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

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  18 <html>
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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="id2482688"></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>, </td>
  56 </tr>
  57 <tr>
  58 <td> </td>
  59 <td> </td>
  60 <td>
  61 <code>)</code>;</td>
  62 </tr>
  63 </table>
  64 <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" style="padding-bottom: 1em">
  65 <tr>
  66 <td><code class="funcdef">
  67 struct hostent *
  68 <b class="fsfunc">lwres_getipnodebyaddr</b>(</code></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>, </td>
  81 </tr>
  82 <tr>
  83 <td> </td>
  84 <td> </td>
  85 <td>, </td>
  86 </tr>
  87 <tr>
  88 <td> </td>
  89 <td> </td>
  90 <td>
  91 <code>)</code>;</td>
  92 </tr>
  93 </table>
  94 <table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
  95 <tr>
  96 <td><code class="funcdef">
  97 void
  98 <b class="fsfunc">lwres_freehostent</b>(</code></td>
  99 <td> </td>
 100 <td>
 101 <code>)</code>;</td>
 102 </tr>
 103 <tr>
 104 <td> </td>
 105 <td> </td>
 106 <td>
 107 <code>)</code>;</td>
 108 </tr>
 109 </table>
 110 </div>
 111 </div>
 112 <div class="refsect1" lang="en">
 113 <a name="id2549461"></a><h2>DESCRIPTION</h2>
 114 <p>
 115 These functions perform thread safe, protocol independent
 116 nodename-to-address and address-to-nodename
 117 translation as defined in RFC2553.
 118 </p>
 119 <p>
 120 They use a
 121 <span class="type">struct hostent</span>
 122 which is defined in
 123 <code class="filename">namedb.h</code>:
 124 </p>
 125 <pre class="programlisting">
 126 struct  hostent {
 127         char    *h_name;        /* official name of host */
 128         char    **h_aliases;    /* alias list */
 129         int     h_addrtype;     /* host address type */
 130         int     h_length;       /* length of address */
 131         char    **h_addr_list;  /* list of addresses from name server */
 132 };
 133 #define h_addr  h_addr_list[0]  /* address, for backward compatibility */
 134 </pre>
 135 <p>
 136 </p>
 137 <p>
 138 The members of this structure are:
 139 </p>
 140 <div class="variablelist"><dl>
 141 <dt><span class="term"><code class="constant">h_name</code></span></dt>
 142 <dd><p>
 143 The official (canonical) name of the host.
 144 </p></dd>
 145 <dt><span class="term"><code class="constant">h_aliases</code></span></dt>
 146 <dd><p>
 147 A NULL-terminated array of alternate names (nicknames) for the host.
 148 </p></dd>
 149 <dt><span class="term"><code class="constant">h_addrtype</code></span></dt>
 150 <dd><p>
 151 The type of address being returned - usually
 152 <span class="type">PF_INET</span>
 153 or
 154 <span class="type">PF_INET6</span>.
 155
 156 </p></dd>
 157 <dt><span class="term"><code class="constant">h_length</code></span></dt>
 158 <dd><p>
 159 The length of the address in bytes.
 160 </p></dd>
 161 <dt><span class="term"><code class="constant">h_addr_list</code></span></dt>
 162 <dd><p>
 163 A
 164 <span class="type">NULL</span>
 165 terminated array of network addresses for the host.
 166 Host addresses are returned in network byte order.
 167 </p></dd>
 168 </dl></div>
 169 <p>
 170 </p>
 171 <p>
 172 <code class="function">lwres_getipnodebyname()</code>
 173 looks up addresses of protocol family
 174 <em class="parameter"><code>af</code></em>
 175
 176 for the hostname
 177 <em class="parameter"><code>name</code></em>.
 178
 179 The
 180 <em class="parameter"><code>flags</code></em>
 181 parameter contains ORed flag bits to
 182 specify the types of addresses that are searched
 183 for, and the types of addresses that are returned.
 184 The flag bits are:
 185 </p>
 186 <div class="variablelist"><dl>
 187 <dt><span class="term"><code class="constant">AI_V4MAPPED</code></span></dt>
 188 <dd><p>
 189 This is used with an
 190 <em class="parameter"><code>af</code></em>
 191 of AF_INET6, and causes IPv4 addresses to be returned as IPv4-mapped
 192 IPv6 addresses.
 193 </p></dd>
 194 <dt><span class="term"><code class="constant">AI_ALL</code></span></dt>
 195 <dd><p>
 196 This is used with an
 197 <em class="parameter"><code>af</code></em>
 198 of AF_INET6, and causes all known addresses (IPv6 and IPv4) to be returned.
