00b67f09dd
Also known as ISC bind. This import adds utilities such as host(1), dig(1), and nslookup(1), as well as many other tools and libraries. Change-Id: I035ca46e64f1965d57019e773f4ff0ef035e4aa3
296 lines
11 KiB
HTML
296 lines
11 KiB
HTML
<!--
|
||
- Copyright (C) 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc. ("ISC")
|
||
- Copyright (C) 2000, 2001, 2003 Internet Software Consortium.
|
||
-
|
||
- Permission to use, copy, modify, and/or distribute this software for any
|
||
- purpose with or without fee is hereby granted, provided that the above
|
||
- copyright notice and this permission notice appear in all copies.
|
||
-
|
||
- THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
|
||
- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
|
||
- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
|
||
- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
|
||
- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
|
||
- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
|
||
- PERFORMANCE OF THIS SOFTWARE.
|
||
-->
|
||
<!-- Id -->
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||
<title>lwres_context</title>
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
|
||
</head>
|
||
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
|
||
<a name="id2476275"></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 — lightweight resolver context management</p>
|
||
</div>
|
||
<div class="refsynopsisdiv">
|
||
<h2>Synopsis</h2>
|
||
<div class="funcsynopsis">
|
||
<pre class="funcsynopsisinfo">#include <lwres/lwres.h></pre>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
|
||
<tr>
|
||
<td><code class="funcdef">
|
||
lwres_result_t
|
||
<b class="fsfunc">lwres_context_create</b>(</code></td>
|
||
<td>lwres_context_t ** </td>
|
||
<td>
|
||
<var class="pdparam">contextp</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>void * </td>
|
||
<td>
|
||
<var class="pdparam">arg</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>lwres_malloc_t </td>
|
||
<td>
|
||
<var class="pdparam">malloc_function</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>lwres_free_t </td>
|
||
<td>
|
||
<var class="pdparam">free_function</var><code>)</code>;</td>
|
||
</tr>
|
||
</table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr>
|
||
<td><code class="funcdef">
|
||
lwres_result_t
|
||
<b class="fsfunc">lwres_context_destroy</b>(</code></td>
|
||
<td>lwres_context_t ** </td>
|
||
<td>
|
||
<var class="pdparam">contextp</var><code>)</code>;</td>
|
||
</tr></table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
|
||
<tr>
|
||
<td><code class="funcdef">
|
||
void
|
||
<b class="fsfunc">lwres_context_initserial</b>(</code></td>
|
||
<td>lwres_context_t * </td>
|
||
<td>
|
||
<var class="pdparam">ctx</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>lwres_uint32_t </td>
|
||
<td>
|
||
<var class="pdparam">serial</var><code>)</code>;</td>
|
||
</tr>
|
||
</table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"><tr>
|
||
<td><code class="funcdef">
|
||
lwres_uint32_t
|
||
<b class="fsfunc">lwres_context_nextserial</b>(</code></td>
|
||
<td>lwres_context_t * </td>
|
||
<td>
|
||
<var class="pdparam">ctx</var><code>)</code>;</td>
|
||
</tr></table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
|
||
<tr>
|
||
<td><code class="funcdef">
|
||
void
|
||
<b class="fsfunc">lwres_context_freemem</b>(</code></td>
|
||
<td>lwres_context_t * </td>
|
||
<td>
|
||
<var class="pdparam">ctx</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>void * </td>
|
||
<td>
|
||
<var class="pdparam">mem</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>size_t </td>
|
||
<td>
|
||
<var class="pdparam">len</var><code>)</code>;</td>
|
||
</tr>
|
||
</table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
|
||
<tr>
|
||
<td><code class="funcdef">
|
||
void
|
||
<b class="fsfunc">lwres_context_allocmem</b>(</code></td>
|
||
<td>lwres_context_t * </td>
|
||
<td>
|
||
<var class="pdparam">ctx</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>size_t </td>
|
||
<td>
|
||
<var class="pdparam">len</var><code>)</code>;</td>
|
||
</tr>
|
||
</table>
|
||
<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
|
||
<tr>
|
||
<td><code class="funcdef">
|
||
void *
|
||
<b class="fsfunc">lwres_context_sendrecv</b>(</code></td>
|
||
<td>lwres_context_t * </td>
|
||
<td>
|
||
<var class="pdparam">ctx</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>void * </td>
|
||
<td>
|
||
<var class="pdparam">sendbase</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>int </td>
|
||
<td>
|
||
<var class="pdparam">sendlen</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>void * </td>
|
||
<td>
|
||
<var class="pdparam">recvbase</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>int </td>
|
||
<td>
|
||
<var class="pdparam">recvlen</var>, </td>
|
||
</tr>
|
||
<tr>
|
||
<td> </td>
|
||
<td>int * </td>
|
||
<td>
|
||
<var class="pdparam">recvd_len</var><code>)</code>;</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</div>
|
||
<div class="refsect1" lang="en">
|
||
<a name="id2543541"></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> — typically a
|
||
lightweight resolver query packet — 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="refsect1" lang="en">
|
||
<a name="id2543729"></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="refsect1" lang="en">
|
||
<a name="id2543779"></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>
|