Fix Node encryption of ArrayBuffer plaintext

ArrayBuffer does not have a property named `length`, and also
Buffer.concat does not accept an argument of type ArrayBuffer.

The createTestMessage stuff introduced in the tests is a result of
wanting to be able to perform multiple tests relating to the same
original data without one test affecting another, given two things:

1. I want to be able to explicitly manipulate the message inside my test
   case (e.g. to change its `data` property to an ArrayBuffer).

2. Message.encode appears to have the side effect of manipulating the
   `data` property of the message that it is passed. This doesn’t feel
   intentional (and indeed is quite surprising), but I haven’t
   investigated it here.

Resolves #1281.

src/platform/nodejs/lib/util/crypto.js

@@ -207,10 +207,13 @@ var Crypto = (function () {
 
   CBCCipher.prototype.encrypt = function (plaintext, callback) {
     Logger.logAction(Logger.LOG_MICRO, 'CBCCipher.encrypt()', '');
-    var plaintextLength = plaintext.length,
+    var plaintextBuffer = Platform.BufferUtils.toBuffer(plaintext);
+    var plaintextLength = plaintextBuffer.length,
       paddedLength = getPaddedLength(plaintextLength),
       iv = this.getIv();
-    var cipherOut = this.encryptCipher.update(Buffer.concat([plaintext, pkcs5Padding[paddedLength - plaintextLength]]));
+    var cipherOut = this.encryptCipher.update(
+      Buffer.concat([plaintextBuffer, pkcs5Padding[paddedLength - plaintextLength]])
+    );
     var ciphertext = Buffer.concat([iv, toBuffer(cipherOut)]);
     return callback(null, ciphertext);
   };

test/realtime/crypto.test.js

@@ -71,11 +71,13 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
           var item = testData.items[i];
 
           /* read messages from test data and decode (ie remove any base64 encoding). */
-          var testMessage = Message.fromEncoded(item.encoded);
+          var createTestMessage = function () {
+            return Message.fromEncoded(item.encoded);
+          };
           var encryptedMessage = Message.fromEncoded(item.encrypted);
           /* reset channel cipher, to ensure it uses the given iv */
           channel.setOptions({ cipher: { key: key, iv: iv } });
-          fixtureTest(channel.channelOptions, testMessage, encryptedMessage, item.msgpack);
+          fixtureTest(channel.channelOptions, createTestMessage, encryptedMessage, item.msgpack);
         }
       } catch (err) {
         closeAndFinish(done, realtime, err);
@@ -85,6 +87,33 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
     });
   }
 
+  /**
+   * Helper for testing that we are able to encrypt data of various buffer-like types.
+   *
+   * If the message created by `createTestMessage` has data of buffer-like type, then this will call `fixtureTest`
+   * with a function that creates that message, and if the data is not already an `ArrayBuffer` then it will also call
+   * `fixtureTest` with a function that creates a version of that message whose data is instead represented as an
+   * `ArrayBuffer`.
+   *
+   * If the message does not have data of buffer-like type, it will simply call `fixtureTest` with `createTestMessage`.
+   */
+  function testEachPlaintextVariant(createTestMessage, fixtureTest) {
+    // Test with plaintext of type same as that of createTestMessage().data
+    fixtureTest(createTestMessage);
+
+    // If createTestMessage().data is buffer-like but not an ArrayBuffer, convert plaintext to ArrayBuffer and test
+    var testMessage = createTestMessage();
+    if (BufferUtils.isBuffer(testMessage.data) && !(testMessage.data instanceof ArrayBuffer)) {
+      var createTestMessageWithArrayBufferData = function () {
+        var testMessageWithArrayBufferData = createTestMessage();
+        testMessageWithArrayBufferData.data = BufferUtils.toArrayBuffer(testMessageWithArrayBufferData.data);
+        return testMessageWithArrayBufferData;
+      };
+
+      fixtureTest(createTestMessageWithArrayBufferData);
+    }
+  }
+
   describe('realtime/crypto', function () {
     this.timeout(60 * 1000);
 
