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411 lines
7.4 KiB
HTML
411 lines
7.4 KiB
HTML
<!--
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- Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
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- Copyright (C) 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 ISC DISCLAIMS ALL WARRANTIES WITH
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- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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- PERFORMANCE OF THIS SOFTWARE.
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-->
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<!-- $Id: lwres_gnba.html,v 1.6.2.1.4.1 2004/03/06 08:15:40 marka Exp $ -->
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<HTML
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><HEAD
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><TITLE
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>lwres_gnba</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.73
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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_gnba</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_gnbarequest_render, lwres_gnbaresponse_render, lwres_gnbarequest_parse, lwres_gnbaresponse_parse, lwres_gnbaresponse_free, lwres_gnbarequest_free -- lightweight resolver getnamebyaddress message handling</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN16"
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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="AEN17"
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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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><CODE
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><CODE
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CLASS="FUNCDEF"
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>lwres_result_t
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lwres_gnbarequest_render</CODE
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>(lwres_context_t *ctx, lwres_gnbarequest_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>lwres_result_t
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lwres_gnbaresponse_render</CODE
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>(lwres_context_t *ctx, lwres_gnbaresponse_t *req, lwres_lwpacket_t *pkt, lwres_buffer_t *b);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>lwres_result_t
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lwres_gnbarequest_parse</CODE
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>(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbarequest_t **structp);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>lwres_result_t
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lwres_gnbaresponse_parse</CODE
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>(lwres_context_t *ctx, lwres_buffer_t *b, lwres_lwpacket_t *pkt, lwres_gnbaresponse_t **structp);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>void
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lwres_gnbaresponse_free</CODE
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>(lwres_context_t *ctx, lwres_gnbaresponse_t **structp);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>void
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lwres_gnbarequest_free</CODE
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>(lwres_context_t *ctx, lwres_gnbarequest_t **structp);</CODE
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></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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><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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>DESCRIPTION</H2
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><P
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>These are low-level routines for creating and parsing
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lightweight resolver address-to-name lookup request and
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response messages.</P
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><P
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>There are four main functions for the getnamebyaddr opcode.
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One render function converts a getnamebyaddr request structure —
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<SPAN
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CLASS="TYPE"
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>lwres_gnbarequest_t</SPAN
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> —
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to the lightweight resolver's canonical format.
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It is complemented by a parse function that converts a packet in this
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canonical format to a getnamebyaddr request structure.
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Another render function converts the getnamebyaddr response structure —
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<SPAN
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CLASS="TYPE"
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>lwres_gnbaresponse_t</SPAN
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>
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to the canonical format.
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This is complemented by a parse function which converts a packet in
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canonical format to a getnamebyaddr response structure.</P
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><P
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>These structures are defined in
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<TT
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CLASS="FILENAME"
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>lwres/lwres.h</TT
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>.
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They are shown below.
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<PRE
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CLASS="PROGRAMLISTING"
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>#define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U
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typedef struct {
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lwres_uint32_t flags;
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lwres_addr_t addr;
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} lwres_gnbarequest_t;
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typedef struct {
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lwres_uint32_t flags;
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lwres_uint16_t naliases;
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char *realname;
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char **aliases;
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lwres_uint16_t realnamelen;
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lwres_uint16_t *aliaslen;
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void *base;
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size_t baselen;
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} lwres_gnbaresponse_t;</PRE
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></P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_render()</TT
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>
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uses resolver context
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<TT
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CLASS="VARNAME"
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>ctx</TT
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>
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to convert getnamebyaddr request structure
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<TT
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CLASS="VARNAME"
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>req</TT
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>
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to canonical format.
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The packet header structure
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<TT
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CLASS="VARNAME"
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>pkt</TT
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>
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is initialised and transferred to
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buffer
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<TT
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CLASS="VARNAME"
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>b</TT
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>.
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The contents of
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<TT
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CLASS="VARNAME"
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>*req</TT
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>
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are then appended to the buffer in canonical format.
