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1 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN"> |
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18 | ||
19 | <!-- $Id: lwres_gabn.docbook,v 1.1 2004/03/15 20:35:25 as Exp $ --> | |
20 | ||
21 | <refentry> | |
22 | <refentryinfo> | |
23 | ||
24 | ||
25 | <date>Jun 30, 2000</date> | |
26 | </refentryinfo> | |
27 | <refmeta> | |
28 | <refentrytitle>lwres_gabn</refentrytitle> | |
29 | <manvolnum>3</manvolnum> | |
30 | <refmiscinfo>BIND9</refmiscinfo> | |
31 | </refmeta> | |
32 | <refnamediv> | |
33 | <refname>lwres_gabnrequest_render</refname> | |
34 | <refname>lwres_gabnresponse_render</refname> | |
35 | <refname>lwres_gabnrequest_parse</refname> | |
36 | <refname>lwres_gabnresponse_parse</refname> | |
37 | <refname>lwres_gabnresponse_free</refname> | |
38 | <refname>lwres_gabnrequest_free</refname> | |
39 | <refpurpose>lightweight resolver getaddrbyname message handling</refpurpose> | |
40 | </refnamediv> | |
41 | <refsynopsisdiv> | |
42 | <funcsynopsis> | |
43 | <funcsynopsisinfo>#include <lwres/lwres.h></funcsynopsisinfo> | |
44 | <funcprototype> | |
45 | <funcdef> | |
46 | lwres_result_t | |
47 | <function>lwres_gabnrequest_render</function></funcdef> | |
48 | <paramdef>lwres_context_t *ctx</paramdef> | |
49 | <paramdef>lwres_gabnrequest_t *req</paramdef> | |
50 | <paramdef>lwres_lwpacket_t *pkt</paramdef> | |
51 | <paramdef>lwres_buffer_t *b</paramdef> | |
52 | </funcprototype> | |
53 | <funcprototype> | |
54 | <funcdef> | |
55 | lwres_result_t | |
56 | <function>lwres_gabnresponse_render</function></funcdef> | |
57 | <paramdef>lwres_context_t *ctx</paramdef> | |
58 | <paramdef>lwres_gabnresponse_t *req</paramdef> | |
59 | <paramdef>lwres_lwpacket_t *pkt</paramdef> | |
60 | <paramdef>lwres_buffer_t *b</paramdef> | |
61 | </funcprototype> | |
62 | <funcprototype> | |
63 | <funcdef> | |
64 | lwres_result_t | |
65 | <function>lwres_gabnrequest_parse</function></funcdef> | |
66 | <paramdef>lwres_context_t *ctx</paramdef> | |
67 | <paramdef>lwres_buffer_t *b</paramdef> | |
68 | <paramdef>lwres_lwpacket_t *pkt</paramdef> | |
69 | <paramdef>lwres_gabnrequest_t **structp</paramdef> | |
70 | </funcprototype> | |
71 | <funcprototype> | |
72 | <funcdef> | |
73 | lwres_result_t | |
74 | <function>lwres_gabnresponse_parse</function></funcdef> | |
75 | <paramdef>lwres_context_t *ctx</paramdef> | |
76 | <paramdef>lwres_buffer_t *b</paramdef> | |
77 | <paramdef>lwres_lwpacket_t *pkt</paramdef> | |
78 | <paramdef>lwres_gabnresponse_t **structp</paramdef> | |
79 | </funcprototype> | |
80 | <funcprototype> | |
81 | <funcdef> | |
82 | void | |
83 | <function>lwres_gabnresponse_free</function></funcdef> | |
84 | <paramdef>lwres_context_t *ctx</paramdef> | |
85 | <paramdef>lwres_gabnresponse_t **structp</paramdef> | |
86 | </funcprototype> | |
87 | <funcprototype> | |
88 | <funcdef> | |
89 | void | |
90 | <function>lwres_gabnrequest_free</function></funcdef> | |
91 | <paramdef>lwres_context_t *ctx</paramdef> | |
92 | <paramdef>lwres_gabnrequest_t **structp</paramdef> | |
93 | </funcprototype> | |
94 | </funcsynopsis> | |
95 | </refsynopsisdiv> | |
96 | <refsect1> | |
97 | <title>DESCRIPTION</title> | |
98 | <para> | |
99 | These are low-level routines for creating and parsing | |
100 | lightweight resolver name-to-address lookup request and | |
101 | response messages. | |
102 | </para><para> | |
103 | There are four main functions for the getaddrbyname opcode. | |
104 | One render function converts a getaddrbyname request structure — | |
105 | <type>lwres_gabnrequest_t</type> — | |
106 | to the lighweight resolver's canonical format. | |
107 | It is complemented by a parse function that converts a packet in this | |
108 | canonical format to a getaddrbyname request structure. | |
109 | Another render function converts the getaddrbyname response structure — | |
110 | <type>lwres_gabnresponse_t</type> — | |
111 | to the canonical format. | |
112 | This is complemented by a parse function which converts a packet in | |
113 | canonical format to a getaddrbyname response structure. | |
114 | </para> | |
115 | <para> | |
116 | These structures are defined in | |
117 | <filename><lwres/lwres.h></filename>. | |
118 | They are shown below. | |
119 | <programlisting> | |
120 | #define LWRES_OPCODE_GETADDRSBYNAME 0x00010001U | |
121 | ||
122 | typedef struct lwres_addr lwres_addr_t; | |
123 | typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t; | |
124 | ||
125 | typedef struct { | |
126 | lwres_uint32_t flags; | |
127 | lwres_uint32_t addrtypes; | |
128 | lwres_uint16_t namelen; | |
