/contrib/bind9/lib/lwres/man/lwres_noop.html
HTML | 317 lines | 298 code | 2 blank | 17 comment | 0 complexity | 16a817d8e1522b11e3a5a36f8dd89134 MD5 | raw file
1<!-- 2 - Copyright (C) 2004, 2005, 2007, 2012 Internet Systems Consortium, Inc. ("ISC") 3 - Copyright (C) 2000, 2001 Internet Software Consortium. 4 - 5 - Permission to use, copy, modify, and/or distribute this software for any 6 - purpose with or without fee is hereby granted, provided that the above 7 - copyright notice and this permission notice appear in all copies. 8 - 9 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 - PERFORMANCE OF THIS SOFTWARE. 16--> 17<!-- $Id$ --> 18<html> 19<head> 20<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 21<title>lwres_noop</title> 22<meta name="generator" content="DocBook XSL Stylesheets V1.71.1"> 23</head> 24<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en"> 25<a name="id2476275"></a><div class="titlepage"></div> 26<div class="refnamediv"> 27<h2>Name</h2> 28<p>lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free — lightweight resolver no-op message handling</p> 29</div> 30<div class="refsynopsisdiv"> 31<h2>Synopsis</h2> 32<div class="funcsynopsis"> 33<pre class="funcsynopsisinfo"> 34#include <lwres/lwres.h></pre> 35<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"> 36<tr> 37<td><code class="funcdef"> 38lwres_result_t 39<b class="fsfunc">lwres_nooprequest_render</b>(</code></td> 40<td>lwres_context_t * </td> 41<td> 42<var class="pdparam">ctx</var>, </td> 43</tr> 44<tr> 45<td> </td> 46<td>lwres_nooprequest_t * </td> 47<td> 48<var class="pdparam">req</var>, </td> 49</tr> 50<tr> 51<td> </td> 52<td>lwres_lwpacket_t * </td> 53<td> 54<var class="pdparam">pkt</var>, </td> 55</tr> 56<tr> 57<td> </td> 58<td>lwres_buffer_t * </td> 59<td> 60<var class="pdparam">b</var><code>)</code>;</td> 61</tr> 62</table> 63<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"> 64<tr> 65<td><code class="funcdef"> 66lwres_result_t 67<b class="fsfunc">lwres_noopresponse_render</b>(</code></td> 68<td>lwres_context_t * </td> 69<td> 70<var class="pdparam">ctx</var>, </td> 71</tr> 72<tr> 73<td> </td> 74<td>lwres_noopresponse_t * </td> 75<td> 76<var class="pdparam">req</var>, </td> 77</tr> 78<tr> 79<td> </td> 80<td>lwres_lwpacket_t * </td> 81<td> 82<var class="pdparam">pkt</var>, </td> 83</tr> 84<tr> 85<td> </td> 86<td>lwres_buffer_t * </td> 87<td> 88<var class="pdparam">b</var><code>)</code>;</td> 89</tr> 90</table> 91<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"> 92<tr> 93<td><code class="funcdef"> 94lwres_result_t 95<b class="fsfunc">lwres_nooprequest_parse</b>(</code></td> 96<td>lwres_context_t * </td> 97<td> 98<var class="pdparam">ctx</var>, </td> 99</tr> 100<tr> 101<td> </td> 102<td>lwres_buffer_t * </td> 103<td> 104<var class="pdparam">b</var>, </td> 105</tr> 106<tr> 107<td> </td> 108<td>lwres_lwpacket_t * </td> 109<td> 110<var class="pdparam">pkt</var>, </td> 111</tr> 112<tr> 113<td> </td> 114<td>lwres_nooprequest_t ** </td> 115<td> 116<var class="pdparam">structp</var><code>)</code>;</td> 117</tr> 118</table> 119<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"> 120<tr> 121<td><code class="funcdef"> 122lwres_result_t 123<b class="fsfunc">lwres_noopresponse_parse</b>(</code></td> 124<td>lwres_context_t * </td> 125<td> 126<var class="pdparam">ctx</var>, </td> 127</tr> 128<tr> 129<td> </td> 130<td>lwres_buffer_t * </td> 131<td> 132<var class="pdparam">b</var>, </td> 133</tr> 134<tr> 135<td> </td> 136<td>lwres_lwpacket_t * </td> 137<td> 138<var class="pdparam">pkt</var>, </td> 139</tr> 140<tr> 141<td> </td> 142<td>lwres_noopresponse_t ** </td> 143<td> 144<var class="pdparam">structp</var><code>)</code>;</td> 145</tr> 146</table> 147<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em"> 148<tr> 149<td><code class="funcdef"> 150void 151<b class="fsfunc">lwres_noopresponse_free</b>(</code></td> 152<td>lwres_context_t * </td> 153<td> 154<var class="pdparam">ctx</var>, </td> 155</tr> 156<tr> 157<td> </td> 158<td>lwres_noopresponse_t ** </td> 159<td> 160<var class="pdparam">structp</var><code>)</code>;</td> 161</tr> 162</table> 163<table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"> 164<tr> 165<td><code class="funcdef"> 166void 167<b class="fsfunc">lwres_nooprequest_free</b>(</code></td> 168<td>lwres_context_t * </td> 169<td> 170<var class="pdparam">ctx</var>, </td> 171</tr> 172<tr> 173<td> </td> 174<td>lwres_nooprequest_t ** </td> 175<td> 176<var class="pdparam">structp</var><code>)</code>;</td> 177</tr> 178</table> 179</div> 180</div> 181<div class="refsect1" lang="en"> 182<a name="id2543526"></a><h2>DESCRIPTION</h2> 183<p> 184 These are low-level routines for creating and parsing 185 lightweight resolver no-op request and response messages. 186 </p> 187<p> 188 The no-op message is analogous to a <span><strong class="command">ping</strong></span> 189 packet: 190 a packet is sent to the resolver daemon and is simply echoed back. 191 The opcode is intended to allow a client to determine if the server is 192 operational or not. 193 </p> 194<p> 195 There are four main functions for the no-op opcode. 