SFML/examples/sockets/UDP.cpp

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Network.hpp>

#include <iomanip>
#include <iostream>
#include <optional>

#include <cstddef>


////////////////////////////////////////////////////////////
/// Launch a server, wait for a message, send an answer.
///
////////////////////////////////////////////////////////////
void runUdpServer(unsigned short port)
{
    // Create a socket to receive a message from anyone
    sf::UdpSocket socket;

    // Listen to messages on the specified port
    if (socket.bind(port) != sf::Socket::Status::Done)
        return;
    std::cout << "Server is listening to port " << port << ", waiting for a message... " << std::endl;

    // Wait for a message
    char                         in[128];
    std::size_t                  received;
    std::optional<sf::IpAddress> sender;
    unsigned short               senderPort;
    if (socket.receive(in, sizeof(in), received, sender, senderPort) != sf::Socket::Status::Done)
        return;
    std::cout << "Message received from client " << sender.value() << ": " << std::quoted(in) << std::endl;

    // Send an answer to the client
    const char out[] = "Hi, I'm the server";
    if (socket.send(out, sizeof(out), sender.value(), senderPort) != sf::Socket::Status::Done)
        return;
    std::cout << "Message sent to the client: " << std::quoted(out) << std::endl;
}


////////////////////////////////////////////////////////////
/// Send a message to the server, wait for the answer
///
////////////////////////////////////////////////////////////
void runUdpClient(unsigned short port)
{
    // Ask for the server address
    std::optional<sf::IpAddress> server;
    do
    {
        std::cout << "Type the address or name of the server to connect to: ";
        std::cin >> server;
    } while (!server.has_value());

    // Create a socket for communicating with the server
    sf::UdpSocket socket;

    // Send a message to the server
    const char out[] = "Hi, I'm a client";
    if (socket.send(out, sizeof(out), server.value(), port) != sf::Socket::Status::Done)
        return;
    std::cout << "Message sent to the server: " << std::quoted(out) << std::endl;

    // Receive an answer from anyone (but most likely from the server)
    char                         in[128];
    std::size_t                  received;
    std::optional<sf::IpAddress> sender;
    unsigned short               senderPort;
    if (socket.receive(in, sizeof(in), received, sender, senderPort) != sf::Socket::Status::Done)
        return;
    std::cout << "Message received from " << sender.value() << ": " << std::quoted(in) << std::endl;
}