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<!-- $Id: lwres_getnameinfo.docbook,v 1.2 2004/09/20 18:00:50 mcr Exp $ -->

<refentry>

<refentryinfo>
<date>Jun 30, 2000</date>
</refentryinfo>

<refmeta>
<refentrytitle>lwres_getnameinfo</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>BIND9</refmiscinfo>
</refmeta>

<refnamediv>
<refname>lwres_getnameinfo</refname>
<refpurpose>lightweight resolver socket address structure to hostname and service name</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;lwres/netdb.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>
int
<function>lwres_getnameinfo</function></funcdef>
<paramdef>const struct sockaddr *sa</paramdef>
<paramdef>size_t salen</paramdef>
<paramdef>char *host</paramdef>
<paramdef>size_t hostlen</paramdef>
<paramdef>char *serv</paramdef>
<paramdef>size_t servlen</paramdef>
<paramdef>int flags</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>

<refsect1>
<title>DESCRIPTION</title>

<para> This function is equivalent to the <citerefentry>
<refentrytitle>getnameinfo</refentrytitle><manvolnum>3</manvolnum>
</citerefentry> function defined in RFC2133.
<function>lwres_getnameinfo()</function> returns the hostname for the
<type>struct sockaddr</type> <parameter>sa</parameter> which is
<parameter>salen</parameter> bytes long.  The hostname is of length
<parameter>hostlen</parameter> and is returned via
<parameter>*host.</parameter> The maximum length of the hostname is
1025 bytes: <constant>NI_MAXHOST</constant>.</para>

<para> The name of the service associated with the port number in
<parameter>sa</parameter> is returned in <parameter>*serv.</parameter>
It is <parameter>servlen</parameter> bytes long.  The maximum length
of the service name is <constant>NI_MAXSERV</constant> - 32 bytes.
</para>

<para> The <parameter>flags</parameter> argument sets the following
bits:
<variablelist>
<varlistentry><term><constant>NI_NOFQDN</constant></term>
<listitem>
<para>
A fully qualified domain name is not required for local hosts.
The local part of the fully qualified domain name is returned instead.
</para></listitem></varlistentry>
<varlistentry><term><constant>NI_NUMERICHOST</constant></term>
<listitem>
<para>
Return the address in numeric form, as if calling inet_ntop(),
instead of a host name.
</para></listitem></varlistentry>
<varlistentry><term><constant>NI_NAMEREQD</constant></term>
<listitem>
<para>
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.
</para></listitem></varlistentry>
<varlistentry><term><constant>NI_NUMERICSERV</constant></term>
<listitem>
<para>
The service name is returned as a digit string representing the port number.
</para></listitem></varlistentry>
<varlistentry><term><constant>NI_DGRAM</constant></term>
<listitem>
<para>
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.
</para></listitem></varlistentry>
</variablelist>
</para>
</refsect1>

<refsect1>
<title>RETURN VALUES</title>
<para>
<function>lwres_getnameinfo()</function>
returns 0 on success or a non-zero error code if an error occurs.
</para>
</refsect1>
<refsect1>
<title>SEE ALSO</title>
<para>
<citerefentry>
<refentrytitle>RFC2133</refentrytitle>
</citerefentry>,
<citerefentry>
<refentrytitle>getservbyport</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>lwres</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>lwres_getnameinfo</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>lwres_getnamebyaddr</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>.
<citerefentry>
<refentrytitle>lwres_net_ntop</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>.
</refsect1>
<refsect1>
<title>BUGS</title>
<para>
RFC2133 fails to define what the nonzero return values of
<citerefentry>
<refentrytitle>getnameinfo</refentrytitle><manvolnum>3</manvolnum>
</citerefentry>
are.
</para>
</refsect1>
</refentry>
