- import of strongswan-2.7.0
- applied patch for charon
This commit is contained in:
Martin Willi
@@ -0,0 +1,407 @@
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
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<!--
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- Copyright (C) 2001 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
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- DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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- INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
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- FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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- NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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- WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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-->
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<!-- $Id: lwres_gethostent.docbook,v 1.1 2004/03/15 20:35:25 as Exp $ -->
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<refentry>
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<refentryinfo>
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<date>Jun 30, 2000</date>
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</refentryinfo>
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<refmeta>
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<refentrytitle>lwres_gethostent</refentrytitle>
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<manvolnum>3</manvolnum>
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<refmiscinfo>BIND9</refmiscinfo>
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</refmeta>
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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 *name</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 *name</paramdef>
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<paramdef>int af</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 *addr</paramdef>
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<paramdef>int len</paramdef>
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<paramdef>int type</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 stayopen</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 *name</paramdef>
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<paramdef>struct hostent *resbuf</paramdef>
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<paramdef>char *buf</paramdef>
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<paramdef>int buflen</paramdef>
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<paramdef>int *error</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 *addr</paramdef>
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<paramdef>int len</paramdef>
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<paramdef>int type</paramdef>
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<paramdef>struct hostent *resbuf</paramdef>
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<paramdef>char *buf</paramdef>
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<paramdef>int buflen</paramdef>
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<paramdef>int *error</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 *resbuf</paramdef>
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<paramdef>char *buf</paramdef>
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<paramdef>int buflen</paramdef>
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<paramdef>int *error</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 stayopen</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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<refsect1>
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<title>DESCRIPTION</title>
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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
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</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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<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><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></varlistentry>
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<varlistentry><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 host.
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</para>
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</listitem></varlistentry>
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<varlistentry><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></varlistentry>
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<varlistentry><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></varlistentry>
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<varlistentry><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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Host addresses are returned in network byte order.
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</para>
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</listitem></varlistentry>
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</variablelist>
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</para>
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<para>
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For backward compatibility with very old software,
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<constant>h_addr</constant>
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is the first address in
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<constant>h_addr_list.</constant>
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</para>
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<para>
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<function>lwres_gethostent()</function>,
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<function>lwres_sethostent()</function>,
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<function>lwres_endhostent()</function>,
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<function>lwres_gethostent_r()</function>,
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<function>lwres_sethostent_r()</function>
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and
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<function>lwres_endhostent_r()</function>
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provide iteration over the known host entries on systems that
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provide such functionality through facilities like
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<filename>/etc/hosts</filename>
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or NIS. The lightweight resolver does not currently implement
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these functions; it only provides them as stub functions that always
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return failure.
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</para>
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<para>
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<function>lwres_gethostbyname()</function> and
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<function>lwres_gethostbyname2()</function> look up the hostname
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<parameter>name</parameter>.
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<function>lwres_gethostbyname()</function> always looks for an IPv4
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address while <function>lwres_gethostbyname2()</function> looks for an
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address of protocol family <parameter>af</parameter>: either
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<type>PF_INET</type> or <type>PF_INET6</type> — IPv4 or IPV6
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addresses respectively. Successful calls of the functions return a
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<type>struct hostent</type>for the name that was looked up.
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<type>NULL</type> is returned if the lookups by
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<function>lwres_gethostbyname()</function> or
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<function>lwres_gethostbyname2()</function> fail.
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</para>
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<para>
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Reverse lookups of addresses are performed by
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<function>lwres_gethostbyaddr()</function>.
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<parameter>addr</parameter> is an address of length
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<parameter>len</parameter> bytes and protocol family
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<parameter>type</parameter> — <type>PF_INET</type> or
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<type>PF_INET6</type>.
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<function>lwres_gethostbyname_r()</function> is a thread-safe function
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for forward lookups. If an error occurs, an error code is returned in
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<parameter>*error</parameter>.
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<parameter>resbuf</parameter> is a pointer to a <type>struct
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hostent</type> which is initialised by a successful call to
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<function>lwres_gethostbyname_r()</function> .
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<parameter>buf</parameter> is a buffer of length
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<parameter>len</parameter> bytes which is used to store the
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<constant>h_name</constant>, <constant>h_aliases</constant>, and
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<constant>h_addr_list</constant> elements of the <type>struct
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hostent</type> returned in <parameter>resbuf</parameter>.
