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

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    21. 

  21. <title>lwres_resutil</title>
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  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_string_parse, lwres_addr_parse, lwres_getaddrsbyname, lwres_getnamebyaddr &#8212; lightweight resolver utility functions</p>
    29. 

  29. </div>
    30. 

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

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

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

  33. <pre class="funcsynopsisinfo">#include &lt;lwres/lwres.h&gt;</pre>
    34. 

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

  35. <tr>
    36. 

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

  37. lwres_result_t
    38. 

  38. <b class="fsfunc">lwres_string_parse</b>(</code></td>
    39. 

  39. <td>lwres_buffer_t * </td>
    40. 

  40. <td>
    41. 

  41. <var class="pdparam">b</var>, </td>
    42. 

  42. </tr>
    43. 

  43. <tr>
    44. 

  44. <td> </td>
    45. 

  45. <td>char ** </td>
    46. 

  46. <td>
    47. 

  47. <var class="pdparam">c</var>, </td>
    48. 

  48. </tr>
    49. 

  49. <tr>
    50. 

  50. <td> </td>
    51. 

  51. <td>lwres_uint16_t * </td>
    52. 

  52. <td>
    53. 

  53. <var class="pdparam">len</var><code>)</code>;</td>
    54. 

  54. </tr>
    55. 

  55. </table>
    56. 

  56. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    57. 

  57. <tr>
    58. 

  58. <td><code class="funcdef">
    59. 

  59. lwres_result_t
    60. 

  60. <b class="fsfunc">lwres_addr_parse</b>(</code></td>
    61. 

  61. <td>lwres_buffer_t * </td>
    62. 

  62. <td>
    63. 

  63. <var class="pdparam">b</var>, </td>
    64. 

  64. </tr>
    65. 

  65. <tr>
    66. 

  66. <td> </td>
    67. 

  67. <td>lwres_addr_t * </td>
    68. 

  68. <td>
    69. 

  69. <var class="pdparam">addr</var><code>)</code>;</td>
    70. 

  70. </tr>
    71. 

  71. </table>
    72. 

  72. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
    73. 

  73. <tr>
    74. 

  74. <td><code class="funcdef">
    75. 

  75. lwres_result_t
    76. 

  76. <b class="fsfunc">lwres_getaddrsbyname</b>(</code></td>
    77. 

  77. <td>lwres_context_t * </td>
    78. 

  78. <td>
    79. 

  79. <var class="pdparam">ctx</var>, </td>
    80. 

  80. </tr>
    81. 

  81. <tr>
    82. 

  82. <td> </td>
    83. 

  83. <td>const char * </td>
    84. 

  84. <td>
    85. 

  85. <var class="pdparam">name</var>, </td>
    86. 

  86. </tr>
    87. 

  87. <tr>
    88. 

  88. <td> </td>
    89. 

  89. <td>lwres_uint32_t  </td>
    90. 

  90. <td>
    91. 

  91. <var class="pdparam">addrtypes</var>, </td>
    92. 

  92. </tr>
    93. 

  93. <tr>
    94. 

  94. <td> </td>
    95. 

  95. <td>lwres_gabnresponse_t ** </td>
    96. 

  96. <td>
    97. 

  97. <var class="pdparam">structp</var><code>)</code>;</td>
    98. 

  98. </tr>
    99. 

  99. </table>
    100. 

  100. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
    101. 

  101. <tr>
    102. 

  102. <td><code class="funcdef">
    103. 

  103. lwres_result_t
    104. 

  104. <b class="fsfunc">lwres_getnamebyaddr</b>(</code></td>
    105. 

  105. <td>lwres_context_t * </td>
    106. 

  106. <td>
    107. 

  107. <var class="pdparam">ctx</var>, </td>
    108. 

  108. </tr>
    109. 

  109. <tr>
    110. 

  110. <td> </td>
    111. 

  111. <td>lwres_uint32_t  </td>
    112. 

  112. <td>
    113. 

  113. <var class="pdparam">addrtype</var>, </td>
    114. 

  114. </tr>
    115. 

  115. <tr>
    116. 

  116. <td> </td>
    117. 

  117. <td>lwres_uint16_t  </td>
    118. 

  118. <td>
    119. 

