1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>TCP, UDP and ICMP</title> 5<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../networking.html" title="Networking"> 9<link rel="prev" href="../networking.html" title="Networking"> 10<link rel="next" href="other_protocols.html" title="Support for Other Protocols"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../networking.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../networking.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="other_protocols.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="boost_asio.overview.networking.protocols"></a><a class="link" href="protocols.html" title="TCP, UDP and ICMP">TCP, UDP 28 and ICMP</a> 29</h4></div></div></div> 30<p> 31 Boost.Asio provides off-the-shelf support for the internet protocols TCP, 32 UDP and ICMP. 33 </p> 34<h6> 35<a name="boost_asio.overview.networking.protocols.h0"></a> 36 <span class="phrase"><a name="boost_asio.overview.networking.protocols.tcp_clients"></a></span><a class="link" href="protocols.html#boost_asio.overview.networking.protocols.tcp_clients">TCP Clients</a> 37 </h6> 38<p> 39 Hostname resolution is performed using a resolver, where host and service 40 names are looked up and converted into one or more endpoints: 41 </p> 42<pre class="programlisting">ip::tcp::resolver resolver(my_io_context); 43ip::tcp::resolver::query query("www.boost.org", "http"); 44ip::tcp::resolver::iterator iter = resolver.resolve(query); 45ip::tcp::resolver::iterator end; // End marker. 46while (iter != end) 47{ 48 ip::tcp::endpoint endpoint = *iter++; 49 std::cout << endpoint << std::endl; 50} 51</pre> 52<p> 53 The list of endpoints obtained above could contain both IPv4 and IPv6 endpoints, 54 so a program should try each of them until it finds one that works. This 55 keeps the client program independent of a specific IP version. 56 </p> 57<p> 58 To simplify the development of protocol-independent programs, TCP clients 59 may establish connections using the free functions <a class="link" href="../../reference/connect.html" title="connect">connect()</a> 60 and <a class="link" href="../../reference/async_connect.html" title="async_connect">async_connect()</a>. 61 These operations try each endpoint in a list until the socket is successfully 62 connected. For example, a single call: 63 </p> 64<pre class="programlisting">ip::tcp::socket socket(my_io_context); 65boost::asio::connect(socket, resolver.resolve(query)); 66</pre> 67<p> 68 will synchronously try all endpoints until one is successfully connected. 69 Similarly, an asynchronous connect may be performed by writing: 70 </p> 71<pre class="programlisting">boost::asio::async_connect(socket_, iter, 72 boost::bind(&client::handle_connect, this, 73 boost::asio::placeholders::error)); 74 75// ... 76 77void handle_connect(const error_code& error) 78{ 79 if (!error) 80 { 81 // Start read or write operations. 82 } 83 else 84 { 85 // Handle error. 86 } 87} 88</pre> 89<p> 90 When a specific endpoint is available, a socket can be created and connected: 91 </p> 92<pre class="programlisting">ip::tcp::socket socket(my_io_context); 93socket.connect(endpoint); 94</pre> 95<p> 96 Data may be read from or written to a connected TCP socket using the <a class="link" href="../../reference/basic_stream_socket/receive.html" title="basic_stream_socket::receive">receive()</a>, 97 <a class="link" href="../../reference/basic_stream_socket/async_receive.html" title="basic_stream_socket::async_receive">async_receive()</a>, 98 <a class="link" href="../../reference/basic_stream_socket/send.html" title="basic_stream_socket::send">send()</a> 99 or <a class="link" href="../../reference/basic_stream_socket/async_send.html" title="basic_stream_socket::async_send">async_send()</a> 100 member functions. However, as these could result in <a class="link" href="../core/streams.html" title="Streams, Short Reads and Short Writes">short 101 writes or reads</a>, an application will typically use the following 102 operations instead: <a class="link" href="../../reference/read.html" title="read">read()</a>, 103 <a class="link" href="../../reference/async_read.html" title="async_read">async_read()</a>, <a class="link" href="../../reference/write.html" title="write">write()</a> and <a class="link" href="../../reference/async_write.html" title="async_write">async_write()</a>. 104 </p> 105<h6> 106<a name="boost_asio.overview.networking.protocols.h1"></a> 107 <span class="phrase"><a name="boost_asio.overview.networking.protocols.tcp_servers"></a></span><a class="link" href="protocols.html#boost_asio.overview.networking.protocols.tcp_servers">TCP Servers</a> 108 </h6> 109<p> 110 A program uses an acceptor to accept incoming TCP connections: 111 </p> 112<pre class="programlisting">ip::tcp::acceptor acceptor(my_io_context, my_endpoint); 113... 114ip::tcp::socket socket(my_io_context); 115acceptor.accept(socket); 116</pre> 117<p> 118 After a socket has been successfully accepted, it may be read from or written 119 to as illustrated for TCP clients above. 