/contrib/bind9/lib/lwres/man/lwres_noop.html

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  18. <html>
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  19. <head>
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  20. <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    21. 

  21. <title>lwres_noop</title>
    22. 

  22. <meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
    23. 

  23. </head>
    24. 

  24. <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
    25. 

  25. <a name="id2476275"></a><div class="titlepage"></div>
    26. 

  26. <div class="refnamediv">
    27. 

  27. <h2>Name</h2>
    28. 

  28. <p>lwres_nooprequest_render, lwres_noopresponse_render, lwres_nooprequest_parse, lwres_noopresponse_parse, lwres_noopresponse_free, lwres_nooprequest_free &#8212; lightweight resolver no-op message handling</p>
    29. 

  29. </div>
    30. 

  30. <div class="refsynopsisdiv">
    31. 

  31. <h2>Synopsis</h2>
    32. 

  32. <div class="funcsynopsis">
    33. 

  33. <pre class="funcsynopsisinfo">
    34. 

  34. #include &lt;lwres/lwres.h&gt;</pre>
    35. 

  35. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    36. 

  36. <tr>
    37. 

  37. <td><code class="funcdef">
    38. 

  38. lwres_result_t
    39. 

  39. <b class="fsfunc">lwres_nooprequest_render</b>(</code></td>
    40. 

  40. <td>lwres_context_t * </td>
    41. 

  41. <td>
    42. 

  42. <var class="pdparam">ctx</var>, </td>
    43. 

  43. </tr>
    44. 

  44. <tr>
    45. 

  45. <td> </td>
    46. 

  46. <td>lwres_nooprequest_t * </td>
    47. 

  47. <td>
    48. 

  48. <var class="pdparam">req</var>, </td>
    49. 

  49. </tr>
    50. 

  50. <tr>
    51. 

  51. <td> </td>
    52. 

  52. <td>lwres_lwpacket_t * </td>
    53. 

  53. <td>
    54. 

  54. <var class="pdparam">pkt</var>, </td>
    55. 

  55. </tr>
    56. 

  56. <tr>
    57. 

  57. <td> </td>
    58. 

  58. <td>lwres_buffer_t * </td>
    59. 

  59. <td>
    60. 

  60. <var class="pdparam">b</var><code>)</code>;</td>
    61. 

  61. </tr>
    62. 

  62. </table>
    63. 

  63. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    64. 

  64. <tr>
    65. 

  65. <td><code class="funcdef">
    66. 

  66. lwres_result_t
    67. 

  67. <b class="fsfunc">lwres_noopresponse_render</b>(</code></td>
    68. 

  68. <td>lwres_context_t * </td>
    69. 

  69. <td>
    70. 

  70. <var class="pdparam">ctx</var>, </td>
    71. 

  71. </tr>
    72. 

  72. <tr>
    73. 

  73. <td> </td>
    74. 

  74. <td>lwres_noopresponse_t * </td>
    75. 

  75. <td>
    76. 

  76. <var class="pdparam">req</var>, </td>
    77. 

  77. </tr>
    78. 

  78. <tr>
    79. 

  79. <td> </td>
    80. 

  80. <td>lwres_lwpacket_t * </td>
    81. 

  81. <td>
    82. 

  82. <var class="pdparam">pkt</var>, </td>
    83. 

  83. </tr>
    84. 

  84. <tr>
    85. 

  85. <td> </td>
    86. 

  86. <td>lwres_buffer_t * </td>
    87. 

  87. <td>
    88. 

  88. <var class="pdparam">b</var><code>)</code>;</td>
    89. 

  89. </tr>
    90. 

  90. </table>
    91. 

  91. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    92. 

  92. <tr>
    93. 

  93. <td><code class="funcdef">
    94. 

  94. lwres_result_t
    95. 

  95. <b class="fsfunc">lwres_nooprequest_parse</b>(</code></td>
    96. 

  96. <td>lwres_context_t * </td>
    97. 

