1 //
2 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // Official repository: https://github.com/boostorg/beast
8 //
9
10 //------------------------------------------------------------------------------
11 //
12 // Example: WebSocket client, coroutine
13 //
14 //------------------------------------------------------------------------------
15
16 #include <boost/beast/core.hpp>
17 #include <boost/beast/websocket.hpp>
18 #include <boost/asio/spawn.hpp>
19 #include <cstdlib>
20 #include <functional>
21 #include <iostream>
22 #include <string>
23
24 namespace beast = boost::beast; // from <boost/beast.hpp>
25 namespace http = beast::http; // from <boost/beast/http.hpp>
26 namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp>
27 namespace net = boost::asio; // from <boost/asio.hpp>
28 using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
29
30 //------------------------------------------------------------------------------
31
32 // Report a failure
33 void
fail(beast::error_code ec,char const * what)34 fail(beast::error_code ec, char const* what)
35 {
36 std::cerr << what << ": " << ec.message() << "\n";
37 }
38
39 // Sends a WebSocket message and prints the response
40 void
do_session(std::string host,std::string const & port,std::string const & text,net::io_context & ioc,net::yield_context yield)41 do_session(
42 std::string host,
43 std::string const& port,
44 std::string const& text,
45 net::io_context& ioc,
46 net::yield_context yield)
47 {
48 beast::error_code ec;
49
50 // These objects perform our I/O
51 tcp::resolver resolver(ioc);
52 websocket::stream<beast::tcp_stream> ws(ioc);
53
54 // Look up the domain name
55 auto const results = resolver.async_resolve(host, port, yield[ec]);
56 if(ec)
57 return fail(ec, "resolve");
58
59 // Set a timeout on the operation
60 beast::get_lowest_layer(ws).expires_after(std::chrono::seconds(30));
61
62 // Make the connection on the IP address we get from a lookup
63 auto ep = beast::get_lowest_layer(ws).async_connect(results, yield[ec]);
64 if(ec)
65 return fail(ec, "connect");
66
67 // Update the host_ string. This will provide the value of the
68 // Host HTTP header during the WebSocket handshake.
69 // See https://tools.ietf.org/html/rfc7230#section-5.4
70 host += ':' + std::to_string(ep.port());
71
72 // Turn off the timeout on the tcp_stream, because
73 // the websocket stream has its own timeout system.
74 beast::get_lowest_layer(ws).expires_never();
75
76 // Set suggested timeout settings for the websocket
77 ws.set_option(
78 websocket::stream_base::timeout::suggested(
79 beast::role_type::client));
80
81 // Set a decorator to change the User-Agent of the handshake
82 ws.set_option(websocket::stream_base::decorator(
83 [](websocket::request_type& req)
84 {
85 req.set(http::field::user_agent,
86 std::string(BOOST_BEAST_VERSION_STRING) +
87 " websocket-client-coro");
88 }));
89
90 // Perform the websocket handshake
91 ws.async_handshake(host, "/", yield[ec]);
92 if(ec)
93 return fail(ec, "handshake");
94
95 // Send the message
96 ws.async_write(net::buffer(std::string(text)), yield[ec]);
97 if(ec)
98 return fail(ec, "write");
99
100 // This buffer will hold the incoming message
101 beast::flat_buffer buffer;
102
103 // Read a message into our buffer
104 ws.async_read(buffer, yield[ec]);
105 if(ec)
106 return fail(ec, "read");
107
108 // Close the WebSocket connection
109 ws.async_close(websocket::close_code::normal, yield[ec]);
110 if(ec)
111 return fail(ec, "close");
112
113 // If we get here then the connection is closed gracefully
114
115 // The make_printable() function helps print a ConstBufferSequence
116 std::cout << beast::make_printable(buffer.data()) << std::endl;
117 }
118
119 //------------------------------------------------------------------------------
120
main(int argc,char ** argv)121 int main(int argc, char** argv)
122 {
123 // Check command line arguments.
124 if(argc != 4)
125 {
126 std::cerr <<
127 "Usage: websocket-client-coro <host> <port> <text>\n" <<
128 "Example:\n" <<
129 " websocket-client-coro echo.websocket.org 80 \"Hello, world!\"\n";
130 return EXIT_FAILURE;
131 }
132 auto const host = argv[1];
133 auto const port = argv[2];
134 auto const text = argv[3];
135
136 // The io_context is required for all I/O
137 net::io_context ioc;
138
139 // Launch the asynchronous operation
140 boost::asio::spawn(ioc, std::bind(
141 &do_session,
142 std::string(host),
143 std::string(port),
144 std::string(text),
145 std::ref(ioc),
146 std::placeholders::_1));
147
148 // Run the I/O service. The call will return when
149 // the socket is closed.
150 ioc.run();
151
152 return EXIT_SUCCESS;
153 }
154