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diff --git a/lib/lwres/man/lwres.html b/lib/lwres/man/lwres.html new file mode 100644 index 0000000..b8cf257 --- /dev/null +++ b/lib/lwres/man/lwres.html @@ -0,0 +1,248 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<!-- + - Copyright (C) 2000, 2001, 2004, 2005, 2007, 2014-2016, 2018, 2019 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/. +--> +<html lang="en"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>lwres</title> +<meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry"> +<a name="id-1"></a><div class="titlepage"></div> + + + + + <div class="refnamediv"> +<h2>Name</h2> +<p> + lwres + — introduction to the lightweight resolver library + </p> +</div> + + + + <div class="refsynopsisdiv"> +<h2>Synopsis</h2> + <div class="funcsynopsis"> +<pre class="funcsynopsisinfo">#include <lwres/lwres.h></pre> +</div> + </div> + + <div class="refsection"> +<a name="id-1.7"></a><h2>DESCRIPTION</h2> + + <p> + 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 + <span class="command"><strong>lwresd</strong></span> + 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. + </p> + </div> + + <div class="refsection"> +<a name="id-1.8"></a><h2>OVERVIEW</h2> + + <p> + The lwresd library implements multiple name service APIs. + The standard + <code class="function">gethostbyname()</code>, + <code class="function">gethostbyaddr()</code>, + <code class="function">gethostbyname_r()</code>, + <code class="function">gethostbyaddr_r()</code>, + <code class="function">getaddrinfo()</code>, + <code class="function">getipnodebyname()</code>, + and + <code class="function">getipnodebyaddr()</code> + 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 + <code class="literal">lwres_</code>. + To define the standard names, applications must include the + header file + <code class="filename"><lwres/netdb.h></code> + which contains macro definitions mapping the standard function names + into + <code class="literal">lwres_</code> + 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. + </p> + <p> + The library also provides a native API consisting of the functions + <code class="function">lwres_getaddrsbyname()</code> + and + <code class="function">lwres_getnamebyaddr()</code>. + These may be called by applications that require more detailed + control over the lookup process than the standard functions + provide. + </p> + <p> + 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 + <code class="function">lwres_getaddrsbyname()</code> + function. + </p> + <p> + 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 + <span class="command"><strong>lwresd</strong></span> + resolver daemon. The use of this low-level API in clients + and servers is outlined in the following sections. + </p> + </div> + <div class="refsection"> +<a name="id-1.9"></a><h2>CLIENT-SIDE LOW-LEVEL API CALL FLOW</h2> + + <p> + When a client program wishes to make an lwres request using the + native low-level API, it typically performs the following + sequence of actions. + </p> + <p> + (1) Allocate or use an existing <span class="type">lwres_packet_t</span>, + called <code class="varname">pkt</code> below. + </p> + <p> + (2) Set <code class="varname">pkt.recvlength</code> 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 + <code class="filename">lwres.h</code>: <code class="constant">LWRES_RECVLENGTH = 4096</code>. + </p> + <p> + (3) Set <code class="varname">pkt.serial</code> + to a unique serial number. This value is echoed + back to the application by the remote server. + </p> + <p> + (4) Set <code class="varname">pkt.pktflags</code>. Usually this is set to + 0. + </p> + <p> + (5) Set <code class="varname">pkt.result</code> to 0. + </p> + <p> + (6) Call <code class="function">lwres_*request_render()</code>, + or marshall in the data using the primitives + such as <code class="function">lwres_packet_render()</code> + and storing the packet data. + </p> + <p> + (7) Transmit the resulting buffer. + </p> + <p> + (8) Call <code class="function">lwres_*response_parse()</code> + to parse any packets received. + </p> + <p> + (9) Verify that the opcode and serial match a request, and process the + packet specific information contained in the body. + </p> + </div> + <div class="refsection"> +<a name="id-1.10"></a><h2>SERVER-SIDE LOW-LEVEL API CALL FLOW</h2> + + <p> + 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. + </p> + <p> + Note that the same <span class="type">lwres_packet_t</span> is used + in both the <code class="function">_parse()</code> and <code class="function">_render()</code> 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. + </p> + <p> + (1) When a packet is received, call <code class="function">lwres_*request_parse()</code> to + unmarshall it. This returns a <span class="type">lwres_packet_t</span> (also called <code class="varname">pkt</code>, below) + as well as a data specific type, such as <span class="type">lwres_gabnrequest_t</span>. + </p> + <p> + (2) Process the request in the data specific type. + </p> + <p> + (3) Set the <code class="varname">pkt.result</code>, + <code class="varname">pkt.recvlength</code> as above. All other fields + can + be left untouched since they were filled in by the <code class="function">*_parse()</code> call + above. If using <code class="function">lwres_*response_render()</code>, + <code class="varname">pkt.pktflags</code> will be set up + properly. Otherwise, the <code class="constant">LWRES_LWPACKETFLAG_RESPONSE</code> bit should be + set. + </p> + <p> + (4) Call the data specific rendering function, such as + <code class="function">lwres_gabnresponse_render()</code>. + </p> + <p> + (5) Send the resulting packet to the client. + </p> + <p></p> + </div> + <div class="refsection"> +<a name="id-1.11"></a><h2>SEE ALSO</h2> + + <p><span class="citerefentry"> + <span class="refentrytitle">lwres_gethostent</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_getipnode</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_getnameinfo</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_noop</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_gabn</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_gnba</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_context</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwres_config</span>(3) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">resolver</span>(5) + </span>, + + <span class="citerefentry"> + <span class="refentrytitle">lwresd</span>(8) + </span>. + + </p> + </div> +</div></body> +</html> |