feat: parse key attributes for Widevine HLS (#88)

src/parser.js

@@ -4,6 +4,7 @@
 import Stream from './stream';
 import LineStream from './line-stream';
 import ParseStream from './parse-stream';
+import decodeB64ToUint8Array from './utils/decode';
 
 /**
  * A parser for M3U8 files. The current interpretation of the input is
@@ -49,6 +50,9 @@ export default class Parser extends Stream {
       'CLOSED-CAPTIONS': {},
       'SUBTITLES': {}
     };
+    // This is the Widevine UUID from DASH IF IOP. The same exact string is
+    // used in MPDs with Widevine encrypted streams.
+    const widevineUuid = 'urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed';
     // group segments into numbered timelines delineated by discontinuities
     let currentTimeline = 0;
 
@@ -143,6 +147,55 @@ export default class Parser extends Stream {
                 });
                 return;
               }
+
+              // check if the content is encrypted for Widevine
+              // Widevine/HLS spec: https://storage.googleapis.com/wvdocs/Widevine_DRM_HLS.pdf
+              if (entry.attributes.KEYFORMAT === widevineUuid) {
+                const VALID_METHODS = ['SAMPLE-AES', 'SAMPLE-AES-CTR', 'SAMPLE-AES-CENC'];
+
+                if (VALID_METHODS.indexOf(entry.attributes.METHOD) === -1) {
+                  this.trigger('warn', {
+                    message: 'invalid key method provided for Widevine'
+                  });
+                  return;
+                }
+
+                if (entry.attributes.METHOD === 'SAMPLE-AES-CENC') {
+                  this.trigger('warn', {
+                    message: 'SAMPLE-AES-CENC is deprecated, please use SAMPLE-AES-CTR instead'
+                  });
+                }
+
+                if (entry.attributes.URI.substring(0, 23) !== 'data:text/plain;base64,') {
+                  this.trigger('warn', {
+                    message: 'invalid key URI provided for Widevine'
+                  });
+                  return;
+                }
+
+                if (!(entry.attributes.KEYID && entry.attributes.KEYID.substring(0, 2) === '0x')) {
+                  this.trigger('warn', {
+                    message: 'invalid key ID provided for Widevine'
+                  });
+                  return;
+                }
+
+                // if Widevine key attributes are valid, store them as `contentProtection`
+                // on the manifest to emulate Widevine tag structure in a DASH mpd
+                this.manifest.contentProtection = {
+                  'com.widevine.alpha': {
+                    attributes: {
+                      schemeIdUri: entry.attributes.KEYFORMAT,
+                      // remove '0x' from the key id string
+                      keyId: entry.attributes.KEYID.substring(2)
+                    },
+                    // decode the base64-encoded PSSH box
+                    pssh: decodeB64ToUint8Array(entry.attributes.URI.split(',')[1])
+                  }
+                };
+                return;
+              }
+
               if (!entry.attributes.METHOD) {
                 this.trigger('warn', {
                   message: 'defaulting key method to AES-128'

src/utils/decode.js

@@ -0,0 +1,11 @@
+import window from 'global/window';
+
+export default function decodeB64ToUint8Array(b64Text) {
+  const decodedString = window.atob(b64Text || '');
+  const array = new Uint8Array(decodedString.length);
+
+  for (let i = 0; i < decodedString.length; i++) {
+    array[i] = decodedString.charCodeAt(i);
+  }
+  return array;
+}

test/m3u8.test.js

@@ -896,6 +896,7 @@ QUnit.test('parses prefixed with 0x or 0X #EXT-X-KEY:IV tags', function(assert)
     0x90abcdef
   ]), 'parsed an IV value with 0X');
 });
+
 // #EXT-X-START
 QUnit.test('parses EXT-X-START tags', function(assert) {
   const manifest = '#EXT-X-START:TIME-OFFSET=1.1\n';
@@ -1173,6 +1174,116 @@ QUnit.test('parses FORCED attribute', function(assert) {
     'parsed FORCED attribute');
 });
 
