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- //
- // protocol.hpp
- // ~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- //
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //
- #ifndef PORTHOPPER_PROTOCOL_HPP
- #define PORTHOPPER_PROTOCOL_HPP
- #include <boost/array.hpp>
- #include <boost/asio.hpp>
- #include <cstring>
- #include <iomanip>
- #include <string>
- #include <strstream>
- // This request is sent by the client to the server over a TCP connection.
- // The client uses it to perform three functions:
- // - To request that data start being sent to a given port.
- // - To request that data is no longer sent to a given port.
- // - To change the target port to another.
- class control_request
- {
- public:
- // Construct an empty request. Used when receiving.
- control_request()
- {
- }
- // Create a request to start sending data to a given port.
- static const control_request start(unsigned short port)
- {
- return control_request(0, port);
- }
- // Create a request to stop sending data to a given port.
- static const control_request stop(unsigned short port)
- {
- return control_request(port, 0);
- }
- // Create a request to change the port that data is sent to.
- static const control_request change(
- unsigned short old_port, unsigned short new_port)
- {
- return control_request(old_port, new_port);
- }
- // Get the old port. Returns 0 for start requests.
- unsigned short old_port() const
- {
- std::istrstream is(data_, encoded_port_size);
- unsigned short port = 0;
- is >> std::setw(encoded_port_size) >> std::hex >> port;
- return port;
- }
- // Get the new port. Returns 0 for stop requests.
- unsigned short new_port() const
- {
- std::istrstream is(data_ + encoded_port_size, encoded_port_size);
- unsigned short port = 0;
- is >> std::setw(encoded_port_size) >> std::hex >> port;
- return port;
- }
- // Obtain buffers for reading from or writing to a socket.
- boost::array<boost::asio::mutable_buffer, 1> to_buffers()
- {
- boost::array<boost::asio::mutable_buffer, 1> buffers
- = { { boost::asio::buffer(data_) } };
- return buffers;
- }
- private:
- // Construct with specified old and new ports.
- control_request(unsigned short old_port_number,
- unsigned short new_port_number)
- {
- std::ostrstream os(data_, control_request_size);
- os << std::setw(encoded_port_size) << std::hex << old_port_number;
- os << std::setw(encoded_port_size) << std::hex << new_port_number;
- }
- // The length in bytes of a control_request and its components.
- enum
- {
- encoded_port_size = 4, // 16-bit port in hex.
- control_request_size = encoded_port_size * 2
- };
- // The encoded request data.
- char data_[control_request_size];
- };
- // This frame is sent from the server to subscribed clients over UDP.
- class frame
- {
- public:
- // The maximum allowable length of the payload.
- enum { payload_size = 32 };
- // Construct an empty frame. Used when receiving.
- frame()
- {
- }
- // Construct a frame with specified frame number and payload.
- frame(unsigned long frame_number, const std::string& payload_data)
- {
- std::ostrstream os(data_, frame_size);
- os << std::setw(encoded_number_size) << std::hex << frame_number;
- os << std::setw(payload_size)
- << std::setfill(' ') << payload_data.substr(0, payload_size);
- }
- // Get the frame number.
- unsigned long number() const
- {
- std::istrstream is(data_, encoded_number_size);
- unsigned long frame_number = 0;
- is >> std::setw(encoded_number_size) >> std::hex >> frame_number;
- return frame_number;
- }
- // Get the payload data.
- const std::string payload() const
- {
- return std::string(data_ + encoded_number_size, payload_size);
- }
- // Obtain buffers for reading from or writing to a socket.
- boost::array<boost::asio::mutable_buffer, 1> to_buffers()
- {
- boost::array<boost::asio::mutable_buffer, 1> buffers
- = { { boost::asio::buffer(data_) } };
- return buffers;
- }
- private:
- // The length in bytes of a frame and its components.
- enum
- {
- encoded_number_size = 8, // Frame number in hex.
- frame_size = encoded_number_size + payload_size
- };
- // The encoded frame data.
- char data_[frame_size];
- };
- #endif // PORTHOPPER_PROTOCOL_HPP
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