- import of strongswan-2.7.0
- applied patch for charon
This commit is contained in:
Martin Willi
@@ -0,0 +1,444 @@
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<!--
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- Copyright (C) 2000, 2001 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
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- DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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- INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
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- FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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- NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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- WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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-->
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<HTML
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><HEAD
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><TITLE
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>lwres</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.61
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"></HEAD
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><BODY
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CLASS="REFENTRY"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><H1
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><A
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NAME="AEN1"
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>lwres</A
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></H1
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><DIV
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CLASS="REFNAMEDIV"
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><A
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NAME="AEN8"
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></A
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><H2
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>Name</H2
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>lwres -- introduction to the lightweight resolver library</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN11"
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></A
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><H2
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>Synopsis</H2
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><DIV
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CLASS="FUNCSYNOPSIS"
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><A
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NAME="AEN12"
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></A
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><P
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></P
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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>#include <lwres/lwres.h></PRE
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><P
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></P
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></DIV
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN14"
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></A
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><H2
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>DESCRIPTION</H2
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><P
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>The BIND 9 lightweight resolver library is a simple, name service
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independent stub resolver library. It provides hostname-to-address
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and address-to-hostname lookup services to applications by
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transmitting lookup requests to a resolver daemon
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<B
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CLASS="COMMAND"
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>lwresd</B
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>
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running on the local host. The resover daemon performs the
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lookup using the DNS or possibly other name service protocols,
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and returns the results to the application through the library.
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The library and resolver daemon communicate using a simple
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UDP-based protocol.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN18"
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></A
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><H2
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>OVERVIEW</H2
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><P
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>The lwresd library implements multiple name service APIs.
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The standard
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<TT
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CLASS="FUNCTION"
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>gethostbyname()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>gethostbyaddr()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>gethostbyname_r()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>gethostbyaddr_r()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>getaddrinfo()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>getipnodebyname()</TT
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>,
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and
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<TT
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CLASS="FUNCTION"
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>getipnodebyaddr()</TT
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>
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functions are all supported. To allow the lwres library to coexist
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with system libraries that define functions of the same name,
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the library defines these functions with names prefixed by
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<TT
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CLASS="LITERAL"
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>lwres_</TT
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>.
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To define the standard names, applications must include the
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header file
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<TT
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CLASS="FILENAME"
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><lwres/netdb.h></TT
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>
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which contains macro definitions mapping the standard function names
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into
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<TT
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CLASS="LITERAL"
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>lwres_</TT
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>
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prefixed ones. Operating system vendors who integrate the lwres
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library into their base distributions should rename the functions
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in the library proper so that the renaming macros are not needed.</P
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><P
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>The library also provides a native API consisting of the functions
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<TT
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CLASS="FUNCTION"
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>lwres_getaddrsbyname()</TT
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>
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and
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<TT
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CLASS="FUNCTION"
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>lwres_getnamebyaddr()</TT
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>.
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These may be called by applications that require more detailed
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control over the lookup process than the standard functions
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provide.</P
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><P
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>In addition to these name service independent address lookup
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functions, the library implements a new, experimental API
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for looking up arbitrary DNS resource records, using the
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<TT
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CLASS="FUNCTION"
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>lwres_getaddrsbyname()</TT
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>
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function.</P
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><P
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>Finally, there is a low-level API for converting lookup
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requests and responses to and from raw lwres protocol packets.
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This API can be used by clients requiring nonblocking operation,
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and is also used when implementing the server side of the lwres
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protocol, for example in the
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<B
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CLASS="COMMAND"
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>lwresd</B
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>
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resolver daemon. The use of this low-level API in clients
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and servers is outlined in the following sections.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN38"
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></A
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><H2
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>CLIENT-SIDE LOW-LEVEL API CALL FLOW</H2
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><P
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>When a client program wishes to make an lwres request using the
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native low-level API, it typically performs the following
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sequence of actions.</P
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><P
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>(1) Allocate or use an existing <SPAN
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CLASS="TYPE"
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>lwres_packet_t</SPAN
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>,
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called <TT
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CLASS="VARNAME"
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>pkt</TT
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> below.</P
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><P
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>(2) Set <TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.recvlength</I
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></TT
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> to the maximum length we will accept.
