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One render function converts a getnamebyaddr request structure — <span class="type">lwres_gnbarequest_t</span> — 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 — <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 typedef struct { lwres_uint32_t flags; lwres_addr_t addr; } lwres_gnbarequest_t; 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="refsect1" lang="en"> <a name="id2549733"></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 <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="id2549866"></a><h2>SEE ALSO</h2> <p> <span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3)</span>. </p> </div> </div></body> </html>