196 One render function converts a no-op request structure — 197 <span class="type">lwres_nooprequest_t</span> — 198 to the lighweight resolver's canonical format. 199 It is complemented by a parse function that converts a packet in this 200 canonical format to a no-op request structure. 201 Another render function converts the no-op response structure — 202 <span class="type">lwres_noopresponse_t</span> 203 to the canonical format. 204 This is complemented by a parse function which converts a packet in 205 canonical format to a no-op response structure. 206 </p> 207<p> 208 These structures are defined in 209 <code class="filename">lwres/lwres.h</code>. 210 211 They are shown below. 212 </p> 213<pre class="programlisting"> 214#define LWRES_OPCODE_NOOP 0x00000000U 215</pre> 216<p> 217 </p> 218<pre class="programlisting"> 219typedef struct { 220 lwres_uint16_t datalength; 221 unsigned char *data; 222} lwres_nooprequest_t; 223</pre> 224<p> 225 </p> 226<pre class="programlisting"> 227typedef struct { 228 lwres_uint16_t datalength; 229 unsigned char *data; 230} lwres_noopresponse_t; 231</pre> 232<p> 233 </p> 234<p> 235 Although the structures have different types, they are identical. 236 This is because the no-op opcode simply echos whatever data was sent: 237 the response is therefore identical to the request. 238 </p> 239<p><code class="function">lwres_nooprequest_render()</code> 240 uses resolver context <em class="parameter"><code>ctx</code></em> to convert 241 no-op request structure <em class="parameter"><code>req</code></em> to canonical 242 format. The packet header structure <em class="parameter"><code>pkt</code></em> 243 is initialised and transferred to buffer 244 <em class="parameter"><code>b</code></em>. The contents of 245 <em class="parameter"><code>*req</code></em> are then appended to the buffer in 246 canonical format. 247 <code class="function">lwres_noopresponse_render()</code> performs the 248 same task, except it converts a no-op response structure 249 <span class="type">lwres_noopresponse_t</span> to the lightweight resolver's 250 canonical format. 251 </p> 252<p><code class="function">lwres_nooprequest_parse()</code> 253 uses context <em class="parameter"><code>ctx</code></em> to convert the contents 254 of packet <em class="parameter"><code>pkt</code></em> to a 255 <span class="type">lwres_nooprequest_t</span> structure. Buffer 256 <em class="parameter"><code>b</code></em> provides space to be used for storing 257 this structure. When the function succeeds, the resulting 258 <span class="type">lwres_nooprequest_t</span> is made available through 259 <em class="parameter"><code>*structp</code></em>. 260 <code class="function">lwres_noopresponse_parse()</code> offers the same 261 semantics as <code class="function">lwres_nooprequest_parse()</code> 262 except it yields a <span class="type">lwres_noopresponse_t</span> structure. 263 </p> 264<p><code class="function">lwres_noopresponse_free()</code> 265 and <code class="function">lwres_nooprequest_free()</code> release the 266 memory in resolver context <em class="parameter"><code>ctx</code></em> that was 267 allocated to the <span class="type">lwres_noopresponse_t</span> or 268 <span class="type">lwres_nooprequest_t</span> structures referenced via 269 <em class="parameter"><code>structp</code></em>. 270 </p> 271</div> 272<div class="refsect1" lang="en"> 273<a name="id2543676"></a><h2>RETURN VALUES</h2> 274<p> 275 The no-op opcode functions 276 <code class="function">lwres_nooprequest_render()</code>, 277 278 <code class="function">lwres_noopresponse_render()</code> 279 <code class="function">lwres_nooprequest_parse()</code> 280 and 281 <code class="function">lwres_noopresponse_parse()</code> 282 all return 283 <span class="errorcode">LWRES_R_SUCCESS</span> 284 on success. 285 They return 286 <span class="errorcode">LWRES_R_NOMEMORY</span> 287 if memory allocation fails. 288 <span class="errorcode">LWRES_R_UNEXPECTEDEND</span> 289 is returned if the available space in the buffer 290 <em class="parameter"><code>b</code></em> 291 is too small to accommodate the packet header or the 292 <span class="type">lwres_nooprequest_t</span> 293 and 294 <span class="type">lwres_noopresponse_t</span> 295 structures. 296 <code class="function">lwres_nooprequest_parse()</code> 297 and 298 <code class="function">lwres_noopresponse_parse()</code> 299 will return 300 <span class="errorcode">LWRES_R_UNEXPECTEDEND</span> 301 if the buffer is not empty after decoding the received packet. 302 These functions will return 303 <span class="errorcode">LWRES_R_FAILURE</span> 304 if 305 <code class="constant">pktflags</code> 306 in the packet header structure 307 <span class="type">lwres_lwpacket_t</span> 308 indicate that the packet is not a response to an earlier query. 309 </p> 310</div> 311<div class="refsect1" lang="en"> 312<a name="id2543742"></a><h2>SEE ALSO</h2> 313<p><span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3)</span> 314 </p> 315</div> 316</div></body> 317</html>