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<title>lwres_gabn</title>
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<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_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free &#8212; lightweight resolver getaddrbyname message handling</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_gabnrequest_render</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t *<var class="pdparam">req</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *<var class="pdparam">b</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_gabnresponse_render</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t *<var class="pdparam">req</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *<var class="pdparam">b</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_gabnrequest_parse</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *<var class="pdparam">b</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t **<var class="pdparam">structp</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_gabnresponse_parse</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_buffer_t *<var class="pdparam">b</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_lwpacket_t *<var class="pdparam">pkt</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t **<var class="pdparam">structp</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_gabnresponse_free</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnresponse_t **<var class="pdparam">structp</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_gabnrequest_free</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gabnrequest_t **<var class="pdparam">structp</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>
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 &#8212;
<span class="type">lwres_gabnrequest_t</span> &#8212;
to the lightweight 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
&#8212; <span class="type">lwres_gabnresponse_t</span> &#8212;
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">&lt;lwres/lwres.h&gt;</code>.
They are shown below.
</p>
<pre class="programlisting">
#define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U
</pre>
<p>
</p>
<pre class="programlisting">
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
</pre>
<p>
</p>
<pre class="programlisting">
typedef struct {
lwres_uint32_t flags;
lwres_uint32_t addrtypes;
lwres_uint16_t namelen;
char *name;
} lwres_gabnrequest_t;
</pre>
<p>
</p>
<pre class="programlisting">
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="refsection">
<a name="id-1.8"></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
<code class="varname">pktflags</code>
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="refsection">
<a name="id-1.9"></a><h2>SEE ALSO</h2>
<p><span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3)</span>
</p>
</div>
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