aboutsummaryrefslogtreecommitdiff
path: root/content/freezer.js
blob: cdd07093d7d4a43e79f1ce3a9dc154e2a3ab3d04 (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
/**
 * Helper functions for blocking scripts in pages, based off NoScript's lib/DocumentFreezer.js
 *
 * Copyright (C) 2005-2021 Giorgio Maone - https://maone.net
 * Copyright (C) 2021 jahoti
 * Redistribution terms are gathered in the `copyright' file.
 */

"use strict";

(() => {
    const loaderAttributes = ["href", "src", "data"];
    const jsOrDataUrlRx = /^(?:data:(?:[^,;]*ml|unknown-content-type)|javascript:)/i;

    function sanitizeAttributes(element) {
	if (element._frozen)
	    return;
	let fa = [];
	let loaders = [];
	for (let a of element.attributes) {
	    let name = a.localName.toLowerCase();
	    if (loaderAttributes.includes(name))
		if (jsOrDataUrlRx.test(a.value))
		    loaders.push(a);

	    else if (name.startsWith("on")) {
		console.debug("Removing", a, element.outerHTML);
		fa.push(a.cloneNode());
		a.value = "";
		element[name] = null;
	    }
	}
	if (loaders.length) {
	    for (let a of loaders) {
		fa.push(a.cloneNode());
		a.value = "javascript://frozen";
	    }
	    if ("contentWindow" in element)
		element.replaceWith(element = element.cloneNode(true));

	}
	if (fa.length)
	    element._frozenAttributes = fa;
	element._frozen = true;
    }
    
    function scriptSuppressor(nonce) {
	const blockExecute = e => {
	    if (document.readyState === 'complete') {
		removeEventListener('beforescriptexecute', blockExecute, true);
		return;
	    }
	    else if (e.isTrusted && e.target.getAttribute('nonce') !== nonce) { // Prevent blocking of injected scripts
		e.preventDefault();
		console.log('Suppressed script', e.target);
	    }
	};
	return blockExecute;
    };
    
    window.scriptSuppressor = scriptSuppressor;
    window.sanitize_attributes = sanitizeAttributes;
})();