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<TT
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CLASS="FUNCTION"
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>lwres_gnbaresponse_render()</TT
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>
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performs the same task, except it converts a getnamebyaddr response structure
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<SPAN
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CLASS="TYPE"
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>lwres_gnbaresponse_t</SPAN
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>
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to the lightweight resolver's canonical format.</P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_parse()</TT
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>
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uses context
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<TT
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CLASS="VARNAME"
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>ctx</TT
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>
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to convert the contents of packet
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<TT
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CLASS="VARNAME"
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>pkt</TT
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>
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to a
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<SPAN
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CLASS="TYPE"
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>lwres_gnbarequest_t</SPAN
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>
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structure.
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Buffer
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<TT
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CLASS="VARNAME"
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>b</TT
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>
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provides space to be used for storing this structure.
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When the function succeeds, the resulting
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<SPAN
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CLASS="TYPE"
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>lwres_gnbarequest_t</SPAN
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>
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is made available through
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<TT
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CLASS="VARNAME"
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>*structp</TT
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>.
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<TT
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CLASS="FUNCTION"
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>lwres_gnbaresponse_parse()</TT
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>
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offers the same semantics as
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<TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_parse()</TT
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>
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except it yields a
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<SPAN
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CLASS="TYPE"
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>lwres_gnbaresponse_t</SPAN
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>
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structure.</P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_gnbaresponse_free()</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_gnbarequest_free()</TT
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>
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release the memory in resolver context
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<TT
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CLASS="VARNAME"
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>ctx</TT
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>
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that was allocated to the
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<SPAN
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CLASS="TYPE"
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>lwres_gnbaresponse_t</SPAN
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>
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or
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<SPAN
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CLASS="TYPE"
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>lwres_gnbarequest_t</SPAN
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>
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structures referenced via
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<TT
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CLASS="VARNAME"
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>structp</TT
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>.
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Any memory associated with ancillary buffers and strings for those
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structures is also discarded.</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="AEN97"
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></A
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><H2
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>RETURN VALUES</H2
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><P
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>The getnamebyaddr opcode functions
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<TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_render()</TT
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>,
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<TT
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CLASS="FUNCTION"
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>lwres_gnbaresponse_render()</TT
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>
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<TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_parse()</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_gnbaresponse_parse()</TT
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>
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all return
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<SPAN
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CLASS="ERRORCODE"
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>LWRES_R_SUCCESS</SPAN
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>
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on success.
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They return
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<SPAN
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CLASS="ERRORCODE"
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>LWRES_R_NOMEMORY</SPAN
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>
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if memory allocation fails.
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<SPAN
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CLASS="ERRORCODE"
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>LWRES_R_UNEXPECTEDEND</SPAN
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>
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is returned if the available space in the buffer
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<TT
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CLASS="VARNAME"
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>b</TT
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>
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is too small to accommodate the packet header or the
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<SPAN
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CLASS="TYPE"
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>lwres_gnbarequest_t</SPAN
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>
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and
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<SPAN
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CLASS="TYPE"
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>lwres_gnbaresponse_t</SPAN
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>
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structures.
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<TT
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CLASS="FUNCTION"
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>lwres_gnbarequest_parse()</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_gnbaresponse_parse()</TT
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>
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will return
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<SPAN
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CLASS="ERRORCODE"
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>LWRES_R_UNEXPECTEDEND</SPAN
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>
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if the buffer is not empty after decoding the received packet.
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These functions will return
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<SPAN
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CLASS="ERRORCODE"
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>LWRES_R_FAILURE</SPAN
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>
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if
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<TT
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CLASS="STRUCTFIELD"
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><I
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>pktflags</I
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></TT
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>
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in the packet header structure
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<SPAN
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CLASS="TYPE"
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>lwres_lwpacket_t</SPAN
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>
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indicate that the packet is not a response to an earlier query.</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="AEN116"
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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_packet</SPAN
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>(3)</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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