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]>
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- Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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-
|
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- This Source Code Form is subject to the terms of the Mozilla Public
|
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- License, v. 2.0. If a copy of the MPL was not distributed with this
|
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704ed8 |
- file, you can obtain one at https://mozilla.org/MPL/2.0/.
|
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-
|
|
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- See the COPYRIGHT file distributed with this work for additional
|
|
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- information regarding copyright ownership.
|
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5ce601 |
-->
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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0">
|
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<info>
|
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<date>2007-06-18</date>
|
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</info>
|
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<refentryinfo>
|
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<corpname>ISC</corpname>
|
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<corpauthor>Internet Systems Consortium, Inc.</corpauthor>
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</refentryinfo>
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|
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<refmeta>
|
|
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<refentrytitle>lwres_gethostent</refentrytitle>
|
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<manvolnum>3</manvolnum>
|
|
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d3afd5 |
<refmiscinfo>BIND9</refmiscinfo>
|
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</refmeta>
|
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|
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<docinfo>
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<copyright>
|
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<year>2001</year>
|
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<year>2004</year>
|
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<year>2005</year>
|
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<year>2007</year>
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<year>2014</year>
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<year>2015</year>
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<year>2016</year>
|
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<year>2018</year>
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<year>2019</year>
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<year>2020</year>
|
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<holder>Internet Systems Consortium, Inc. ("ISC")</holder>
|
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</copyright>
|
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</docinfo>
|
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|
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<refnamediv>
|
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<refname>lwres_gethostbyname</refname>
|
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<refname>lwres_gethostbyname2</refname>
|
|
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<refname>lwres_gethostbyaddr</refname>
|
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<refname>lwres_gethostent</refname>
|
|
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<refname>lwres_sethostent</refname>
|
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<refname>lwres_endhostent</refname>
|
|
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<refname>lwres_gethostbyname_r</refname>
|
|
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<refname>lwres_gethostbyaddr_r</refname>
|
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<refname>lwres_gethostent_r</refname>
|
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<refname>lwres_sethostent_r</refname>
|
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<refname>lwres_endhostent_r</refname>
|
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<refpurpose>lightweight resolver get network host entry</refpurpose>
|
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</refnamediv>
|
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<refsynopsisdiv>
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<funcsynopsis>
|
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<funcsynopsisinfo>#include <lwres/netdb.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>
|
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struct hostent *
|
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<function>lwres_gethostbyname</function></funcdef>
|
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<paramdef>const char *<parameter>name</parameter></paramdef>
|
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</funcprototype>
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<funcprototype>
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<funcdef>
|
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struct hostent *
|
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<function>lwres_gethostbyname2</function></funcdef>
|
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<paramdef>const char *<parameter>name</parameter></paramdef>
|
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<paramdef>int <parameter>af</parameter></paramdef>
|
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</funcprototype>
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<funcprototype>
|
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<funcdef>
|
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struct hostent *
|
|
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<function>lwres_gethostbyaddr</function></funcdef>
|
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<paramdef>const char *<parameter>addr</parameter></paramdef>
|
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<paramdef>int <parameter>len</parameter></paramdef>
|
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<paramdef>int <parameter>type</parameter></paramdef>
|
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</funcprototype>
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<funcprototype>
|
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<funcdef>
|
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struct hostent *
|
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<function>lwres_gethostent</function></funcdef>
|
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<paramdef>void</paramdef>
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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void
|
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<function>lwres_sethostent</function></funcdef>
|
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<paramdef>int <parameter>stayopen</parameter></paramdef>
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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void
|
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<function>lwres_endhostent</function></funcdef>
|
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<paramdef>void</paramdef>
|
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</funcprototype>
|
|
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<funcprototype>
|
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<funcdef>
|
|
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struct hostent *
|
|
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<function>lwres_gethostbyname_r</function></funcdef>
|
|
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<paramdef>const char *<parameter>name</parameter></paramdef>
|
|
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<paramdef>struct hostent *<parameter>resbuf</parameter></paramdef>
|
|
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<paramdef>char *<parameter>buf</parameter></paramdef>
