ceph/src/boost/libs/asio/example/cpp03/porthopper/protocol.hpp

   1 //
   2 // protocol.hpp
   3 // ~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef PORTHOPPER_PROTOCOL_HPP
  12 #define PORTHOPPER_PROTOCOL_HPP
  13
  14 #include <boost/array.hpp>
  15 #include <boost/asio.hpp>
  16 #include <cstring>
  17 #include <iomanip>
  18 #include <string>
  19 #include <strstream>
  20
  21 // This request is sent by the client to the server over a TCP connection.
  22 // The client uses it to perform three functions:
  23 // - To request that data start being sent to a given port.
  24 // - To request that data is no longer sent to a given port.
  25 // - To change the target port to another.
  26 class control_request
  27 {
  28 public:
  29   // Construct an empty request. Used when receiving.
  30   control_request()
  31   {
  32   }
  33
  34   // Create a request to start sending data to a given port.
  35   static const control_request start(unsigned short port)
  36   {
  37     return control_request(0, port);
  38   }
  39
  40   // Create a request to stop sending data to a given port.
  41   static const control_request stop(unsigned short port)
  42   {
  43     return control_request(port, 0);
  44   }
  45
  46   // Create a request to change the port that data is sent to.
  47   static const control_request change(
  48       unsigned short old_port, unsigned short new_port)
  49   {
  50     return control_request(old_port, new_port);
  51   }
  52
  53   // Get the old port. Returns 0 for start requests.
  54   unsigned short old_port() const
  55   {
  56     std::istrstream is(data_, encoded_port_size);
  57     unsigned short port = 0;
  58     is >> std::setw(encoded_port_size) >> std::hex >> port;
  59     return port;
  60   }
  61
  62   // Get the new port. Returns 0 for stop requests.
  63   unsigned short new_port() const
  64   {
  65     std::istrstream is(data_ + encoded_port_size, encoded_port_size);
  66     unsigned short port = 0;
  67     is >> std::setw(encoded_port_size) >> std::hex >> port;
  68     return port;
  69   }
  70
  71   // Obtain buffers for reading from or writing to a socket.
  72   boost::array<boost::asio::mutable_buffer, 1> to_buffers()
  73   {
  74     boost::array<boost::asio::mutable_buffer, 1> buffers
  75       = { { boost::asio::buffer(data_) } };
  76     return buffers;
  77   }
  78
  79 private:
  80   // Construct with specified old and new ports.
  81   control_request(unsigned short old_port_number,
  82       unsigned short new_port_number)
  83   {
  84     std::ostrstream os(data_, control_request_size);
  85     os << std::setw(encoded_port_size) << std::hex << old_port_number;
  86     os << std::setw(encoded_port_size) << std::hex << new_port_number;
  87   }
  88
  89   // The length in bytes of a control_request and its components.
  90   enum
  91   {
  92     encoded_port_size = 4, // 16-bit port in hex.
  93     control_request_size = encoded_port_size * 2
  94   };
  95
  96   // The encoded request data.
  97   char data_[control_request_size];
  98 };
  99
 100 // This frame is sent from the server to subscribed clients over UDP.
 101 class frame
 102 {
 103 public:
 104   // The maximum allowable length of the payload.
 105   enum { payload_size = 32 };
 106
 107   // Construct an empty frame. Used when receiving.
 108   frame()
 109   {
 110   }
 111
 112   // Construct a frame with specified frame number and payload.
 113   frame(unsigned long frame_number, const std::string& payload_data)
 114   {
 115     std::ostrstream os(data_, frame_size);
 116     os << std::setw(encoded_number_size) << std::hex << frame_number;
 117     os << std::setw(payload_size)
 118       << std::setfill(' ') << payload_data.substr(0, payload_size);
 119   }
 120
 121   // Get the frame number.
 122   unsigned long number() const
 123   {
 124     std::istrstream is(data_, encoded_number_size);
 125     unsigned long frame_number = 0;
 126     is >> std::setw(encoded_number_size) >> std::hex >> frame_number;
 127     return frame_number;
 128   }
 129
 130   // Get the payload data.
 131   const std::string payload() const
 132   {
 133     return std::string(data_ + encoded_number_size, payload_size);
 134   }
 135
 136   // Obtain buffers for reading from or writing to a socket.
 137   boost::array<boost::asio::mutable_buffer, 1> to_buffers()
 138   {
 139     boost::array<boost::asio::mutable_buffer, 1> buffers
 140       = { { boost::asio::buffer(data_) } };
 141     return buffers;
 142   }
 143
 144 private:
 145   // The length in bytes of a frame and its components.
 146   enum
 147   {
 148     encoded_number_size = 8, // Frame number in hex.
 149     frame_size = encoded_number_size + payload_size
 150   };
 151
 152   // The encoded frame data.
 153   char data_[frame_size];
 154 };
 155
 156 #endif // PORTHOPPER_PROTOCOL_HPP