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diff --git a/lib/lwres/man/lwres.docbook b/lib/lwres/man/lwres.docbook new file mode 100644 index 0000000..0cabe65 --- /dev/null +++ b/lib/lwres/man/lwres.docbook @@ -0,0 +1,258 @@ +<!-- + - Copyright (C) Internet Systems Consortium, Inc. ("ISC") + - + - This Source Code Form is subject to the terms of the Mozilla Public + - License, v. 2.0. If a copy of the MPL was not distributed with this + - file, You can obtain one at http://mozilla.org/MPL/2.0/. + - + - See the COPYRIGHT file distributed with this work for additional + - information regarding copyright ownership. +--> + +<!-- Converted by db4-upgrade version 1.0 --> +<refentry xmlns:db="http://docbook.org/ns/docbook" version="5.0"> + <info> + <date>2007-06-18</date> + </info> + <refentryinfo> + <corpname>ISC</corpname> + <corpauthor>Internet Systems Consortium, Inc.</corpauthor> + </refentryinfo> + + <refmeta> + <refentrytitle>lwres</refentrytitle> + <manvolnum>3</manvolnum> + <refmiscinfo>BIND9</refmiscinfo> + </refmeta> + <refnamediv> + <refname>lwres</refname> + <refpurpose>introduction to the lightweight resolver library</refpurpose> + </refnamediv> + + <docinfo> + <copyright> + <year>2000</year> + <year>2001</year> + <year>2004</year> + <year>2005</year> + <year>2007</year> + <year>2014</year> + <year>2015</year> + <year>2016</year> + <year>2018</year> + <year>2019</year> + <holder>Internet Systems Consortium, Inc. ("ISC")</holder> + </copyright> + </docinfo> + + <refsynopsisdiv> + <funcsynopsis> +<funcsynopsisinfo>#include <lwres/lwres.h></funcsynopsisinfo> +</funcsynopsis> + </refsynopsisdiv> + + <refsection><info><title>DESCRIPTION</title></info> + + <para> + The BIND 9 lightweight resolver library is a simple, name service + independent stub resolver library. It provides hostname-to-address + and address-to-hostname lookup services to applications by + transmitting lookup requests to a resolver daemon + <command>lwresd</command> + running on the local host. The resolver daemon performs the + lookup using the DNS or possibly other name service protocols, + and returns the results to the application through the library. + The library and resolver daemon communicate using a simple + UDP-based protocol. + </para> + </refsection> + + <refsection><info><title>OVERVIEW</title></info> + + <para> + The lwresd library implements multiple name service APIs. + The standard + <function>gethostbyname()</function>, + <function>gethostbyaddr()</function>, + <function>gethostbyname_r()</function>, + <function>gethostbyaddr_r()</function>, + <function>getaddrinfo()</function>, + <function>getipnodebyname()</function>, + and + <function>getipnodebyaddr()</function> + functions are all supported. To allow the lwres library to coexist + with system libraries that define functions of the same name, + the library defines these functions with names prefixed by + <literal>lwres_</literal>. + To define the standard names, applications must include the + header file + <filename><lwres/netdb.h></filename> + which contains macro definitions mapping the standard function names + into + <literal>lwres_</literal> + prefixed ones. Operating system vendors who integrate the lwres + library into their base distributions should rename the functions + in the library proper so that the renaming macros are not needed. + </para> + <para> + The library also provides a native API consisting of the functions + <function>lwres_getaddrsbyname()</function> + and + <function>lwres_getnamebyaddr()</function>. + These may be called by applications that require more detailed + control over the lookup process than the standard functions + provide. + </para> + <para> + In addition to these name service independent address lookup + functions, the library implements a new, experimental API + for looking up arbitrary DNS resource records, using the + <function>lwres_getaddrsbyname()</function> + function. + </para> + <para> + Finally, there is a low-level API for converting lookup + requests and responses to and from raw lwres protocol packets. + This API can be used by clients requiring nonblocking operation, + and is also used when implementing the server side of the lwres + protocol, for example in the + <command>lwresd</command> + resolver daemon. The use of this low-level API in clients + and servers is outlined in the following sections. + </para> + </refsection> + <refsection><info><title>CLIENT-SIDE LOW-LEVEL API CALL FLOW</title></info> + + <para> + When a client program wishes to make an lwres request using the + native low-level API, it typically performs the following + sequence of actions. + </para> + <para> + (1) Allocate or use an existing <type>lwres_packet_t</type>, + called <varname>pkt</varname> below. + </para> + <para> + (2) Set <varname remap="structfield">pkt.recvlength</varname> to the maximum length + we will accept. + This is done so the receiver of our packets knows how large our receive + buffer is. The "default" is a constant in + <filename>lwres.h</filename>: <constant>LWRES_RECVLENGTH = 4096</constant>. + </para> + <para> + (3) Set <varname remap="structfield">pkt.serial</varname> + to a unique serial number. This value is echoed + back to the application by the remote server. + </para> + <para> + (4) Set <varname remap="structfield">pkt.pktflags</varname>. Usually this is set to + 0. + </para> + <para> + (5) Set <varname remap="structfield">pkt.result</varname> to 0. + </para> + <para> + (6) Call <function>lwres_*request_render()</function>, + or marshall in the data using the primitives + such as <function>lwres_packet_render()</function> + and storing the packet data. + </para> + <para> + (7) Transmit the resulting buffer. + </para> + <para> + (8) Call <function>lwres_*response_parse()</function> + to parse any packets received. + </para> + <para> + (9) Verify that the opcode and serial match a request, and process the + packet specific information contained in the body. + </para> + </refsection> + <refsection><info><title>SERVER-SIDE LOW-LEVEL API CALL FLOW</title></info> + + <para> + When implementing the server side of the lightweight resolver + protocol using the lwres library, a sequence of actions like the + following is typically involved in processing each request packet. + </para> + <para> + Note that the same <type>lwres_packet_t</type> is used + in both the <function>_parse()</function> and <function>_render()</function> calls, + with only a few modifications made + to the packet header's contents between uses. This method is + recommended + as it keeps the serial, opcode, and other fields correct. + </para> + <para> + (1) When a packet is received, call <function>lwres_*request_parse()</function> to + unmarshall it. This returns a <type>lwres_packet_t</type> (also called <varname>pkt</varname>, below) + as well as a data specific type, such as <type>lwres_gabnrequest_t</type>. + </para> + <para> + (2) Process the request in the data specific type. + </para> + <para> + (3) Set the <varname remap="structfield">pkt.result</varname>, + <varname remap="structfield">pkt.recvlength</varname> as above. All other fields + can + be left untouched since they were filled in by the <function>*_parse()</function> call + above. If using <function>lwres_*response_render()</function>, + <varname remap="structfield">pkt.pktflags</varname> will be set up + properly. Otherwise, the <constant>LWRES_LWPACKETFLAG_RESPONSE</constant> bit should be + set. + </para> + <para> + (4) Call the data specific rendering function, such as + <function>lwres_gabnresponse_render()</function>. + </para> + <para> + (5) Send the resulting packet to the client. + </para> + <para/> + </refsection> + <refsection><info><title>SEE ALSO</title></info> + + <para><citerefentry> + <refentrytitle>lwres_gethostent</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_getipnode</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_getnameinfo</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_noop</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_gabn</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_gnba</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_context</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwres_config</refentrytitle><manvolnum>3</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>resolver</refentrytitle><manvolnum>5</manvolnum> + </citerefentry>, + + <citerefentry> + <refentrytitle>lwresd</refentrytitle><manvolnum>8</manvolnum> + </citerefentry>. + + </para> + </refsection> +</refentry> |