Revert of Revert of IPC::ChannelMojo: Make IPC handling robust against bad messages.

ipc/mojo/ipc_mojo_bootstrap.cc

 // 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.
 
 #include "ipc/mojo/ipc_mojo_bootstrap.h"
 
 #include "base/logging.h"
 #include "base/process/process_handle.h"
 #include "ipc/ipc_message_utils.h"
 #include "ipc/ipc_platform_file.h"
@@ skipping 82 matching lines @@
   SendClientPipeIfReady();
 }
 
 void MojoServerBootstrap::OnChannelConnected(int32 peer_pid) {
   DCHECK_EQ(state(), STATE_INITIALIZED);
   connected_ = true;
   SendClientPipeIfReady();
 }
 
 bool MojoServerBootstrap::OnMessageReceived(const Message&) {
-  DCHECK_EQ(state(), STATE_WAITING_ACK);
+  if (state() != STATE_WAITING_ACK) {
+    set_state(STATE_ERROR);
+    LOG(ERROR) << "Got inconsistent message from client.";
+    return false;
+  }
+
   set_state(STATE_READY);
-
+  CHECK(server_pipe_.is_valid());
   delegate()->OnPipeAvailable(
       mojo::embedder::ScopedPlatformHandle(server_pipe_.release()));
 
   return true;
 }
 
 // MojoBootstrap for client processes. You should create the instance
 // using MojoBootstrap::Create().
 class MojoClientBootstrap : public MojoBootstrap {
  public:
   MojoClientBootstrap();
 
   void OnClientLaunched(base::ProcessHandle process) override;
 
  private:
   // Listener implementations
   bool OnMessageReceived(const Message& message) override;
   void OnChannelConnected(int32 peer_pid) override;
 
   DISALLOW_COPY_AND_ASSIGN(MojoClientBootstrap);
 };
 
 MojoClientBootstrap::MojoClientBootstrap() {
 }
 
 bool MojoClientBootstrap::OnMessageReceived(const Message& message) {
+  if (state() != STATE_INITIALIZED) {
+    set_state(STATE_ERROR);
+    LOG(ERROR) << "Got inconsistent message from server.";
+    return false;
+  }
+
   PlatformFileForTransit pipe;
   PickleIterator iter(message);
   if (!ParamTraits<PlatformFileForTransit>::Read(&message, &iter, &pipe)) {
     DLOG(WARNING) << "Failed to read a file handle from bootstrap channel.";
     message.set_dispatch_error();
     return false;
   }
 
   // Sends ACK back.
   Send(new Message());
@@ skipping 75 matching lines @@
 int MojoBootstrap::GetClientFileDescriptor() const {
   return channel_->GetClientFileDescriptor();
 }
 
 base::ScopedFD MojoBootstrap::TakeClientFileDescriptor() {
   return channel_->TakeClientFileDescriptor();
 }
 #endif  // defined(OS_POSIX) && !defined(OS_NACL)
 
 }  // namespace IPC