Validate incoming JS Message Headers

mojo/public/js/bindings/codec.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 define("mojo/public/js/bindings/codec", [
   "mojo/public/js/bindings/unicode"
 ], function(unicode) {
 
   var kErrorUnsigned = "Passing negative value to unsigned";
 
@@ skipping 434 matching lines @@
     var encodedSize = kArrayHeaderSize + unicode.utf8Length(val);
     var encoder = this.createAndEncodeEncoder(encodedSize);
     encoder.encodeString(val);
   };
 
   // Message ------------------------------------------------------------------
 
   var kMessageExpectsResponse = 1 << 0;
   var kMessageIsResponse      = 1 << 1;
 
+  // Message header is a struct, begins with a struct header.
+  var kNumBytesOffset = 0;
+  var kNumFieldsOffset = 4;
+
   // Skip over num_bytes, num_fields, and message_name.
   var kFlagsOffset = 4 + 4 + 4;
 
   // Skip over num_bytes, num_fields, message_name, and flags.
   var kRequestIDOffset = 4 + 4 + 4 + 4;
 
   function Message(buffer, handles) {
     this.buffer = buffer;
     this.handles = handles;
   }
 
   Message.prototype.setRequestID = function(requestID) {
     // TODO(darin): Verify that space was reserved for this field!
     setUint64(this.buffer.dataView, kRequestIDOffset, requestID);
   };
 
-  Message.prototype.getFlags = function() {
+  Message.prototype.getHeaderNumBytes = function() {
+    return this.buffer.dataView.getUint32(kNumBytesOffset, kHostIsLittleEndian);
+  };
+
+  Message.prototype.getHeaderNumFields = function() {
+    return this.buffer.dataView.getUint32(kNumFieldsOffset,
+                                          kHostIsLittleEndian);
+  };
+
+  Message.prototype.getHeaderFlags = function() {
     return this.buffer.dataView.getUint32(kFlagsOffset, kHostIsLittleEndian);
   };
 
+  Message.prototype.byteLength = function() {
+    return this.buffer.dataView.byteLength;
+  }
+
   // MessageBuilder -----------------------------------------------------------
 
   function MessageBuilder(messageName, payloadSize) {
     // Currently, we don't compute the payload size correctly ahead of time.
     // Instead, we resize the buffer at the end.
     var numberOfBytes = kMessageHeaderSize + payloadSize;
     this.buffer = new Buffer(numberOfBytes);
     this.handles = [];
     var encoder = this.createEncoder(kMessageHeaderSize);
     encoder.writeUint32(kMessageHeaderSize);
@@ skipping 280 matching lines @@
   var exports = {};
   exports.align = align;
   exports.Buffer = Buffer;
   exports.Message = Message;
   exports.MessageBuilder = MessageBuilder;
   exports.MessageWithRequestIDBuilder = MessageWithRequestIDBuilder;
   exports.MessageReader = MessageReader;
   exports.kArrayHeaderSize = kArrayHeaderSize;
   exports.kStructHeaderSize = kStructHeaderSize;
   exports.kMessageHeaderSize = kMessageHeaderSize;
+  exports.kMessageWithRequestIDHeaderSize = kMessageWithRequestIDHeaderSize;
   exports.kMessageExpectsResponse = kMessageExpectsResponse;
   exports.kMessageIsResponse = kMessageIsResponse;
   exports.Int8 = Int8;
   exports.Uint8 = Uint8;
   exports.Int16 = Int16;
   exports.Uint16 = Uint16;
   exports.Int32 = Int32;
   exports.Uint32 = Uint32;
   exports.Int64 = Int64;
   exports.Uint64 = Uint64;
   exports.Float = Float;
   exports.Double = Double;
   exports.String = String;
   exports.PointerTo = PointerTo;
   exports.ArrayOf = ArrayOf;
   exports.ArrayOfBoolArrayPointers = ArrayOfBoolArrayPointers;
   exports.Handle = Handle;
   return exports;
 });