  97. <td>
    98. 

  98. <var class="pdparam">ctx</var>, </td>
    99. 

  99. </tr>
    100. 

  100. <tr>
    101. 

  101. <td> </td>
    102. 

  102. <td>lwres_buffer_t * </td>
    103. 

  103. <td>
    104. 

  104. <var class="pdparam">b</var>, </td>
    105. 

  105. </tr>
    106. 

  106. <tr>
    107. 

  107. <td> </td>
    108. 

  108. <td>lwres_lwpacket_t * </td>
    109. 

  109. <td>
    110. 

  110. <var class="pdparam">pkt</var>, </td>
    111. 

  111. </tr>
    112. 

  112. <tr>
    113. 

  113. <td> </td>
    114. 

  114. <td>lwres_nooprequest_t ** </td>
    115. 

  115. <td>
    116. 

  116. <var class="pdparam">structp</var><code>)</code>;</td>
    117. 

  117. </tr>
    118. 

  118. </table>
    119. 

  119. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    120. 

  120. <tr>
    121. 

  121. <td><code class="funcdef">
    122. 

  122. lwres_result_t
    123. 

  123. <b class="fsfunc">lwres_noopresponse_parse</b>(</code></td>
    124. 

  124. <td>lwres_context_t * </td>
    125. 

  125. <td>
    126. 

  126. <var class="pdparam">ctx</var>, </td>
    127. 

  127. </tr>
    128. 

  128. <tr>
    129. 

  129. <td> </td>
    130. 

  130. <td>lwres_buffer_t * </td>
    131. 

  131. <td>
    132. 

  132. <var class="pdparam">b</var>, </td>
    133. 

  133. </tr>
    134. 

  134. <tr>
    135. 

  135. <td> </td>
    136. 

  136. <td>lwres_lwpacket_t * </td>
    137. 

  137. <td>
    138. 

  138. <var class="pdparam">pkt</var>, </td>
    139. 

  139. </tr>
    140. 

  140. <tr>
    141. 

  141. <td> </td>
    142. 

  142. <td>lwres_noopresponse_t ** </td>
    143. 

  143. <td>
    144. 

  144. <var class="pdparam">structp</var><code>)</code>;</td>
    145. 

  145. </tr>
    146. 

  146. </table>
    147. 

  147. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    148. 

  148. <tr>
    149. 

  149. <td><code class="funcdef">
    150. 

  150. void
    151. 

  151. <b class="fsfunc">lwres_noopresponse_free</b>(</code></td>
    152. 

  152. <td>lwres_context_t * </td>
    153. 

  153. <td>
    154. 

  154. <var class="pdparam">ctx</var>, </td>
    155. 

  155. </tr>
    156. 

  156. <tr>
    157. 

  157. <td> </td>
    158. 

  158. <td>lwres_noopresponse_t ** </td>
    159. 

  159. <td>
    160. 

  160. <var class="pdparam">structp</var><code>)</code>;</td>
    161. 

  161. </tr>
    162. 

  162. </table>
    163. 

  163. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
    164. 

  164. <tr>
    165. 

  165. <td><code class="funcdef">
    166. 

  166. void
    167. 

  167. <b class="fsfunc">lwres_nooprequest_free</b>(</code></td>
    168. 

  168. <td>lwres_context_t * </td>
    169. 

  169. <td>
    170. 

  170. <var class="pdparam">ctx</var>, </td>
    171. 

  171. </tr>
    172. 

  172. <tr>
    173. 

  173. <td> </td>
    174. 

  174. <td>lwres_nooprequest_t ** </td>
    175. 

  175. <td>
    176. 

  176. <var class="pdparam">structp</var><code>)</code>;</td>
    177. 

  177. </tr>
    178. 

  178. </table>
    179. 

  179. </div>
    180. 

  180. </div>
    181. 

  181. <div class="refsect1" lang="en">
    182. 

