Function server

example/cpp11/echo/blocking_udp_echo_server.cpp:19–30

enum { max_length = 1024 };

void server(boost::asio::io_context& io_context, unsigned short port)
{
  udp::socket sock(io_context, udp::endpoint(udp::v4(), port));
  for (;;)
  {
    char data[max_length];
    udp::endpoint sender_endpoint;
    size_t length = sock.receive_from(
        boost::asio::buffer(data, max_length), sender_endpoint);
    sock.send_to(boost::asio::buffer(data, length), sender_endpoint);
  }
}

int main(int argc, char* argv[])
{