1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>TCP, UDP and ICMP</title>
<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
<link rel="home" href="../../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../networking.html" title="Networking">
<link rel="prev" href="../networking.html" title="Networking">
<link rel="next" href="other_protocols.html" title="Support for Other Protocols">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td>
<td align="center"><a href="../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<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>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.overview.networking.protocols"></a><a class="link" href="protocols.html" title="TCP, UDP and ICMP">TCP, UDP
and ICMP</a>
</h4></div></div></div>
<p>
Boost.Asio provides off-the-shelf support for the internet protocols TCP,
UDP and ICMP.
</p>
<h6>
<a name="boost_asio.overview.networking.protocols.h0"></a>
<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>
</h6>
<p>
Hostname resolution is performed using a resolver, where host and service
names are looked up and converted into one or more endpoints:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span> <span class="identifier">resolver</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">query</span> <span class="identifier">query</span><span class="special">(</span><span class="string">"www.boost.org"</span><span class="special">,</span> <span class="string">"http"</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">resolver</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">query</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">;</span> <span class="comment">// End marker.</span>
<span class="keyword">while</span> <span class="special">(</span><span class="identifier">iter</span> <span class="special">!=</span> <span class="identifier">end</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">endpoint</span> <span class="identifier">endpoint</span> <span class="special">=</span> <span class="special">*</span><span class="identifier">iter</span><span class="special">++;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">endpoint</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
The list of endpoints obtained above could contain both IPv4 and IPv6 endpoints,
so a program should try each of them until it finds one that works. This
keeps the client program independent of a specific IP version.
</p>
<p>
To simplify the development of protocol-independent programs, TCP clients
may establish connections using the free functions <a class="link" href="../../reference/connect.html" title="connect">connect()</a>
and <a class="link" href="../../reference/async_connect.html" title="async_connect">async_connect()</a>.
These operations try each endpoint in a list until the socket is successfully
connected. For example, a single call:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">connect</span><span class="special">(</span><span class="identifier">socket</span><span class="special">,</span> <span class="identifier">resolver</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">query</span><span class="special">));</span>
</pre>
<p>
will synchronously try all endpoints until one is successfully connected.
Similarly, an asynchronous connect may be performed by writing:
</p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">async_connect</span><span class="special">(</span><span class="identifier">socket_</span><span class="special">,</span> <span class="identifier">iter</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">handle_connect</span><span class="special">,</span> <span class="keyword">this</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">error</span><span class="special">));</span>
<span class="comment">// ...</span>
<span class="keyword">void</span> <span class="identifier">handle_connect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">error</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">error</span><span class="special">)</span>
<span class="special">{</span>
<span class="comment">// Start read or write operations.</span>
<span class="special">}</span>
<span class="keyword">else</span>
<span class="special">{</span>
<span class="comment">// Handle error.</span>
<span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
When a specific endpoint is available, a socket can be created and connected:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">socket</span><span class="special">.</span><span class="identifier">connect</span><span class="special">(</span><span class="identifier">endpoint</span><span class="special">);</span>
</pre>
<p>
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>,
<a class="link" href="../../reference/basic_stream_socket/async_receive.html" title="basic_stream_socket::async_receive">async_receive()</a>,
<a class="link" href="../../reference/basic_stream_socket/send.html" title="basic_stream_socket::send">send()</a>
or <a class="link" href="../../reference/basic_stream_socket/async_send.html" title="basic_stream_socket::async_send">async_send()</a>
member functions. However, as these could result in <a class="link" href="../core/streams.html" title="Streams, Short Reads and Short Writes">short
writes or reads</a>, an application will typically use the following
operations instead: <a class="link" href="../../reference/read.html" title="read">read()</a>,
<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>.
</p>
<h6>
<a name="boost_asio.overview.networking.protocols.h1"></a>
<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>
</h6>
<p>
A program uses an acceptor to accept incoming TCP connections:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">acceptor</span> <span class="identifier">acceptor</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">,</span> <span class="identifier">my_endpoint</span><span class="special">);</span>
<span class="special">...</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">acceptor</span><span class="special">.</span><span class="identifier">accept</span><span class="special">(</span><span class="identifier">socket</span><span class="special">);</span>
</pre>
<p>
After a socket has been successfully accepted, it may be read from or written
to as illustrated for TCP clients above.