|
|
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<paramdef>int <parameter>buflen</parameter></paramdef>
|
|
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<paramdef>int *<parameter>error</parameter></paramdef>
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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struct hostent *
|
|
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<function>lwres_gethostbyaddr_r</function></funcdef>
|
|
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<paramdef>const char *<parameter>addr</parameter></paramdef>
|
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<paramdef>int <parameter>len</parameter></paramdef>
|
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<paramdef>int <parameter>type</parameter></paramdef>
|
|
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<paramdef>struct hostent *<parameter>resbuf</parameter></paramdef>
|
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<paramdef>char *<parameter>buf</parameter></paramdef>
|
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<paramdef>int <parameter>buflen</parameter></paramdef>
|
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<paramdef>int *<parameter>error</parameter></paramdef>
|
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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struct hostent *
|
|
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<function>lwres_gethostent_r</function></funcdef>
|
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<paramdef>struct hostent *<parameter>resbuf</parameter></paramdef>
|
|
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<paramdef>char *<parameter>buf</parameter></paramdef>
|
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<paramdef>int <parameter>buflen</parameter></paramdef>
|
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<paramdef>int *<parameter>error</parameter></paramdef>
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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void
|
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<function>lwres_sethostent_r</function></funcdef>
|
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<paramdef>int <parameter>stayopen</parameter></paramdef>
|
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</funcprototype>
|
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<funcprototype>
|
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<funcdef>
|
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void
|
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<function>lwres_endhostent_r</function></funcdef>
|
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<paramdef>void</paramdef>
|
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</funcprototype>
|
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</funcsynopsis>
|
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</refsynopsisdiv>
|
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|
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<refsection><info><title>DESCRIPTION</title></info>
|
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|
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<para>
|
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These functions provide hostname-to-address and
|
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address-to-hostname lookups by means of the lightweight resolver.
|
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They are similar to the standard
|
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<citerefentry>
|
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<refentrytitle>gethostent</refentrytitle><manvolnum>3</manvolnum>
|
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</citerefentry>
|
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functions provided by most operating systems.
|
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They use a
|
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<type>struct hostent</type>
|
|
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which is usually defined in
|
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<filename><namedb.h></filename>.
|
|
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</para>
|
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<para><programlisting>
|
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struct hostent {
|
|
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char *h_name; /* official name of host */
|
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char **h_aliases; /* alias list */
|
|
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int h_addrtype; /* host address type */
|
|
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int h_length; /* length of address */
|
|
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char **h_addr_list; /* list of addresses from name server */
|
|
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};
|
|
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#define h_addr h_addr_list[0] /* address, for backward compatibility */
|
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</programlisting>
|
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</para>
|
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<para>
|
|
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The members of this structure are:
|
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<variablelist>
|
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<varlistentry>
|
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<term><constant>h_name</constant></term>
|
|
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<listitem>
|
|
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<para>
|
|
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The official (canonical) name of the host.
|
|
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</para>
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
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<term><constant>h_aliases</constant></term>
|
|
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<listitem>
|
|
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<para>
|
|
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A NULL-terminated array of alternate names (nicknames) for the
|
|
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host.
|
|
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</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><constant>h_addrtype</constant></term>
|
|
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<listitem>
|
|
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<para>
|
|
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The type of address being returned —
|
|
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<type>PF_INET</type>
|
|
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or
|
|
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<type>PF_INET6</type>.
|
|
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</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><constant>h_length</constant></term>
|
|
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<listitem>
|
|
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<para>
|
|
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The length of the address in bytes.
|
|
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</para>
|
|
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</listitem>
|
|
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5ce601 |
</varlistentry>
|
|
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5ce601 |
<varlistentry>
|
|
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<term><constant>h_addr_list</constant></term>
|
|
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<listitem>
|
|
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<para>
|
|
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A <type>NULL</type>
|
|
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terminated array of network addresses for the host.
|
|
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5ce601 |
Host addresses are returned in network byte order.
