Native Messaging!

chrome/browser/extensions/native_message_process.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 CHROME_BROWSER_EXTENSIONS_NATIVE_MESSAGE_PROCESS_H_
+#define CHROME_BROWSER_EXTENSIONS_NATIVE_MESSAGE_PROCESS_H_
+
+#include <deque>
+
+#include "base/file_util.h"
+#include "base/message_loop.h"
+#include "base/process.h"
+
+namespace extensions {
+class MessageService;
+
+// TODO(eriq): Only posix right now.
+// This class ensures that all pipes will be closed and the process will be
+// killed upon deconstruction.
+class NativeMessageProcess : public MessageLoopForIO::Watcher {
+ public:
+  // Append any new types to the end. Changing the ordering will break native
+  // apps.
+  enum MessageType {
+    TYPE_SEND_MESSAGE_REQUEST,  // Used when an extension is sending a one-off
+                                // message to a native app.
+    TYPE_SEND_MESSAGE_RESPONSE,  // Used by a native app to respond to a one-off
+                                  // message.

[Matt Perry, 2012/08/09 02:13:00]

indenting is off here

[eaugusti, 2012/08/13 23:22:34]

Done.

+    TYPE_CONNECT,  // Used when an extension wants to establish a persistent
+                    // connection with a native app.
+    TYPE_CONNECT_MESSAGE,  // Used for messages after a connection has already

[Matt Perry, 2012/08/09 02:13:00]

Do we need to expose the difference between connect and sendMessage to the app?
We could instead expose 4 primitives:
- connect (establishes the connection)
- message (message from extension -> app)
- response (message from app -> extension)
- close (closes the connection)

sendMessage then is just [connect,message,response,close] in sequence.

[Aaron Boodman, 2012/08/09 18:36:12]

We could do that. I was just mirroring the API we have elsewhere for other
clients.

If we just have the four primitives, it makes it more work for simple clients
who know that they just want to send a single message. They have to read through
the connect message and discard it.

[eaugusti, 2012/08/13 23:22:34]

I think the app knowing the difference between sendMessage and connect could be
useful. Then again, the extension could always just send this information in its
message.

+                            // been established.
+    NUM_MESSAGE_TYPES  // The number of types of messages.
+  };
+
+  ~NativeMessageProcess();
+
+  // Must be called on the FILE thread.

[Matt Perry, 2012/08/09 02:13:00]

Is there a reason you chose the FILE thread (say, as opposed to the IO thread,
or a new worker thread)? I'm not fmailiar with these classes, but using
MessageLoopForIO::Watcher on the FILE thread seems weird to me.

[eaugusti, 2012/08/13 23:22:34]

On Posix, the FILE and IO threads both have an IO type MessageLoop.

+  // |type|must be TYPE_CONNECT or TYPE_SEND_MESSAGE_REQUEST.
+  static NativeMessageProcess* Create(const std::string& native_app_name,
+                               const std::string& connection_message,

[Matt Perry, 2012/08/09 02:13:00]

indent should align with first param after (

[eaugusti, 2012/08/13 23:22:34]

Done.

+                               MessageService* service,
+                               int dest_port,
+                               MessageType type);
+
+  // TYPE_SEND_MESSAGE_REQUEST will be sent via the connection messege in
+  // NativeMessageProcess::Create, so only TYPE_CONNECT_MESSAGE is expected.
+  void Send(const std::string& json) {
+    Send(TYPE_CONNECT_MESSAGE, json);
+  }
+
+  // MessageLoopForIO::Watcher
+  virtual void OnFileCanReadWithoutBlocking(int fd);
+  virtual void OnFileCanWriteWithoutBlocking(int fd);
+
+ private:
+  struct MessageData {
+    MessageData();
+    MessageData(MessageType message_type, std::string message_data);
+
+    MessageType type;
+    std::string data;
+  };
+
+  // Ensures the termination of |handle|. Must be called on the FILE thread.
+  static void KillProcess(base::ProcessHandle handle);
+
+  NativeMessageProcess(
+    MessageService* service,

[Matt Perry, 2012/08/09 02:13:00]

indent to 4 from the N

see
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Functi...

[eaugusti, 2012/08/13 23:22:34]

Done.

+    int dest_port,
+    base::ProcessHandle handle,
+    int read_fd,
+    int write_fd,
+    bool is_send_message);
+
+  void Send(MessageType type, const std::string& json);
+
+  // Called on the FILE thread to start watching |write_fd_|.
+  void WatchWrite();
+
+  bool WriteMessage(int fd, const MessageData& data);
+  bool ReadMessage(int fd, MessageData* data);
+
+  MessageService* service_;
+  int dest_port_;
+  std::deque<MessageData> pending_messages_;
+  base::ProcessHandle handle_;
+
+  MessageLoopForIO::FileDescriptorWatcher read_watcher_;
+  MessageLoopForIO::FileDescriptorWatcher write_watcher_;
+
+  bool watching_write_;
+
+  int read_fd_;
+  int write_fd_;
+  file_util::ScopedFD scoped_read_fd_;
+  file_util::ScopedFD scoped_write_fd_;
+
+  // Only looking for one response.
+  bool is_send_message_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeMessageProcess);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_NATIVE_MESSAGE_PROCESS_H_