Asynchronous Daytime Server using boost-asio

ASYNC_TCP_DAYTIME_SERVER.md

Asynchronous TCP Daytime Server

Based on this asynchronous daytime server example from the Boost-Asio documentation.

Example use:

    	try
	{
		boost::asio::io_context io_context;
		AsyncDaytimeServer s(io_context);
		s.start();
		io_context.run();
	}
	catch (std::exception& e)
	{
		std::cerr << e.what() << std::endl;
	}

Example tested with this daytime client example from the Boost-Asio documentation, using localhost and private IP.

asyncDaytimeServer.cpp

#include "AsyncDaytimeServer.h"

#include <iostream>
#include <string>
#include <boost\bind.hpp>

using boost::asio::ip::tcp;

std::string make_daytime_string();


AsyncDaytimeServer::AsyncDaytimeServer(boost::asio::io_context& io_context)
	:	context_(io_context),
		acceptor_(io_context, tcp::endpoint(tcp::v4(), 13)),
		socket_(io_context)
{
}

AsyncDaytimeServer::~AsyncDaytimeServer()
{
}

void AsyncDaytimeServer::start()
{
	if (socket_.is_open())
	{
		socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both);
		socket_.close();
	}
	wait_connection();
}

void AsyncDaytimeServer::wait_connection()
{
	std::cout << "wait_connection()" << std::endl;
	if (socket_.is_open())
	{
		std::cout << "Error: Can't accept new connection from an open socket" << std::endl;
		return;
	}
	acceptor_.async_accept(
		socket_, 
		boost::bind(
			&AsyncDaytimeServer::connection_received_cb, 
			this, 
			boost::asio::placeholders::error
			)
		);
}

void AsyncDaytimeServer::answer()
{
	std::cout << "answer()" << std::endl;
	msg = make_daytime_string();
	boost::asio::async_write(
		socket_,
		boost::asio::buffer(msg),
		boost::bind(
			&AsyncDaytimeServer::response_sent_cb,
			this,
			boost::asio::placeholders::error,
			boost::asio::placeholders::bytes_transferred
		)
	);
	socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both);
	socket_.close();
}


void AsyncDaytimeServer::connection_received_cb(const boost::system::error_code& error)
{
	std::cout << "connection_received_cb()" << std::endl;
	if (!error) {
		answer();
		wait_connection();
	}
	else {
		std::cout << error.message() << std::endl;
	}
}

void AsyncDaytimeServer::response_sent_cb(const boost::system::error_code& error,
								size_t bytes_sent)
{
	std::cout << "response_sent_cb()" << std::endl;
	if (!error) {
		std::cout << "Response sent. " << bytes_sent << " bytes." << std::endl;
	}

}


std::string make_daytime_string()
{
#pragma warning(disable : 4996)
	using namespace std; // For time_t, time and ctime;
	time_t now = time(0);
	return ctime(&now);
}

asyncDaytimeServer.h

#pragma once

/*
	Asynchronous TCP Daytime Server
	Based on:
	https://www.boost.org/doc/libs/1_72_0/doc/html/boost_asio/tutorial/tutdaytime3/src.html

	Example use:
		boost::asio::io_context io_context;
		AsyncDaytimeServer s(io_context);
		s.start();
		io_context.run();

	Tested with client from:
	https://www.boost.org/doc/libs/1_72_0/doc/html/boost_asio/tutorial/tutdaytime1/src.html

*/



#include <boost\asio.hpp>
#include <string>
class AsyncDaytimeServer
{
public:
	AsyncDaytimeServer(boost::asio::io_context& context);
	~AsyncDaytimeServer();

	void start();

private:
	void wait_connection();
	void answer();
	void connection_received_cb(const boost::system::error_code& error);
	void response_sent_cb(const boost::system::error_code& error, size_t bytes_sent);

	std::string msg;	

	boost::asio::io_context& context_;
	boost::asio::ip::tcp::socket socket_;
	boost::asio::ip::tcp::acceptor acceptor_;
};