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

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    21. 

  21. <title>lwres_getipnode</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_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent &#8212; lightweight resolver nodename / address translation API</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/netdb.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. struct hostent *
    38. 

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

  39. <td>const char * </td>
    40. 

  40. <td>
    41. 

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

  42. </tr>
    43. 

  43. <tr>
    44. 

  44. <td> </td>
    45. 

  45. <td>int  </td>
    46. 

  46. <td>
    47. 

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

  48. </tr>
    49. 

  49. <tr>
    50. 

  50. <td> </td>
    51. 

  51. <td>int  </td>
    52. 

  52. <td>
    53. 

  53. <var class="pdparam">flags</var>, </td>
    54. 

  54. </tr>
    55. 

  55. <tr>
    56. 

  56. <td> </td>
    57. 

  57. <td>int * </td>
    58. 

  58. <td>
    59. 

  59. <var class="pdparam">error_num</var><code>)</code>;</td>
    60. 

  60. </tr>
    61. 

  61. </table>
    62. 

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

  63. <tr>
    64. 

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

  65. struct hostent *
    66. 

  66. <b class="fsfunc">lwres_getipnodebyaddr</b>(</code></td>
    67. 

  67. <td>const void * </td>
    68. 

  68. <td>
    69. 

  69. <var class="pdparam">src</var>, </td>
    70. 

  70. </tr>
    71. 

  71. <tr>
    72. 

  72. <td> </td>
    73. 

  73. <td>size_t  </td>
    74. 

  74. <td>
    75. 

  75. <var class="pdparam">len</var>, </td>
    76. 

  76. </tr>
    77. 

  77. <tr>
    78. 

  78. <td> </td>
    79. 

  79. <td>int  </td>
    80. 

  80. <td>
    81. 

  81. <var class="pdparam">af</var>, </td>
    82. 

  82. </tr>
    83. 

  83. <tr>
    84. 

  84. <td> </td>
    85. 

  85. <td>int * </td>
    86. 

  86. <td>
    87. 

  87. <var class="pdparam">error_num</var><code>)</code>;</td>
    88. 

  88. </tr>
    89. 

  89. </table>
    90. 

  90. <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr>
    91. 

  91. <td><code class="funcdef">
    92. 

  92. void
    93. 

  93. <b class="fsfunc">lwres_freehostent</b>(</code></td>
    94. 

  94. <td>struct hostent * </td>
    95. 

  95. <td>
    96. 

  96. <var class="pdparam">he</var><code>)</code>;</td>
    97. 

  97. </tr></table>
    98. 

  98. </div>
    99. 

  99. </div>
    100. 

  100. <div class="refsect1" lang="en">
    101. 

  101. <a name="id2543435"></a><h2>DESCRIPTION</h2>
    102. 

  102. <p>
    103. 

  103.       These functions perform thread safe, protocol independent
    104. 

  104.       nodename-to-address and address-to-nodename
    105. 

  105.       translation as defined in RFC2553.
    106. 

  106.     </p>
    107. 

  107. <p>
    108. 

  108.       They use a
    109. 

  109.       <span class="type">struct hostent</span>
    110. 

  110.       which is defined in
    111. 

  111.       <code class="filename">namedb.h</code>:
    112. 

  112.     </p>
    113. 

  113. <pre class="programlisting">
    114. 

  114. struct  hostent {
    115. 

  115.         char    *h_name;        /* official name of host */
    116. 

  116.         char    **h_aliases;    /* alias list */
    117. 

  117.         int     h_addrtype;     /* host address type */
    118. 

  118.         int     h_length;       /* length of address */
    119. 

  119.         char    **h_addr_list;  /* list of addresses from name server */
    120. 

  120. };
    121. 

  121. #define h_addr  h_addr_list[0]  /* address, for backward compatibility */
    122. 

  122. </pre>
    123. 

  123. <p>
    124. 

  124.     </p>
    125. 

  125. <p>
    126. 

  126.       The members of this structure are:
    127. 

  127.       </p>
    128. 

  128. <div class="variablelist"><dl>
    129. 

  129. <dt><span class="term"><code class="constant">h_name</code></span></dt>
    130. 

  130. <dd><p>
    131. 

