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27 .TH "LWRES_NOOP" "3" "2007\-06\-18" "ISC" "BIND9"
28 .\" -----------------------------------------------------------------
29 .\" * Define some portability stuff
30 .\" -----------------------------------------------------------------
31 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
32 .\" http://bugs.debian.org/507673
33 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
34 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
37 .\" -----------------------------------------------------------------
38 .\" * set default formatting
39 .\" -----------------------------------------------------------------
40 .\" disable hyphenation
42 .\" disable justification (adjust text to left margin only)
44 .\" -----------------------------------------------------------------
45 .\" * MAIN CONTENT STARTS HERE *
46 .\" -----------------------------------------------------------------
48 lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free \- lightweight resolver no\-op message handling
53 #include <lwres/lwres\&.h>
56 .HP \w'lwres_result_t\ lwres_nooprequest_render('u
57 .BI "lwres_result_t lwres_nooprequest_render(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
58 .HP \w'lwres_result_t\ lwres_noopresponse_render('u
59 .BI "lwres_result_t lwres_noopresponse_render(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
60 .HP \w'lwres_result_t\ lwres_nooprequest_parse('u
61 .BI "lwres_result_t lwres_nooprequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_nooprequest_t\ **" "structp" ");"
62 .HP \w'lwres_result_t\ lwres_noopresponse_parse('u
63 .BI "lwres_result_t lwres_noopresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_noopresponse_t\ **" "structp" ");"
64 .HP \w'void\ lwres_noopresponse_free('u
65 .BI "void lwres_noopresponse_free(lwres_context_t\ *" "ctx" ", lwres_noopresponse_t\ **" "structp" ");"
66 .HP \w'void\ lwres_nooprequest_free('u
67 .BI "void lwres_nooprequest_free(lwres_context_t\ *" "ctx" ", lwres_nooprequest_t\ **" "structp" ");"
70 These are low\-level routines for creating and parsing lightweight resolver no\-op request and response messages\&.
72 The no\-op message is analogous to a
74 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\&.
76 There are four main functions for the no\-op opcode\&. One render function converts a no\-op request structure \(em
77 \fBlwres_nooprequest_t\fR
78 \(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
79 \fBlwres_noopresponse_t\fR
80 to the canonical format\&. This is complemented by a parse function which converts a packet in canonical format to a no\-op response structure\&.
82 These structures are defined in
83 lwres/lwres\&.h\&. They are shown below\&.
89 #define LWRES_OPCODE_NOOP 0x00000000U
100 lwres_uint16_t datalength;
102 } lwres_nooprequest_t;
113 lwres_uint16_t datalength;
115 } lwres_noopresponse_t;
121 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\&.
123 \fBlwres_nooprequest_render()\fR
124 uses resolver context
126 to convert no\-op request structure
128 to canonical format\&. The packet header structure
130 is initialised and transferred to buffer
131 \fIb\fR\&. The contents of
133 are then appended to the buffer in canonical format\&.
134 \fBlwres_noopresponse_render()\fR
135 performs the same task, except it converts a no\-op response structure
136 \fBlwres_noopresponse_t\fR
137 to the lightweight resolver\*(Aqs canonical format\&.
139 \fBlwres_nooprequest_parse()\fR
142 to convert the contents of packet
145 \fBlwres_nooprequest_t\fR
148 provides space to be used for storing this structure\&. When the function succeeds, the resulting
149 \fBlwres_nooprequest_t\fR
150 is made available through
152 \fBlwres_noopresponse_parse()\fR
153 offers the same semantics as
154 \fBlwres_nooprequest_parse()\fR
156 \fBlwres_noopresponse_t\fR
159 \fBlwres_noopresponse_free()\fR
161 \fBlwres_nooprequest_free()\fR
162 release the memory in resolver context
164 that was allocated to the
165 \fBlwres_noopresponse_t\fR
167 \fBlwres_nooprequest_t\fR
168 structures referenced via
172 The no\-op opcode functions
173 \fBlwres_nooprequest_render()\fR,
174 \fBlwres_noopresponse_render()\fR\fBlwres_nooprequest_parse()\fR
176 \fBlwres_noopresponse_parse()\fR
178 \fBLWRES_R_SUCCESS\fR
179 on success\&. They return
180 \fBLWRES_R_NOMEMORY\fR
181 if memory allocation fails\&.
182 \fBLWRES_R_UNEXPECTEDEND\fR
183 is returned if the available space in the buffer
185 is too small to accommodate the packet header or the
186 \fBlwres_nooprequest_t\fR
188 \fBlwres_noopresponse_t\fR
190 \fBlwres_nooprequest_parse()\fR
192 \fBlwres_noopresponse_parse()\fR
194 \fBLWRES_R_UNEXPECTEDEND\fR
195 if the buffer is not empty after decoding the received packet\&. These functions will return
196 \fBLWRES_R_FAILURE\fR
199 in the packet header structure
200 \fBlwres_lwpacket_t\fR
201 indicate that the packet is not a response to an earlier query\&.
204 \fBlwres_packet\fR(3)
207 \fBInternet Systems Consortium, Inc\&.\fR
210 Copyright \(co 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
212 Copyright \(co 2000, 2001 Internet Software Consortium.