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Add ms:laurl and mspr:pro parsing #1010

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Add ms:laurl and mspr:pro parsing #1010

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187 changes: 186 additions & 1 deletion lib/dash/content_protection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,179 @@ shaka.dash.ContentProtection.parseFromRepresentation = function(
return repContext.defaultKeyId || context.defaultKeyId;
};

/**
* Gets a Widevine license URL from a content protection element
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Unless I am mistaken, 'ms:laurl' is a Microsoft specific element. I don't believe Widevine has a standard way of embedding URLs in the manifest.

* containing a custom `ms:laurl` element
*
* @param {shaka.dash.ContentProtection.Element} element
* @return {string}
* @private
*/
shaka.dash.ContentProtection.getWidevineLicenseUrl_ = function(element) {
var mslaurlNode = shaka.util.XmlUtils.findChild(element.node, 'ms:laurl');

if (mslaurlNode) {
return mslaurlNode.getAttribute('licenseUrl') || '';
}

return '';
};

/**
* @typedef {{
* type: number,
* length: number,
* value: string
* }}
*
* @description
* The parsed result of a PlayReady object record.
*
* @property {number} type
* Type of data stored in the record.
* @property {number} length
* Size of the record in bytes.
* @property {string} value
* Record content.
*/
shaka.dash.ContentProtection.PlayReadyRecord;

/**
* @typedef {{
* length: number,
* recordCount: number,
* records: Array.<shaka.dash.ContentProtection.PlayReadyRecord>,
* }}
*
* @description
* The parsed result of a PlayReady object.
*
* @property {number} length
* Size of the PlayReady header object in bytes.
* @property {number} recordCount
* Number of records in the PlayReady object.
* @property {Array.<shaka.dash.ContentProtection.PlayReadyRecord>} records
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For object types like Array and Uint16Array, use a ! to make it non-nullable. E.g. {!Array.<T>}.

* Contains a variable number of records that contain license acquisition information.
*/
shaka.dash.ContentProtection.PlayReadyHeaderObject;
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You never use the length and recordCount members; how about just returning the array of records directly?


/**
* A map of PlayReady record types to description.
*
* @const {!Object.<number, string>}
* @private
*/
var PLAYREADY_RECORD_TYPES = {
0x0001 : 'RIGHTS_MANAGEMENT',
0x0002 : 'RESERVED',
0x0003 : 'EMBEDDED_LICENSE'
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It would be better to reverse this enum:

/** @enum {number} */
var PLAYREADY_RECORD_TYPES = {
  RIGHTS_MANAGEMENT: 0x001,
  RESERVED: 0x002,
  EMBEDDED_LICENSE: 0x003
};

If you look at my suggestion below, it allows us to use the compiler to check we don't misspell the name. Your enum here just converts a magic number to a magic string. Also, our compiler will remove the enum completely, so it avoids an object lookup at runtime.

};

/**
* @param {Uint16Array} recordData
* @param {number} recordCount
* @return {Array.<shaka.dash.ContentProtection.PlayReadyRecord>}
* @private
*/
shaka.dash.ContentProtection.parseRecords_ = function(recordData, recordCount) {
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How about renaming this so it is clear it is a 'mspr:pro' record? Something like parseMsProRecords_?

var head = 0;
var records = [];
for (var i = 0; i < recordCount; i++) {
var recordRaw = recordData.subarray(head);

var type = recordRaw[0];
var length = recordRaw[1];
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Here too, there are unchecked indexes. Can we add some checks to insure that the right amount of data is present before indexing?

var offset = 2;
var charCount = length / 2;
var end = charCount + offset;

// subarray end is exclusive
var rawValue = recordRaw.subarray(offset, end);
var value = String.fromCharCode.apply(null, rawValue);
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Please use shaka.util.StringUtils.fromUTF8 to parse UTF-8 correctly and avoid a possible stack overflow with large strings.


records.push({
type: type,
length: length,
value: value
});

head = end;
}

return records;
};

/**
* Based off getLicenseServerURLFromInitData from dash.js
* https://github.com/Dash-Industry-Forum/dash.js
*
* @param {Uint16Array} bytes
* @return {shaka.dash.ContentProtection.PlayReadyHeaderObject}
* @private
*/
shaka.dash.ContentProtection.parsePro_ = function(bytes) {
var length = bytes[0] | bytes[1];
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Did you forget a shift here? (bytes[0] << 16) | bytes[1]

var recordCount = bytes[2];
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Is there a guarantee that there will be at least 3 elements in bytes?


