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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="id2549720"></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="id2549853"></a><h2>SEE ALSO</h2> <p> <span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3 )</span> </p> </div> </div></body> </html>