184 lines
6.1 KiB
Groff
184 lines
6.1 KiB
Groff
.\" Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
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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/or 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_noop.3,v 1.28.418.1 2009/07/11 01:55:21 tbox Exp $
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.\"
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.hy 0
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.ad l
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.\" Title: lwres_noop
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.\" Author:
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.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
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.\" Date: Jun 30, 2000
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.\" Manual: BIND9
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.\" Source: BIND9
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.\"
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.TH "LWRES_NOOP" "3" "Jun 30, 2000" "BIND9" "BIND9"
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.\" disable hyphenation
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.nh
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.\" disable justification (adjust text to left margin only)
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.ad l
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.SH "NAME"
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lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free \- lightweight resolver no\-op message handling
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.SH "SYNOPSIS"
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.nf
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#include <lwres/lwres.h>
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.fi
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.HP 40
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.BI "lwres_result_t lwres_nooprequest_render(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
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.HP 41
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.BI "lwres_result_t lwres_noopresponse_render(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
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.HP 39
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.BI "lwres_result_t lwres_nooprequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_nooprequest_t\ **" "structp" ");"
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.HP 40
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.BI "lwres_result_t lwres_noopresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_noopresponse_t\ **" "structp" ");"
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.HP 29
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.BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
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.HP 28
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.BI "void lwres_nooprequest_free(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ **" "structp" ");"
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.SH "DESCRIPTION"
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.PP
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These are low\-level routines for creating and parsing lightweight resolver no\-op request and response messages.
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.PP
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The no\-op message is analogous to a
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\fBping\fR
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packet: a packet is sent to the resolver daemon and is simply echoed back. The opcode is intended to allow a client to determine if the server is operational or not.
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.PP
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There are four main functions for the no\-op opcode. One render function converts a no\-op request structure \(em
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\fBlwres_nooprequest_t\fR
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\(em to the lighweight resolver's canonical format. It is complemented by a parse function that converts a packet in this canonical format to a no\-op request structure. Another render function converts the no\-op response structure \(em
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\fBlwres_noopresponse_t\fR
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to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a no\-op response structure.
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.PP
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These structures are defined in
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\fIlwres/lwres.h\fR. They are shown below.
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.PP
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.RS 4
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.nf
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#define LWRES_OPCODE_NOOP 0x00000000U
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.fi
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.RE
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.sp
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.PP
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.RS 4
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.nf
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typedef struct {
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lwres_uint16_t datalength;
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unsigned char *data;
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} lwres_nooprequest_t;
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.fi
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.RE
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.sp
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.PP
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.RS 4
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.nf
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typedef struct {
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lwres_uint16_t datalength;
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unsigned char *data;
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} lwres_noopresponse_t;
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.fi
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.RE
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.sp
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.PP
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Although the structures have different types, they are identical. This is because the no\-op opcode simply echos whatever data was sent: the response is therefore identical to the request.
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.PP
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\fBlwres_nooprequest_render()\fR
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uses resolver context
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\fIctx\fR
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to convert no\-op request structure
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\fIreq\fR
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to canonical format. The packet header structure
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\fIpkt\fR
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is initialised and transferred to buffer
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\fIb\fR. The contents of
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\fI*req\fR
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are then appended to the buffer in canonical format.
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\fBlwres_noopresponse_render()\fR
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performs the same task, except it converts a no\-op response structure
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\fBlwres_noopresponse_t\fR
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to the lightweight resolver's canonical format.
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.PP
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\fBlwres_nooprequest_parse()\fR
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uses context
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\fIctx\fR
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to convert the contents of packet
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\fIpkt\fR
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to a
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\fBlwres_nooprequest_t\fR
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structure. Buffer
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\fIb\fR
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provides space to be used for storing this structure. When the function succeeds, the resulting
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\fBlwres_nooprequest_t\fR
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is made available through
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\fI*structp\fR.
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\fBlwres_noopresponse_parse()\fR
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offers the same semantics as
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\fBlwres_nooprequest_parse()\fR
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except it yields a
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\fBlwres_noopresponse_t\fR
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structure.
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.PP
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\fBlwres_noopresponse_free()\fR
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and
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\fBlwres_nooprequest_free()\fR
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release the memory in resolver context
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\fIctx\fR
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that was allocated to the
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\fBlwres_noopresponse_t\fR
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or
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\fBlwres_nooprequest_t\fR
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structures referenced via
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\fIstructp\fR.
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.SH "RETURN VALUES"
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.PP
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The no\-op opcode functions
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\fBlwres_nooprequest_render()\fR,
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\fBlwres_noopresponse_render()\fR
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\fBlwres_nooprequest_parse()\fR
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and
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\fBlwres_noopresponse_parse()\fR
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all return
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\fBLWRES_R_SUCCESS\fR
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on success. They return
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\fBLWRES_R_NOMEMORY\fR
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if memory allocation fails.
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\fBLWRES_R_UNEXPECTEDEND\fR
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is returned if the available space in the buffer
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\fIb\fR
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is too small to accommodate the packet header or the
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\fBlwres_nooprequest_t\fR
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and
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\fBlwres_noopresponse_t\fR
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structures.
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\fBlwres_nooprequest_parse()\fR
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and
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\fBlwres_noopresponse_parse()\fR
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will return
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\fBLWRES_R_UNEXPECTEDEND\fR
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if the buffer is not empty after decoding the received packet. These functions will return
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\fBLWRES_R_FAILURE\fR
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if
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\fBpktflags\fR
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in the packet header structure
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\fBlwres_lwpacket_t\fR
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indicate that the packet is not a response to an earlier query.
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.SH "SEE ALSO"
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.PP
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\fBlwres_packet\fR(3)
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.SH "COPYRIGHT"
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Copyright \(co 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
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.br
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Copyright \(co 2000, 2001 Internet Software Consortium.
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.br
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