Ensure that only byte values are sent by sockets and web sockets

sdk/lib/io/websocket_impl.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 const String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 class _WebSocketMessageType {
   static const int NONE = 0;
@@ skipping 513 matching lines @@
     // Write the length in network byte order into the header.
     for (int i = 0; i < lengthBytes; i++) {
       header[index++] = dataLength >> (((lengthBytes - 1) - i) * 8) & 0xFF;
     }
     if (mask) {
       header[1] |= 1 << 7;
       var maskBytes = _IOCrypto.getRandomBytes(4);
       header.setRange(index, index + 4, maskBytes);
       index += 4;
       if (data != null) {
-        var list = new Uint8List(data.length);
-        for (int i = 0; i < data.length; i++) {
-          list[i] = data[i] ^ maskBytes[i % 4];
+        var list;
+        // If this is a text message just do the masking inside the
+        // encoded data.
+        if (opcode == _WebSocketOpcode.TEXT) {
+          list = data;
+        } else {
+          list = new Uint8List(data.length);
+        }
+        if (data is Uint8List) {
+          for (int i = 0; i < data.length; i++) {
+            list[i] = data[i] ^ maskBytes[i % 4];
+          }
+        } else {
+          for (int i = 0; i < data.length; i++) {
+            if (data[i] < 0 || 255 < data[i]) {
+              throw new ArgumentError(
+                  "List element is not a byte value "
+                  "(value ${data[i]} at index $i)");
+            }
+            list[i] = data[i] ^ maskBytes[i % 4];
+          }
         }
         data = list;
       }
     }
     assert(index == headerSize);
     if (data == null) {
       return [header];
     } else {
       return [header, data];
     }
@@ skipping 249 matching lines @@
            (code < WebSocketStatus.NORMAL_CLOSURE ||
             code == WebSocketStatus.RESERVED_1004 ||
             code == WebSocketStatus.NO_STATUS_RECEIVED ||
             code == WebSocketStatus.ABNORMAL_CLOSURE ||
             (code > WebSocketStatus.INTERNAL_SERVER_ERROR &&
              code < WebSocketStatus.RESERVED_1015) ||
             (code >= WebSocketStatus.RESERVED_1015 &&
              code < 3000));
   }
 }