Mojo: Add NotifyBadMessage API

mojo/public/cpp/bindings/lib/connector.cc

 // Copyright 2013 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.
 
 #include "mojo/public/cpp/bindings/lib/connector.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 248 matching lines @@
   bool receiver_result = false;
 
   // Detect if |this| was destroyed during message dispatch. Allow for the
   // possibility of re-entering ReadMore() through message dispatch.
   base::WeakPtr<Connector> weak_self = weak_self_;
 
   Message message;
   const MojoResult rv = ReadMessage(message_pipe_.get(), &message);
   *read_result = rv;
 
-  if (rv == MOJO_RESULT_OK) {
-    receiver_result =
-        incoming_receiver_ && incoming_receiver_->Accept(&message);
+  if (rv == MOJO_RESULT_OK && incoming_receiver_) {
+    receiver_result = incoming_receiver_->Accept(&message);
+    if (!receiver_result)
+      message.NotifyBadMessage(interface_name_);

[yzshen1, 2016/06/11 00:10:59]

For multiplex router, we may get here because of message header validation
failure. In that case, it can be any associated interface, not necessarily the
master interface. So the interface name is misleading.

Besides, there are places that this CL doesn't report bad messages:
- in multiplex_router.cc, pipe control message validation failure.
- in router.cc, we may delay processing of async messages, although the messages
have passed default validation, it hasn't done custom validation (enforced by
users' StructTraits, etc.) yet. So when the message is actually dispatched, it
may still fail.

One way that may be easier to catch all cases, is to check the result value here
(the synchronous case) plus Connector::RaiseError (the async case). And we don't
need to worry about inserting NotifyBadMessage at high level.

If we go down this direction, we will need to add parameter to RaiseError to
distinguish bad message from other reasons.

[Ken Rockot(use gerrit already), 2016/06/11 21:48:30]

Ah right. It's a bit more complicated than this too because MessageFilters can
reject along the way. Given the additional complexity required to get this right
in the bindings, I've removed all bindings changes from this CL and will send
you a follow-up CL with those changes. Thanks!

   }
 
   if (!weak_self)
     return false;
 
   if (rv == MOJO_RESULT_SHOULD_WAIT)
     return true;
 
   if (rv != MOJO_RESULT_OK) {
     HandleError(rv != MOJO_RESULT_FAILED_PRECONDITION, false);
@@ skipping 65 matching lines @@
   if (sync_watcher_)
     return;
   sync_watcher_.reset(new SyncHandleWatcher(
       message_pipe_.get(), MOJO_HANDLE_SIGNAL_READABLE,
       base::Bind(&Connector::OnSyncHandleWatcherHandleReady,
                  base::Unretained(this))));
 }
 
 }  // namespace internal
 }  // namespace mojo