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<!-- $Id: lwres_gabn.html,v 1.6.2.1.4.7 2005/07/18 02:36:52 marka Exp $ -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>lwres_gabn</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.68.1">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="id2456972"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>lwres_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free — lightweight resolver getaddrbyname message handling</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_gabnrequest_render</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<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_gabnresponse_render</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<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_gabnrequest_parse</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<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_gabnresponse_parse</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<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_gabnresponse_free</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<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_gabnrequest_free</b>(</code></td>
<td> </td>
<td>, </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td>
<code>)</code>;</td>
</tr>
</table>
</div>
</div>
<div class="refsect1" lang="en">
<a name="id2514646"></a><h2>DESCRIPTION</h2>
<p>
These are low-level routines for creating and parsing
lightweight resolver name-to-address lookup request and
response messages.
</p>
<p>
There are four main functions for the getaddrbyname opcode.
One render function converts a getaddrbyname request structure —
<span class="type">lwres_gabnrequest_t</span> —
to the lighweight resolver's canonical format.
It is complemented by a parse function that converts a packet in this
canonical format to a getaddrbyname request structure.
Another render function converts the getaddrbyname response structure —
<span class="type">lwres_gabnresponse_t</span> —
to the canonical format.
This is complemented by a parse function which converts a packet in
canonical format to a getaddrbyname response structure.
</p>
<p>
These structures are defined in
<code class="filename"><lwres/lwres.h></code>.
They are shown below.
</p>
<pre class="programlisting">
#define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint32_t addrtypes;
lwres_uint16_t namelen;
char *name;
} lwres_gabnrequest_t;
typedef struct {
lwres_uint32_t flags;
lwres_uint16_t naliases;
lwres_uint16_t naddrs;
char *realname;
char **aliases;
lwres_uint16_t realnamelen;
lwres_uint16_t *aliaslen;
lwres_addrlist_t addrs;
void *base;
size_t baselen;
} lwres_gabnresponse_t;
</pre>
<p>
</p>
<p>
<code class="function">lwres_gabnrequest_render()</code>
uses resolver context
<em class="parameter"><code>ctx</code></em>
to convert getaddrbyname request structure
<em class="parameter"><code>req</code></em>
to canonical format.
The packet header structure
<em class="parameter"><code>pkt</code></em>
is initialised and transferred to
buffer
<em class="parameter"><code>b</code></em>.
The contents of
<em class="parameter"><code>*req</code></em>
are then appended to the buffer in canonical format.
<code class="function">lwres_gabnresponse_render()</code>
performs the same task, except it converts a getaddrbyname response structure
<span class="type">lwres_gabnresponse_t</span>
to the lightweight resolver's canonical format.
</p>
<p>
<code class="function">lwres_gabnrequest_parse()</code>
uses context
<em class="parameter"><code>ctx</code></em>
to convert the contents of packet
<em class="parameter"><code>pkt</code></em>
to a
<span class="type">lwres_gabnrequest_t</span>
structure.
Buffer
<em class="parameter"><code>b</code></em>
provides space to be used for storing this structure.
When the function succeeds, the resulting
<span class="type">lwres_gabnrequest_t</span>
is made available through
<em class="parameter"><code>*structp</code></em>.
<code class="function">lwres_gabnresponse_parse()</code>
offers the same semantics as
<code class="function">lwres_gabnrequest_parse()</code>
except it yields a
<span class="type">lwres_gabnresponse_t</span>
structure.
</p>
<p>
<code class="function">lwres_gabnresponse_free()</code>
and
<code class="function">lwres_gabnrequest_free()</code>
release the memory in resolver context
<em class="parameter"><code>ctx</code></em>
that was allocated to the
<span class="type">lwres_gabnresponse_t</span>
or
<span class="type">lwres_gabnrequest_t</span>
structures referenced via
<em class="parameter"><code>structp</code></em>.
Any memory associated with ancillary buffers and strings for those
structures is also discarded.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2514906"></a><h2>RETURN VALUES</h2>
<p>
The getaddrbyname opcode functions
<code class="function">lwres_gabnrequest_render()</code>,
<code class="function">lwres_gabnresponse_render()</code>
<code class="function">lwres_gabnrequest_parse()</code>
and
<code class="function">lwres_gabnresponse_parse()</code>
all return
<span class="errorcode">LWRES_R_SUCCESS</span>
on success.
They return
<span class="errorcode">LWRES_R_NOMEMORY</span>
if memory allocation fails.
<span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
is returned if the available space in the buffer
<em class="parameter"><code>b</code></em>
is too small to accommodate the packet header or the
<span class="type">lwres_gabnrequest_t</span>
and
<span class="type">lwres_gabnresponse_t</span>
structures.
<code class="function">lwres_gabnrequest_parse()</code>
and
<code class="function">lwres_gabnresponse_parse()</code>
will return
<span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
if the buffer is not empty after decoding the received packet.
These functions will return
<span class="errorcode">LWRES_R_FAILURE</span>
if
<em class="structfield"><code>pktflags</code></em>
in the packet header structure
<span class="type">lwres_lwpacket_t</span>
indicate that the packet is not a response to an earlier query.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id2515040"></a><h2>SEE ALSO</h2>
<p>
<span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3
)</span>
</p>
</div>
</div></body>
</html>
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