120 </p> 121<h6> 122<a name="boost_asio.overview.networking.protocols.h2"></a> 123 <span class="phrase"><a name="boost_asio.overview.networking.protocols.udp"></a></span><a class="link" href="protocols.html#boost_asio.overview.networking.protocols.udp">UDP</a> 124 </h6> 125<p> 126 UDP hostname resolution is also performed using a resolver: 127 </p> 128<pre class="programlisting">ip::udp::resolver resolver(my_io_context); 129ip::udp::resolver::query query("localhost", "daytime"); 130ip::udp::resolver::iterator iter = resolver.resolve(query); 131... 132</pre> 133<p> 134 A UDP socket is typically bound to a local endpoint. The following code 135 will create an IP version 4 UDP socket and bind it to the "any" 136 address on port <code class="computeroutput">12345</code>: 137 </p> 138<pre class="programlisting">ip::udp::endpoint endpoint(ip::udp::v4(), 12345); 139ip::udp::socket socket(my_io_context, endpoint); 140</pre> 141<p> 142 Data may be read from or written to an unconnected UDP socket using the 143 <a class="link" href="../../reference/basic_datagram_socket/receive_from.html" title="basic_datagram_socket::receive_from">receive_from()</a>, 144 <a class="link" href="../../reference/basic_datagram_socket/async_receive_from.html" title="basic_datagram_socket::async_receive_from">async_receive_from()</a>, 145 <a class="link" href="../../reference/basic_datagram_socket/send_to.html" title="basic_datagram_socket::send_to">send_to()</a> 146 or <a class="link" href="../../reference/basic_datagram_socket/async_send_to.html" title="basic_datagram_socket::async_send_to">async_send_to()</a> 147 member functions. For a connected UDP socket, use the <a class="link" href="../../reference/basic_datagram_socket/receive.html" title="basic_datagram_socket::receive">receive()</a>, 148 <a class="link" href="../../reference/basic_datagram_socket/async_receive.html" title="basic_datagram_socket::async_receive">async_receive()</a>, 149 <a class="link" href="../../reference/basic_datagram_socket/send.html" title="basic_datagram_socket::send">send()</a> 150 or <a class="link" href="../../reference/basic_datagram_socket/async_send.html" title="basic_datagram_socket::async_send">async_send()</a> 151 member functions. 152 </p> 153<h6> 154<a name="boost_asio.overview.networking.protocols.h3"></a> 155 <span class="phrase"><a name="boost_asio.overview.networking.protocols.icmp"></a></span><a class="link" href="protocols.html#boost_asio.overview.networking.protocols.icmp">ICMP</a> 156 </h6> 157<p> 158 As with TCP and UDP, ICMP hostname resolution is performed using a resolver: 159 </p> 160<pre class="programlisting">ip::icmp::resolver resolver(my_io_context); 161ip::icmp::resolver::query query("localhost", ""); 162ip::icmp::resolver::iterator iter = resolver.resolve(query); 163... 164</pre> 165<p> 166 An ICMP socket may be bound to a local endpoint. The following code will 167 create an IP version 6 ICMP socket and bind it to the "any" address: 168 </p> 169<pre class="programlisting">ip::icmp::endpoint endpoint(ip::icmp::v6(), 0); 170ip::icmp::socket socket(my_io_context, endpoint); 171</pre> 172<p> 173 The port number is not used for ICMP. 174 </p> 175<p> 176 Data may be read from or written to an unconnected ICMP socket using the 177 <a class="link" href="../../reference/basic_raw_socket/receive_from.html" title="basic_raw_socket::receive_from">receive_from()</a>, 178 <a class="link" href="../../reference/basic_raw_socket/async_receive_from.html" title="basic_raw_socket::async_receive_from">async_receive_from()</a>, 179 <a class="link" href="../../reference/basic_raw_socket/send_to.html" title="basic_raw_socket::send_to">send_to()</a> 180 or <a class="link" href="../../reference/basic_raw_socket/async_send_to.html" title="basic_raw_socket::async_send_to">async_send_to()</a> 181 member functions. 182 </p> 183<h6> 184<a name="boost_asio.overview.networking.protocols.h4"></a> 185 <span class="phrase"><a name="boost_asio.overview.networking.protocols.see_also"></a></span><a class="link" href="protocols.html#boost_asio.overview.networking.protocols.see_also">See 186 Also</a> 187 </h6> 188<p> 189 <a class="link" href="../../reference/ip__tcp.html" title="ip::tcp">ip::tcp</a>, <a class="link" href="../../reference/ip__udp.html" title="ip::udp">ip::udp</a>, 190 <a class="link" href="../../reference/ip__icmp.html" title="ip::icmp">ip::icmp</a>, <a class="link" href="../../tutorial/tutdaytime1.html" title="Daytime.1 - A synchronous TCP daytime client">daytime 191 protocol tutorials</a>, <a class="link" href="../../examples/cpp03_examples.html#boost_asio.examples.cpp03_examples.icmp">ICMP 192 ping example</a>. 193 </p> 194</div> 195<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 196<td align="left"></td> 197<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 198 Kohlhoff<p> 199 Distributed under the Boost Software License, Version 1.0. (See accompanying 200 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 201 </p> 202</div></td> 203</tr></table> 204<hr> 205<div class="spirit-nav"> 206<a accesskey="p" href="../networking.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../networking.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="other_protocols.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 207</div> 208</body> 209</html> 210