  119. <var class="pdparam">addrlen</var>, </td>
    120. 

  120. </tr>
    121. 

  121. <tr>
    122. 

  122. <td> </td>
    123. 

  123. <td>const unsigned char * </td>
    124. 

  124. <td>
    125. 

  125. <var class="pdparam">addr</var>, </td>
    126. 

  126. </tr>
    127. 

  127. <tr>
    128. 

  128. <td> </td>
    129. 

  129. <td>lwres_gnbaresponse_t ** </td>
    130. 

  130. <td>
    131. 

  131. <var class="pdparam">structp</var><code>)</code>;</td>
    132. 

  132. </tr>
    133. 

  133. </table>
    134. 

  134. </div>
    135. 

  135. </div>
    136. 

  136. <div class="refsect1" lang="en">
    137. 

  137. <a name="id2543470"></a><h2>DESCRIPTION</h2>
    138. 

  138. <p><code class="function">lwres_string_parse()</code>
    139. 

  139.       retrieves a DNS-encoded string starting the current pointer of
    140. 

  140.       lightweight resolver buffer <em class="parameter"><code>b</code></em>: i.e.
    141. 

  141.       <code class="constant">b-&gt;current</code>.  When the function returns,
    142. 

  142.       the address of the first byte of the encoded string is returned
    143. 

  143.       via <em class="parameter"><code>*c</code></em> and the length of that string is
    144. 

  144.       given by <em class="parameter"><code>*len</code></em>.  The buffer's current
    145. 

  145.       pointer is advanced to point at the character following the
    146. 

  146.       string length, the encoded string, and the trailing
    147. 

  147.       <span class="type">NULL</span> character.
    148. 

  148.     </p>
    149. 

  149. <p><code class="function">lwres_addr_parse()</code>
    150. 

  150.       extracts an address from the buffer <em class="parameter"><code>b</code></em>.
    151. 

  151.       The buffer's current pointer <code class="constant">b-&gt;current</code>
    152. 

  152.       is presumed to point at an encoded address: the address preceded
    153. 

  153.       by a 32-bit protocol family identifier and a 16-bit length
    154. 

  154.       field.  The encoded address is copied to
    155. 

  155.       <code class="constant">addr-&gt;address</code> and
    156. 

  156.       <code class="constant">addr-&gt;length</code> indicates the size in bytes
    157. 

  157.       of the address that was copied.
    158. 

  158.       <code class="constant">b-&gt;current</code> is advanced to point at the
    159. 

  159.       next byte of available data in the buffer following the encoded
    160. 

  160.       address.
    161. 

  161.     </p>
    162. 

  162. <p><code class="function">lwres_getaddrsbyname()</code>
    163. 

  163.       and <code class="function">lwres_getnamebyaddr()</code> use the
    164. 

  164.       <span class="type">lwres_gnbaresponse_t</span> structure defined below:
    165. 

  165.     </p>
    166. 

  166. <pre class="programlisting">
    167. 

  167. typedef struct {
    168. 

  168.         lwres_uint32_t          flags;
    169. 

  169.         lwres_uint16_t          naliases;
    170. 

  170.         lwres_uint16_t          naddrs;
    171. 

  171.         char                   *realname;
    172. 

  172.         char                  **aliases;
    173. 

  173.         lwres_uint16_t          realnamelen;
    174. 

  174.         lwres_uint16_t         *aliaslen;
    175. 

  175.         lwres_addrlist_t        addrs;
    176. 

  176.         void                   *base;
    177. 

  177.         size_t                  baselen;
    178. 

  178. } lwres_gabnresponse_t;
    179. 

  179. </pre>
    180. 

  180. <p>
    181. 

  181.       The contents of this structure are not manipulated directly but
    182. 

  182.       they are controlled through the
    183. 

  183.       <span class="citerefentry"><span class="refentrytitle">lwres_gabn</span>(3)</span>
    184. 

  184.       functions.
    185. 

  185.     </p>
    186. 

  186. <p>
    187. 

  187.       The lightweight resolver uses
    188. 

  188.       <code class="function">lwres_getaddrsbyname()</code> to perform
    189. 

  189.       foward lookups.
    190. 

  190.       Hostname <em class="parameter"><code>name</code></em> is looked up using the
    191. 

  191.       resolver
    192. 

