1 //
2 // async_tcp_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 <memory>
14 #include <utility>
15 #include <boost/asio.hpp>
16
17 using boost::asio::ip::tcp;
18
19 // Define a helper macro to invoke BOOST_ASIO_HANDLER_LOCATION with the current
20 // file name, line number, and function name. For the function name, you might
21 // also consider using __PRETTY_FUNCTION__, BOOST_CURRENT_FUNCTION, or a hand-
22 // crafted name. For C++20 or later, you may also use std::source_location.
23 #define HANDLER_LOCATION \
24 BOOST_ASIO_HANDLER_LOCATION((__FILE__, __LINE__, __func__))
25
26 class session
27 : public std::enable_shared_from_this<session>
28 {
29 public:
session(tcp::socket socket)30 session(tcp::socket socket)
31 : socket_(std::move(socket))
32 {
33 }
34
start()35 void start()
36 {
37 HANDLER_LOCATION;
38
39 do_read();
40 }
41
42 private:
do_read()43 void do_read()
44 {
45 HANDLER_LOCATION;
46
47 auto self(shared_from_this());
48 socket_.async_read_some(boost::asio::buffer(data_, max_length),
49 [this, self](boost::system::error_code ec, std::size_t length)
50 {
51 HANDLER_LOCATION;
52
53 if (!ec)
54 {
55 do_write(length);
56 }
57 });
58 }
59
do_write(std::size_t length)60 void do_write(std::size_t length)
61 {
62 HANDLER_LOCATION;
63
64 auto self(shared_from_this());
65 boost::asio::async_write(socket_, boost::asio::buffer(data_, length),
66 [this, self](boost::system::error_code ec, std::size_t /*length*/)
67 {
68 HANDLER_LOCATION;
69
70 if (!ec)
71 {
72 do_read();
73 }
74 });
75 }
76
77 tcp::socket socket_;
78 enum { max_length = 1024 };
79 char data_[max_length];
80 };
81
82 class server
83 {
84 public:
server(boost::asio::io_context & io_context,short port)85 server(boost::asio::io_context& io_context, short port)
86 : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
87 {
88 do_accept();
89 }
90
91 private:
do_accept()92 void do_accept()
93 {
94 HANDLER_LOCATION;
95
96 acceptor_.async_accept(
97 [this](boost::system::error_code ec, tcp::socket socket)
98 {
99 HANDLER_LOCATION;
100
101 if (!ec)
102 {
103 std::make_shared<session>(std::move(socket))->start();
104 }
105
106 do_accept();
107 });
108 }
109
110 tcp::acceptor acceptor_;
111 };
112
main(int argc,char * argv[])113 int main(int argc, char* argv[])
114 {
115 try
116 {
117 if (argc != 2)
118 {
119 std::cerr << "Usage: async_tcp_echo_server <port>\n";
120 return 1;
121 }
122
123 boost::asio::io_context io_context;
124
125 server s(io_context, std::atoi(argv[1]));
126
127 io_context.run();
128 }
129 catch (std::exception& e)
130 {
131 std::cerr << "Exception: " << e.what() << "\n";
132 }
133
134 return 0;
135 }
136