  182. <a name="id2543526"></a><h2>DESCRIPTION</h2>
    183. 

  183. <p>
    184. 

  184.       These are low-level routines for creating and parsing
    185. 

  185.       lightweight resolver no-op request and response messages.
    186. 

  186.     </p>
    187. 

  187. <p>
    188. 

  188.       The no-op message is analogous to a <span><strong class="command">ping</strong></span>
    189. 

  189.       packet:
    190. 

  190.       a packet is sent to the resolver daemon and is simply echoed back.
    191. 

  191.       The opcode is intended to allow a client to determine if the server is
    192. 

  192.       operational or not.
    193. 

  193.     </p>
    194. 

  194. <p>
    195. 

  195.       There are four main functions for the no-op opcode.
    196. 

  196.       One render function converts a no-op request structure &#8212;
    197. 

  197.       <span class="type">lwres_nooprequest_t</span> &#8212;
    198. 

  198.       to the lighweight resolver's canonical format.
    199. 

  199.       It is complemented by a parse function that converts a packet in this
    200. 

  200.       canonical format to a no-op request structure.
    201. 

  201.       Another render function converts the no-op response structure &#8212;
    202. 

  202.       <span class="type">lwres_noopresponse_t</span>
    203. 

  203.       to the canonical format.
    204. 

  204.       This is complemented by a parse function which converts a packet in
    205. 

  205.       canonical format to a no-op response structure.
    206. 

  206.     </p>
    207. 

  207. <p>
    208. 

  208.       These structures are defined in
    209. 

  209.       <code class="filename">lwres/lwres.h</code>.
    210. 

  210. 

  211.       They are shown below.
    212. 

  212.     </p>
    213. 

  213. <pre class="programlisting">
    214. 

  214. #define LWRES_OPCODE_NOOP       0x00000000U
    215. 

  215. </pre>
    216. 

  216. <p>
    217. 

  217.     </p>
    218. 

  218. <pre class="programlisting">
    219. 

  219. typedef struct {
    220. 

  220.         lwres_uint16_t  datalength;
    221. 

  221.         unsigned char   *data;
    222. 

  222. } lwres_nooprequest_t;
    223. 

  223. </pre>
    224. 

  224. <p>
    225. 

  225.     </p>
    226. 

  226. <pre class="programlisting">
    227. 

  227. typedef struct {
    228. 

  228.         lwres_uint16_t  datalength;
    229. 

  229.         unsigned char   *data;
    230. 

  230. } lwres_noopresponse_t;
    231. 

  231. </pre>
    232. 

  232. <p>
    233. 

  233.     </p>
    234. 

  234. <p>
    235. 

  235.       Although the structures have different types, they are identical.
    236. 

  236.       This is because the no-op opcode simply echos whatever data was sent:
    237. 

  237.       the response is therefore identical to the request.
    238. 

  238.     </p>
    239. 

  239. <p><code class="function">lwres_nooprequest_render()</code>
    240. 

  240.       uses resolver context <em class="parameter"><code>ctx</code></em> to convert
    241. 

  241.       no-op request structure <em class="parameter"><code>req</code></em> to canonical
    242. 

  242.       format.  The packet header structure <em class="parameter"><code>pkt</code></em>
    243. 

  243.       is initialised and transferred to buffer
    244. 

  244.       <em class="parameter"><code>b</code></em>.  The contents of
    245. 

  245.       <em class="parameter"><code>*req</code></em> are then appended to the buffer in
    246. 

  246.       canonical format.
    247. 

  247.       <code class="function">lwres_noopresponse_render()</code> performs the
    248. 

  248.       same task, except it converts a no-op response structure
    249. 

  249.       <span class="type">lwres_noopresponse_t</span> to the lightweight resolver's
    250. 

  250.       canonical format.
    251. 

  251.     </p>
    252. 

  252. <p><code class="function">lwres_nooprequest_parse()</code>
    253. 

  253.       uses context <em class="parameter"><code>ctx</code></em> to convert the contents
    254. 

