377 lines
9.6 KiB
HTML
377 lines
9.6 KiB
HTML
<!--
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- Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC")
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- Copyright (C) 2000, 2001, 2003 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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- PERFORMANCE OF THIS SOFTWARE.
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-->
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<!-- $Id: lwres_context.html,v 1.5.2.2.2.12 2006/06/29 13:02:31 marka Exp $ -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>lwres_context</title>
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<meta name="generator" content="DocBook XSL Stylesheets V1.70.1">
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</head>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
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<a name="id2482688"></a><div class="titlepage"></div>
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<div class="refnamediv">
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<h2>Name</h2>
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<p>lwres_context_create, lwres_context_destroy, lwres_context_nextserial, lwres_context_initserial, lwres_context_freemem, lwres_context_allocmem, lwres_context_sendrecv — lightweight resolver context management</p>
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</div>
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<div class="refsynopsisdiv">
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<h2>Synopsis</h2>
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<div class="funcsynopsis">
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<pre class="funcsynopsisinfo">#include <lwres/lwres.h></pre>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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lwres_result_t
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<b class="fsfunc">lwres_context_create</b>(</code></td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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lwres_result_t
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<b class="fsfunc">lwres_context_destroy</b>(</code></td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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void
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<b class="fsfunc">lwres_context_initserial</b>(</code></td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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lwres_uint32_t
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<b class="fsfunc">lwres_context_nextserial</b>(</code></td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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void
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<b class="fsfunc">lwres_context_freemem</b>(</code></td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
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<tr>
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<td><code class="funcdef">
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void
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<b class="fsfunc">lwres_context_allocmem</b>(</code></td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
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<tr>
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<td><code class="funcdef">
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void *
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<b class="fsfunc">lwres_context_sendrecv</b>(</code></td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>, </td>
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</tr>
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<tr>
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<td> </td>
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<td> </td>
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<td>
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<code>)</code>;</td>
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</tr>
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</table>
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</div>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2549540"></a><h2>DESCRIPTION</h2>
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<p>
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<code class="function">lwres_context_create()</code>
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creates a
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<span class="type">lwres_context_t</span>
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structure for use in lightweight resolver operations.
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It holds a socket and other data needed for communicating
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with a resolver daemon.
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The new
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<span class="type">lwres_context_t</span>
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is returned through
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<em class="parameter"><code>contextp</code></em>,
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a pointer to a
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<span class="type">lwres_context_t</span>
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pointer. This
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<span class="type">lwres_context_t</span>
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pointer must initially be NULL, and is modified
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to point to the newly created
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<span class="type">lwres_context_t</span>.
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</p>
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<p>
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When the lightweight resolver needs to perform dynamic memory
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allocation, it will call
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<em class="parameter"><code>malloc_function</code></em>
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to allocate memory and
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<em class="parameter"><code>free_function</code></em>
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to free it. If
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<em class="parameter"><code>malloc_function</code></em>
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and
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<em class="parameter"><code>free_function</code></em>
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are NULL, memory is allocated using
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.Xr malloc 3
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and
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<span class="citerefentry"><span class="refentrytitle">free</span>(3)</span>.
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It is not permitted to have a NULL
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<em class="parameter"><code>malloc_function</code></em>
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and a non-NULL
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<em class="parameter"><code>free_function</code></em>
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or vice versa.
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<em class="parameter"><code>arg</code></em>
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is passed as the first parameter to the memory
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allocation functions.
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If
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<em class="parameter"><code>malloc_function</code></em>
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and
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<em class="parameter"><code>free_function</code></em>
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are NULL,
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<em class="parameter"><code>arg</code></em>
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is unused and should be passed as NULL.
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</p>
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<p>
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Once memory for the structure has been allocated,
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it is initialized using
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<span class="citerefentry"><span class="refentrytitle">lwres_conf_init</span>(3)</span>
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and returned via
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<em class="parameter"><code>*contextp</code></em>.
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</p>
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<p>
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<code class="function">lwres_context_destroy()</code>
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destroys a
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<span class="type">lwres_context_t</span>,
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closing its socket.
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<em class="parameter"><code>contextp</code></em>
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is a pointer to a pointer to the context that is to be destroyed.
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The pointer will be set to NULL when the context has been destroyed.
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</p>
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<p>
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The context holds a serial number that is used to identify resolver
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request packets and associate responses with the corresponding requests.
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This serial number is controlled using
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<code class="function">lwres_context_initserial()</code>
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and
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<code class="function">lwres_context_nextserial()</code>.
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<code class="function">lwres_context_initserial()</code>
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sets the serial number for context
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<em class="parameter"><code>*ctx</code></em>
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to
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<em class="parameter"><code>serial</code></em>.
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<code class="function">lwres_context_nextserial()</code>
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increments the serial number and returns the previous value.
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</p>
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<p>
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Memory for a lightweight resolver context is allocated and freed using
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<code class="function">lwres_context_allocmem()</code>
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and
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<code class="function">lwres_context_freemem()</code>.
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These use whatever allocations were defined when the context was
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created with
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<code class="function">lwres_context_create()</code>.
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<code class="function">lwres_context_allocmem()</code>
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allocates
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<em class="parameter"><code>len</code></em>
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bytes of memory and if successful returns a pointer to the allocated
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storage.
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<code class="function">lwres_context_freemem()</code>
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frees
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<em class="parameter"><code>len</code></em>
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bytes of space starting at location
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<em class="parameter"><code>mem</code></em>.
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</p>
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<p>
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<code class="function">lwres_context_sendrecv()</code>
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performs I/O for the context
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<em class="parameter"><code>ctx</code></em>.
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Data are read and written from the context's socket.
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It writes data from
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<em class="parameter"><code>sendbase</code></em>
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— typically a lightweight resolver query packet —
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and waits for a reply which is copied to the receive buffer at
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<em class="parameter"><code>recvbase</code></em>.
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The number of bytes that were written to this receive buffer is
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returned in
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<em class="parameter"><code>*recvd_len</code></em>.
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</p>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2549789"></a><h2>RETURN VALUES</h2>
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<p>
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<code class="function">lwres_context_create()</code>
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returns
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<span class="errorcode">LWRES_R_NOMEMORY</span>
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if memory for the
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<span class="type">struct lwres_context</span>
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could not be allocated,
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<span class="errorcode">LWRES_R_SUCCESS</span>
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otherwise.
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</p>
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<p>
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Successful calls to the memory allocator
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<code class="function">lwres_context_allocmem()</code>
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return a pointer to the start of the allocated space.
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It returns NULL if memory could not be allocated.
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</p>
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<p>
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<span class="errorcode">LWRES_R_SUCCESS</span>
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is returned when
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<code class="function">lwres_context_sendrecv()</code>
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completes successfully.
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<span class="errorcode">LWRES_R_IOERROR</span>
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is returned if an I/O error occurs and
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<span class="errorcode">LWRES_R_TIMEOUT</span>
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is returned if
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<code class="function">lwres_context_sendrecv()</code>
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times out waiting for a response.
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</p>
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</div>
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<div class="refsect1" lang="en">
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<a name="id2549841"></a><h2>SEE ALSO</h2>
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<p>
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<span class="citerefentry"><span class="refentrytitle">lwres_conf_init</span>(3)</span>,
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<span class="citerefentry"><span class="refentrytitle">malloc</span>(3)</span>,
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<span class="citerefentry"><span class="refentrytitle">free</span>(3
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)</span>.
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</p>
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</div>
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</div></body>
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</html>
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