lwres/man/lwres_gnba.html

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<title>lwres_gnba</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_gnbarequest_render,
    lwres_gnbaresponse_render,
    lwres_gnbarequest_parse,
    lwres_gnbaresponse_parse,
    lwres_gnbaresponse_free,
    lwres_gnbarequest_free
     &#8212; lightweight resolver getnamebyaddress 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_gnbarequest_render</b>
(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gnbarequest_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_gnbaresponse_render</b>
(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gnbaresponse_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_gnbarequest_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_gnbarequest_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_gnbaresponse_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_gnbaresponse_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_gnbaresponse_free</b>
(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gnbaresponse_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_gnbarequest_free</b>(</code></td>
<td>lwres_context_t *<var class="pdparam">ctx</var>, </td>
</tr>
<tr>
<td>�</td>
<td>lwres_gnbarequest_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 address-to-name lookup request and
      response messages.
    </p>
    <p>
      There are four main functions for the getnamebyaddr opcode.
      One render function converts a getnamebyaddr request structure &#8212;
      <span class="type">lwres_gnbarequest_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 getnamebyaddr request structure.
      Another render function converts the getnamebyaddr response structure
      &#8212;
      <span class="type">lwres_gnbaresponse_t</span>
      to the canonical format.
      This is complemented by a parse function which converts a packet in
      canonical format to a getnamebyaddr 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_GETNAMEBYADDR      0x00010002U
</pre>
<p>
    </p>
    <pre class="programlisting">
typedef struct {
        lwres_uint32_t  flags;
        lwres_addr_t    addr;
} lwres_gnbarequest_t;
</pre>
<p>
    </p>
    <pre class="programlisting">
typedef struct {
        lwres_uint32_t  flags;
        lwres_uint16_t  naliases;
        char           *realname;
        char          **aliases;
        lwres_uint16_t  realnamelen;
        lwres_uint16_t *aliaslen;
        void           *base;
        size_t          baselen;
} lwres_gnbaresponse_t;
</pre>
<p>
    </p>

    <p><code class="function">lwres_gnbarequest_render()</code>
      uses resolver context <code class="varname">ctx</code> to convert
      getnamebyaddr request structure <code class="varname">req</code> to
      canonical format.  The packet header structure
      <code class="varname">pkt</code> is initialised and transferred to buffer
      <code class="varname">b</code>.  The contents of <code class="varname">*req</code>
      are then appended to the buffer in canonical format.
      <code class="function">lwres_gnbaresponse_render()</code> performs the
      same task, except it converts a getnamebyaddr response structure
      <span class="type">lwres_gnbaresponse_t</span> to the lightweight resolver's
      canonical format.
    </p>

    <p><code class="function">lwres_gnbarequest_parse()</code>
      uses context <code class="varname">ctx</code> to convert the contents of
      packet <code class="varname">pkt</code> to a
      <span class="type">lwres_gnbarequest_t</span> structure.  Buffer
      <code class="varname">b</code> provides space to be used for storing this
      structure.  When the function succeeds, the resulting
      <span class="type">lwres_gnbarequest_t</span> is made available through
      <code class="varname">*structp</code>.
      <code class="function">lwres_gnbaresponse_parse()</code> offers the same
      semantics as <code class="function">lwres_gnbarequest_parse()</code>
      except it yields a <span class="type">lwres_gnbaresponse_t</span> structure.
    </p>

    <p><code class="function">lwres_gnbaresponse_free()</code>
      and <code class="function">lwres_gnbarequest_free()</code> release the
      memory in resolver context <code class="varname">ctx</code> that was
      allocated to the <span class="type">lwres_gnbaresponse_t</span> or
      <span class="type">lwres_gnbarequest_t</span> structures referenced via
      <code class="varname">structp</code>.  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 getnamebyaddr opcode functions
      <code class="function">lwres_gnbarequest_render()</code>,
      <code class="function">lwres_gnbaresponse_render()</code>
      <code class="function">lwres_gnbarequest_parse()</code>
      and
      <code class="function">lwres_gnbaresponse_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
      <code class="varname">b</code>
      is too small to accommodate the packet header or the
      <span class="type">lwres_gnbarequest_t</span>
      and
      <span class="type">lwres_gnbaresponse_t</span>
      structures.
      <code class="function">lwres_gnbarequest_parse()</code>
      and
      <code class="function">lwres_gnbaresponse_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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