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+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
+<!--
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+ -
+ - This Source Code Form is subject to the terms of the Mozilla Public
+ - License, v. 2.0. If a copy of the MPL was not distributed with this
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+<html lang="en">
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+<title>lwres_context</title>
+<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
+</head>
+<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry">
+<a name="id-1"></a><div class="titlepage"></div>
+
+
+
+
+
+
+
+ <div class="refnamediv">
+<h2>Name</h2>
+<p>
+ lwres_context_create,
+ lwres_context_destroy,
+ lwres_context_nextserial,
+ lwres_context_initserial,
+ lwres_context_freemem,
+ lwres_context_allocmem,
+ lwres_context_sendrecv
+ &#8212; lightweight resolver context management
+ </p>
+</div>
+ <div class="refsynopsisdiv">
+<h2>Synopsis</h2>
+ <div class="funcsynopsis">
+<pre class="funcsynopsisinfo">#include &lt;lwres/lwres.h&gt;</pre>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
+<tr>
+<td><code class="funcdef">
+lwres_result_t
+<b class="fsfunc">lwres_context_create</b>(</code></td>
+<td>lwres_context_t **<var class="pdparam">contextp</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>void *<var class="pdparam">arg</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>lwres_malloc_t <var class="pdparam">malloc_function</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>lwres_free_t <var class="pdparam">free_function</var><code>)</code>;</td>
+</tr>
+</table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr>
+<td><code class="funcdef">
+lwres_result_t
+<b class="fsfunc">lwres_context_destroy</b>(</code></td>
+<td>lwres_context_t **<var class="pdparam">contextp</var><code>)</code>;</td>
+</tr></table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
+<tr>
+<td><code class="funcdef">
+void
+<b class="fsfunc">lwres_context_initserial</b>(</code></td>
+<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>uint32_t <var class="pdparam">serial</var><code>)</code>;</td>
+</tr>
+</table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr>
+<td><code class="funcdef">
+uint32_t
+<b class="fsfunc">lwres_context_nextserial</b>(</code></td>
+<td>lwres_context_t *<var class="pdparam">ctx</var><code>)</code>;</td>
+</tr></table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
+<tr>
+<td><code class="funcdef">
+void
+<b class="fsfunc">lwres_context_freemem</b>(</code></td>
+<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>void *<var class="pdparam">mem</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>size_t <var class="pdparam">len</var><code>)</code>;</td>
+</tr>
+</table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
+<tr>
+<td><code class="funcdef">
+void
+<b class="fsfunc">lwres_context_allocmem</b>(</code></td>
+<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>size_t <var class="pdparam">len</var><code>)</code>;</td>
+</tr>
+</table>
+<div class="funcprototype-spacer"> </div>
+<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
+<tr>
+<td><code class="funcdef">
+void *
+<b class="fsfunc">lwres_context_sendrecv</b>(</code></td>
+<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>void *<var class="pdparam">sendbase</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>int <var class="pdparam">sendlen</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>void *<var class="pdparam">recvbase</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>int <var class="pdparam">recvlen</var>, </td>
+</tr>
+<tr>
+<td> </td>
+<td>int *<var class="pdparam">recvd_len</var><code>)</code>;</td>
+</tr>
+</table>
+<div class="funcprototype-spacer"> </div>
+</div>
+ </div>
+ <div class="refsection">
+<a name="id-1.7"></a><h2>DESCRIPTION</h2>
+
+
+ <p><code class="function">lwres_context_create()</code>
+ creates a <span class="type">lwres_context_t</span> structure for use in
+ lightweight resolver operations. It holds a socket and other
+ data needed for communicating with a resolver daemon. The new
+ <span class="type">lwres_context_t</span> is returned through
+ <em class="parameter"><code>contextp</code></em>, a pointer to a
+ <span class="type">lwres_context_t</span> pointer. This
+ <span class="type">lwres_context_t</span> pointer must initially be NULL, and
+ is modified to point to the newly created
+ <span class="type">lwres_context_t</span>.
+ </p>
+ <p>
+ When the lightweight resolver needs to perform dynamic memory
+ allocation, it will call
+ <em class="parameter"><code>malloc_function</code></em>
+ to allocate memory and
+ <em class="parameter"><code>free_function</code></em>
+ to free it. If
+ <em class="parameter"><code>malloc_function</code></em>
+ and
+ <em class="parameter"><code>free_function</code></em>
+ are NULL, memory is allocated using
+ <span class="citerefentry">
+ <span class="refentrytitle">malloc</span>(3)
+ </span>.
+ and
+ <span class="citerefentry">
+ <span class="refentrytitle">free</span>(3)
+ </span>.