|
|
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5ce601 |
</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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</variablelist>
|
|
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5ce601 |
</para>
|
|
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5ce601 |
<para>
|
|
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5ce601 |
For backward compatibility with very old software,
|
|
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5ce601 |
<constant>h_addr</constant>
|
|
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5ce601 |
is the first address in
|
|
Packit |
5ce601 |
<constant>h_addr_list.</constant>
|
|
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5ce601 |
</para>
|
|
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5ce601 |
<para><function>lwres_gethostent()</function>,
|
|
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5ce601 |
<function>lwres_sethostent()</function>,
|
|
Packit |
5ce601 |
<function>lwres_endhostent()</function>,
|
|
Packit |
5ce601 |
<function>lwres_gethostent_r()</function>,
|
|
Packit |
5ce601 |
<function>lwres_sethostent_r()</function>
|
|
Packit |
5ce601 |
and
|
|
Packit |
5ce601 |
<function>lwres_endhostent_r()</function>
|
|
Packit |
5ce601 |
provide iteration over the known host entries on systems that
|
|
Packit |
5ce601 |
provide such functionality through facilities like
|
|
Packit |
5ce601 |
<filename>/etc/hosts</filename>
|
|
Packit |
5ce601 |
or NIS. The lightweight resolver does not currently implement
|
|
Packit |
5ce601 |
these functions; it only provides them as stub functions that always
|
|
Packit |
5ce601 |
return failure.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><function>lwres_gethostbyname()</function>
|
|
Packit |
5ce601 |
and <function>lwres_gethostbyname2()</function> look up the
|
|
Packit |
5ce601 |
hostname <parameter>name</parameter>.
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname()</function> always looks for an
|
|
Packit |
5ce601 |
IPv4 address while <function>lwres_gethostbyname2()</function>
|
|
Packit |
5ce601 |
looks for an address of protocol family
|
|
Packit |
5ce601 |
<parameter>af</parameter>: either <type>PF_INET</type> or
|
|
Packit |
5ce601 |
<type>PF_INET6</type> — IPv4 or IPV6 addresses
|
|
Packit |
5ce601 |
respectively. Successful calls of the functions return a
|
|
Packit |
5ce601 |
<type>struct hostent</type>for the name that was looked up.
|
|
Packit |
5ce601 |
<type>NULL</type> is returned if the lookups by
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname()</function> or
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname2()</function> fail.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
Reverse lookups of addresses are performed by
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr()</function>.
|
|
Packit |
5ce601 |
<parameter>addr</parameter> is an address of length
|
|
Packit |
5ce601 |
<parameter>len</parameter> bytes and protocol family
|
|
Packit |
5ce601 |
<parameter>type</parameter> — <type>PF_INET</type> or
|
|
Packit |
5ce601 |
<type>PF_INET6</type>.
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname_r()</function> is a
|
|
Packit |
5ce601 |
thread-safe function
|
|
Packit |
5ce601 |
for forward lookups. If an error occurs, an error code is returned in
|
|
Packit |
5ce601 |
<parameter>*error</parameter>.
|
|
Packit |
5ce601 |
<parameter>resbuf</parameter> is a pointer to a
|
|
Packit |
5ce601 |
<type>struct hostent</type> which is initialised by a successful call to
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname_r()</function>.
|
|
Packit |
5ce601 |
<parameter>buf</parameter> is a buffer of length
|
|
Packit |
5ce601 |
<parameter>len</parameter> bytes which is used to store the
|
|
Packit |
5ce601 |
<constant>h_name</constant>, <constant>h_aliases</constant>, and
|
|
Packit |
5ce601 |
<constant>h_addr_list</constant> elements of the
|
|
Packit |
5ce601 |
<type>struct hostent</type> returned in <parameter>resbuf</parameter>.
