diff options
Diffstat (limited to 'lib/liblwres/man/lwres.html')
| -rw-r--r-- | lib/liblwres/man/lwres.html | 444 |
1 files changed, 444 insertions, 0 deletions
diff --git a/lib/liblwres/man/lwres.html b/lib/liblwres/man/lwres.html new file mode 100644 index 000000000..7b9f88dcb --- /dev/null +++ b/lib/liblwres/man/lwres.html @@ -0,0 +1,444 @@ +<!-- + - Copyright (C) 2000, 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 INTERNET SOFTWARE CONSORTIUM + - DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL + - IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL + - INTERNET SOFTWARE CONSORTIUM 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. +--> +<HTML +><HEAD +><TITLE +>lwres</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.61 +"></HEAD +><BODY +CLASS="REFENTRY" +BGCOLOR="#FFFFFF" +TEXT="#000000" +LINK="#0000FF" +VLINK="#840084" +ALINK="#0000FF" +><H1 +><A +NAME="AEN1" +>lwres</A +></H1 +><DIV +CLASS="REFNAMEDIV" +><A +NAME="AEN8" +></A +><H2 +>Name</H2 +>lwres -- introduction to the lightweight resolver library</DIV +><DIV +CLASS="REFSYNOPSISDIV" +><A +NAME="AEN11" +></A +><H2 +>Synopsis</H2 +><DIV +CLASS="FUNCSYNOPSIS" +><A +NAME="AEN12" +></A +><P +></P +><PRE +CLASS="FUNCSYNOPSISINFO" +>#include <lwres/lwres.h></PRE +><P +></P +></DIV +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN14" +></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 +<B +CLASS="COMMAND" +>lwresd</B +> +running on the local host. The resover 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="REFSECT1" +><A +NAME="AEN18" +></A +><H2 +>OVERVIEW</H2 +><P +>The lwresd library implements multiple name service APIs. +The standard +<TT +CLASS="FUNCTION" +>gethostbyname()</TT +>, +<TT +CLASS="FUNCTION" +>gethostbyaddr()</TT +>, +<TT +CLASS="FUNCTION" +>gethostbyname_r()</TT +>, +<TT +CLASS="FUNCTION" +>gethostbyaddr_r()</TT +>, +<TT +CLASS="FUNCTION" +>getaddrinfo()</TT +>, +<TT +CLASS="FUNCTION" +>getipnodebyname()</TT +>, +and +<TT +CLASS="FUNCTION" +>getipnodebyaddr()</TT +> +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 +<TT +CLASS="LITERAL" +>lwres_</TT +>. +To define the standard names, applications must include the +header file +<TT +CLASS="FILENAME" +><lwres/netdb.h></TT +> +which contains macro definitions mapping the standard function names +into +<TT +CLASS="LITERAL" +>lwres_</TT +> +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 +<TT +CLASS="FUNCTION" +>lwres_getaddrsbyname()</TT +> +and +<TT +CLASS="FUNCTION" +>lwres_getnamebyaddr()</TT +>. +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 +<TT +CLASS="FUNCTION" +>lwres_getaddrsbyname()</TT +> +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 +<B +CLASS="COMMAND" +>lwresd</B +> +resolver daemon. The use of this low-level API in clients +and servers is outlined in the following sections.</P +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN38" +></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 <TT +CLASS="VARNAME" +>pkt</TT +> below.</P +><P +>(2) Set <TT +CLASS="STRUCTFIELD" +><I +>pkt.recvlength</I +></TT +> 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 +<TT +CLASS="FILENAME" +>lwres.h</TT +>: <TT +CLASS="CONSTANT" +>LWRES_RECVLENGTH = 4096</TT +>.</P +><P +>(3) Set <TT +CLASS="STRUCTFIELD" +><I +>pkt.serial</I +></TT +> +to a unique serial number. This value is echoed +back to the application by the remote server.</P +><P +>(4) Set <TT +CLASS="STRUCTFIELD" +><I +>pkt.pktflags</I +></TT +>. Usually this is set to 0.</P +><P +>(5) Set <TT +CLASS="STRUCTFIELD" +><I +>pkt.result</I +></TT +> to 0.</P +><P +>(6) Call <TT +CLASS="FUNCTION" +>lwres_*request_render()</TT +>, +or marshall in the data using the primitives +such as <TT +CLASS="FUNCTION" +>lwres_packet_render()</TT +> +and storing the packet data.</P +><P +>(7) Transmit the resulting buffer.</P +><P +>(8) Call <TT +CLASS="FUNCTION" +>lwres_*response_parse()</TT +> +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="REFSECT1" +><A +NAME="AEN61" +></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 <TT +CLASS="FUNCTION" +>_parse()</TT +> and <TT +CLASS="FUNCTION" +>_render()</TT +> 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 <TT +CLASS="FUNCTION" +>lwres_*request_parse()</TT +> to +unmarshall it. This returns a <SPAN +CLASS="TYPE" +>lwres_packet_t</SPAN +> (also called <TT +CLASS="VARNAME" +>pkt</TT +>, 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 <TT +CLASS="STRUCTFIELD" +><I +>pkt.result</I +></TT +>, +<TT +CLASS="STRUCTFIELD" +><I +>pkt.recvlength</I +></TT +> as above. All other fields can +be left untouched since they were filled in by the <TT +CLASS="FUNCTION" +>*_parse()</TT +> call +above. If using <TT +CLASS="FUNCTION" +>lwres_*response_render()</TT +>, +<TT +CLASS="STRUCTFIELD" +><I +>pkt.pktflags</I +></TT +> will be set up +properly. Otherwise, the <TT +CLASS="CONSTANT" +>LWRES_LWPACKETFLAG_RESPONSE</TT +> bit should be +set.</P +><P +>(4) Call the data specific rendering function, such as +<TT +CLASS="FUNCTION" +>lwres_gabnresponse_render()</TT +>.</P +><P +>(5) Send the resulting packet to the client.</P +><P +></P +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN85" +></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 +></BODY +></HTML +>
\ No newline at end of file |