129 | char *name; | |
130 | } lwres_gabnrequest_t; | |
131 | ||
132 | typedef struct { | |
133 | lwres_uint32_t flags; | |
134 | lwres_uint16_t naliases; | |
135 | lwres_uint16_t naddrs; | |
136 | char *realname; | |
137 | char **aliases; | |
138 | lwres_uint16_t realnamelen; | |
139 | lwres_uint16_t *aliaslen; | |
140 | lwres_addrlist_t addrs; | |
141 | void *base; | |
142 | size_t baselen; | |
143 | } lwres_gabnresponse_t; | |
144 | </programlisting> | |
145 | </para> | |
146 | <para> | |
147 | <function>lwres_gabnrequest_render()</function> | |
148 | uses resolver context | |
149 | <parameter>ctx</parameter> | |
150 | to convert getaddrbyname request structure | |
151 | <parameter>req</parameter> | |
152 | to canonical format. | |
153 | The packet header structure | |
154 | <parameter>pkt</parameter> | |
155 | is initialised and transferred to | |
156 | buffer | |
157 | <parameter>b</parameter>. | |
158 | ||
159 | The contents of | |
160 | <parameter>*req</parameter> | |
161 | are then appended to the buffer in canonical format. | |
162 | <function>lwres_gabnresponse_render()</function> | |
163 | performs the same task, except it converts a getaddrbyname response structure | |
164 | <type>lwres_gabnresponse_t</type> | |
165 | to the lightweight resolver's canonical format. | |
166 | </para> | |
167 | <para> | |
168 | <function>lwres_gabnrequest_parse()</function> | |
169 | uses context | |
170 | <parameter>ctx</parameter> | |
171 | to convert the contents of packet | |
172 | <parameter>pkt</parameter> | |
173 | to a | |
174 | <type>lwres_gabnrequest_t</type> | |
175 | structure. | |
176 | Buffer | |
177 | <parameter>b</parameter> | |
178 | provides space to be used for storing this structure. | |
179 | When the function succeeds, the resulting | |
180 | <type>lwres_gabnrequest_t</type> | |
181 | is made available through | |
182 | <parameter>*structp</parameter>. | |
183 | ||
184 | <function>lwres_gabnresponse_parse()</function> | |
185 | offers the same semantics as | |
186 | <function>lwres_gabnrequest_parse()</function> | |
187 | except it yields a | |
188 | <type>lwres_gabnresponse_t</type> | |
189 | structure. | |
190 | </para> | |
191 | <para> | |
192 | <function>lwres_gabnresponse_free()</function> | |
193 | and | |
194 | <function>lwres_gabnrequest_free()</function> | |
195 | release the memory in resolver context | |
196 | <parameter>ctx</parameter> | |
197 | that was allocated to the | |
198 | <type>lwres_gabnresponse_t</type> | |
199 | or | |
200 | <type>lwres_gabnrequest_t</type> | |
201 | structures referenced via | |
202 | <parameter>structp</parameter>. | |
203 | ||
204 | Any memory associated with ancillary buffers and strings for those | |
205 | structures is also discarded. | |
206 | </para> | |
207 | </refsect1> | |
208 | <refsect1> | |
209 | <title>RETURN VALUES</title> | |
210 | <para> | |
211 | The getaddrbyname opcode functions | |
212 | <function>lwres_gabnrequest_render()</function>, | |
213 | <function>lwres_gabnresponse_render()</function> | |
214 | <function>lwres_gabnrequest_parse()</function> | |
215 | and | |
216 | <function>lwres_gabnresponse_parse()</function> | |
217 | all return | |
218 | <errorcode>LWRES_R_SUCCESS</errorcode> | |
219 | on success. | |
220 | They return | |
221 | <errorcode>LWRES_R_NOMEMORY</errorcode> | |
222 | if memory allocation fails. | |
223 | <errorcode>LWRES_R_UNEXPECTEDEND</errorcode> | |
224 | is returned if the available space in the buffer | |
225 | <parameter>b</parameter> | |
226 | is too small to accommodate the packet header or the | |
227 | <type>lwres_gabnrequest_t</type> | |
228 | and | |
229 | <type>lwres_gabnresponse_t</type> | |
230 | structures. | |
231 | <function>lwres_gabnrequest_parse()</function> | |
232 | and | |
233 | <function>lwres_gabnresponse_parse()</function> | |
234 | will return | |
235 | <errorcode>LWRES_R_UNEXPECTEDEND</errorcode> | |
236 | if the buffer is not empty after decoding the received packet. | |
237 | These functions will return | |
238 | <errorcode>LWRES_R_FAILURE</errorcode> | |
239 | if | |
240 | <structfield>pktflags</structfield> | |
241 | in the packet header structure | |
242 | <type>lwres_lwpacket_t</type> | |
243 | indicate that the packet is not a response to an earlier query. | |
244 | </para> | |
245 | </refsect1> | |
246 | <refsect1> | |
247 | <title>SEE ALSO</title> | |
248 | <para> | |
249 | <citerefentry> | |
250 | <refentrytitle>lwres_packet</refentrytitle><manvolnum>3 | |
251 | </manvolnum> | |
252 | </citerefentry> | |
253 | </para> | |
254 | </refsect1> | |
255 | </refentry> |