<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation"> <title>dn_comp()--Compress Domain Name</title> <!-- Begin Header Records ========================================== --> <!-- All rights reserved. Licensed Materials Property of IBM --> <!-- US Government Users Restricted Rights --> <!-- Use, duplication or disclosure restricted by --> <!-- GSA ADP Schedule Contract with IBM Corp. --> <!-- Change History: --> <!-- YYMMDD USERID Change description --> <!-- Unix8 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 --> <!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 --> <!-- Edited by Kersten Feb 02 --> <!-- End Header Records --> <link rel="stylesheet" type="text/css" href="../rzahg/ic.css"> </head> <body> <!-- Java sync-link --> <script type="text/javascript" language="Javascript" src="../rzahg/synch.js"> </script> <a name="Top_Of_Page"></a> <h2>dn_comp()--Compress Domain Name</h2> <div class="box" style="width: 80%;"> <br> Syntax <pre> #include <sys/types.h> #include <netinet/in.h> #include <arpa/nameser.h> #include <resolv.h> int dn_comp(unsigned char *<em>expanded_domain_name</em>, unsigned char *<em>compressed_domain_name</em>, int <em>answer_buffer_length</em>, unsigned char **<em>domain_name_pointers</em>, unsigned char **<em>last_domain_name</em>) </pre> <br> Service Program Name: QSOSRV2<br> <!-- iddvc RMBR --> <br> Default Public Authority: *USE<br> <!-- iddvc RMBR --> <br> Threadsafe: Yes<br> <!-- iddvc RMBR --> <br> </div> <p>The <em>dn_comp()</em> function is used to compress an expanded domain name.</p> <br> <!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. --> <!-- Instead, use the commented out coding below to indicate NONE. --> <h3>Authorities and Locks</h3> <!-- Use this if there are no authorities and locks. --> <p>None.</p> <br> <h3>Parameters</h3> <dl> <dt><strong>expanded_domain_name</strong></dt> <dd>(Input) The pointer to the expanded domain name.<br> <br> </dd> <dt><strong>compressed_domain_name</strong></dt> <dd>(Output) The pointer to where the compressed domain name will be stored.<br> <br> </dd> <dt><strong>answer_buffer_length</strong></dt> <dd>(Input) The size of the <em>compressed_domain_name</em> buffer.<br> <br> </dd> <dt><strong>domain_name_pointers</strong></dt> <dd>(Input) The pointer to an array of pointers to previously compressed domain names in the current message.<br> <br> </dd> <dt><strong>last_domain_name</strong></dt> <dd>(Input) The pointer to the end of the array specified by <em>domain_name_pointers</em>.</dd> </dl> <br> <h3>Return Value</h3> <p><em>dn_comp()</em> returns an integer. Possible values are: </p> <ul> <li>-1 (unsuccessful)<br> <br> </li> <li>n (successful), where n is the size of the compressed domain name. <p><em>dn_comp()</em> compresses the domain name pointed to by <em>expanded_domain_name</em>. The result is placed in <em>compressed_domain_name</em>.</p> </li> </ul> <br> <h3>Error Conditions</h3> <p>When the <em>dn_comp()</em> function fails, it does not set specific <em>errno</em> or <em>h_errno</em> values. An error occurs under the following conditions:</p> <ul> <li>NULL pointer(s) passed to the function.<br><br></li> <li>Invalid pointer(s) passed to the function.<br><br></li> <li><em>Compressed_domain_name</em> too small for the compressed domain name.</li> </ul> <br> <h3>Usage Notes</h3> <ol> <li><em>domain_name_pointers</em>[0] points to the beginning of the DNS packet. The list of pointers ends with a NULL pointer. After <em>domain_name_pointers</em>[0] is initialized to the beginning of the packet and <em>domain_name_pointers</em>[1] is initialized to NULL, <em>dn_comp()</em> updates the list each time it is called.<br> <br> </li> <li><em>dn_comp()</em> calls <em>dn_find()</em> to attempt to locate the different parts of the domain name being compressed.<br> <br> </li> <li><em>dn_comp()</em> expects EBCDIC data as input. The output from <em>dn_comp()</em> is also EBCDIC.</li> </ol> <br> <h3>Related Information</h3> <ul> <li><a href="dnexp.htm">dn_expand()</a>--Expand Domain Name<br> <br> </li> <li><a href="dnfind.htm">dn_find()-</a>-Search for Compressed Domain Name<br> <br> </li> <li><a href="dnsknm.htm">dn_skipname()</a>--Skip over Compressed Domain Name</li> </ul> <br> <hr> API introduced: V3R1 <hr> <table cellpadding="2" cellspacing="2" align="center"> <tr align="center"> <td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href= "unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a> </td> </tr> </table> </body> </html>