|
|
Packit |
5ce601 |
Successful calls to <function>lwres_gethostbyname_r()</function>
|
|
Packit |
5ce601 |
return <parameter>resbuf</parameter>,
|
|
Packit |
5ce601 |
which is a pointer to the <type>struct hostent</type> it created.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><function>lwres_gethostbyaddr_r()</function>
|
|
Packit |
5ce601 |
is a thread-safe function
|
|
Packit |
5ce601 |
that performs a reverse lookup of address <parameter>addr</parameter>
|
|
Packit |
5ce601 |
which is <parameter>len</parameter> bytes long and is of
|
|
Packit |
5ce601 |
protocol
|
|
Packit |
5ce601 |
family <parameter>type</parameter> — <type>PF_INET</type> or
|
|
Packit |
5ce601 |
<type>PF_INET6</type>. If an error occurs, the error code is returned
|
|
Packit |
5ce601 |
in <parameter>*error</parameter>. The other function
|
|
Packit |
5ce601 |
parameters are
|
|
Packit |
5ce601 |
identical to those in <function>lwres_gethostbyname_r()</function>.
|
|
Packit |
5ce601 |
<parameter>resbuf</parameter> is a pointer to a
|
|
Packit |
5ce601 |
<type>struct hostent</type> which is initialised by a successful call to
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr_r()</function>.
|
|
Packit |
5ce601 |
<parameter>buf</parameter> is a buffer of length
|
|
Packit |
5ce601 |
<parameter>len</parameter> bytes which is used to store the
|
|
Packit |
5ce601 |
<constant>h_name</constant>, <constant>h_aliases</constant>, and
|
|
Packit |
5ce601 |
<constant>h_addr_list</constant> elements of the
|
|
Packit |
5ce601 |
<type>struct hostent</type> returned in <parameter>resbuf</parameter>.
|
|
Packit |
5ce601 |
Successful calls to <function>lwres_gethostbyaddr_r()</function> return
|
|
Packit |
5ce601 |
<parameter>resbuf</parameter>, which is a pointer to the
|
|
Packit |
5ce601 |
<function>struct hostent()</function> it created.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
</refsection>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<refsection><info><title>RETURN VALUES</title></info>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
The functions
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname()</function>,
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname2()</function>,
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr()</function>,
|
|
Packit |
5ce601 |
and
|
|
Packit |
5ce601 |
<function>lwres_gethostent()</function>
|
|
Packit |
5ce601 |
return NULL to indicate an error. In this case the global variable
|
|
Packit |
5ce601 |
<type>lwres_h_errno</type>
|
|
Packit |
5ce601 |
will contain one of the following error codes defined in
|
|
Packit |
5ce601 |
<filename><lwres/netdb.h></filename>:
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<variablelist>
|
|
Packit |
5ce601 |
<varlistentry>
|
|
Packit |
5ce601 |
<term><constant>HOST_NOT_FOUND</constant></term>
|
|
Packit |
5ce601 |
<listitem>
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
The host or address was not found.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</listitem>
|
|
Packit |
5ce601 |
</varlistentry>
|
|
Packit |
5ce601 |
<varlistentry>
|
|
Packit |
5ce601 |
<term><constant>TRY_AGAIN</constant></term>
|
|
Packit |
5ce601 |
<listitem>
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
A recoverable error occurred, e.g., a timeout.
