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/** \file
* \brief This file contains wrappers for the Media Capabilities APIs
*
* \see https://developer.mozilla.org/en-US/docs/Web/API/Media_Capabilities_API
*
* \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
*
* `` provides access to `MediaKeySystemAccess` object that
* allows to query supported codecs and other informations about the system.
*
* For example, visit https://www.fit.vutbr.cz/~polcak/jsr/hdcp/ and try a different browser or
* computer.
*
* \see https://w3c.github.io/media-capabilities/
*
* We provide two modes of protection:
*
* 1. Strict approach prevents accessing the API.
* 2. Farbling approach changes the output to a non-existing codec with 12.5% probability.
*/
/*
* Create private namespace
*/
(function() {
var helping_code = `var approach = args[0];`;
function prepareConfig(config) {
let changed = {
type: config.type,
};
if (config.audio) {
changed.audio = {
contentType: prng().toString(),
channels: config.audio.channels,
bitrate: config.audio.bitrate,
samplerate: config.audio.samplerate,
};
}
else {
changed.video = {
contentType: prng().toString(),
width: config.video.width,
height: config.video.height,
bitrate: config.video.bitrate,
framerate: config.video.framerate,
};
}
return forPage(changed);
}
var wrappers = [
{
parent_object: "MediaCapabilities.prototype",
parent_object_property: "encodingInfo",
wrapped_objects: [{
original_name: "MediaCapabilities.prototype.encodingInfo",
wrapped_name: "origF",
}],
helping_code: helping_code + prepareConfig,
wrapping_function_args: "config",
wrapping_function_body: `
if (approach == 2) {
return new Promise(() => {}); // Never resolves
}
else if (approach == 1) {
return origF.call(this, prepareConfig(config));
}
else {
let media = config.audio || config.video;
var normalized = media.contentType.replace(/\s|\\n|\\t|\\r/g, '');
var medcap_prng = alea(domainHash, "MediaCapabilities.prototype.encodingInfo", normalized);
var rnd = medcap_prng.get_bits(3);
if (rnd == 0) {
return origF.call(this, prepareConfig(config));
}
else {
return origF.call(this, config);
}
}
`,
},
{
parent_object: "MediaCapabilities.prototype",
parent_object_property: "decodingInfo",
wrapped_objects: [{
original_name: "MediaCapabilities.prototype.decodingInfo",
wrapped_name: "origF",
}],
helping_code: helping_code + prepareConfig,
wrapping_function_args: "config",
wrapping_function_body: `
if (approach == 2) {
return new Promise(() => {}); // Never resolves
}
else if (approach == 1) {
return origF.call(this, prepareConfig(config));
}
else {
let media = config.audio || config.video;
var normalized = media.contentType.replace(/\s|\\n|\\t|\\r/g, '');
var medcap_prng = alea(domainHash, "MediaCapabilities.prototype.decodingInfo", normalized);
var rnd = medcap_prng.get_bits(3);
if (rnd == 0) {
return origF.call(this, prepareConfig(config));
}
else {
return origF.call(this, config);
}
}
`,
},
]
add_wrappers(wrappers);
})()
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