extensions/browser/api/cast_channel/cast_framer.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 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_