@@ -204,11 +233,14 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
         'crypto-data-128.json',
         'encrypt_message_128',
         2,
-        function (channelOpts, testMessage, encryptedMessage) {
-          /* encrypt plaintext message; encode() also to handle data that is not already string or buffer */
-          Message.encode(testMessage, channelOpts, function () {
-            /* compare */
-            testMessageEquality(done, testMessage, encryptedMessage);
+        function (channelOpts, createTestMessage, encryptedMessage) {
+          testEachPlaintextVariant(createTestMessage, function (createTestMessage) {
+            var testMessage = createTestMessage();
+            /* encrypt plaintext message; encode() also to handle data that is not already string or buffer */
+            Message.encode(testMessage, channelOpts, function () {
+              /* compare */
+              testMessageEquality(done, testMessage, encryptedMessage);
+            });
           });
         }
       );
@@ -220,11 +252,14 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
         'crypto-data-256.json',
         'encrypt_message_256',
         2,
-        function (channelOpts, testMessage, encryptedMessage) {
-          /* encrypt plaintext message; encode() also to handle data that is not already string or buffer */
-          Message.encode(testMessage, channelOpts, function () {
-            /* compare */
-            testMessageEquality(done, testMessage, encryptedMessage);
+        function (channelOpts, createTestMessage, encryptedMessage) {
+          testEachPlaintextVariant(createTestMessage, function (createTestMessage) {
+            var testMessage = createTestMessage();
+            /* encrypt plaintext message; encode() also to handle data that is not already string or buffer */
+            Message.encode(testMessage, channelOpts, function () {
+              /* compare */
+              testMessageEquality(done, testMessage, encryptedMessage);
+            });
           });
         }
       );
@@ -236,7 +271,8 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
         'crypto-data-128.json',
         'decrypt_message_128',
         2,
-        function (channelOpts, testMessage, encryptedMessage) {
+        function (channelOpts, createTestMessage, encryptedMessage) {
+          var testMessage = createTestMessage();
           /* decrypt encrypted message; decode() also to handle data that is not string or buffer */
           Message.decode(encryptedMessage, channelOpts);
           /* compare */
@@ -251,7 +287,8 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
         'crypto-data-256.json',
         'decrypt_message_256',
         2,
-        function (channelOpts, testMessage, encryptedMessage) {
+        function (channelOpts, createTestMessage, encryptedMessage) {
+          var testMessage = createTestMessage();
           /* decrypt encrypted message; decode() also to handle data that is not string or buffer */
           Message.decode(encryptedMessage, channelOpts);
           /* compare */
@@ -292,7 +329,8 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
           'crypto-data-128.json',
           'msgpack_128',
           2,
-          function (channelOpts, testMessage, encryptedMessage, msgpackEncodedMessage) {
+          function (channelOpts, createTestMessage, encryptedMessage, msgpackEncodedMessage) {
+            var testMessage = createTestMessage();
             Message.encode(testMessage, channelOpts, function () {
               var msgpackFromEncoded = msgpack.encode(testMessage);
               var msgpackFromEncrypted = msgpack.encode(encryptedMessage);
@@ -325,7 +363,8 @@ define(['ably', 'shared_helper', 'async', 'chai'], function (Ably, helper, async
           'crypto-data-256.json',
           'msgpack_256',
           2,
-          function (channelOpts, testMessage, encryptedMessage, msgpackEncodedMessage) {
+          function (channelOpts, createTestMessage, encryptedMessage, msgpackEncodedMessage) {
+            var testMessage = createTestMessage();
             Message.encode(testMessage, channelOpts, function () {
               var msgpackFromEncoded = msgpack.encode(testMessage);
               var msgpackFromEncrypted = msgpack.encode(encryptedMessage);