ipc/message_filter.h

   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
  13 namespace IPC {
  14
  15 class Sender;
  16 class 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.
  20 class 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_