+
+ It is not permitted to have a NULL
+ <em class="parameter"><code>malloc_function</code></em> and a non-NULL
+ <em class="parameter"><code>free_function</code></em> or vice versa.
+ <em class="parameter"><code>arg</code></em> is passed as the first parameter to
+ the memory allocation functions. If
+ <em class="parameter"><code>malloc_function</code></em> and
+ <em class="parameter"><code>free_function</code></em> are NULL,
+ <em class="parameter"><code>arg</code></em> is unused and should be passed as
+ NULL.
+ </p>
+
+ <p>
+ Once memory for the structure has been allocated,
+ it is initialized using
+ <span class="citerefentry">
+ <span class="refentrytitle">lwres_conf_init</span>(3)
+ </span>
+ and returned via <em class="parameter"><code>*contextp</code></em>.
+ </p>
+
+ <p><code class="function">lwres_context_destroy()</code>
+ destroys a <span class="type">lwres_context_t</span>, closing its socket.
+ <em class="parameter"><code>contextp</code></em> is a pointer to a pointer to the
+ context that is to be destroyed. The pointer will be set to
+ NULL when the context has been destroyed.
+ </p>
+
+ <p>
+ The context holds a serial number that is used to identify
+ resolver request packets and associate responses with the
+ corresponding requests. This serial number is controlled using
+ <code class="function">lwres_context_initserial()</code> and
+ <code class="function">lwres_context_nextserial()</code>.
+ <code class="function">lwres_context_initserial()</code> sets the serial
+ number for context <em class="parameter"><code>*ctx</code></em> to
+ <em class="parameter"><code>serial</code></em>.
+ <code class="function">lwres_context_nextserial()</code> increments the
+ serial number and returns the previous value.
+ </p>
+
+ <p>
+ Memory for a lightweight resolver context is allocated and freed
+ using <code class="function">lwres_context_allocmem()</code> and
+ <code class="function">lwres_context_freemem()</code>. These use
+ whatever allocations were defined when the context was created
+ with <code class="function">lwres_context_create()</code>.
+ <code class="function">lwres_context_allocmem()</code> allocates
+ <em class="parameter"><code>len</code></em> bytes of memory and if successful
+ returns a pointer to the allocated storage.
+ <code class="function">lwres_context_freemem()</code> frees
+ <em class="parameter"><code>len</code></em> bytes of space starting at location
+ <em class="parameter"><code>mem</code></em>.
+ </p>
+
+ <p><code class="function">lwres_context_sendrecv()</code>
+ performs I/O for the context <em class="parameter"><code>ctx</code></em>. Data
+ are read and written from the context's socket. It writes data
+ from <em class="parameter"><code>sendbase</code></em> &#8212; typically a
+ lightweight resolver query packet &#8212; and waits for a reply
+ which is copied to the receive buffer at
+ <em class="parameter"><code>recvbase</code></em>. The number of bytes that were
+ written to this receive buffer is returned in
+ <em class="parameter"><code>*recvd_len</code></em>.
+ </p>
+ </div>
+
+ <div class="refsection">
+<a name="id-1.8"></a><h2>RETURN VALUES</h2>
+
+
+ <p><code class="function">lwres_context_create()</code>
+ returns <span class="errorcode">LWRES_R_NOMEMORY</span> if memory for
+ the <span class="type">struct lwres_context</span> could not be allocated,
+ <span class="errorcode">LWRES_R_SUCCESS</span> otherwise.
+ </p>
+ <p>
+ Successful calls to the memory allocator
+ <code class="function">lwres_context_allocmem()</code>
+ return a pointer to the start of the allocated space.
+ It returns NULL if memory could not be allocated.
+ </p>
+ <p><span class="errorcode">LWRES_R_SUCCESS</span>
+ is returned when
+ <code class="function">lwres_context_sendrecv()</code>
+ completes successfully.
+ <span class="errorcode">LWRES_R_IOERROR</span>
+ is returned if an I/O error occurs and
+ <span class="errorcode">LWRES_R_TIMEOUT</span>
+ is returned if
+ <code class="function">lwres_context_sendrecv()</code>
+ times out waiting for a response.
+ </p>
+ </div>
+ <div class="refsection">
+<a name="id-1.9"></a><h2>SEE ALSO</h2>
+
+ <p><span class="citerefentry">
+ <span class="refentrytitle">lwres_conf_init</span>(3)
+ </span>,
+
+ <span class="citerefentry">
+ <span class="refentrytitle">malloc</span>(3)
+ </span>,
+
+ <span class="citerefentry">
+ <span class="refentrytitle">free</span>(3)
+ </span>.
+ </p>
+ </div>
+</div></body>
+</html>