so here's the thing: We don't need to use the
hub 2018/10/31 16:35:48 Done.
+ if (typeof descriptor.get == "undefined")
+ descriptor.get = currentDescriptor.get;
+ if (typeof descriptor.set == "undefined")
+ descriptor.set = currentDescriptor.set;
+ }
+ Object.defineProperty(object, property, descriptor);
+}
+
+/**
+ * Patches a property on the window object to abort execution when the
+ * property is read.
+ * No error will be printed in the console.
+ * The idea originates from
+ * {@link https://github.com/uBlockOrigin/uAssets/blob/80b195436f8f8d78ba713237bfc268ecfc9d9d2b/filters/resources.txt#L1703 uBlock Origin}
+ *
+ * @param {string} property The name of the property.
+ */
+function abortOnPropertyRead(property)
+{
+ if (!property)
+ return;
+
+ let rid = randomId();
+
+ function abort()
+ {
+ throw new ReferenceError(rid);
+ }
+
+ let {onerror} = window;
+ window.onerror = (message, ...rest) =>
+ {
+ if (typeof message == "string" && message.includes(rid))
+ return true;
+ if (typeof onerror == "function")
+ return (() => {}).call.call(onerror, this, message, ...rest);
+ };
+
+ wrapPropertyAccess(window, property, {get: abort, set() {}});
+}
+
+exports["abort-on-property-read"] = makeInjector(abortOnPropertyRead,
+ wrapPropertyAccess,
+ randomId);
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