  254.       of packet <em class="parameter"><code>pkt</code></em> to a
    255. 

  255.       <span class="type">lwres_nooprequest_t</span> structure.  Buffer
    256. 

  256.       <em class="parameter"><code>b</code></em> provides space to be used for storing
    257. 

  257.       this structure.  When the function succeeds, the resulting
    258. 

  258.       <span class="type">lwres_nooprequest_t</span> is made available through
    259. 

  259.       <em class="parameter"><code>*structp</code></em>.
    260. 

  260.       <code class="function">lwres_noopresponse_parse()</code> offers the same
    261. 

  261.       semantics as <code class="function">lwres_nooprequest_parse()</code>
    262. 

  262.       except it yields a <span class="type">lwres_noopresponse_t</span> structure.
    263. 

  263.     </p>
    264. 

  264. <p><code class="function">lwres_noopresponse_free()</code>
    265. 

  265.       and <code class="function">lwres_nooprequest_free()</code> release the
    266. 

  266.       memory in resolver context <em class="parameter"><code>ctx</code></em> that was
    267. 

  267.       allocated to the <span class="type">lwres_noopresponse_t</span> or
    268. 

  268.       <span class="type">lwres_nooprequest_t</span> structures referenced via
    269. 

  269.       <em class="parameter"><code>structp</code></em>.
    270. 

  270.     </p>
    271. 

  271. </div>
    272. 

  272. <div class="refsect1" lang="en">
    273. 

  273. <a name="id2543676"></a><h2>RETURN VALUES</h2>
    274. 

  274. <p>
    275. 

  275.       The no-op opcode functions
    276. 

  276.       <code class="function">lwres_nooprequest_render()</code>,
    277. 

  277. 

  278.       <code class="function">lwres_noopresponse_render()</code>
    279. 

  279.       <code class="function">lwres_nooprequest_parse()</code>
    280. 

  280.       and
    281. 

  281.       <code class="function">lwres_noopresponse_parse()</code>
    282. 

  282.       all return
    283. 

  283.       <span class="errorcode">LWRES_R_SUCCESS</span>
    284. 

  284.       on success.
    285. 

  285.       They return
    286. 

  286.       <span class="errorcode">LWRES_R_NOMEMORY</span>
    287. 

  287.       if memory allocation fails.
    288. 

  288.       <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
    289. 

  289.       is returned if the available space in the buffer
    290. 

  290.       <em class="parameter"><code>b</code></em>
    291. 

  291.       is too small to accommodate the packet header or the
    292. 

  292.       <span class="type">lwres_nooprequest_t</span>
    293. 

  293.       and
    294. 

  294.       <span class="type">lwres_noopresponse_t</span>
    295. 

  295.       structures.
    296. 

  296.       <code class="function">lwres_nooprequest_parse()</code>
    297. 

  297.       and
    298. 

  298.       <code class="function">lwres_noopresponse_parse()</code>
    299. 

  299.       will return
    300. 

  300.       <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
    301. 

  301.       if the buffer is not empty after decoding the received packet.
    302. 

  302.       These functions will return
    303. 

  303.       <span class="errorcode">LWRES_R_FAILURE</span>
    304. 

  304.       if
    305. 

  305.       <code class="constant">pktflags</code>
    306. 

  306.       in the packet header structure
    307. 

  307.       <span class="type">lwres_lwpacket_t</span>
    308. 

  308.       indicate that the packet is not a response to an earlier query.
    309. 

  309.     </p>
    310. 

  310. </div>
    311. 

  311. <div class="refsect1" lang="en">
    312. 

  312. <a name="id2543742"></a><h2>SEE ALSO</h2>
    313. 

  313. <p><span class="citerefentry"><span class="refentrytitle">lwres_packet</span>(3)</span>
    314. 

  314.     </p>
    315. 

  315. </div>
    316. 

  316. </div></body>
    317. 

  317. </html>
    318.