contrib/bind-9.3/lib/lwres/man/lwres_getipnode.html

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  18 <html>
  19 <head>
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  21 <title>lwres_getipnode</title>
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  24 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
  25 <a name="id2463721"></a><div class="titlepage"></div>
  26 <div class="refnamediv">
  27 <h2>Name</h2>
  28 <p>lwres_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent &#8212; lightweight resolver nodename / address translation API</p>
  29 </div>
  30 <div class="refsynopsisdiv">
  31 <h2>Synopsis</h2>
  32 <div class="funcsynopsis">
  33 <pre class="funcsynopsisinfo">#include &lt;lwres/netdb.h&gt;</pre>
  34 <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
  35 <tr>
  36 <td><code class="funcdef">
  37 struct hostent *
  38 <b class="fsfunc">lwres_getipnodebyname</b>(</code></td>
  39 <td> </td>
  40 <td>, </td>
  41 </tr>
  42 <tr>
  43 <td> </td>
  44 <td> </td>
  45 <td>, </td>
  46 </tr>
  47 <tr>
  48 <td> </td>
  49 <td> </td>
  50 <td>, </td>
  51 </tr>
  52 <tr>
  53 <td> </td>
  54 <td> </td>
  55 <td>
  56 <code>)</code>;</td>
  57 </tr>
  58 </table>
  59 <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
  60 <tr>
  61 <td><code class="funcdef">
  62 struct hostent *
  63 <b class="fsfunc">lwres_getipnodebyaddr</b>(</code></td>
  64 <td> </td>
  65 <td>, </td>
  66 </tr>
  67 <tr>
  68 <td> </td>
  69 <td> </td>
  70 <td>, </td>
  71 </tr>
  72 <tr>
  73 <td> </td>
  74 <td> </td>
  75 <td>, </td>
  76 </tr>
  77 <tr>
  78 <td> </td>
  79 <td> </td>
  80 <td>
  81 <code>)</code>;</td>
  82 </tr>
  83 </table>
  84 <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr>
  85 <td><code class="funcdef">
  86 void
  87 <b class="fsfunc">lwres_freehostent</b>(</code></td>
  88 <td> </td>
  89 <td>
  90 <code>)</code>;</td>
  91 </tr></table>
  92 </div>
  93 </div>
  94 <div class="refsect1" lang="en">
  95 <a name="id2525896"></a><h2>DESCRIPTION</h2>
  96 <p>
  97 These functions perform thread safe, protocol independent
  98 nodename-to-address and address-to-nodename
  99 translation as defined in RFC2553.
 100 </p>
 101 <p>
 102 They use a
 103 <span class="type">struct hostent</span>
 104 which is defined in
 105 <code class="filename">namedb.h</code>:
 106 </p>
 107 <pre class="programlisting">
 108 struct  hostent {
 109         char    *h_name;        /* official name of host */
 110         char    **h_aliases;    /* alias list */
 111         int     h_addrtype;     /* host address type */
 112         int     h_length;       /* length of address */
 113         char    **h_addr_list;  /* list of addresses from name server */
 114 };
 115 #define h_addr  h_addr_list[0]  /* address, for backward compatibility */
 116 </pre>
 117 <p>
 118 </p>
 119 <p>
 120 The members of this structure are:
 121 </p>
 122 <div class="variablelist"><dl>
 123 <dt><span class="term"><code class="constant">h_name</code></span></dt>
 124 <dd><p>
 125 The official (canonical) name of the host.
 126 </p></dd>
 127 <dt><span class="term"><code class="constant">h_aliases</code></span></dt>
 128 <dd><p>
 129 A NULL-terminated array of alternate names (nicknames) for the host.
 130 </p></dd>
 131 <dt><span class="term"><code class="constant">h_addrtype</code></span></dt>
 132 <dd><p>
 133 The type of address being returned - usually
 134 <span class="type">PF_INET</span>
 135 or
 136 <span class="type">PF_INET6</span>.
 137
 138 </p></dd>
 139 <dt><span class="term"><code class="constant">h_length</code></span></dt>
 140 <dd><p>
 141 The length of the address in bytes.
 142 </p></dd>
 143 <dt><span class="term"><code class="constant">h_addr_list</code></span></dt>
 144 <dd><p>
 145 A
 146 <span class="type">NULL</span>
 147 terminated array of network addresses for the host.
 148 Host addresses are returned in network byte order.
 149 </p></dd>
 150 </dl></div>
 151 <p>
 152 </p>
 153 <p>
 154 <code class="function">lwres_getipnodebyname()</code>
 155 looks up addresses of protocol family
 156 <em class="parameter"><code>af</code></em>
 157
 158 for the hostname
 159 <em class="parameter"><code>name</code></em>.
 160
 161 The
 162 <em class="parameter"><code>flags</code></em>
 163 parameter contains ORed flag bits to
 164 specify the types of addresses that are searched
 165 for, and the types of addresses that are returned.
