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