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 EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_FRAMER_H_
6#define EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_FRAMER_H_
7
8#include "base/basictypes.h"
9#include "extensions/common/api/cast_channel.h"
10#include "net/base/io_buffer.h"
11
12namespace extensions {
13namespace core_api {
14namespace cast_channel {
15class CastMessage;
16
17// Class for constructing and parsing CastMessage packet data.
18class MessageFramer {
19 public:
20  // |input_buffer|: The input buffer used by all socket read operations that
21  //                 feed data into the framer.
22  explicit MessageFramer(scoped_refptr<net::GrowableIOBuffer> input_buffer);
23  ~MessageFramer();
24
25  // The number of bytes required from |input_buffer| to complete the
26  // CastMessage being read.
27  // Returns zero if |error_| is true (framer is in an invalid state.)
28  size_t BytesRequested();
29
30  // Serializes |message_proto| into |message_data|.
31  // Returns true if the message was serialized successfully, false otherwise.
32  static bool Serialize(const CastMessage& message_proto,
33                        std::string* message_data);
34
35  // Reads bytes from |input_buffer_| and returns a new CastMessage if one
36  // is fully read.
37  //
38  // |num_bytes| The number of bytes received by a read operation.
39  //             Value must be <= BytesRequested().
40  // |message_length| Size of the deserialized message object, in bytes. For
41  //                  logging purposes. Set to zero if no message was parsed.
42  // |error| The result of the ingest operation. Set to CHANNEL_ERROR_NONE
43  //         if no error occurred.
44  // Returns A pointer to a parsed CastMessage if a message was received
45  //         in its entirety, NULL otherwise.
46  scoped_ptr<CastMessage> Ingest(size_t num_bytes,
47                                 size_t* message_length,
48                                 ChannelError* error);
49
50  // Message header struct. If fields are added, be sure to update
51  // header_size().  Public to allow use of *_size() methods in unit tests.
52  struct MessageHeader {
53    MessageHeader();
54    // Sets the message size.
55    void SetMessageSize(size_t message_size);
56    // Prepends this header to |str|.
57    void PrependToString(std::string* str);
58    // Reads |header| from the bytes specified by |data|.
59    static void Deserialize(char* data, MessageHeader* header);
60    // Size (in bytes) of the message header.
61    static size_t header_size();
62    // Maximum size (in bytes) of a message payload on the wire (does not
63    // include header).
64    static size_t max_message_size();
65    std::string ToString();
66    // The size of the following protocol message in bytes, in host byte order.
67    size_t message_size;
68  };
69
70 private:
71  enum MessageElement { HEADER, BODY };
72
73  // Prepares the framer for ingesting a new message.
74  void Reset();
75
76  // The element of the message that will be read on the next call to Ingest().
77  MessageElement current_element_;
78
79  // Total size of the message, in bytes (head + body).
80  size_t message_bytes_received_;
81
82  // Size of the body alone, in bytes.
83  size_t body_size_;
84
85  // Input buffer which carries message data read from the socket.
86  // Caller is responsible for writing into this buffer.
87  scoped_refptr<net::GrowableIOBuffer> input_buffer_;
88
89  // Disables Ingest functionality is the parser receives invalid data.
90  bool error_;
91
92  DISALLOW_COPY_AND_ASSIGN(MessageFramer);
93};
94}  // namespace cast_channel
95}  // namespace core_api
96}  // namespace extensions
97#endif  // EXTENSIONS_BROWSER_API_CAST_CHANNEL_CAST_FRAMER_H_
98