|
|
Packit |
5ce601 |
Retrying the lookup may succeed.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</listitem>
|
|
Packit |
5ce601 |
</varlistentry>
|
|
Packit |
5ce601 |
<varlistentry>
|
|
Packit |
5ce601 |
<term><constant>NO_RECOVERY</constant></term>
|
|
Packit |
5ce601 |
<listitem>
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
A non-recoverable error occurred.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</listitem>
|
|
Packit |
5ce601 |
</varlistentry>
|
|
Packit |
5ce601 |
<varlistentry>
|
|
Packit |
5ce601 |
<term><constant>NO_DATA</constant></term>
|
|
Packit |
5ce601 |
<listitem>
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
The name exists, but has no address information
|
|
Packit |
5ce601 |
associated with it (or vice versa in the case
|
|
Packit |
5ce601 |
of a reverse lookup). The code NO_ADDRESS
|
|
Packit |
5ce601 |
is accepted as a synonym for NO_DATA for backwards
|
|
Packit |
5ce601 |
compatibility.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</listitem>
|
|
Packit |
5ce601 |
</varlistentry>
|
|
Packit |
5ce601 |
</variablelist>
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><citerefentry>
|
|
Packit |
5ce601 |
<refentrytitle>lwres_hstrerror</refentrytitle><manvolnum>3</manvolnum>
|
|
Packit |
5ce601 |
</citerefentry>
|
|
Packit |
5ce601 |
translates these error codes to suitable error messages.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><function>lwres_gethostent()</function>
|
|
Packit |
5ce601 |
and <function>lwres_gethostent_r()</function>
|
|
Packit |
5ce601 |
always return <type>NULL</type>.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
Successful calls to <function>lwres_gethostbyname_r()</function> and
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr_r()</function> return
|
|
Packit |
5ce601 |
<parameter>resbuf</parameter>, a pointer to the
|
|
Packit |
5ce601 |
<type>struct hostent</type> that was initialised by these functions. They return
|
|
Packit |
5ce601 |
<type>NULL</type> if the lookups fail or if <parameter>buf</parameter>
|
|
Packit |
5ce601 |
was too small to hold the list of addresses and names referenced by
|
|
Packit |
5ce601 |
the <constant>h_name</constant>, <constant>h_aliases</constant>, and
|
|
Packit |
5ce601 |
<constant>h_addr_list</constant> elements of the
|
|
Packit |
5ce601 |
<type>struct hostent</type>.
|
|
Packit |
5ce601 |
If <parameter>buf</parameter> was too small, both
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname_r()</function> and
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr_r()</function> set the global
|
|
Packit |
5ce601 |
variable
|
|
Packit |
5ce601 |
<type>errno</type> to <errorcode>ERANGE</errorcode>.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
</refsection>
|
|
Packit |
5ce601 |
<refsection><info><title>SEE ALSO</title></info>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><citerefentry>
|
|
Packit |
5ce601 |
<refentrytitle>gethostent</refentrytitle><manvolnum>3</manvolnum>
|
|
Packit |
5ce601 |
</citerefentry>,
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<citerefentry>
|
|
Packit |
5ce601 |
<refentrytitle>lwres_getipnode</refentrytitle><manvolnum>3</manvolnum>
|
|
Packit |
5ce601 |
</citerefentry>,
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<citerefentry>
|
|
Packit |
5ce601 |
<refentrytitle>lwres_hstrerror</refentrytitle><manvolnum>3</manvolnum>
|
|
Packit |
5ce601 |
</citerefentry>
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</refsection>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<refsection><info><title>BUGS</title></info>
|
|
Packit |
5ce601 |
|
|
Packit |
5ce601 |
<para><function>lwres_gethostbyname()</function>,
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname2()</function>,
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr()</function>
|
|
Packit |
5ce601 |
and
|
|
Packit |
5ce601 |
<function>lwres_endhostent()</function>
|
|
Packit |
5ce601 |
are not thread safe; they return pointers to static data and
|
|
Packit |
5ce601 |
provide error codes through a global variable.
|
|
Packit |
5ce601 |
Thread-safe versions for name and address lookup are provided by
|
|
Packit |
5ce601 |
<function>lwres_gethostbyname_r()</function>,
|
|
Packit |
5ce601 |
and
|
|
Packit |
5ce601 |
<function>lwres_gethostbyaddr_r()</function>
|
|
Packit |
5ce601 |
respectively.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
<para>
|
|
Packit |
5ce601 |
The resolver daemon does not currently support any non-DNS
|
|
Packit |
5ce601 |
name services such as
|
|
Packit |
5ce601 |
<filename>/etc/hosts</filename>
|
|
Packit |
5ce601 |
or
|
|
Packit |
5ce601 |
<type>NIS</type>,
|
|
Packit |
5ce601 |
consequently the above functions don't, either.
|
|
Packit |
5ce601 |
</para>
|
|
Packit |
5ce601 |
</refsection>
|
|
Packit |
5ce601 |
</refentry>
|