193 lines
5.0 KiB
HTML
193 lines
5.0 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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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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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>dn_comp()--Compress Domain Name</title>
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<!-- Begin Header Records ========================================== -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Unix8 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>dn_comp()--Compress Domain Name</h2>
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<div class="box" style="width: 80%;">
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<br>
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Syntax
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<pre>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <resolv.h>
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int dn_comp(unsigned char *<em>expanded_domain_name</em>,
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unsigned char *<em>compressed_domain_name</em>,
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int <em>answer_buffer_length</em>,
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unsigned char **<em>domain_name_pointers</em>,
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unsigned char **<em>last_domain_name</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV2<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <em>dn_comp()</em> function is used to compress an expanded domain
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name.</p>
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<br>
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<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
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<!-- Instead, use the commented out coding below to indicate NONE. -->
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<h3>Authorities and Locks</h3>
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<!-- Use this if there are no authorities and locks. -->
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>expanded_domain_name</strong></dt>
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<dd>(Input) The pointer to the expanded domain name.<br>
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<br>
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</dd>
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<dt><strong>compressed_domain_name</strong></dt>
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<dd>(Output) The pointer to where the compressed domain name will be
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stored.<br>
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<br>
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</dd>
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<dt><strong>answer_buffer_length</strong></dt>
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<dd>(Input) The size of the <em>compressed_domain_name</em> buffer.<br>
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<br>
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</dd>
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<dt><strong>domain_name_pointers</strong></dt>
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<dd>(Input) The pointer to an array of pointers to previously compressed domain
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names in the current message.<br>
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<br>
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</dd>
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<dt><strong>last_domain_name</strong></dt>
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<dd>(Input) The pointer to the end of the array specified by
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<em>domain_name_pointers</em>.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<p><em>dn_comp()</em> returns an integer. Possible values are: </p>
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<ul>
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<li>-1 (unsuccessful)<br>
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<br>
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</li>
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<li>n (successful), where n is the size of the compressed domain name.
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<p><em>dn_comp()</em> compresses the domain name pointed to by
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<em>expanded_domain_name</em>. The result is placed in
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<em>compressed_domain_name</em>.</p>
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</li>
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</ul>
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<br>
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<h3>Error Conditions</h3>
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<p>When the <em>dn_comp()</em> function fails, it does not set specific
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<em>errno</em> or <em>h_errno</em> values. An error occurs under the following
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conditions:</p>
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<ul>
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<li>NULL pointer(s) passed to the function.<br><br></li>
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<li>Invalid pointer(s) passed to the function.<br><br></li>
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<li><em>Compressed_domain_name</em> too small for the compressed domain
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name.</li>
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</ul>
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<br>
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<h3>Usage Notes</h3>
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<ol>
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<li><em>domain_name_pointers</em>[0] points to the beginning of the DNS packet.
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The list of pointers ends with a NULL pointer. After
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<em>domain_name_pointers</em>[0] is initialized to the beginning of the packet
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and <em>domain_name_pointers</em>[1] is initialized to NULL, <em>dn_comp()</em>
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updates the list each time it is called.<br>
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<br>
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</li>
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<li><em>dn_comp()</em> calls <em>dn_find()</em> to attempt to locate the
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different parts of the domain name being compressed.<br>
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<br>
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</li>
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<li><em>dn_comp()</em> expects EBCDIC data as input. The output from
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<em>dn_comp()</em> is also EBCDIC.</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li><a href="dnexp.htm">dn_expand()</a>--Expand Domain Name<br>
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<br>
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</li>
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<li><a href="dnfind.htm">dn_find()-</a>-Search for Compressed Domain Name<br>
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<br>
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</li>
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<li><a href="dnsknm.htm">dn_skipname()</a>--Skip over Compressed Domain
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Name</li>
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</ul>
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<br>
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<hr>
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API introduced: V3R1
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<hr>
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<table cellpadding="2" cellspacing="2" align="center">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a> </td>
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</tr>
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</table>
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</body>
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</html>
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