411 lines
11 KiB
HTML
411 lines
11 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>getpeername()--Retrieve Destination Address of Socket</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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<!-- 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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<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 --><!-- Edited by Kersten Feb 02 -->
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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>getpeername()--Retrieve Destination Address of Socket</h2>
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<div class="box" style="width: 70%;">
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<br>
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BSD 4.3 Syntax<br>
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<pre>
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#include <sys/types.h>
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#include <sys/socket.h>
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int getpeername(int <em>socket_descriptor</em>,
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struct sockaddr *<em>destination_address</em>,
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int *<em>address_length</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV1<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><br>
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<div class="box" style="width: 70%;">
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<br>
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<a href="_xopen_source.htm">UNIX 98 Compatible Syntax</a><br>
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<pre>
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#define _XOPEN_SOURCE 520
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#include <sys/socket.h>
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int getpeername(int <em>socket_descriptor</em>,
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struct sockaddr *<em>destination_address</em>,
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socklen_t *<em>address_length</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV1<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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<br>
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<p>The <em>getpeername()</em> function is used to retrieve the destination
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address to which the socket is connected.</p>
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<p> There are two versions of
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the API, as shown above. The base i5/OS API uses BSD 4.3 structures and
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syntax. The other uses syntax and structures compatible with the UNIX 98
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programming interface specifications. You can select the UNIX 98 compatible
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interface with the <a href="_xopen_source.htm">_XOPEN_SOURCE</a> macro.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>socket_descriptor</strong></dt>
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<dd>(Input) The descriptor of the socket for which the destination address is
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to be retrieved.<br>
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<br>
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</dd>
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<dt><strong>destination_address</strong></dt>
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<dd>(Output) A pointer to a buffer of type <strong>struct sockaddr</strong> in
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which the destination address to which the socket connects is stored. The
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structure <strong>sockaddr</strong> is defined in
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<strong><sys/socket.h></strong>.
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<p> The BSD 4.3 structure
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is:</p>
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<pre>
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struct sockaddr {
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u_short sa_family;
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char sa_data[14];
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};
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</pre>
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<p>The BSD 4.4/UNIX 98 compatible structure is:</p>
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<pre>
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typedef uchar sa_family_t;
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struct sockaddr {
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uint8_t sa_len;
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sa_family_t sa_family;
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char sa_data[14];
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};
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</pre>
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<p>The BSD 4.4 <em>sa_len</em> field is the length of the address. The <em>sa_family</em> field identifies
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the address family to which the address belongs, and <em>sa_data</em> is the
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address whose format is dependent on the address family.</p>
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<p> <strong>Note:</strong> See
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the usage notes about using different address families with
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<strong>sockaddr_storage</strong>.</p>
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</dd>
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<dt><strong>address_length</strong></dt>
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<dd>(I/O) This parameter is a value-result field. The caller passes a pointer
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to the length of the <em>destination_address</em> parameter. On return from the
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call, the <em>address_length</em> parameter contains the actual length of the
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destination address.</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>No authorization is required.</p>
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<br>
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<h3>Return Value</h3>
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<p><em>getpeername()</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>0 (successful)
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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 <em>getpeername()</em> fails, <em>errno</em> can be set to one of the
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following:</p>
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><em>[EBADF]</em></td>
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<td align="left" valign="top">Descriptor not valid.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EFAULT]</em></td>
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<td align="left" valign="top">Bad address.
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<p>The system detected an address which was not valid while attempting to
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access the <em>destination_address</em> or <em>address_length</em>
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parameters.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EINVAL]</em></td>
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<td align="left" valign="top">Parameter not valid.
