1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef IPC_MESSAGE_FILTER_H_
6#define IPC_MESSAGE_FILTER_H_
7
8#include <vector>
9
10#include "base/memory/ref_counted.h"
11#include "ipc/ipc_export.h"
12
13namespace IPC {
14
15class Sender;
16class Message;
17
18// A class that receives messages on the thread where the IPC channel is
19// running.  It can choose to prevent the default action for an IPC message.
20class IPC_EXPORT MessageFilter
21    : public base::RefCountedThreadSafe<MessageFilter> {
22 public:
23  MessageFilter();
24
25  // Called on the background thread to provide the filter with access to the
26  // channel.  Called when the IPC channel is initialized or when AddFilter
27  // is called if the channel is already initialized.
28  virtual void OnFilterAdded(Sender* sender);
29
30  // Called on the background thread when the filter has been removed from
31  // the ChannelProxy and when the Channel is closing.  After a filter is
32  // removed, it will not be called again.
33  virtual void OnFilterRemoved();
34
35  // Called to inform the filter that the IPC channel is connected and we
36  // have received the internal Hello message from the peer.
37  virtual void OnChannelConnected(int32 peer_pid);
38
39  // Called when there is an error on the channel, typically that the channel
40  // has been closed.
41  virtual void OnChannelError();
42
43  // Called to inform the filter that the IPC channel will be destroyed.
44  // OnFilterRemoved is called immediately after this.
45  virtual void OnChannelClosing();
46
47  // Return true to indicate that the message was handled, or false to let
48  // the message be handled in the default way.
49  virtual bool OnMessageReceived(const Message& message);
50
51  // Called to query the Message classes supported by the filter.  Return
52  // false to indicate that all message types should reach the filter, or true
53  // if the resulting contents of |supported_message_classes| may be used to
54  // selectively offer messages of a particular class to the filter.
55  virtual bool GetSupportedMessageClasses(
56      std::vector<uint32>* supported_message_classes) const;
57
58 protected:
59  virtual ~MessageFilter();
60
61 private:
62  friend class base::RefCountedThreadSafe<MessageFilter>;
63};
64
65}  // namespace IPC
66
67#endif  // IPC_MESSAGE_FILTER_H_
68