1 //
2 // async_udp_echo_server.cpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10
11 #include <cstdlib>
12 #include <iostream>
13 #include <boost/asio.hpp>
14
15 using boost::asio::ip::udp;
16
17 class server
18 {
19 public:
server(boost::asio::io_context & io_context,short port)20 server(boost::asio::io_context& io_context, short port)
21 : socket_(io_context, udp::endpoint(udp::v4(), port))
22 {
23 do_receive();
24 }
25
do_receive()26 void do_receive()
27 {
28 socket_.async_receive_from(
29 boost::asio::buffer(data_, max_length), sender_endpoint_,
30 [this](boost::system::error_code ec, std::size_t bytes_recvd)
31 {
32 if (!ec && bytes_recvd > 0)
33 {
34 do_send(bytes_recvd);
35 }
36 else
37 {
38 do_receive();
39 }
40 });
41 }
42
do_send(std::size_t length)43 void do_send(std::size_t length)
44 {
45 socket_.async_send_to(
46 boost::asio::buffer(data_, length), sender_endpoint_,
47 [this](boost::system::error_code /*ec*/, std::size_t /*bytes_sent*/)
48 {
49 do_receive();
50 });
51 }
52
53 private:
54 udp::socket socket_;
55 udp::endpoint sender_endpoint_;
56 enum { max_length = 1024 };
57 char data_[max_length];
58 };
59
main(int argc,char * argv[])60 int main(int argc, char* argv[])
61 {
62 try
63 {
64 if (argc != 2)
65 {
66 std::cerr << "Usage: async_udp_echo_server <port>\n";
67 return 1;
68 }
69
70 boost::asio::io_context io_context;
71
72 server s(io_context, std::atoi(argv[1]));
73
74 io_context.run();
75 }
76 catch (std::exception& e)
77 {
78 std::cerr << "Exception: " << e.what() << "\n";
79 }
80
81 return 0;
82 }
83