UDP communication

We have discussed how to communicate through TCP enough, so it is time to switch to UDP now. UDP is a connectionless protocol, and it is easier to use than TCP. There is a client/server example. Below is client code:

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

int main()
{
    try
    {
        boost::asio::io_context io_context;

        boost::asio::ip::udp::socket socket{io_context};
        socket.open(boost::asio::ip::udp::v4());

        socket.send_to(
                boost::asio::buffer("Hello world!"),
                boost::asio::ip::udp::endpoint{boost::asio::ip::make_address("192.168.35.145"), 3303});
    }
    catch (std::exception& e)
    {
        std::cerr << e.what() << '\n';
        return -1;
    }

    return 0;
}

Although there is no need to call socket.connect function, you need call socket.open explicitly. Furthermore, the server's endpoint needs to be specified when invoking socket.send_to.

Server code is like this:

#include <ctime>
#include <functional>
#include <iostream>
#include <string>
#include <boost/asio.hpp>

int main()
{
    try
    {
        boost::asio::io_context io_context;

        for (;;)
        {
            boost::asio::ip::udp::socket socket(
                    io_context,
                    boost::asio::ip::udp::endpoint{boost::asio::ip::udp::v4(), 3303});

            boost::asio::ip::udp::endpoint client;
            char recv_str[1024] = {};

            socket.receive_from(
                    boost::asio::buffer(recv_str),
                    client);
            std::cout << client << ": " << recv_str << '\n';
        }
    }
    catch (std::exception& e)
    {
        std::cerr << e.what() << std::endl;
    }

    return 0;
}

Very easy, isn't it? Build and run client and server. The following log will be printed on server side:

$ ./server
10.217.242.21:63838: Hello world!
10.217.242.21:61259: Hello world!