lwres_getnameinfo.html revision fd2597f75693a2279fdf588bd40dfe2407c42028
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<title>lwres_getnameinfo</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry">
<a name="id-1"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>lwres_getnameinfo &#8212; lightweight resolver socket address structure to hostname and
service name
</p>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="funcsynopsis">
<pre class="funcsynopsisinfo">#include &lt;lwres/netdb.h&gt;</pre>
<table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;">
<tr>
<td><code class="funcdef">
int
<b class="fsfunc">lwres_getnameinfo</b>(</code></td>
<td>const struct sockaddr *<var class="pdparam">sa</var>, </td>
</tr>
<tr>
<td>�</td>
<td>size_t <var class="pdparam">salen</var>, </td>
</tr>
<tr>
<td>�</td>
<td>char *<var class="pdparam">host</var>, </td>
</tr>
<tr>
<td>�</td>
<td>size_t <var class="pdparam">hostlen</var>, </td>
</tr>
<tr>
<td>�</td>
<td>char *<var class="pdparam">serv</var>, </td>
</tr>
<tr>
<td>�</td>
<td>size_t <var class="pdparam">servlen</var>, </td>
</tr>
<tr>
<td>�</td>
<td>int <var class="pdparam">flags</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer">�</div>
</div>
</div>
<div class="refsection">
<a name="id-1.7"></a><h2>DESCRIPTION</h2>
<p>
This function is equivalent to the
<span class="citerefentry"><span class="refentrytitle">getnameinfo</span>(3)</span> function defined in RFC2133.
<code class="function">lwres_getnameinfo()</code> returns the
hostname for the
<span class="type">struct sockaddr</span> <em class="parameter"><code>sa</code></em> which
is
<em class="parameter"><code>salen</code></em> bytes long. The hostname is of
length
<em class="parameter"><code>hostlen</code></em> and is returned via
<em class="parameter"><code>*host.</code></em> The maximum length of the
hostname is
1025 bytes: <code class="constant">NI_MAXHOST</code>.
</p>
<p> The name of the service associated with the port number in
<em class="parameter"><code>sa</code></em> is returned in <em class="parameter"><code>*serv.</code></em>
It is <em class="parameter"><code>servlen</code></em> bytes long. The
maximum length
of the service name is <code class="constant">NI_MAXSERV</code> - 32
bytes.
</p>
<p>
The <em class="parameter"><code>flags</code></em> argument sets the
following
bits:
</p>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term"><code class="constant">NI_NOFQDN</code></span></dt>
<dd><p>
A fully qualified domain name is not required for local hosts.
The local part of the fully qualified domain name is returned
instead.
</p></dd>
<dt><span class="term"><code class="constant">NI_NUMERICHOST</code></span></dt>
<dd><p>
Return the address in numeric form, as if calling inet_ntop(),
instead of a host name.
</p></dd>
<dt><span class="term"><code class="constant">NI_NAMEREQD</code></span></dt>
<dd><p>
A name is required. If the hostname cannot be found in the DNS
and
this flag is set, a non-zero error code is returned.
If the hostname is not found and the flag is not set, the
address is returned in numeric form.
</p></dd>
<dt><span class="term"><code class="constant">NI_NUMERICSERV</code></span></dt>
<dd><p>
The service name is returned as a digit string representing the
port number.
</p></dd>
<dt><span class="term"><code class="constant">NI_DGRAM</code></span></dt>
<dd><p>
Specifies that the service being looked up is a datagram
service, and causes getservbyport() to be called with a second
argument of "udp" instead of its default of "tcp". This is
required
for the few ports (512-514) that have different services for UDP
and
TCP.
</p></dd>
</dl></div>
<p>
</p>
</div>
<div class="refsection">
<a name="id-1.8"></a><h2>RETURN VALUES</h2>
<p><code class="function">lwres_getnameinfo()</code>
returns 0 on success or a non-zero error code if an error occurs.
</p>
</div>
<div class="refsection">
<a name="id-1.9"></a><h2>SEE ALSO</h2>
<p><span class="citerefentry"><span class="refentrytitle">RFC2133</span></span>,
<span class="citerefentry"><span class="refentrytitle">getservbyport</span>(3)</span>,
<span class="citerefentry"><span class="refentrytitle">lwres</span>(3)</span>,
<span class="citerefentry"><span class="refentrytitle">lwres_getnameinfo</span>(3)</span>,
<span class="citerefentry"><span class="refentrytitle">lwres_getnamebyaddr</span>(3)</span>.
<span class="citerefentry"><span class="refentrytitle">lwres_net_ntop</span>(3)</span>.
</p>
</div>
<div class="refsection">
<a name="id-1.10"></a><h2>BUGS</h2>
<p>
RFC2133 fails to define what the nonzero return values of
<span class="citerefentry"><span class="refentrytitle">getnameinfo</span>(3)</span>
are.
</p>
</div>
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