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Diffstat (limited to 'data/extensions/jsr@javascriptrestrictor/wrappingS-MCS.js')
| -rw-r--r-- | data/extensions/jsr@javascriptrestrictor/wrappingS-MCS.js | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/data/extensions/jsr@javascriptrestrictor/wrappingS-MCS.js b/data/extensions/jsr@javascriptrestrictor/wrappingS-MCS.js new file mode 100644 index 0000000..bba9bd0 --- /dev/null +++ b/data/extensions/jsr@javascriptrestrictor/wrappingS-MCS.js @@ -0,0 +1,166 @@ +/** \file + * \brief Wrappers for Media Capture and Streams standard + * + * \see https://www.w3.org/TR/mediacapture-streams/ + * + * \author Copyright (C) 2021 Libor Polcak + * \author Copyright (C) 2021 Matus Svancar + * + * \license SPDX-License-Identifier: GPL-3.0-or-later + * \license SPDX-License-Identifier: MPL-2.0 + */ +// +// 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/>. +// +// Alternatively, the contents of this file may be used under the terms +// of the Mozilla Public License, v. 2.0, as described below: +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this file, +// You can obtain one at http://mozilla.org/MPL/2.0/. +// +// \copyright Copyright (c) 2020 The Brave Authors. + +/** \file + * This file contains wrapper for MediaDevices.enumerateDevices https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/enumerateDevices + * \ingroup wrappers + * + * The goal is to prevent fingerprinting by modifying return value of enumerateDevices. + * + * This wrapper operates with three levels of protection: + * + * * (0) - return promise with suffled array + * * (1) - return promise with shuffled array with additional 0-4 fake devices + * * (2) - return empty promise + * + * The shuffling approach is inspired by the algorithms created by [Brave Software](https://brave.com) + * available [here](https://github.com/brave/brave-core/blob/master/chromium_src/third_party/blink/renderer/modules/mediastream/media_devices.cc). + * + */ +/* + +/* + * Create private namespace + */ +(function() { + /** + * \brief change reurn value of enumerateDevices + * + * Depending on level chosen this function returns: + * * (0,1) - promise with modified device array + * * (2) - empty promise + */ + function farbleEnumerateDevices() { + // to emulate correctly we need a fresh Promise and a fresh Array (with same values) on every call + return cachedDevices.then(r => { + r = r.concat(); + return r; + }); + } + /** + * \brief create and return MediaDeviceInfo object by overlaying a native one with fake properties + * + * \param browserEnum enum specifying browser 0 - Chrome 1 - Firefox + */ + function fakeDevice(device, fd_prng){ + var kinds = ["videoinput", "audioinput", "audiooutput"]; + let browserEnum = device.groupId.length == 44 ? 1 : 0; + var deviceId = browserEnum == 1 ? randomString(43, browserEnum, fd_prng)+ "=" : ""; + let fakeData = { + deviceId, + groupId: deviceRandomString(browserEnum), + kind: kinds[Math.floor(fd_prng() * 3)], + label: "", + }; + let json = JSON.stringify(fakeData); + fakeData.toJSON = () => json; + let overlay = WrapHelper.overlay(device, fakeData); + return overlay; + } + /** + * \brief return random string for MediaDeviceInfo parameters + * + * \param browserEnum enum specifying browser 0 - Chrome 1 - Firefox + */ + function deviceRandomString(browserEnum) { + var ret = ""; + var lengths = [64, 43]; + var charSets = ["abcdefghijklmnopqrstuvwxyz0123456789","abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+/"]; + var length = lengths[browserEnum]; + var charSet = charSets[browserEnum]; + for ( var i = 0; i < length; i++ ) { + ret += charSet.charAt(Math.floor(Math.random() * charSet.length)); + } + if(browserEnum == 1) + ret += "="; + return ret; + } + var wrappers = [ + { + parent_object: "MediaDevices.prototype", + parent_object_property: "enumerateDevices", + wrapped_objects: [{ + original_name: "MediaDevices.prototype.enumerateDevices", + callable_name: "origEnumerateDevices", + }], + helping_code: farbleEnumerateDevices + shuffleArray + deviceRandomString + randomString + fakeDevice + ` + var fd_prng = alea(domainHash, "S-MCS MediaDevices.prototype.enumerateDevices"); + let [level] = args; + let cachedDevices = level < 2 ? + origEnumerateDevices.call(navigator.mediaDevices).then(result => { + try { + let shuffle = () => { + if (result.length > 1) shuffleArray(result); + return result; + }; + if (level === 1 && result.length) { + var enumd_prng = alea(domainHash, "MediaDevices.prototype.enumerateDevices"); + let additional = Math.floor(enumd_prng()*4); + if (additional > 0) { + let adding = []; + while (additional-- > 0) { + adding.push(origEnumerateDevices.call(navigator.mediaDevices).then(([device]) => { + let fake = fakeDevice(device, fd_prng); + result.push(fake); + })); + } + return Promise.all(adding).then(r => { + return shuffle(); + }); + } + } + return shuffle(); + } catch (e) { + console.error("Error in farble promise callback", e); + throw e; + } + }) + : Promise.resolve([]); + `, + wrapping_function_args: "", + /** \fn fake MediaDevices.prototype.enumerateDevices + * \brief Modifies return value + * + * Depending on level chosen this function returns: + * * (0) - promise with shuffled array + * * (1) - promise with shuffled array with additional 0-4 fake devices + * * (2) - empty promise + */ + wrapping_function_body: ` + return farbleEnumerateDevices(); + `, + }, + ] + add_wrappers(wrappers); +})() |