  131.               The official (canonical) name of the host.
    132. 

  132.             </p></dd>
    133. 

  133. <dt><span class="term"><code class="constant">h_aliases</code></span></dt>
    134. 

  134. <dd><p>
    135. 

  135.               A NULL-terminated array of alternate names (nicknames) for the
    136. 

  136.               host.
    137. 

  137.             </p></dd>
    138. 

  138. <dt><span class="term"><code class="constant">h_addrtype</code></span></dt>
    139. 

  139. <dd><p>
    140. 

  140.               The type of address being returned - usually
    141. 

  141.               <span class="type">PF_INET</span>
    142. 

  142.               or
    143. 

  143.               <span class="type">PF_INET6</span>.
    144. 

  144. 

  145.             </p></dd>
    146. 

  146. <dt><span class="term"><code class="constant">h_length</code></span></dt>
    147. 

  147. <dd><p>
    148. 

  148.               The length of the address in bytes.
    149. 

  149.             </p></dd>
    150. 

  150. <dt><span class="term"><code class="constant">h_addr_list</code></span></dt>
    151. 

  151. <dd><p>
    152. 

  152.               A
    153. 

  153.               <span class="type">NULL</span>
    154. 

  154.               terminated array of network addresses for the host.
    155. 

  155.               Host addresses are returned in network byte order.
    156. 

  156.             </p></dd>
    157. 

  157. </dl></div>
    158. 

  158. <p>
    159. 

  159.     </p>
    160. 

  160. <p><code class="function">lwres_getipnodebyname()</code>
    161. 

  161.       looks up addresses of protocol family <em class="parameter"><code>af</code></em>
    162. 

  162.       for the hostname <em class="parameter"><code>name</code></em>.  The
    163. 

  163.       <em class="parameter"><code>flags</code></em> parameter contains ORed flag bits
    164. 

  164.       to specify the types of addresses that are searched for, and the
    165. 

  165.       types of addresses that are returned.  The flag bits are:
    166. 

  166. 

  167.       </p>
    168. 

  168. <div class="variablelist"><dl>
    169. 

  169. <dt><span class="term"><code class="constant">AI_V4MAPPED</code></span></dt>
    170. 

  170. <dd><p>
    171. 

  171.               This is used with an
    172. 

  172.               <em class="parameter"><code>af</code></em>
    173. 

  173.               of AF_INET6, and causes IPv4 addresses to be returned as
    174. 

  174.               IPv4-mapped
    175. 

  175.               IPv6 addresses.
    176. 

  176.             </p></dd>
    177. 

  177. <dt><span class="term"><code class="constant">AI_ALL</code></span></dt>
    178. 

  178. <dd><p>
    179. 

  179.               This is used with an
    180. 

  180.               <em class="parameter"><code>af</code></em>
    181. 

  181.               of AF_INET6, and causes all known addresses (IPv6 and IPv4) to
    182. 

  182.               be returned.
    183. 

  183.               If AI_V4MAPPED is also set, the IPv4 addresses are return as
    184. 

  184.               mapped
    185. 

  185.               IPv6 addresses.
    186. 

  186.             </p></dd>
    187. 

  187. <dt><span class="term"><code class="constant">AI_ADDRCONFIG</code></span></dt>
    188. 

  188. <dd><p>
    189. 

  189.               Only return an IPv6 or IPv4 address if here is an active network
    190. 

  190.               interface of that type.  This is not currently implemented
    191. 

  191.               in the BIND 9 lightweight resolver, and the flag is ignored.
    192. 

  192.             </p></dd>
    193. 

  193. <dt><span class="term"><code class="constant">AI_DEFAULT</code></span></dt>
    194. 

  194. <dd><p>
    195. 

  195.               This default sets the
    196. 

  196.               <code class="constant">AI_V4MAPPED</code>
    197. 

  197.               and
    198. 

  198.               <code class="constant">AI_ADDRCONFIG</code>
    199. 

  199.               flag bits.
    200. 

  200.             </p></dd>
    201. 

  201. </dl></div>
    202. 

  202. <p>
    203. 

  203.     </p>
    204. 

  204. <p><code class="function">lwres_getipnodebyaddr()</code>
    205. 

  205.       performs a reverse lookup of address <em class="parameter"><code>src</code></em>
    206. 

