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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 
12 namespace extensions {
13 namespace core_api {
14 namespace cast_channel {
15 class CastMessage;
16 
17 // Class for constructing and parsing CastMessage packet data.
18 class 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