Accept connections

Server needs to accept clients' connections. First server creates an acceptor:

......
boost::asio::io_context io_context;
    boost::asio::ip::tcp::acceptor acceptor{
        io_context,
        boost::asio::ip::tcp::endpoint{boost::asio::ip::tcp::v6(), 3303}};
......

boost::asio::ip::tcp::acceptor is an instance of basic_socket_acceptor:

class tcp
{
......
  /// The TCP acceptor type.
  typedef basic_socket_acceptor<tcp> acceptor;
......
}

The following constructor of basic_socket_acceptor combines creating socket, setting reuse address, binding & listening functions:

basic_socket_acceptor(boost::asio::io_context& io_context,
    const endpoint_type& endpoint, bool reuse_addr = true)
  : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
{
......
}

Then acceptor will accept the clients' connections. Following simple example just shows client's address and close the connection:

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

int main()
{
    try
    {
        boost::asio::io_context io_context;
        boost::asio::ip::tcp::acceptor acceptor{
            io_context,
            boost::asio::ip::tcp::endpoint{boost::asio::ip::tcp::v6(), 3303}};

        while (1)
        {
            boost::asio::ip::tcp::socket socket{io_context};
            acceptor.accept(socket);

            std::cout << socket.remote_endpoint() << " connects to " << socket.local_endpoint() << '\n';
        }
    }
    catch (std::exception& e)
    {
        std::cerr << e.what() << '\n';
        return -1;
    }

    return 0;
}

The running result is like this:

[::ffff:10.217.242.61]:39290 connects to [::ffff:192.168.35.145]:3303
......