1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
.\" Copyright (C) 2000, 2001, 2004, 2005, 2007, 2014-2016, 2018, 2019 Internet Systems Consortium, Inc. ("ISC")
.\"
.\" This Source Code Form is subject to the terms of the Mozilla Public
.\" License, v. 2.0. If a copy of the MPL was not distributed with this
.\" file, You can obtain one at http://mozilla.org/MPL/2.0/.
.\"
.hy 0
.ad l
'\" t
.\" Title: lwres_noop
.\" Author:
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\" Date: 2007-06-18
.\" Manual: BIND9
.\" Source: ISC
.\" Language: English
.\"
.TH "LWRES_NOOP" "3" "2007\-06\-18" "ISC" "BIND9"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free \- lightweight resolver no\-op message handling
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <lwres/lwres\&.h>
.fi
.ft
.HP \w'lwres_result_t\ lwres_nooprequest_render('u
.BI "lwres_result_t lwres_nooprequest_render(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
.HP \w'lwres_result_t\ lwres_noopresponse_render('u
.BI "lwres_result_t lwres_noopresponse_render(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
.HP \w'lwres_result_t\ lwres_nooprequest_parse('u
.BI "lwres_result_t lwres_nooprequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_nooprequest_t\ **" "structp" ");"
.HP \w'lwres_result_t\ lwres_noopresponse_parse('u
.BI "lwres_result_t lwres_noopresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_noopresponse_t\ **" "structp" ");"
.HP \w'void\ lwres_noopresponse_free('u
.BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
.HP \w'void\ lwres_nooprequest_free('u
.BI "void lwres_nooprequest_free(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ **" "structp" ");"
.SH "DESCRIPTION"
.PP
These are low\-level routines for creating and parsing lightweight resolver no\-op request and response messages\&.
.PP
The no\-op message is analogous to a
\fBping\fR
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\&.
.PP
There are four main functions for the no\-op opcode\&. One render function converts a no\-op request structure \(em
\fBlwres_nooprequest_t\fR
\(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
\fBlwres_noopresponse_t\fR
to the canonical format\&. This is complemented by a parse function which converts a packet in canonical format to a no\-op response structure\&.
.PP
These structures are defined in
lwres/lwres\&.h\&. They are shown below\&.
.PP
.if n \{\
.RS 4
.\}
.nf
#define LWRES_OPCODE_NOOP 0x00000000U
.fi
.if n \{\
.RE
.\}
.PP
.if n \{\
.RS 4
.\}
.nf
typedef struct {
uint16_t datalength;
unsigned char *data;
} lwres_nooprequest_t;
.fi
.if n \{\
.RE
.\}
.PP
.if n \{\
.RS 4
.\}
.nf
typedef struct {
uint16_t datalength;
unsigned char *data;
} lwres_noopresponse_t;
.fi
.if n \{\
.RE
.\}
.PP
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\&.
.PP
\fBlwres_nooprequest_render()\fR
uses resolver context
\fIctx\fR
to convert no\-op request structure
\fIreq\fR
to canonical format\&. The packet header structure
\fIpkt\fR
is initialised and transferred to buffer
\fIb\fR\&. The contents of
\fI*req\fR
are then appended to the buffer in canonical format\&.
\fBlwres_noopresponse_render()\fR
performs the same task, except it converts a no\-op response structure
\fBlwres_noopresponse_t\fR
to the lightweight resolver\*(Aqs canonical format\&.
.PP
\fBlwres_nooprequest_parse()\fR
uses context
\fIctx\fR
to convert the contents of packet
\fIpkt\fR
to a
\fBlwres_nooprequest_t\fR
structure\&. Buffer
\fIb\fR
provides space to be used for storing this structure\&. When the function succeeds, the resulting
\fBlwres_nooprequest_t\fR
is made available through
\fI*structp\fR\&.
\fBlwres_noopresponse_parse()\fR
offers the same semantics as
\fBlwres_nooprequest_parse()\fR
except it yields a
\fBlwres_noopresponse_t\fR
structure\&.
.PP
\fBlwres_noopresponse_free()\fR
and
\fBlwres_nooprequest_free()\fR
release the memory in resolver context
\fIctx\fR
that was allocated to the
\fBlwres_noopresponse_t\fR
or
\fBlwres_nooprequest_t\fR
structures referenced via
\fIstructp\fR\&.
.SH "RETURN VALUES"
.PP
The no\-op opcode functions
\fBlwres_nooprequest_render()\fR,
\fBlwres_noopresponse_render()\fR\fBlwres_nooprequest_parse()\fR
and
\fBlwres_noopresponse_parse()\fR
all return
\fBLWRES_R_SUCCESS\fR
on success\&. They return
\fBLWRES_R_NOMEMORY\fR
if memory allocation fails\&.
\fBLWRES_R_UNEXPECTEDEND\fR
is returned if the available space in the buffer
\fIb\fR
is too small to accommodate the packet header or the
\fBlwres_nooprequest_t\fR
and
\fBlwres_noopresponse_t\fR
structures\&.
\fBlwres_nooprequest_parse()\fR
and
\fBlwres_noopresponse_parse()\fR
will return
\fBLWRES_R_UNEXPECTEDEND\fR
if the buffer is not empty after decoding the received packet\&. These functions will return
\fBLWRES_R_FAILURE\fR
if
\fBpktflags\fR
in the packet header structure
\fBlwres_lwpacket_t\fR
indicate that the packet is not a response to an earlier query\&.
.SH "SEE ALSO"
.PP
\fBlwres_packet\fR(3)
.SH "AUTHOR"
.PP
\fBInternet Systems Consortium, Inc\&.\fR
.SH "COPYRIGHT"
.br
Copyright \(co 2000, 2001, 2004, 2005, 2007, 2014-2016, 2018, 2019 Internet Systems Consortium, Inc. ("ISC")
.br
|
