101 lines
7.7 KiB
HTML
101 lines
7.7 KiB
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
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<title>Daytime.5 - A synchronous UDP daytime server</title>
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<link rel="stylesheet" href="../../boostbook.css" type="text/css">
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<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
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<link rel="home" href="../../index.html" title="Asio">
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<link rel="up" href="../tutorial.html" title="Tutorial">
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<link rel="prev" href="tutdaytime4/src.html" title="Source listing for Daytime.4">
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<link rel="next" href="tutdaytime5/src.html" title="Source listing for Daytime.5">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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</head>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
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<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
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<hr>
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<div class="spirit-nav">
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<a accesskey="p" href="tutdaytime4/src.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="tutdaytime5/src.html"><img src="../../next.png" alt="Next"></a>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="asio.tutorial.tutdaytime5"></a><a class="link" href="tutdaytime5.html" title="Daytime.5 - A synchronous UDP daytime server">Daytime.5 - A synchronous
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UDP daytime server</a>
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</h3></div></div></div>
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<p>
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This tutorial program shows how to use asio to implement a server application
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with UDP.
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</p>
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<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
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<span class="special">{</span>
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<span class="keyword">try</span>
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<span class="special">{</span>
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<span class="identifier">asio</span><span class="special">::</span><span class="identifier">io_context</span> <span class="identifier">io_context</span><span class="special">;</span>
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</pre>
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<p>
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Create an <a class="link" href="../reference/ip__udp/socket.html" title="ip::udp::socket">ip::udp::socket</a>
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object to receive requests on UDP port 13.
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</p>
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<pre class="programlisting"> <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">io_context</span><span class="special">,</span> <span class="identifier">udp</span><span class="special">::</span><span class="identifier">endpoint</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">13</span><span class="special">));</span>
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</pre>
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<p>
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Wait for a client to initiate contact with us. The remote_endpoint object
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will be populated by <a class="link" href="../reference/basic_datagram_socket/receive_from.html" title="basic_datagram_socket::receive_from">ip::udp::socket::receive_from()</a>.
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</p>
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<pre class="programlisting"> <span class="keyword">for</span> <span class="special">(;;)</span>
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<span class="special">{</span>
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<span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">1</span><span class="special">></span> <span class="identifier">recv_buf</span><span class="special">;</span>
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<span class="identifier">udp</span><span class="special">::</span><span class="identifier">endpoint</span> <span class="identifier">remote_endpoint</span><span class="special">;</span>
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<span class="identifier">socket</span><span class="special">.</span><span class="identifier">receive_from</span><span class="special">(</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">recv_buf</span><span class="special">),</span> <span class="identifier">remote_endpoint</span><span class="special">);</span>
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</pre>
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<p>
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Determine what we are going to send back to the client.
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</p>
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<pre class="programlisting"> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">message</span> <span class="special">=</span> <span class="identifier">make_daytime_string</span><span class="special">();</span>
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</pre>
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<p>
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Send the response to the remote_endpoint.
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</p>
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<pre class="programlisting"> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ignored_error</span><span class="special">;</span>
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<span class="identifier">socket</span><span class="special">.</span><span class="identifier">send_to</span><span class="special">(</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">message</span><span class="special">),</span>
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<span class="identifier">remote_endpoint</span><span class="special">,</span> <span class="number">0</span><span class="special">,</span> <span class="identifier">ignored_error</span><span class="special">);</span>
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<span class="special">}</span>
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<span class="special">}</span>
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</pre>
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<p>
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Finally, handle any exceptions.
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</p>
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<pre class="programlisting"> <span class="keyword">catch</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span>
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<span class="special">{</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">cerr</span> <span class="special"><<</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">what</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
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<span class="special">}</span>
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<span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
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<span class="special">}</span>
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</pre>
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<p>
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See the <a class="link" href="tutdaytime5/src.html" title="Source listing for Daytime.5">full source listing</a>
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</p>
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<p>
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Return to the <a class="link" href="../tutorial.html" title="Tutorial">tutorial index</a>
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</p>
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<p>
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Previous: <a class="link" href="tutdaytime4.html" title="Daytime.4 - A synchronous UDP daytime client">Daytime.4 - A synchronous
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UDP daytime client</a>
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</p>
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<p>
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Next: <a class="link" href="tutdaytime6.html" title="Daytime.6 - An asynchronous UDP daytime server">Daytime.6 - An asynchronous
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UDP daytime server</a>
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</p>
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</div>
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<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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>)
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</p>
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</div>
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<hr>
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<div class="spirit-nav">
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<a accesskey="p" href="tutdaytime4/src.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../tutorial.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="tutdaytime5/src.html"><img src="../../next.png" alt="Next"></a>
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</div>
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</body>
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</html>
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