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
64
65
66
67
68
69
70
71
72
73
74
75
76
|
/** \file
* \brief This file contains wrappers for HTML Audio and Video elements
*
* \see https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/canPlayType
*
* \author Copyright (C) 2022 Libor Polcak
*
* \license SPDX-License-Identifier: GPL-3.0-or-later
*/
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
/** \file
* \ingroup wrappers
*
* Supported codecs (multimedia media types) can be misued for fingerprinting,
* see for example the [FPMon paper](https://fpmon.github.io/fingerprinting-monitor/files/FPMON.pdf).
*
* JShelter provides two modes of protection:
*
* 1. Strict approach returns all media types as not supported.
* 2. Modifies the output of probably/maybe supported codecs.
*/
/*
* Create private namespace
*/
(function() {
var wrappers = [
{
parent_object: "HTMLMediaElement.prototype",
parent_object_property: "canPlayType",
wrapped_objects: [{
original_name: "HTMLMediaElement.prototype.canPlayType",
wrapped_name: "origF",
}],
helping_code: `var approach = args[0];`,
wrapping_function_args: "media, ...args",
wrapping_function_body: `
if ((approach == 2) || (approach == 1)) {
return "";
}
else {
var normalized = media.replace(/\s|\\n|\\t|\\r/g, '');
var origVal = origF.call(this, media);
if (origVal === "") {
return origVal;
}
else {
var medcap_prng = alea(domainHash, "MediaCapabilities.prototype.encodingInfo", normalized);
var rnd = medcap_prng.get_bits(1);
if (rnd == 0) {
return "probably";
}
else {
return "maybe";
}
}
}
`,
},
]
add_wrappers(wrappers);
})()
|