1// Copyright (c) 2012 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 PPAPI_HOST_RESOURCE_MESSAGE_HANDLER_H_
6#define PPAPI_HOST_RESOURCE_MESSAGE_HANDLER_H_
7
8#include "base/basictypes.h"
9#include "ppapi/c/pp_stdint.h"
10#include "ppapi/host/ppapi_host_export.h"
11
12namespace IPC {
13class Message;
14}
15
16namespace ppapi {
17namespace host {
18
19struct HostMessageContext;
20struct ReplyMessageContext;
21
22// This is the base class of classes that can handle resource messages. It
23// mainly exists at present to share code for checking replies to resource
24// messages are valid.
25class PPAPI_HOST_EXPORT ResourceMessageHandler {
26 public:
27  ResourceMessageHandler();
28  virtual ~ResourceMessageHandler();
29
30  // Called when this handler should handle a particular message. This should
31  // call into the the message handler implemented by subclasses (i.e.
32  // |OnResourceMessageReceived|) and perform any additional work necessary to
33  // handle the message (e.g. checking resource replies are valid). True is
34  // returned if the message is handled and false otherwise.
35  virtual bool HandleMessage(const IPC::Message& msg,
36                             HostMessageContext* context) = 0;
37
38  // Send a resource reply message.
39  virtual void SendReply(const ReplyMessageContext& context,
40                         const IPC::Message& msg) = 0;
41
42 protected:
43  // Runs the message handler and checks that a reply was sent if necessary.
44  void RunMessageHandlerAndReply(const IPC::Message& msg,
45                                 HostMessageContext* context);
46
47  // Handles messages associated with a given resource object. If the flags
48  // indicate that a response is required, the return value of this function
49  // will be sent as a resource message "response" along with the message
50  // specified in the reply of the context.
51  //
52  // You can do a response asynchronously by returning PP_OK_COMPLETIONPENDING.
53  // This will cause the reply to be skipped, and the class implementing this
54  // function will take responsibility for issuing the callback. The callback
55  // can be issued inside OnResourceMessageReceived before it returns, or at
56  // a future time.
57  //
58  // If you don't have a particular reply message, you can just ignore
59  // the reply in the message context. However, if you have a reply more than
60  // just the int32_t result code, set the reply to be the message of your
61  // choosing.
62  //
63  // The default implementation just returns PP_ERROR_NOTSUPPORTED.
64  virtual int32_t OnResourceMessageReceived(const IPC::Message& msg,
65                                            HostMessageContext* context);
66
67 private:
68  DISALLOW_COPY_AND_ASSIGN(ResourceMessageHandler);
69};
70
71}  // namespace host
72}  // namespace ppapi
73
74#endif  // PPAPI_HOST_RESOURCE_MESSAGE_HANDLER_H_
75