</p>
<h6>
<a name="boost_asio.overview.networking.protocols.h2"></a>
<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>
</h6>
<p>
UDP hostname resolution is also performed using a resolver:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">resolver</span> <span class="identifier">resolver</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">query</span> <span class="identifier">query</span><span class="special">(</span><span class="string">"localhost"</span><span class="special">,</span> <span class="string">"daytime"</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">resolver</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">query</span><span class="special">);</span>
<span class="special">...</span>
</pre>
<p>
A UDP socket is typically bound to a local endpoint. The following code
will create an IP version 4 UDP socket and bind it to the "any"
address on port <code class="computeroutput"><span class="number">12345</span></code>:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">endpoint</span> <span class="identifier">endpoint</span><span class="special">(</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">v4</span><span class="special">(),</span> <span class="number">12345</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">udp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">,</span> <span class="identifier">endpoint</span><span class="special">);</span>
</pre>
<p>
Data may be read from or written to an unconnected UDP socket using the
<a class="link" href="../../reference/basic_datagram_socket/receive_from.html" title="basic_datagram_socket::receive_from">receive_from()</a>,
<a class="link" href="../../reference/basic_datagram_socket/async_receive_from.html" title="basic_datagram_socket::async_receive_from">async_receive_from()</a>,
<a class="link" href="../../reference/basic_datagram_socket/send_to.html" title="basic_datagram_socket::send_to">send_to()</a>
or <a class="link" href="../../reference/basic_datagram_socket/async_send_to.html" title="basic_datagram_socket::async_send_to">async_send_to()</a>
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>,
<a class="link" href="../../reference/basic_datagram_socket/async_receive.html" title="basic_datagram_socket::async_receive">async_receive()</a>,
<a class="link" href="../../reference/basic_datagram_socket/send.html" title="basic_datagram_socket::send">send()</a>
or <a class="link" href="../../reference/basic_datagram_socket/async_send.html" title="basic_datagram_socket::async_send">async_send()</a>
member functions.
</p>
<h6>
<a name="boost_asio.overview.networking.protocols.h3"></a>
<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>
</h6>
<p>
As with TCP and UDP, ICMP hostname resolution is performed using a resolver:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">resolver</span> <span class="identifier">resolver</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">query</span> <span class="identifier">query</span><span class="special">(</span><span class="string">"localhost"</span><span class="special">,</span> <span class="string">""</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">resolver</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">query</span><span class="special">);</span>
<span class="special">...</span>
</pre>
<p>
An ICMP socket may be bound to a local endpoint. The following code will
create an IP version 6 ICMP socket and bind it to the "any" address:
</p>
<pre class="programlisting"><span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">endpoint</span> <span class="identifier">endpoint</span><span class="special">(</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">v6</span><span class="special">(),</span> <span class="number">0</span><span class="special">);</span>
<span class="identifier">ip</span><span class="special">::</span><span class="identifier">icmp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">(</span><span class="identifier">my_io_service</span><span class="special">,</span> <span class="identifier">endpoint</span><span class="special">);</span>
</pre>
<p>
The port number is not used for ICMP.
</p>
<p>
Data may be read from or written to an unconnected ICMP socket using the
<a class="link" href="../../reference/basic_raw_socket/receive_from.html" title="basic_raw_socket::receive_from">receive_from()</a>,
<a class="link" href="../../reference/basic_raw_socket/async_receive_from.html" title="basic_raw_socket::async_receive_from">async_receive_from()</a>,
<a class="link" href="../../reference/basic_raw_socket/send_to.html" title="basic_raw_socket::send_to">send_to()</a>
or <a class="link" href="../../reference/basic_raw_socket/async_send_to.html" title="basic_raw_socket::async_send_to">async_send_to()</a>
member functions.
</p>
<h6>
<a name="boost_asio.overview.networking.protocols.h4"></a>
<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
Also</a>
</h6>
<p>
<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>,
<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
protocol tutorials</a>, <a class="link" href="../../examples/cpp03_examples.html#boost_asio.examples.cpp03_examples.icmp">ICMP
ping example</a>.
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2003-2013 Christopher M. Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
</p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<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>
</div>
</body>
</html>
|
