Echo server

echo_server.cpp

#include <cstdlib>
#include <iostream>
#include <boost/asio.hpp>
#include <functional>

using boost::asio::ip::udp;

class server
{
public:
    server(boost::asio::io_service& io_service, short port)
        : socket_(io_service, udp::endpoint(udp::v4(), port))
    {
        do_receive();
    }

    void do_receive() {
        socket_.async_receive_from(
            boost::asio::buffer(data_, max_length),
            sender_endpoint_,
            [this] (boost::system::error_code ec, std::size_t bytes_recvd) {
                std::cout << "Received request from "
                          << sender_endpoint_
                                 .address()
                                 .to_string()
                          << std::endl;
                if (!ec && bytes_recvd > 0) do_send(bytes_recvd);
                else do_receive();
            });
    }

    void do_send(std::size_t length)
    {
        socket_.async_send_to(
            boost::asio::buffer(data_, length),
            sender_endpoint_,
            [this](boost::system::error_code /*ec*/, std::size_t /*bytes_sent*/) {
                do_receive();
            });
    }

private:
    udp::socket socket_;
    udp::endpoint sender_endpoint_;
    enum { max_length = 1024 };
    char data_[max_length];
};

int main(int argc, char* argv[])
{
    try {
        if (argc != 2) {
            std::cerr << "Usage: async_udp_echo_server <port>\n";
            return 1;
        }

        boost::asio::io_service io_service;
        server s(io_service, std::atoi(argv[1]));
        io_service.run();
    } catch (std::exception& e) {
        std::cerr << "Exception: " << e.what() << "\n";
    }

    return 0;
}