 166 The flag bits are:
 167 </p>
 168 <div class="variablelist"><dl>
 169 <dt><span class="term"><code class="constant">AI_V4MAPPED</code></span></dt>
 170 <dd><p>
 171 This is used with an
 172 <em class="parameter"><code>af</code></em>
 173 of AF_INET6, and causes IPv4 addresses to be returned as IPv4-mapped
 174 IPv6 addresses.
 175 </p></dd>
 176 <dt><span class="term"><code class="constant">AI_ALL</code></span></dt>
 177 <dd><p>
 178 This is used with an
 179 <em class="parameter"><code>af</code></em>
 180 of AF_INET6, and causes all known addresses (IPv6 and IPv4) to be returned.
 181 If AI_V4MAPPED is also set, the IPv4 addresses are return as mapped
 182 IPv6 addresses.
 183 </p></dd>
 184 <dt><span class="term"><code class="constant">AI_ADDRCONFIG</code></span></dt>
 185 <dd><p>
 186 Only return an IPv6 or IPv4 address if here is an active network
 187 interface of that type.  This is not currently implemented
 188 in the BIND 9 lightweight resolver, and the flag is ignored.
 189 </p></dd>
 190 <dt><span class="term"><code class="constant">AI_DEFAULT</code></span></dt>
 191 <dd><p>
 192 This default sets the
 193 <code class="constant">AI_V4MAPPED</code>
 194 and
 195 <code class="constant">AI_ADDRCONFIG</code>
 196 flag bits.
 197 </p></dd>
 198 </dl></div>
 199 <p>
 200 </p>
 201 <p>
 202 <code class="function">lwres_getipnodebyaddr()</code>
 203 performs a reverse lookup
 204 of address
 205 <em class="parameter"><code>src</code></em>
 206 which is
 207 <em class="parameter"><code>len</code></em>
 208 bytes long.
 209 <em class="parameter"><code>af</code></em>
 210 denotes the protocol family, typically
 211 <span class="type">PF_INET</span>
 212 or
 213 <span class="type">PF_INET6</span>.
 214
 215 </p>
 216 <p>
 217 <code class="function">lwres_freehostent()</code>
 218 releases all the memory associated with
 219 the
 220 <span class="type">struct hostent</span>
 221 pointer
 222 <em class="parameter"><code>he</code></em>.
 223
 224 Any memory allocated for the
 225 <code class="constant">h_name</code>,
 226
 227 <code class="constant">h_addr_list</code>
 228 and
 229 <code class="constant">h_aliases</code>
 230 is freed, as is the memory for the
 231 <span class="type">hostent</span>
 232 structure itself.
 233 </p>
 234 </div>
 235 <div class="refsect1" lang="en">
 236 <a name="id2526131"></a><h2>RETURN VALUES</h2>
 237 <p>
 238 If an error occurs,
 239 <code class="function">lwres_getipnodebyname()</code>
 240 and
 241 <code class="function">lwres_getipnodebyaddr()</code>
 242 set
 243 <em class="parameter"><code>*error_num</code></em>
 244 to an appropriate error code and the function returns a
 245 <span class="type">NULL</span>
 246 pointer.
 247 The error codes and their meanings are defined in
 248 <code class="filename">&lt;lwres/netdb.h&gt;</code>:
 249 </p>
 250 <div class="variablelist"><dl>
 251 <dt><span class="term"><code class="constant">HOST_NOT_FOUND</code></span></dt>
 252 <dd><p>
 253 No such host is known.
 254 </p></dd>
 255 <dt><span class="term"><code class="constant">NO_ADDRESS</code></span></dt>
 256 <dd><p>
 257 The server recognised the request and the name but no address is
 258 available.  Another type of request to the name server for the
 259 domain might return an answer.
 260 </p></dd>
 261 <dt><span class="term"><code class="constant">TRY_AGAIN</code></span></dt>
 262 <dd><p>
 263 A temporary and possibly transient error occurred, such as a
 264 failure of a server to respond.  The request may succeed if
 265 retried.
 266 </p></dd>
 267 <dt><span class="term"><code class="constant">NO_RECOVERY</code></span></dt>
 268 <dd><p>
 269 An unexpected failure occurred, and retrying the request
 270 is pointless.
 271 </p></dd>
 272 </dl></div>
 273 <p>
 274 </p>
 275 <p>
 276 <span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3
 277 )</span>
 278 translates these error codes to suitable error messages.
 279 </p>
 280 </div>
 281 <div class="refsect1" lang="en">
 282 <a name="id2526290"></a><h2>SEE ALSO</h2>
 283 <p>
 284 <span class="citerefentry"><span class="refentrytitle">RFC2553</span></span>,
 285
 286 <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
 287
 288 <span class="citerefentry"><span class="refentrytitle">lwres_gethostent</span>(3)</span>,
 289
 290 <span class="citerefentry"><span class="refentrytitle">lwres_getaddrinfo</span>(3)</span>,
 291
 292 <span class="citerefentry"><span class="refentrytitle">lwres_getnameinfo</span>(3)</span>,
 293
 294 <span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3)</span>.
 295 </p>
 296 </div>
 297 </div></body>
 298 </html>