  192.       context <em class="parameter"><code>ctx</code></em> for memory allocation.
    193. 

  193.       <em class="parameter"><code>addrtypes</code></em> is a bitmask indicating
    194. 

  194.       which type of
    195. 

  195.       addresses are to be looked up.  Current values for this bitmask are
    196. 

  196.       <span class="type">LWRES_ADDRTYPE_V4</span> for IPv4 addresses and
    197. 

  197.       <span class="type">LWRES_ADDRTYPE_V6</span> for IPv6 addresses.  Results of the
    198. 

  198.       lookup are returned in <em class="parameter"><code>*structp</code></em>.
    199. 

  199.     </p>
    200. 

  200. <p><code class="function">lwres_getnamebyaddr()</code>
    201. 

  201.       performs reverse lookups.  Resolver context
    202. 

  202.       <em class="parameter"><code>ctx</code></em> is used for memory allocation.  The
    203. 

  203.       address type is indicated by <em class="parameter"><code>addrtype</code></em>:
    204. 

  204.       <span class="type">LWRES_ADDRTYPE_V4</span> or
    205. 

  205.       <span class="type">LWRES_ADDRTYPE_V6</span>.  The address to be looked up is
    206. 

  206.       given by <em class="parameter"><code>addr</code></em> and its length is
    207. 

  207.       <em class="parameter"><code>addrlen</code></em> bytes.  The result of the
    208. 

  208.       function call is made available through
    209. 

  209.       <em class="parameter"><code>*structp</code></em>.
    210. 

  210.     </p>
    211. 

  211. </div>
    212. 

  212. <div class="refsect1" lang="en">
    213. 

  213. <a name="id2543609"></a><h2>RETURN VALUES</h2>
    214. 

  214. <p>
    215. 

  215.       Successful calls to
    216. 

  216.       <code class="function">lwres_string_parse()</code>
    217. 

  217.       and
    218. 

  218.       <code class="function">lwres_addr_parse()</code>
    219. 

  219.       return
    220. 

  220.       <span class="errorcode">LWRES_R_SUCCESS.</span>
    221. 

  221.       Both functions return
    222. 

  222.       <span class="errorcode">LWRES_R_FAILURE</span>
    223. 

  223.       if the buffer is corrupt or
    224. 

  224.       <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
    225. 

  225.       if the buffer has less space than expected for the components of the
    226. 

  226.       encoded string or address.
    227. 

  227.     </p>
    228. 

  228. <p><code class="function">lwres_getaddrsbyname()</code>
    229. 

  229.       returns <span class="errorcode">LWRES_R_SUCCESS</span> on success and it
    230. 

  230.       returns <span class="errorcode">LWRES_R_NOTFOUND</span> if the hostname
    231. 

  231.       <em class="parameter"><code>name</code></em> could not be found.
    232. 

  232.     </p>
    233. 

  233. <p><span class="errorcode">LWRES_R_SUCCESS</span>
    234. 

  234.       is returned by a successful call to
    235. 

  235.       <code class="function">lwres_getnamebyaddr()</code>.
    236. 

  236.     </p>
    237. 

  237. <p>
    238. 

  238.       Both
    239. 

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

  240.       and
    241. 

  241.       <code class="function">lwres_getnamebyaddr()</code>
    242. 

  242.       return
    243. 

  243.       <span class="errorcode">LWRES_R_NOMEMORY</span>
    244. 

  244.       when memory allocation requests fail and
    245. 

  245.       <span class="errorcode">LWRES_R_UNEXPECTEDEND</span>
    246. 

  246.       if the buffers used for sending queries and receiving replies are too
    247. 

  247.       small.
    248. 

  248.     </p>
    249. 

  249. </div>
    250. 

  250. <div class="refsect1" lang="en">
    251. 

  251. <a name="id2543681"></a><h2>SEE ALSO</h2>
    252. 

  252. <p><span class="citerefentry"><span class="refentrytitle">lwres_buffer</span>(3)</span>,
    253. 

  253. 

  254.       <span class="citerefentry"><span class="refentrytitle">lwres_gabn</span>(3)</span>.
    255. 

  255.     </p>
    256. 

  256. </div>
    257. 

  257. </div></body>
    258. 

  258. </html>
    259.