feat: on license request errors, return response body as cause (#137)

This adds a new cause property to the error object returned by player.error() when a license request fails with a 4xx or 5xx status code. It's a string representation, so, if it's JSON a consumer would need to call JSON.parse manually as we can't know whether it's JSON or not.

src/eme.js

@@ -2,6 +2,7 @@ import videojs from 'video.js';
 import { requestPlayreadyLicense } from './playready';
 import window from 'global/window';
 import {mergeAndRemoveNull} from './utils';
+import {httpResponseHandler} from './http-handler.js';
 
 /**
  * Returns an array of MediaKeySystemConfigurationObjects provided in the keySystem
@@ -284,20 +285,8 @@ export const defaultGetLicense = (keySystemOptions) => (emeOptions, keyMessage,
     responseType: 'arraybuffer',
     body: keyMessage,
     headers
-  }, (err, response, responseBody) => {
-    if (err) {
-      callback(err);
-      return;
-    }
-
-    if (response.statusCode >= 400 && response.statusCode <= 599) {
-      // Pass an empty object as the error to use the default code 5 error message
-      callback({});
-      return;
-    }
-
-    callback(null, responseBody);
-  });
+  }, httpResponseHandler(callback, true)
+  );
 };
 
 const promisifyGetLicense = (getLicenseFn, eventBus) => {

src/fairplay.js

@@ -7,6 +7,7 @@
 import videojs from 'video.js';
 import window from 'global/window';
 import {stringToUint16Array, uint8ArrayToString, getHostnameFromUri, mergeAndRemoveNull} from './utils';
+import {httpResponseHandler} from './http-handler.js';
 
 export const FAIRPLAY_KEY_SYSTEM = 'com.apple.fps.1_0';
 
@@ -112,14 +113,17 @@ export const defaultGetCertificate = (fairplayOptions) => {
       uri: fairplayOptions.certificateUri,
       responseType: 'arraybuffer',
       headers
-    }, (err, response, responseBody) => {
+    }, httpResponseHandler((err, license) => {
       if (err) {
         callback(err);
         return;
       }
 
-      callback(null, new Uint8Array(responseBody));
-    });
+      // in this case, license is still the raw ArrayBuffer,
+      // (we don't want httpResponseHandler to decode it)
+      // convert it into Uint8Array as expected
+      callback(null, new Uint8Array(license));
+    }));
   };
 };
 
@@ -141,20 +145,7 @@ export const defaultGetLicense = (fairplayOptions) => {
       responseType: 'arraybuffer',
       body: keyMessage,
       headers
-    }, (err, response, responseBody) => {
-      if (err) {
-        callback(err);
-        return;
-      }
-
-      if (response.statusCode >= 400 && response.statusCode <= 599) {
-        // Pass an empty object as the error to use the default code 5 error message
-        callback({});
-        return;
-      }
-
-      callback(null, responseBody);
-    });
+    }, httpResponseHandler(callback, true));
   };
 };
 

src/http-handler.js

@@ -0,0 +1,30 @@
+import videojs from 'video.js';
+
+let httpResponseHandler = videojs.xhr.httpHandler;
+
+// to make sure this doesn't break with older versions of Video.js,
+// do a super simple wrapper instead
+if (!httpResponseHandler) {
+  httpResponseHandler = (callback, decodeResponseBody) => (err, response, responseBody) => {
+    if (err) {
+      callback(err);
+      return;
+    }
+
+    // if the HTTP status code is 4xx or 5xx, the request also failed
+    if (response.statusCode >= 400 && response.statusCode <= 599) {
+      let cause = responseBody;
+
+      if (decodeResponseBody) {
+        cause = String.fromCharCode.apply(null, new Uint8Array(responseBody));
+      }
+
+      callback({cause});
+      return;
+    }
+
+    // otherwise, request succeeded
+    callback(null, responseBody);
+  };
+}
+export { httpResponseHandler };

src/playready.js

@@ -1,6 +1,7 @@
 import videojs from 'video.js';
 import window from 'global/window';
 import {mergeAndRemoveNull} from './utils';
+import {httpResponseHandler} from './http-handler.js';
 
 /**
  * Parses the EME key message XML to extract HTTP headers and the Challenge element to use
@@ -57,18 +58,5 @@ export const requestPlayreadyLicense = (keySystemOptions, messageBuffer, emeOpti
     headers,
     body: message,
     responseType: 'arraybuffer'
-  }, (err, response, responseBody) => {
-    if (err) {
-      callback(err);
-      return;
-    }
-
-    if (response.statusCode >= 400 && response.statusCode <= 599) {
-      // Pass an empty object as the error to use the default code 5 error message
-      callback({});
-      return;
-    }
-
-    callback(null, responseBody);
-  });
+  }, httpResponseHandler(callback, true));
 };

src/plugin.js

@@ -185,13 +185,25 @@ export const setupSessions = (player) => {
  */
 export const emeErrorHandler = (player) => {
   return (objOrErr) => {
-    const message = typeof objOrErr === 'string' ? objOrErr : (objOrErr && objOrErr.message) || null;
-
-    player.error({
+    const error = {
       // MEDIA_ERR_ENCRYPTED is code 5
-      code: 5,
-      message
-    });
+      code: 5
+    };
+
+    if (typeof objOrErr === 'string') {
+      error.message = objOrErr;
+    } else if (objOrErr) {
+      if (objOrErr.message) {
+        error.message = objOrErr.message;
+      }
+      if (objOrErr.cause &&
+          (objOrErr.cause.length ||
+           objOrErr.cause.byteLength)) {
+        error.cause = objOrErr.cause;
+      }
+    }
+
+    player.error(error);
   };
 };
 

test/eme.test.js

@@ -797,26 +797,39 @@ QUnit.test('getLicense calls back with error for 400 and 500 status codes', func
   const getLicenseCallback = sinon.spy();
   const getLicense = defaultGetLicense({});
 
+  function toArrayBuffer(obj) {
+    const json = JSON.stringify(obj);
+    const buffer = new ArrayBuffer(json.length);
+    const bufferView = new Uint8Array(buffer);
+
+    for (let i = 0; i < json.length; i++) {
+      bufferView[i] = json.charCodeAt(i);
+    }
+    return buffer;
+  }
+
   videojs.xhr = (params, callback) => {
-    return callback(null, {statusCode: 400}, {body: 'some-body'});
+    return callback(null, {statusCode: 400}, toArrayBuffer({body: 'some-body'}));
   };
 
   getLicense({}, null, getLicenseCallback);
 
   videojs.xhr = (params, callback) => {
-    return callback(null, {statusCode: 500}, {body: 'some-body'});
+    return callback(null, {statusCode: 500}, toArrayBuffer({body: 'some-body'}));
   };
 
   getLicense({}, null, getLicenseCallback);
 
   videojs.xhr = (params, callback) => {
-    return callback(null, {statusCode: 599}, {body: 'some-body'});
+    return callback(null, {statusCode: 599}, toArrayBuffer({body: 'some-body'}));
   };
 
   getLicense({}, null, getLicenseCallback);
 
   assert.equal(getLicenseCallback.callCount, 3, 'correct callcount');
-  assert.equal(getLicenseCallback.alwaysCalledWith({}), true, 'getLicense callback called with correct error');
+  assert.ok(getLicenseCallback.alwaysCalledWith({
+    cause: JSON.stringify({body: 'some-body'})
+  }), 'getLicense callback called with correct error');
 });
 
 QUnit.test('getLicense calls back with response body for non-400/500 status codes', function(assert) {