  206.       which is <em class="parameter"><code>len</code></em> bytes long.
    207. 

  207.       <em class="parameter"><code>af</code></em> denotes the protocol family, typically
    208. 

  208.       <span class="type">PF_INET</span> or <span class="type">PF_INET6</span>.
    209. 

  209.     </p>
    210. 

  210. <p><code class="function">lwres_freehostent()</code>
    211. 

  211.       releases all the memory associated with the <span class="type">struct
    212. 

  212.       hostent</span> pointer <em class="parameter"><code>he</code></em>.  Any memory
    213. 

  213.       allocated for the <code class="constant">h_name</code>,
    214. 

  214.       <code class="constant">h_addr_list</code> and
    215. 

  215.       <code class="constant">h_aliases</code> is freed, as is the memory for
    216. 

  216.       the <span class="type">hostent</span> structure itself.
    217. 

  217.     </p>
    218. 

  218. </div>
    219. 

  219. <div class="refsect1" lang="en">
    220. 

  220. <a name="id2543693"></a><h2>RETURN VALUES</h2>
    221. 

  221. <p>
    222. 

  222.       If an error occurs,
    223. 

  223.       <code class="function">lwres_getipnodebyname()</code>
    224. 

  224.       and
    225. 

  225.       <code class="function">lwres_getipnodebyaddr()</code>
    226. 

  226.       set
    227. 

  227.       <em class="parameter"><code>*error_num</code></em>
    228. 

  228.       to an appropriate error code and the function returns a
    229. 

  229.       <span class="type">NULL</span>
    230. 

  230.       pointer.
    231. 

  231.       The error codes and their meanings are defined in
    232. 

  232.       <code class="filename">&lt;lwres/netdb.h&gt;</code>:
    233. 

  233.       </p>
    234. 

  234. <div class="variablelist"><dl>
    235. 

  235. <dt><span class="term"><code class="constant">HOST_NOT_FOUND</code></span></dt>
    236. 

  236. <dd><p>
    237. 

  237.               No such host is known.
    238. 

  238.             </p></dd>
    239. 

  239. <dt><span class="term"><code class="constant">NO_ADDRESS</code></span></dt>
    240. 

  240. <dd><p>
    241. 

  241.               The server recognised the request and the name but no address is
    242. 

  242.               available.  Another type of request to the name server for the
    243. 

  243.               domain might return an answer.
    244. 

  244.             </p></dd>
    245. 

  245. <dt><span class="term"><code class="constant">TRY_AGAIN</code></span></dt>
    246. 

  246. <dd><p>
    247. 

  247.               A temporary and possibly transient error occurred, such as a
    248. 

  248.               failure of a server to respond.  The request may succeed if
    249. 

  249.               retried.
    250. 

  250.             </p></dd>
    251. 

  251. <dt><span class="term"><code class="constant">NO_RECOVERY</code></span></dt>
    252. 

  252. <dd><p>
    253. 

  253.               An unexpected failure occurred, and retrying the request
    254. 

  254.               is pointless.
    255. 

  255.             </p></dd>
    256. 

  256. </dl></div>
    257. 

  257. <p>
    258. 

  258.     </p>
    259. 

  259. <p><span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3)</span>
    260. 

  260.       translates these error codes to suitable error messages.
    261. 

  261.     </p>
    262. 

  262. </div>
    263. 

  263. <div class="refsect1" lang="en">
    264. 

  264. <a name="id2543790"></a><h2>SEE ALSO</h2>
    265. 

  265. <p><span class="citerefentry"><span class="refentrytitle">RFC2553</span></span>,
    266. 

  266. 

  267.       <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
    268. 

  268. 

  269.       <span class="citerefentry"><span class="refentrytitle">lwres_gethostent</span>(3)</span>,
    270. 

  270. 

  271.       <span class="citerefentry"><span class="refentrytitle">lwres_getaddrinfo</span>(3)</span>,
    272. 

  272. 

  273.       <span class="citerefentry"><span class="refentrytitle">lwres_getnameinfo</span>(3)</span>,
    274. 

  274. 

  275.       <span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3)</span>.
    276. 

  276.     </p>
    277. 

  277. </div>
    278. 

  278. </div></body>
    279. 

  279. </html>
    280.