Validate incoming JS Message Headers

mojo/public/js/bindings/codec.js

Index: mojo/public/js/bindings/codec.js
diff --git a/mojo/public/js/bindings/codec.js b/mojo/public/js/bindings/codec.js
index 9756f4a5d6b59ca478cc6187808c7a256556c308..8f27af1d8707cac83d3d700d454a4610598b6c0b 100644
--- a/mojo/public/js/bindings/codec.js
+++ b/mojo/public/js/bindings/codec.js
@@ -452,6 +452,10 @@ define("mojo/public/js/bindings/codec", [
   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;
 
@@ -468,10 +472,23 @@ define("mojo/public/js/bindings/codec", [
     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) {
@@ -772,6 +789,7 @@ define("mojo/public/js/bindings/codec", [
   exports.kArrayHeaderSize = kArrayHeaderSize;
   exports.kStructHeaderSize = kStructHeaderSize;
   exports.kMessageHeaderSize = kMessageHeaderSize;
+  exports.kMessageWithRequestIDHeaderSize = kMessageWithRequestIDHeaderSize;
   exports.kMessageExpectsResponse = kMessageExpectsResponse;
   exports.kMessageIsResponse = kMessageIsResponse;
   exports.Int8 = Int8;