1 //
2 // async_udp_echo_server.cpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2016 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/bind.hpp>
14 #include "asio.hpp"
15
16 using asio::ip::udp;
17
18 class server
19 {
20 public:
server(asio::io_context & io_context,short port)21 server(asio::io_context& io_context, short port)
22 : socket_(io_context, udp::endpoint(udp::v4(), port))
23 {
24 socket_.async_receive_from(
25 asio::buffer(data_, max_length), sender_endpoint_,
26 boost::bind(&server::handle_receive_from, this,
27 asio::placeholders::error,
28 asio::placeholders::bytes_transferred));
29 }
30
handle_receive_from(const asio::error_code & error,size_t bytes_recvd)31 void handle_receive_from(const asio::error_code& error,
32 size_t bytes_recvd)
33 {
34 if (!error && bytes_recvd > 0)
35 {
36 socket_.async_send_to(
37 asio::buffer(data_, bytes_recvd), sender_endpoint_,
38 boost::bind(&server::handle_send_to, this,
39 asio::placeholders::error,
40 asio::placeholders::bytes_transferred));
41 }
42 else
43 {
44 socket_.async_receive_from(
45 asio::buffer(data_, max_length), sender_endpoint_,
46 boost::bind(&server::handle_receive_from, this,
47 asio::placeholders::error,
48 asio::placeholders::bytes_transferred));
49 }
50 }
51
handle_send_to(const asio::error_code &,size_t)52 void handle_send_to(const asio::error_code& /*error*/,
53 size_t /*bytes_sent*/)
54 {
55 socket_.async_receive_from(
56 asio::buffer(data_, max_length), sender_endpoint_,
57 boost::bind(&server::handle_receive_from, this,
58 asio::placeholders::error,
59 asio::placeholders::bytes_transferred));
60 }
61
62 private:
63 udp::socket socket_;
64 udp::endpoint sender_endpoint_;
65 enum { max_length = 1024 };
66 char data_[max_length];
67 };
68
main(int argc,char * argv[])69 int main(int argc, char* argv[])
70 {
71 try
72 {
73 if (argc != 2)
74 {
75 std::cerr << "Usage: async_udp_echo_server <port>\n";
76 return 1;
77 }
78
79 asio::io_context io_context;
80
81 using namespace std; // For atoi.
82 server s(io_context, atoi(argv[1]));
83
84 io_context.run();
85 }
86 catch (std::exception& e)
87 {
88 std::cerr << "Exception: " << e.what() << "\n";
89 }
90
91 return 0;
92 }
93