var recordData = bytes.subarray(3);
var records = shaka.dash.ContentProtection.parseRecords_(recordData, recordCount);

return {
length: length,
recordCount: recordCount,
records: records
};
};

/**
* @param {!Element} xml
* @return {string}
* @private
*/
shaka.dash.ContentProtection.getLaurl_ = function(xml) {
var laurlNode = xml.getElementsByTagName('LA_URL')[0];
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Is there a guarantee that there will be an element with the given tag name?

if (laurlNode) {
var laurl = laurlNode.childNodes[0].nodeValue;
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Is there a guarantee that there will be a child node?


if (laurl) {
return laurl;
}
}
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Could you reduce this down to:

var laurlNode = ...
return (laurlNode ? laurlNode.childNodes[0].nodeValue : null) || '';


return '';
};

/**
* Gets a PlayReady license URL from a content protection element
* containing a PlayReady Header Object
*
* @param {shaka.dash.ContentProtection.Element} element
* @return {string}
* @private
*/
shaka.dash.ContentProtection.getPlayReadyLicenseServerURL_ = function(element) {
var proNode = shaka.util.XmlUtils.findChild(element.node, 'mspr:pro');

if (!proNode) {
return '';
}

var bytes = shaka.util.Uint8ArrayUtils.fromBase64(proNode.textContent);
var parsedPro = shaka.dash.ContentProtection.parsePro_(new Uint16Array(bytes.buffer));
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If I remember correctly, Uint16Array uses the host byte order, whereas PlayReady uses little-endian. You may need to use DataView to read the data with the correct byte order.


var records = parsedPro.records;
var parser = new DOMParser();
for (var i = 0; i < records.length; i++) {
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I would prefer it if we could avoid indexed array iteration. Can we do something like:

var record = records.filter(function(record) {
  return PLAYREADY_RECORD_TYPES[record.type] == 'RIGHTS_MANAGEMENT';
}).pop();

if (record) {
  var xml = ...
  return ...
} else {
  return ...
}

var record = records[i];
if (PLAYREADY_RECORD_TYPES[record.type] === 'RIGHTS_MANAGEMENT') {
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if (record.type == PLAYREADY_RECORD_TYPES.RIGHTS_MANAGEMENT)

var xml = parser.parseFromString(record.value, 'application/xml').documentElement;

return shaka.dash.ContentProtection.getLaurl_(xml);
}
}

return '';
};

/**
* Creates DrmInfo objects from the given element.
Expand All @@ -276,7 +449,19 @@ shaka.dash.ContentProtection.convertElements_ = function(
goog.asserts.assert(!element.init || element.init.length,
'Init data must be null or non-empty.');
var initData = element.init || defaultInit;
return [ManifestParserUtils.createDrmInfo(keySystem, initData)];
var drmInfo = ManifestParserUtils.createDrmInfo(keySystem, initData);

// extract Widevine license URL
if (keySystem === 'com.widevine.alpha') {
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To make it easier for us to add support for other schemes, could we structure this like:

var license_url_parsers = {
  'com.widevine.alpha': shaka.dash...
  'com.microsoft.playready': shaka.dash...
};

var license_parser = license_parsers[keySystem];

if (license_parser) {
  drmInfo.licenseServerUri = license_parser(element);
}

drmInfo.licenseServerUri = shaka.dash.ContentProtection.getWidevineLicenseUrl_(element);
}

// extract PlayReady license URL from PlayReady header Object
if (keySystem === 'com.microsoft.playready') {
drmInfo.licenseServerUri = shaka.dash.ContentProtection.getPlayReadyLicenseServerURL_(element);
}

return [drmInfo];
} else {
goog.asserts.assert(
callback, 'ContentProtection callback is required');
Expand Down
176 changes: 176 additions & 0 deletions test/dash/dash_parser_content_protection_unit.js
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Expand Up @@ -717,3 +717,179 @@ describe('DashParser ContentProtection', function() {
Dash.testFails(done, source, expected);
});
});

describe('In-manifest PlayReady and Widevine', function() {
var ContentProtection = shaka.dash.ContentProtection;
var strToXml = function(str) {
var parser = new DOMParser();

