lwres_noop.docbook revision 938440694b33cd752e9e4b71a526368b4811c177
5cd4555ad444fd391002ae32450572054369fd42Rob Austein<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
5cd4555ad444fd391002ae32450572054369fd42Rob Austein "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein [<!ENTITY mdash "—">]>
938440694b33cd752e9e4b71a526368b4811c177Tinderbox User - Copyright (C) 2004, 2005, 2007, 2014 Internet Systems Consortium, Inc. ("ISC")
c651f15b30f1dae5cc2f00878fb5da5b3a35a468Mark Andrews - Copyright (C) 2000, 2001 Internet Software Consortium.
ec5347e2c775f027573ce5648b910361aa926c01Automatic Updater - Permission to use, copy, modify, and/or distribute this software for any
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson - purpose with or without fee is hereby granted, provided that the above
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson - copyright notice and this permission notice appear in all copies.
dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
dafcb997e390efa4423883dafd100c975c4095d6Mark Andrews - PERFORMANCE OF THIS SOFTWARE.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <refentryinfo>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </refentryinfo>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <holder>Internet Systems Consortium, Inc. ("ISC")</holder>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </copyright>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </copyright>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <refnamediv>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <refpurpose>lightweight resolver no-op message handling</refpurpose>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </refnamediv>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <refsynopsisdiv>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <funcsynopsis>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcsynopsisinfo>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson#include <lwres/lwres.h></funcsynopsisinfo>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_nooprequest_render</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_nooprequest_t *<parameter>req</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_noopresponse_render</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_noopresponse_t *<parameter>req</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_nooprequest_parse</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_nooprequest_t **<parameter>structp</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_noopresponse_parse</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_buffer_t *<parameter>b</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_lwpacket_t *<parameter>pkt</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_noopresponse_t **<parameter>structp</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_noopresponse_free</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_noopresponse_t **<parameter>structp</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson<function>lwres_nooprequest_free</function></funcdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <paramdef>lwres_nooprequest_t **<parameter>structp</parameter></paramdef>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </funcprototype>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson</funcsynopsis>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </refsynopsisdiv>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein These are low-level routines for creating and parsing
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein lightweight resolver no-op request and response messages.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein The no-op message is analogous to a <command>ping</command>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein a packet is sent to the resolver daemon and is simply echoed back.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein The opcode is intended to allow a client to determine if the server is
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein operational or not.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein There are four main functions for the no-op opcode.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein One render function converts a no-op request structure —
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein to the lighweight resolver's canonical format.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein It is complemented by a parse function that converts a packet in this
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein canonical format to a no-op request structure.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein Another render function converts the no-op response structure —
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein to the canonical format.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein This is complemented by a parse function which converts a packet in
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein canonical format to a no-op response structure.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein These structures are defined in
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein They are shown below.
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson#define LWRES_OPCODE_NOOP 0x00000000U
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein</programlisting>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafssontypedef struct {
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t datalength;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson unsigned char *data;
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson} lwres_nooprequest_t;
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein</programlisting>
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafssontypedef struct {
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson lwres_uint16_t datalength;
8eea877894ea5bcf5cdd9ca124a8601ad421d753Andreas Gustafsson unsigned char *data;
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson} lwres_noopresponse_t;
ddccd5811feff696ba460dabfb666ce61040f545Andreas Gustafsson</programlisting>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein Although the structures have different types, they are identical.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein This is because the no-op opcode simply echos whatever data was sent:
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein the response is therefore identical to the request.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <para><function>lwres_nooprequest_render()</function>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein uses resolver context <parameter>ctx</parameter> to convert
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein no-op request structure <parameter>req</parameter> to canonical
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein format. The packet header structure <parameter>pkt</parameter>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein is initialised and transferred to buffer
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <parameter>*req</parameter> are then appended to the buffer in
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein canonical format.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <function>lwres_noopresponse_render()</function> performs the
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein same task, except it converts a no-op response structure
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <type>lwres_noopresponse_t</type> to the lightweight resolver's
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein canonical format.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <para><function>lwres_nooprequest_parse()</function>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein uses context <parameter>ctx</parameter> to convert the contents
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <type>lwres_nooprequest_t</type> structure. Buffer
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <parameter>b</parameter> provides space to be used for storing
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein this structure. When the function succeeds, the resulting
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <type>lwres_nooprequest_t</type> is made available through
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <function>lwres_noopresponse_parse()</function> offers the same
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein semantics as <function>lwres_nooprequest_parse()</function>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein except it yields a <type>lwres_noopresponse_t</type> structure.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <para><function>lwres_noopresponse_free()</function>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein and <function>lwres_nooprequest_free()</function> release the
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein memory in resolver context <parameter>ctx</parameter> that was
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein allocated to the <type>lwres_noopresponse_t</type> or
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <type>lwres_nooprequest_t</type> structures referenced via
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein The no-op opcode functions
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <function>lwres_nooprequest_render()</function>,
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <function>lwres_noopresponse_render()</function>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein if memory allocation fails.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein is returned if the available space in the buffer
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein is too small to accommodate the packet header or the
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein if the buffer is not empty after decoding the received packet.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein These functions will return
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein in the packet header structure
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein indicate that the packet is not a response to an earlier query.
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein <refentrytitle>lwres_packet</refentrytitle><manvolnum>3</manvolnum>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein </citerefentry>
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein - Local variables:
268a4475065fe6a8cd7cc707820982cf5e98f430Rob Austein - mode: sgml