 199 If AI_V4MAPPED is also set, the IPv4 addresses are return as mapped
 200 IPv6 addresses.
 201 </p></dd>
 202 <dt><span class="term"><code class="constant">AI_ADDRCONFIG</code></span></dt>
 203 <dd><p>
 204 Only return an IPv6 or IPv4 address if here is an active network
 205 interface of that type.  This is not currently implemented
 206 in the BIND 9 lightweight resolver, and the flag is ignored.
 207 </p></dd>
 208 <dt><span class="term"><code class="constant">AI_DEFAULT</code></span></dt>
 209 <dd><p>
 210 This default sets the
 211 <code class="constant">AI_V4MAPPED</code>
 212 and
 213 <code class="constant">AI_ADDRCONFIG</code>
 214 flag bits.
 215 </p></dd>
 216 </dl></div>
 217 <p>
 218 </p>
 219 <p>
 220 <code class="function">lwres_getipnodebyaddr()</code>
 221 performs a reverse lookup
 222 of address
 223 <em class="parameter"><code>src</code></em>
 224 which is
 225 <em class="parameter"><code>len</code></em>
 226 bytes long.
 227 <em class="parameter"><code>af</code></em>
 228 denotes the protocol family, typically
 229 <span class="type">PF_INET</span>
 230 or
 231 <span class="type">PF_INET6</span>.
 232
 233 </p>
 234 <p>
 235 <code class="function">lwres_freehostent()</code>
 236 releases all the memory associated with
 237 the
 238 <span class="type">struct hostent</span>
 239 pointer
 240 <em class="parameter"><code>he</code></em>.
 241
 242 Any memory allocated for the
 243 <code class="constant">h_name</code>,
 244
 245 <code class="constant">h_addr_list</code>
 246 and
 247 <code class="constant">h_aliases</code>
 248 is freed, as is the memory for the
 249 <span class="type">hostent</span>
 250 structure itself.
 251 </p>
 252 </div>
 253 <div class="refsect1" lang="en">
 254 <a name="id2549832"></a><h2>RETURN VALUES</h2>
 255 <p>
 256 If an error occurs,
 257 <code class="function">lwres_getipnodebyname()</code>
 258 and
 259 <code class="function">lwres_getipnodebyaddr()</code>
 260 set
 261 <em class="parameter"><code>*error_num</code></em>
 262 to an appropriate error code and the function returns a
 263 <span class="type">NULL</span>
 264 pointer.
 265 The error codes and their meanings are defined in
 266 <code class="filename">&lt;lwres/netdb.h&gt;</code>:
 267 </p>
 268 <div class="variablelist"><dl>
 269 <dt><span class="term"><code class="constant">HOST_NOT_FOUND</code></span></dt>
 270 <dd><p>
 271 No such host is known.
 272 </p></dd>
 273 <dt><span class="term"><code class="constant">NO_ADDRESS</code></span></dt>
 274 <dd><p>
 275 The server recognised the request and the name but no address is
 276 available.  Another type of request to the name server for the
 277 domain might return an answer.
 278 </p></dd>
 279 <dt><span class="term"><code class="constant">TRY_AGAIN</code></span></dt>
 280 <dd><p>
 281 A temporary and possibly transient error occurred, such as a
 282 failure of a server to respond.  The request may succeed if
 283 retried.
 284 </p></dd>
 285 <dt><span class="term"><code class="constant">NO_RECOVERY</code></span></dt>
 286 <dd><p>
 287 An unexpected failure occurred, and retrying the request
 288 is pointless.
 289 </p></dd>
 290 </dl></div>
 291 <p>
 292 </p>
 293 <p>
 294 <span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3
 295 )</span>
 296 translates these error codes to suitable error messages.
 297 </p>
 298 </div>
 299 <div class="refsect1" lang="en">
 300 <a name="id2549923"></a><h2>SEE ALSO</h2>
 301 <p>
 302 <span class="citerefentry"><span class="refentrytitle">RFC2553</span></span>,
 303
 304 <span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
 305
 306 <span class="citerefentry"><span class="refentrytitle">lwres_gethostent</span>(3)</span>,
 307
 308 <span class="citerefentry"><span class="refentrytitle">lwres_getaddrinfo</span>(3)</span>,
 309
 310 <span class="citerefentry"><span class="refentrytitle">lwres_getnameinfo</span>(3)</span>,
 311
 312 <span class="citerefentry"><span class="refentrytitle">lwres_hstrerror</span>(3)</span>.
 313 </p>
 314 </div>
 315 </div></body>
 316 </html>