+QUnit.test('parses Widevine #EXT-X-KEY attributes and attaches to manifest', function(assert) {
+  const parser = new Parser();
+
+  const manifest = [
+    '#EXTM3U',
+    '#EXT-X-KEY:METHOD=SAMPLE-AES-CTR,' +
+      'URI="data:text/plain;base64,AAAAPnBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAB4iFnN' +
+      'oYWthX2NlYzJmNjRhYTc4OTBhMTFI49yVmwY=",KEYID=0x800AACAA522958AE888062B5695DB6BF,' +
+      'KEYFORMATVERSIONS="1",KEYFORMAT="urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed"',
+    '#EXTINF:5,',
+    'ex1.ts',
+    '#EXT-X-ENDLIST'
+  ].join('\n');
+
+  parser.push(manifest);
+
+  assert.ok(parser.manifest.contentProtection, 'contentProtection property added');
+  assert.equal(
+    parser.manifest.contentProtection['com.widevine.alpha'].attributes.schemeIdUri,
+    'urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed',
+    'schemeIdUri set correctly'
+  );
+  assert.equal(
+    parser.manifest.contentProtection['com.widevine.alpha'].attributes.keyId,
+    '800AACAA522958AE888062B5695DB6BF',
+    'keyId set correctly'
+  );
+  assert.equal(
+    parser.manifest.contentProtection['com.widevine.alpha'].pssh.byteLength,
+    62,
+    'base64 URI decoded to TypedArray'
+  );
+});
+
+QUnit.test('Widevine #EXT-X-KEY attributes not attached to manifest if METHOD is invalid', function(assert) {
+  const parser = new Parser();
+
+  const manifest = [
+    '#EXTM3U',
+    '#EXT-X-KEY:METHOD=NONE,' +
+      'URI="data:text/plain;base64,AAAAPnBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAB4iFnN' +
+      'oYWthX2NlYzJmNjRhYTc4OTBhMTFI49yVmwY=",KEYID=0x800AACAA522958AE888062B5695DB6BF,' +
+      'KEYFORMATVERSIONS="1",KEYFORMAT="urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed"',
+    '#EXTINF:5,',
+    'ex1.ts',
+    '#EXT-X-ENDLIST'
+  ].join('\n');
+
+  parser.push(manifest);
+
+  assert.notOk(parser.manifest.contentProtection, 'contentProtection not added');
+});
+
+QUnit.test('Widevine #EXT-X-KEY attributes not attached to manifest if URI is invalid', function(assert) {
+  const parser = new Parser();
+
+  const manifest = [
+    '#EXTM3U',
+    '#EXT-X-KEY:METHOD=SAMPLE-AES-CTR,' +
+      'URI="AAAAPnBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAB4iFnN' +
+      'oYWthX2NlYzJmNjRhYTc4OTBhMTFI49yVmwY=",KEYID=0x800AACAA522958AE888062B5695DB6BF,' +
+      'KEYFORMATVERSIONS="1",KEYFORMAT="urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed"',
+    '#EXTINF:5,',
+    'ex1.ts',
+    '#EXT-X-ENDLIST'
+  ].join('\n');
+
+  parser.push(manifest);
+
+  assert.notOk(parser.manifest.contentProtection, 'contentProtection not added');
+});
+
+QUnit.test('Widevine #EXT-X-KEY attributes not attached to manifest if KEYID is invalid', function(assert) {
+  const parser = new Parser();
+
+  const manifest = [
+    '#EXTM3U',
+    '#EXT-X-KEY:METHOD=SAMPLE-AES-CTR,' +
+      'URI="data:text/plain;base64,AAAAPnBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAB4iFnN' +
+      'oYWthX2NlYzJmNjRhYTc4OTBhMTFI49yVmwY=",KEYID=800AACAA522958AE888062B5695DB6BF,' +
+      'KEYFORMATVERSIONS="1",KEYFORMAT="urn:uuid:edef8ba9-79d6-4ace-a3c8-27dcd51d21ed"',
+    '#EXTINF:5,',
+    'ex1.ts',
+    '#EXT-X-ENDLIST'
+  ].join('\n');
+
+  parser.push(manifest);
+
+  assert.notOk(parser.manifest.contentProtection, 'contentProtection not added');
+});
+
+QUnit.test('Widevine #EXT-X-KEY attributes not attached to manifest if KEYFORMAT is not Widevine UUID', function(assert) {
+  const parser = new Parser();
+
+  const manifest = [
+    '#EXTM3U',
+    '#EXT-X-KEY:METHOD=SAMPLE-AES-CTR,' +
+      'URI="data:text/plain;base64,AAAAPnBzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAAB4iFnN' +
+      'oYWthX2NlYzJmNjRhYTc4OTBhMTFI49yVmwY=",KEYID=0x800AACAA522958AE888062B5695DB6BF,' +
+      'KEYFORMATVERSIONS="1",KEYFORMAT="invalid-keyformat"',
+    '#EXTINF:5,',
+    'ex1.ts',
+    '#EXT-X-ENDLIST'
+  ].join('\n');
+
+  parser.push(manifest);
+
+  assert.notOk(parser.manifest.contentProtection, 'contentProtection not added');
+});
+
 QUnit.module('m3u8s');
 
 QUnit.test('parses static manifests as expected', function(assert) {