Mojo cpp bindings: add support for validating incoming messages.

mojo/public/cpp/bindings/sync_dispatcher.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_SYNC_DISPATCHER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_SYNC_DISPATCHER_H_
 
+#include "mojo/public/cpp/bindings/lib/filter_chain.h"
+#include "mojo/public/cpp/bindings/lib/message_header_validator.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 
 class MessageReceiver;
 
 // Waits for one message to arrive on the message pipe, and dispatch it to the
 // receiver. Returns true on success, false on failure.
+//
+// NOTE: The message hasn't been validated and may be malformed!
 bool WaitForMessageAndDispatch(MessagePipeHandle handle,
                                mojo::MessageReceiver* receiver);
 
 template<typename Interface> class SyncDispatcher {
  public:
   SyncDispatcher(ScopedMessagePipeHandle message_pipe, Interface* sink)
       : message_pipe_(message_pipe.Pass()) {
     stub_.set_sink(sink);
+
+    validators_.Append(new internal::MessageHeaderValidator)

[darin (slow to review), 2014/05/14 06:51:51]

nit: validators_ -> filters_

[yzshen1, 2014/05/14 08:14:03]

Done. (I was thinking validators_ is a more specific name to indicate that all
filters we put in it are validators. But I am fine with either way.)

+               .Append(new typename Interface::RequestValidator_);
+    validators_.set_sink(&stub_);
   }
 
   bool WaitAndDispatchOneMessage() {
-    return WaitForMessageAndDispatch(message_pipe_.get(), &stub_);
+    return WaitForMessageAndDispatch(message_pipe_.get(),
+                                     validators_.GetHead());
   }
 
  private:
   ScopedMessagePipeHandle message_pipe_;
   typename Interface::Stub_ stub_;
+  internal::FilterChain validators_;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_SYNC_DISPATCHER_H_