return parser.parseFromString(str, 'application/xml').documentElement;
};

describe('getWidevineLicenseUrl_', function() {
it('valid ms:laurl node', function() {
var input = {
node: strToXml('<test><ms:laurl licenseUrl="www.example.com"></ms:laurl></test>')
};
var actual = ContentProtection.getWidevineLicenseUrl_(input);
var expected = 'www.example.com';
expect(actual).toEqual(expected);
});

it('ms:laurl without license url', function() {
var input = { node: strToXml('<test><ms:laurl></ms:laurl></test>') };
var actual = ContentProtection.getWidevineLicenseUrl_(input);
var expected = '';
expect(actual).toEqual(expected);
});

it('no ms:laurl node', function() {
var input = { node: strToXml('<test></test>') };
var actual = ContentProtection.getWidevineLicenseUrl_(input);
var expected = '';
expect(actual).toEqual(expected);
});
});

describe('parseRecords_', function() {
it('one record', function() {
var input = Uint16Array.from([
// Type
1,
// Size
2,
// Value
116
]);
var actual = ContentProtection.parseRecords_(input, 1);
var expected = [{ type: 1, length: 2, value: 't' }];
expect(actual).toEqual(expected);
});

it('multiple records', function() {
var input = Uint16Array.from([
1, 2, 116,
2, 2, 120
]);
var actual = ContentProtection.parseRecords_(input, 2);
var expected = [
{ type: 1, length: 2, value: 't' },
{ type: 2, length: 2, value: 'x' }
];
expect(actual).toEqual(expected);
});
});

describe('parsePro_', function() {
it('one record', function() {
var input = Uint16Array.from([
// PlayReady Object size
12, 0,
// Record count
1,

// Record
// Type
1,
// Size
2,
// Value
116
]);
var actual = ContentProtection.parsePro_(input);
var expected = {
length: 12, recordCount: 1,
records: [{ type: 1, length: 2, value: 't' }]
};
expect(actual).toEqual(expected);
});

it('multiple records', function() {
var input = Uint16Array.from([
// PlayReady Object
18, 0, 2,

// Record
1, 2, 116,

// Record
2, 2, 120
]);
var actual = ContentProtection.parsePro_(input);
var expected = {
length: 18, recordCount: 2,
records: [
{ type: 1, length: 2, value: 't' },
{ type: 2, length: 2, value: 'x' }
]
};
expect(actual).toEqual(expected);
});

it('no records', function() {
var input = Uint16Array.from([
// PlayReady Object
6, 0, 0,
]);
var actual = ContentProtection.parsePro_(input);
var expected = { length: 6, recordCount: 0, records: [] };
expect(actual).toEqual(expected);
});
});

describe('getLaurl_', function() {
it('contains LA_URL', function() {
var input = strToXml('<test><LA_URL>www.example.com</LA_URL></test>');
var actual = ContentProtection.getLaurl_(input);
var expected = 'www.example.com';
expect(actual).toEqual(expected);
});

it('does not contain LA_URL', function() {
var input = strToXml('<test></test>');
var actual = ContentProtection.getLaurl_(input);
var expected = '';
expect(actual).toEqual(expected);
});
});

describe('getPlayReadyLicenseServerURL_', function() {
it('mspro', function() {
var laurl = '<test><LA_URL>www.example.com</LA_URL></test>';
var laurlCodes = laurl.split('').map(function(c) {
return c.charCodeAt();
});
var prBytes = Uint16Array.from([
// pr object size (unused)
0, 0,
// record count
1,

// type
0x0001,
// record size
laurl.length * 2,
// value
].concat(laurlCodes));

var encodedPrObject = btoa(String.fromCharCode.apply(null, new Uint8Array(prBytes.buffer)));

var input = {
node: strToXml('<test><mspr:pro>' + encodedPrObject + '</mspr:pro></test>')
};

var actual = ContentProtection.getPlayReadyLicenseServerURL_(input);
var expected = 'www.example.com';
expect(actual).toEqual(expected);
});

it('no mspro', function() {
var input = {
node: strToXml('<test></test>')
};
var actual = ContentProtection.getPlayReadyLicenseServerURL_(input);
var expected = '';
expect(actual).toEqual(expected);
});
});
});