Introduce ChannelMojo

ipc/ipc_channel.h

 // Copyright (c) 2012 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 IPC_IPC_CHANNEL_H_
 #define IPC_IPC_CHANNEL_H_
 
 #include <string>
 
 #if defined(OS_POSIX)
@@ skipping 152 matching lines @@
   //
   // Returns base::kNullProcessId if the peer is not connected yet. Watch out
   // for race conditions. You can easily get a channel to another process, but
   // if your process has not yet processed the "hello" message from the remote
   // side, this will fail. You should either make sure calling this is either
   // in response to a message from the remote side (which guarantees that it's
   // been connected), or you wait for the "connected" notification on the
   // listener.
   virtual base::ProcessId GetPeerPID() const = 0;
 
+  // Get its own process id. This value is told to the peer.

[Tom Sepez, 2014/08/07 18:36:22]

Can you elaborate on "this value is told to the peer."  Can an evil renderer lie
about this?  What happens then?

[Hajime Morrita, 2014/08/07 19:58:21]

Yes it can, as it can do that for current IPC implementation. (modulo secret
number check.) This just follows what existing IPC::Channel implementation does.
 
I don't know much about how the peer PID is used in the codebase.
One notable use it that this value is passed to
IPC::Listener::OnChannelConnected().

+  virtual base::ProcessId GetSelfPID() const = 0;
+
+  // Return connected ChannelHandle which the channel has owned.
+  // This method transfers the ownership to the caller
+  // so the channel isn't valid after the call.
+  virtual ChannelHandle TakePipeHandle() WARN_UNUSED_RESULT = 0;
+
   // Send a message over the Channel to the listener on the other end.
   //
   // |message| must be allocated using operator new.  This object will be
   // deleted once the contents of the Message have been sent.
   virtual bool Send(Message* message) = 0;
 
 #if defined(OS_POSIX) && !defined(OS_NACL)
   // On POSIX an IPC::Channel wraps a socketpair(), this method returns the
   // FD # for the client end of the socket.
   // This method may only be called on the server side of a channel.
@@ skipping 40 matching lines @@
 
 #if defined(OS_POSIX)
 // SocketPair() creates a pair of socket FDs suitable for using with
 // IPC::Channel.
 IPC_EXPORT bool SocketPair(int* fd1, int* fd2);
 #endif
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_H_