203 lines
6.7 KiB
Groff
203 lines
6.7 KiB
Groff
.\" Copyright (C) 2000, 2001, 2004, 2005, 2007, 2014-2016 Internet Systems Consortium, Inc. ("ISC")
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.\"
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.\" This Source Code Form is subject to the terms of the Mozilla Public
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.\" License, v. 2.0. If a copy of the MPL was not distributed with this
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.\" file, You can obtain one at http://mozilla.org/MPL/2.0/.
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.\"
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.hy 0
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.ad l
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'\" t
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.\" Title: lwres_noop
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.\" Author:
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.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
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.\" Date: 2007-06-18
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.\" Manual: BIND9
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.\" Source: ISC
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.\" Language: English
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.\"
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.TH "LWRES_NOOP" "3" "2007\-06\-18" "ISC" "BIND9"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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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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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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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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.sp
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.ft B
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.nf
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#include <lwres/lwres\&.h>
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.fi
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.ft
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.HP \w'lwres_result_t\ lwres_nooprequest_render('u
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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 \w'lwres_result_t\ lwres_noopresponse_render('u
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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 \w'lwres_result_t\ lwres_nooprequest_parse('u
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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 \w'lwres_result_t\ lwres_noopresponse_parse('u
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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 \w'void\ lwres_noopresponse_free('u
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.BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
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.HP \w'void\ lwres_nooprequest_free('u
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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 lightweight resolver\*(Aqs 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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lwres/lwres\&.h\&. They are shown below\&.
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.PP
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.if n \{\
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.RS 4
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.\}
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.nf
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#define LWRES_OPCODE_NOOP 0x00000000U
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.fi
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.if n \{\
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.RE
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.\}
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.PP
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.if n \{\
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.RS 4
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.\}
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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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.if n \{\
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.RE
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.\}
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.PP
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.if n \{\
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.RS 4
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.\}
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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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.if n \{\
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.RE
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.\}
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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\*(Aqs 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\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 "AUTHOR"
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.PP
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\fBInternet Systems Consortium, Inc\&.\fR
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.SH "COPYRIGHT"
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.br
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Copyright \(co 2000, 2001, 2004, 2005, 2007, 2014-2016 Internet Systems Consortium, Inc. ("ISC")
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.br
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