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<p>The <em>address_length</em> parameter specifies a negative value.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EIO]</em></td>
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<td align="left" valign="top">Input/output error.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOBUFS]</em></td>
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<td align="left" valign="top">There is not enough buffer space for the
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requested operation.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOTCONN]</em></td>
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<td align="left" valign="top">Requested operation requires a connection.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOTSOCK]</em></td>
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<td align="left" valign="top">The specified descriptor does not reference a
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socket.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNKNOWN]</em></td>
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<td align="left" valign="top">Unknown system state.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNATCH]</em></td>
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<td align="left" valign="top">The protocol required to support the specified
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address family is not available at this time.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Messages</h3>
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<table width="100%" cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top">Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td width="15%" valign="top">CPE3418 E</td>
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<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF9872 E</td>
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<td align="left" valign="top">Program or service program &1 in library
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&2 ended. Reason code &3.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPFA081 E</td>
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<td align="left" valign="top">Unable to set return value or error code.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Usage Notes</h3>
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<ol>
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<li><em>getpeername()</em> fails if issued against a socket for which a
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<em>connect()</em> has not been done.<br>
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<br>
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</li>
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<li>For connection oriented sockets, <em>getpeername()</em> fails if both the
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write side and the read side have been closed through the use of one or more
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previous <em>shutdown()</em> functions.<br>
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<br>
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</li>
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<li>If the length of the address to be returned exceeds the length of the
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<em>destination_address</em> parameter, the returned address is truncated.<br>
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<br>
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</li>
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<li>The structure
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<strong>sockaddr</strong> is a generic structure used for any address family
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but it is only 16 bytes long. The actual address returned for some address
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families may be much larger. You should declare storage for the address with
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the structure <strong>sockaddr_storage</strong>. This structure is large enough
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and aligned for any protocol-specific structure. It may then be cast as
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<strong>sockaddr</strong> structure for use on the APIs. The <em>ss_family</em>
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field of the <strong>sockaddr_storage</strong> will always align with the
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family field of any protocol-specific structure.
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<p>The BSD 4.3 structure is:</p>
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<pre>
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#define _SS_MAXSIZE 304
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#define _SS_ALIGNSIZE (sizeof (char*))
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#define _SS_PAD1SIZE (_SS_ALIGNSIZE - sizeof(sa_family_t))
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#define _SS_PAD2SIZE (_SS_MAXSIZE - (sizeof(sa_family_t)+
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_SS_PAD1SIZE + _SS_ALIGNSIZE))
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struct sockaddr_storage {
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sa_family_t ss_family;
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char _ss_pad1[_SS_PAD1SIZE];
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char* _ss_align;
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char _ss_pad2[_SS_PAD2SIZE];
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};
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</pre>
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<p>The BSD 4.4/UNIX 98 compatible structure is:</p>
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<pre>
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#define _SS_MAXSIZE 304
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#define _SS_ALIGNSIZE (sizeof (char*))
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#define _SS_PAD1SIZE (_SS_ALIGNSIZE - (sizeof(uint8_t) + sizeof(sa_family_t)))
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#define _SS_PAD2SIZE (_SS_MAXSIZE - (sizeof(uint8_t) + sizeof(sa_family_t)+
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_SS_PAD1SIZE + _SS_ALIGNSIZE))
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struct sockaddr_storage {
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uint8_t ss_len;
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sa_family_t ss_family;
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char _ss_pad1[_SS_PAD1SIZE];
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char* _ss_align;
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char _ss_pad2[_SS_PAD2SIZE];
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};
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</pre>
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</li>
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<li>When used with an address family of <samp>AF_UNIX</samp> or
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<samp>AF_UNIX_CCSID</samp>, <em>getpeername()</em> always returns the same path
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name that was specified on the <em>bind()</em> in the peer program. If the path
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name specified by the peer program was not a fully qualified path name, the
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output of <em>getpeername()</em> is meaningful only if your program knows what
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current directory was in effect for the peer program when it issued the
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<em>bind()</em>. For <samp>AF_UNIX</samp>, the path name is returned in the
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default coded character set identifier (CCSID) currently in effect for the job.
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For <samp>AF_UNIX_CCSID</samp>, the output structure sockaddr_unc defines the
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format and CCSID of the returned path name.<br>
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<br>
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</li>
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<li>When you develop in C-based
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languages and an application is compiled with the _XOPEN_SOURCE macro defined
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to the value 520 or greater, the <em>getpeername()</em> API is mapped to
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<em>qso_getpeername98()</em>.</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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||
|
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|
||
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<ul>
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||
|
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<li><a href=
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||
|
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"_xopen_source.htm">_XOPEN_SOURCE</a>--Using _XOPEN_SOURCE for the UNIX 98
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||
|
|
compatible interface<br>
|
||
|
|
<br>
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||
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</li>
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<li><a href="accept.htm">accept()</a>--Wait for Connection Request and Make
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Connection<br>
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<br>
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</li>
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||
|
|
|
||
|
|
<li><a href="bind.htm">bind()</a>--Set Local Address for Socket<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="connec.htm">connect()</a>--Establish Connection or Destination
|
||
|
|
Address<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="gsockn.htm">getsockname()</a>--Retrieve Local Address of
|
||
|
|
Socket</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
API introduced: V3R1
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<center>
|
||
|
|
<table cellpadding="2" cellspacing="2">
|
||
|
|
<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></center>
|
||
|
|
</body>
|
||
|
|
</html>
|
||
|
|
|