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This is done so the receiver of our packets knows how large our receive
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buffer is. The "default" is a constant in
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<TT
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CLASS="FILENAME"
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>lwres.h</TT
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>: <TT
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CLASS="CONSTANT"
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>LWRES_RECVLENGTH = 4096</TT
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>.</P
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><P
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>(3) Set <TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.serial</I
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></TT
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>
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to a unique serial number. This value is echoed
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back to the application by the remote server.</P
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><P
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>(4) Set <TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.pktflags</I
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></TT
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>. Usually this is set to 0.</P
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><P
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>(5) Set <TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.result</I
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></TT
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> to 0.</P
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><P
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>(6) Call <TT
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CLASS="FUNCTION"
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>lwres_*request_render()</TT
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>,
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or marshall in the data using the primitives
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such as <TT
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CLASS="FUNCTION"
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>lwres_packet_render()</TT
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>
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and storing the packet data.</P
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><P
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>(7) Transmit the resulting buffer.</P
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><P
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>(8) Call <TT
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CLASS="FUNCTION"
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>lwres_*response_parse()</TT
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>
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to parse any packets received.</P
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><P
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>(9) Verify that the opcode and serial match a request, and process the
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packet specific information contained in the body.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN61"
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></A
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><H2
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>SERVER-SIDE LOW-LEVEL API CALL FLOW</H2
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><P
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>When implementing the server side of the lightweight resolver
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protocol using the lwres library, a sequence of actions like the
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following is typically involved in processing each request packet.</P
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><P
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>Note that the same <SPAN
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CLASS="TYPE"
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>lwres_packet_t</SPAN
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> is used
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in both the <TT
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CLASS="FUNCTION"
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>_parse()</TT
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> and <TT
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CLASS="FUNCTION"
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>_render()</TT
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> calls,
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with only a few modifications made
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to the packet header's contents between uses. This method is recommended
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as it keeps the serial, opcode, and other fields correct.</P
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><P
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>(1) When a packet is received, call <TT
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CLASS="FUNCTION"
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>lwres_*request_parse()</TT
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> to
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unmarshall it. This returns a <SPAN
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CLASS="TYPE"
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>lwres_packet_t</SPAN
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> (also called <TT
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CLASS="VARNAME"
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>pkt</TT
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>, below)
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as well as a data specific type, such as <SPAN
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CLASS="TYPE"
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>lwres_gabnrequest_t</SPAN
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>.</P
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><P
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>(2) Process the request in the data specific type.</P
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><P
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>(3) Set the <TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.result</I
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></TT
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>,
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<TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.recvlength</I
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></TT
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> as above. All other fields can
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be left untouched since they were filled in by the <TT
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CLASS="FUNCTION"
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>*_parse()</TT
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> call
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above. If using <TT
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CLASS="FUNCTION"
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>lwres_*response_render()</TT
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>,
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<TT
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CLASS="STRUCTFIELD"
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><I
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>pkt.pktflags</I
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></TT
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> will be set up
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properly. Otherwise, the <TT
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CLASS="CONSTANT"
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>LWRES_LWPACKETFLAG_RESPONSE</TT
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> bit should be
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set.</P
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><P
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>(4) Call the data specific rendering function, such as
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<TT
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CLASS="FUNCTION"
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>lwres_gabnresponse_render()</TT
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>.</P
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><P
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>(5) Send the resulting packet to the client.</P
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><P
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></P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN85"
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></A
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><H2
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>SEE ALSO</H2
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><P
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><SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_gethostent</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_getipnode</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_getnameinfo</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_noop</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_gabn</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_gnba</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_context</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwres_config</SPAN
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>(3)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>resolver</SPAN
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>(5)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>lwresd</SPAN
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>(8)</SPAN
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>. </P
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></DIV
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></BODY
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||||
></HTML
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||||
>
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||||
Reference in New Issue
Block a user