<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN"><!-- - Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC") - Copyright (C) 2001  Internet Software Consortium. - - Permission to use, copy, modify, and distribute this software for any - purpose with or without fee is hereby granted, provided that the above - copyright notice and this permission notice appear in all copies. - - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY - AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR - PERFORMANCE OF THIS SOFTWARE.--><!-- $Id: lwres_gabn.docbook,v 1.2 2004/09/20 18:00:50 mcr Exp $ --><refentry><refentryinfo><date>Jun 30, 2000</date></refentryinfo><refmeta><refentrytitle>lwres_gabn</refentrytitle><manvolnum>3</manvolnum><refmiscinfo>BIND9</refmiscinfo></refmeta><refnamediv><refname>lwres_gabnrequest_render</refname><refname>lwres_gabnresponse_render</refname><refname>lwres_gabnrequest_parse</refname><refname>lwres_gabnresponse_parse</refname><refname>lwres_gabnresponse_free</refname><refname>lwres_gabnrequest_free</refname><refpurpose>lightweight resolver getaddrbyname message handling</refpurpose></refnamediv><refsynopsisdiv><funcsynopsis><funcsynopsisinfo>#include &lt;lwres/lwres.h&gt;</funcsynopsisinfo><funcprototype><funcdef>lwres_result_t<function>lwres_gabnrequest_render</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_gabnrequest_t *req</paramdef><paramdef>lwres_lwpacket_t *pkt</paramdef><paramdef>lwres_buffer_t *b</paramdef></funcprototype><funcprototype><funcdef>lwres_result_t<function>lwres_gabnresponse_render</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_gabnresponse_t *req</paramdef><paramdef>lwres_lwpacket_t *pkt</paramdef><paramdef>lwres_buffer_t *b</paramdef></funcprototype><funcprototype><funcdef>lwres_result_t<function>lwres_gabnrequest_parse</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_buffer_t *b</paramdef><paramdef>lwres_lwpacket_t *pkt</paramdef><paramdef>lwres_gabnrequest_t **structp</paramdef></funcprototype><funcprototype><funcdef>lwres_result_t<function>lwres_gabnresponse_parse</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_buffer_t *b</paramdef><paramdef>lwres_lwpacket_t *pkt</paramdef><paramdef>lwres_gabnresponse_t **structp</paramdef></funcprototype><funcprototype><funcdef>void<function>lwres_gabnresponse_free</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_gabnresponse_t **structp</paramdef></funcprototype><funcprototype><funcdef>void<function>lwres_gabnrequest_free</function></funcdef><paramdef>lwres_context_t *ctx</paramdef><paramdef>lwres_gabnrequest_t **structp</paramdef></funcprototype></funcsynopsis></refsynopsisdiv><refsect1><title>DESCRIPTION</title><para>These are low-level routines for creating and parsinglightweight resolver name-to-address lookup request and response messages.</para><para>There are four main functions for the getaddrbyname opcode.One render function converts a getaddrbyname request structure &mdash;<type>lwres_gabnrequest_t</type> &mdash;to the lighweight resolver's canonical format.It is complemented by a parse function that converts a packet in thiscanonical format to a getaddrbyname request structure.Another render function converts the getaddrbyname response structure &mdash;<type>lwres_gabnresponse_t</type> &mdash;to the canonical format.This is complemented by a parse function which converts a packet incanonical format to a getaddrbyname response structure.</para><para>These structures are defined in<filename>&lt;lwres/lwres.h&gt;</filename>.They are shown below.<programlisting>#define LWRES_OPCODE_GETADDRSBYNAME     0x00010001Utypedef 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;</programlisting></para><para><function>lwres_gabnrequest_render()</function>uses resolver context<parameter>ctx</parameter>to convert getaddrbyname request structure<parameter>req</parameter>to canonical format.The packet header structure<parameter>pkt</parameter>is initialised and transferred tobuffer<parameter>b</parameter>.The contents of<parameter>*req</parameter>are then appended to the buffer in canonical format.<function>lwres_gabnresponse_render()</function>performs the same task, except it converts a getaddrbyname response structure<type>lwres_gabnresponse_t</type>to the lightweight resolver's canonical format.</para><para><function>lwres_gabnrequest_parse()</function>uses context<parameter>ctx</parameter>to convert the contents of packet<parameter>pkt</parameter>to a<type>lwres_gabnrequest_t</type>structure.Buffer<parameter>b</parameter>provides space to be used for storing this structure.When the function succeeds, the resulting<type>lwres_gabnrequest_t</type>is made available through<parameter>*structp</parameter>.<function>lwres_gabnresponse_parse()</function>offers the same semantics as<function>lwres_gabnrequest_parse()</function>except it yields a<type>lwres_gabnresponse_t</type>structure.</para><para><function>lwres_gabnresponse_free()</function>and<function>lwres_gabnrequest_free()</function>release the memory in resolver context<parameter>ctx</parameter>that was allocated to the<type>lwres_gabnresponse_t</type>or<type>lwres_gabnrequest_t</type>structures referenced via<parameter>structp</parameter>.Any memory associated with ancillary buffers and strings for thosestructures is also discarded.</para></refsect1><refsect1><title>RETURN VALUES</title><para>The getaddrbyname opcode functions<function>lwres_gabnrequest_render()</function>, <function>lwres_gabnresponse_render()</function><function>lwres_gabnrequest_parse()</function>and<function>lwres_gabnresponse_parse()</function>all return<errorcode>LWRES_R_SUCCESS</errorcode>on success.They return<errorcode>LWRES_R_NOMEMORY</errorcode>if memory allocation fails.<errorcode>LWRES_R_UNEXPECTEDEND</errorcode>is returned if the available space in the buffer<parameter>b</parameter>is too small to accommodate the packet header or the<type>lwres_gabnrequest_t</type>and<type>lwres_gabnresponse_t</type>structures.<function>lwres_gabnrequest_parse()</function>and<function>lwres_gabnresponse_parse()</function>will return<errorcode>LWRES_R_UNEXPECTEDEND</errorcode>if the buffer is not empty after decoding the received packet.These functions will return<errorcode>LWRES_R_FAILURE</errorcode>if<structfield>pktflags</structfield>in the packet header structure<type>lwres_lwpacket_t</type>indicate that the packet is not a response to an earlier query.</para></refsect1><refsect1><title>SEE ALSO</title><para><citerefentry><refentrytitle>lwres_packet</refentrytitle><manvolnum>3</manvolnum></citerefentry></para></refsect1></refentry>