shaka-player
Version:
DASH/EME video player library
234 lines (205 loc) • 6.35 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.drm.PlayReady');
goog.require('shaka.log');
goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.StringUtils');
goog.require('shaka.util.TXml');
goog.require('shaka.util.Uint8ArrayUtils');
/**
* @summary A set of functions for parsing Microsoft Playready Objects.
*/
shaka.drm.PlayReady = class {
/**
* Parses an Array buffer starting at byteOffset for PlayReady Object Records.
* Each PRO Record is preceded by its PlayReady Record type and length in
* bytes.
*
* PlayReady Object Record format: https://goo.gl/FTcu46
*
* @param {!DataView} view
* @param {number} byteOffset
* @return {!Array<shaka.drm.PlayReady.PlayReadyRecord>}
* @private
*/
static parseMsProRecords_(view, byteOffset) {
const records = [];
while (byteOffset < view.byteLength - 1) {
const type = view.getUint16(byteOffset, true);
byteOffset += 2;
const byteLength = view.getUint16(byteOffset, true);
byteOffset += 2;
if ((byteLength & 1) != 0 || byteLength + byteOffset > view.byteLength) {
shaka.log.warning('Malformed MS PRO object');
return [];
}
const recordValue = shaka.util.BufferUtils.toUint8(
view, byteOffset, byteLength);
records.push({
type: type,
value: recordValue,
});
byteOffset += byteLength;
}
return records;
}
/**
* Parses a buffer for PlayReady Objects. The data
* should contain a 32-bit integer indicating the length of
* the PRO in bytes. Following that, a 16-bit integer for
* the number of PlayReady Object Records in the PRO. Lastly,
* a byte array of the PRO Records themselves.
*
* PlayReady Object format: https://goo.gl/W8yAN4
*
* @param {BufferSource} data
* @return {!Array<shaka.drm.PlayReady.PlayReadyRecord>}
* @private
*/
static parseMsPro_(data) {
let byteOffset = 0;
const view = shaka.util.BufferUtils.toDataView(data);
// First 4 bytes is the PRO length (DWORD)
const byteLength = view.getUint32(byteOffset, /* littleEndian= */ true);
byteOffset += 4;
if (byteLength != data.byteLength) {
// Malformed PRO
shaka.log.warning('PlayReady Object with invalid length encountered.');
return [];
}
// Skip PRO Record count (WORD)
byteOffset += 2;
// Rest of the data contains the PRO Records
return shaka.drm.PlayReady.parseMsProRecords_(view, byteOffset);
}
/**
* PlayReady Header format: https://goo.gl/dBzxNA
*
* @param {!shaka.extern.xml.Node} xml
* @return {string}
* @private
*/
static getLaurl_(xml) {
const TXml = shaka.util.TXml;
// LA_URL element is optional and no more than one is
// allowed inside the DATA element. Only absolute URLs are allowed.
// If the LA_URL element exists, it must not be empty.
for (const elem of TXml.getElementsByTagName(xml, 'DATA')) {
if (elem.children) {
for (const child of elem.children) {
if (child.tagName == 'LA_URL') {
return /** @type {string} */(
shaka.util.TXml.getTextContents(child));
}
}
}
}
// Not found
return '';
}
/**
* Gets a PlayReady Header Object
*
* @param {!shaka.extern.xml.Node} element
* @return {?shaka.extern.xml.Node}
* @private
*/
static getPlayReadyHeaderObject_(element) {
const PLAYREADY_RECORD_TYPES = shaka.drm.PlayReady.PLAYREADY_RECORD_TYPES;
const bytes = shaka.util.Uint8ArrayUtils.fromBase64(
/** @type {string} */ (shaka.util.TXml.getTextContents(element)));
const records = shaka.drm.PlayReady.parseMsPro_(bytes);
const record = records.filter((record) => {
return record.type === PLAYREADY_RECORD_TYPES.RIGHTS_MANAGEMENT;
})[0];
if (!record) {
return null;
}
const xml = shaka.util.StringUtils.fromUTF16(record.value, true);
const rootElement = shaka.util.TXml.parseXmlString(xml, 'WRMHEADER');
if (!rootElement) {
return null;
}
return rootElement;
}
/**
* Gets a PlayReady license URL from a PlayReady Header Object
*
* @param {!shaka.extern.xml.Node} element
* @return {string}
*/
static getLicenseUrl(element) {
try {
const headerObject =
shaka.drm.PlayReady.getPlayReadyHeaderObject_(element);
if (!headerObject) {
return '';
}
return shaka.drm.PlayReady.getLaurl_(headerObject);
} catch (e) {
return '';
}
}
/**
* Gets a PlayReady KID from a protection element containing a
* PlayReady Header Object
*
* @param {!shaka.extern.xml.Node} element
* @return {?string}
*/
static getPlayReadyKID(element) {
const rootElement = shaka.drm.PlayReady.getPlayReadyHeaderObject_(element);
if (!rootElement) {
return null;
}
const TXml = shaka.util.TXml;
// KID element is optional and no more than one is
// allowed inside the DATA element.
for (const elem of TXml.getElementsByTagName(rootElement, 'DATA')) {
const kid = TXml.findChild(elem, 'KID');
if (kid) {
// GUID: [DWORD, WORD, WORD, 8-BYTE]
const guidBytes =
shaka.util.Uint8ArrayUtils.fromBase64(
/** @type {string} */ (shaka.util.TXml.getTextContents(kid)));
// Reverse byte order from little-endian to big-endian
const kidBytes = new Uint8Array([
guidBytes[3], guidBytes[2], guidBytes[1], guidBytes[0],
guidBytes[5], guidBytes[4],
guidBytes[7], guidBytes[6],
...guidBytes.slice(8),
]);
return shaka.util.Uint8ArrayUtils.toHex(kidBytes);
}
}
// Not found
return null;
}
};
/**
* @typedef {{
* type: number,
* value: !Uint8Array
* }}
*
* @description
* The parsed result of a PlayReady object record.
*
* @property {number} type
* Type of data stored in the record.
* @property {!Uint8Array} value
* Record content.
*/
shaka.drm.PlayReady.PlayReadyRecord;
/**
* Enum for PlayReady record types.
* @enum {number}
*/
shaka.drm.PlayReady.PLAYREADY_RECORD_TYPES = {
RIGHTS_MANAGEMENT: 0x001,
RESERVED: 0x002,
EMBEDDED_LICENSE: 0x003,
};