159 lines
5.2 KiB
HTML
159 lines
5.2 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html><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>if_nameindex--Return All Interface Names and Indexes API</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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<!-- Created for V5R4 by Tim Mullenbach -->
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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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<!-- End Header Records -->
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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><img src="delta.gif" ALT="Start of change">if_nameindex()--Return All Interface Names and Indexes</h2>
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<div class="box" style="width: 80%;">
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<br>
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<br>
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Syntax
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<pre>
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#include <net/if.h>
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struct if_nameindex *if_nameindex(void);
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</pre>
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Service Program Name: QSOSRV2
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<br>
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Default Public Authority: *USE
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<br>
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Threadsafe: Yes<br><br>
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</div>
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<p>The <strong><em>if_nameindex()</em></strong> function returns an array
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of <em>if_nameindex</em> structures, one structure per interface.
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The end of the array of structures is indicated by a structure with an
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<em>if_index</em> of 0 and an <em>if_name</em> of NULL.
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</p>
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<br>
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<h3><a name="Header_2">Parameters</a></h3>
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<p>None.</p>
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<br>
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<h3><a name="Header_3">Authorities</a></h3>
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<p>
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No authorization is required.</p>
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<br>
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<h3><a name="Header_4">Return Value</a></h3>
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<p><strong>if_nameindex()</strong> returns a pointer to an array of <em>if_nameindex</em> structures.
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Possible values are:</p>
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<ul>
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<li>Pointer to dynamically allocated memory for the array of <em>if_nameindex</em> structures.
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(successful). Note: the <strong><em>if_freenameindex()</em></strong> API should be used to
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free the array once it is no longer needed.</li>
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<li>NULL (unsuccessful)</li>
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</ul>
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<p>The structure <strong>struct if_nameindex</strong> is defined in
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<strong><net/if.h></strong>.</p>
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<pre>
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struct if_nameindex {
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unsigned int if_index; /* 1, 2, ... */
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char *if_name; /* null terminated line name */
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};
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</pre>
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<br>
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<h3><a name="Header_5">Error Conditions</a></h3>
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<p>When <em>if_nameindex()</em> fails, <em>errno</em> can be set to one of the following:</p>
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<dl compact>
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<dt><em>[ENXIO]</em></dt>
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<dd>No interfaces names and indexes exist.</dd>
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<dt><em>[ENOMEM]</em></dt>
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<dd>No memory available for the <em>if_nameindex</em> array.</dd>
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</dl>
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<br>
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<h3>Usage Notes</h3>
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<ol>
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<li>The interface (line description) names stored at <em>if_name</em> will be
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returned in the default coded character set identifier (CCSID) currently in
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effect for the job.</li>
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<li>It is important to note that the term "Interface" refers to the name on a line
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description (i.e. a physical interface) for this API. Other parts of the
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operating system, when refering to "Interface," mean an IP address.</li>
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<li>The array returned will contain only interfaces (line descriptions) that are
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IPv6 capable. The array may also contain a *LOOPBACK entry.</li>
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</ol>
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<br>
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<h3><a name="Header_8">Related Information</a></h3>
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<ul>
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<li><a href="gsocko.htm">"getsockopt()</a>--Retrieve Information about Socket Options</li>
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<li><a href="if_freenameindex.htm">if_freenameindex()</a>--Free Memory Allocated by
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if_nameindex()</li>
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<li><a href="if_indextoname.htm">if_indextoname()</a>--Map an Interface Index to its
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Corresponding Name</li>
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<li><a href="if_nametoindex.htm">if_nametoindex()</a>--Map an Interface Name to its
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Corresponding Index</li>
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<li><a href="ssocko.htm">setsockopt()</a>--Set Socket Options</li>
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</ul>
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<br>
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<h3><a name="Header_9">Example</a></h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<p>The following example shows how <strong>if_nameindex()</strong> is used:</p>
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<pre>
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#include <net/if.h>
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#include <sys/types.h>
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#include <errno.h>
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void main()
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{
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struct if_nameindex *interfaceArray = NULL;
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<strong>interfaceArray = if_nameindex(void); /* retrieve the current interfaces */</strong>
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if (interfaceArray != NULL)
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{
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...
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if_freenameindex(interfaceArray); /* free the dynamic memory */
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interfaceArray = NULL; /* prevent use after free */
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}
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else
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{
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printf("if_nameindex() failed with errno = %d %s \n",
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errno,strerror(errno));
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return;
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}
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...
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}</pre>
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<img src="deltaend.gif" ALT="End of change">
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<br>
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<hr>
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API introduced: V5R4
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<hr>
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<center>
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<table cellpadding=2 cellspacing=2>
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<tr align=center><td valign=middle align=center>
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<a href="#Top_Of_Page">Top</a> |
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<a href="unix.htm">UNIX-Type APIs</a> |
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<a href="aplist.htm">APIs by category</a>
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</td></tr>
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</table>
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</center>
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</body>
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</html>
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