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Successful calls to <function>lwres_gethostbyname_r()</function>
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return <parameter>resbuf</parameter>,
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which is a pointer to the <type>struct hostent</type> it created.
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</para>
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<para>
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<function>lwres_gethostbyaddr_r()</function> is a thread-safe function
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that performs a reverse lookup of address <parameter>addr</parameter>
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which is <parameter>len</parameter> bytes long and is of protocol
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family <parameter>type</parameter> — <type>PF_INET</type> or
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<type>PF_INET6</type>. If an error occurs, the error code is returned
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in <parameter>*error</parameter>. The other function parameters are
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identical to those in <function>lwres_gethostbyname_r()</function>.
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<parameter>resbuf</parameter> is a pointer to a <type>struct
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hostent</type> which is initialised by a successful call to
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<function>lwres_gethostbyaddr_r()</function>.
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<parameter>buf</parameter> is a buffer of length
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<parameter>len</parameter> bytes which is used to store the
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<constant>h_name</constant>, <constant>h_aliases</constant>, and
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<constant>h_addr_list</constant> elements of the <type>struct
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hostent</type> returned in <parameter>resbuf</parameter>. Successful
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calls to <function>lwres_gethostbyaddr_r()</function> return
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<parameter>resbuf</parameter>, which is a pointer to the
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<function>struct hostent()</function> it created.
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</para>
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</refsect1>
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<refsect1>
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<title>RETURN VALUES</title>
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<para>
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The functions
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<function>lwres_gethostbyname()</function>,
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<function>lwres_gethostbyname2()</function>,
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<function>lwres_gethostbyaddr()</function>,
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and
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<function>lwres_gethostent()</function>
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return NULL to indicate an error. In this case the global variable
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<type>lwres_h_errno</type>
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will contain one of the following error codes defined in
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<filename><lwres/netdb.h></filename>:
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<variablelist>
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<varlistentry><term><constant>HOST_NOT_FOUND</constant></term>
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<listitem>
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<para>
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The host or address was not found.
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</para>
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</listitem></varlistentry>
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<varlistentry><term><constant>TRY_AGAIN</constant></term>
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<listitem>
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<para>
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A recoverable error occurred, e.g., a timeout.
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Retrying the lookup may succeed.
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</para>
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</listitem></varlistentry>
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<varlistentry><term><constant>NO_RECOVERY</constant></term>
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<listitem>
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<para>
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A non-recoverable error occurred.
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</para>
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</listitem></varlistentry>
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<varlistentry><term><constant>NO_DATA</constant></term>
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<listitem>
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<para>
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The name exists, but has no address information
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associated with it (or vice versa in the case
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of a reverse lookup). The code NO_ADDRESS
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is accepted as a synonym for NO_DATA for backwards
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compatibility.
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</para>
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</listitem></varlistentry>
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</variablelist>
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</para>
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<para>
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<citerefentry>
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<refentrytitle>lwres_hstrerror</refentrytitle><manvolnum>3
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</manvolnum>
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</citerefentry>
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translates these error codes to suitable error messages.
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</para>
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<para>
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<function>lwres_gethostent()</function>
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and
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<function>lwres_gethostent_r()</function>
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always return
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<type>NULL</type>.
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</para>
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<para>
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Successful calls to <function>lwres_gethostbyname_r()</function> and
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<function>lwres_gethostbyaddr_r()</function> return
|
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<parameter>resbuf</parameter>, a pointer to the <type>struct
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hostent</type> that was initialised by these functions. They return
|
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<type>NULL</type> if the lookups fail or if <parameter>buf</parameter>
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was too small to hold the list of addresses and names referenced by
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the <constant>h_name</constant>, <constant>h_aliases</constant>, and
|
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<constant>h_addr_list</constant> elements of the <type>struct
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hostent</type>. If <parameter>buf</parameter> was too small, both
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<function>lwres_gethostbyname_r()</function> and
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<function>lwres_gethostbyaddr_r()</function> set the global variable
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<type>errno</type> to <errorcode>ERANGE</errorcode>.
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</para>
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||||
</refsect1>
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||||
<refsect1>
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||||
<title>SEE ALSO</title>
|
||||
<para>
|
||||
<citerefentry>
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||||
<refentrytitle>gethostent</refentrytitle><manvolnum>3</manvolnum>
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||||
</citerefentry>,
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|
||||
<citerefentry>
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||||
<refentrytitle>lwres_getipnode</refentrytitle><manvolnum>3</manvolnum>
|
||||
</citerefentry>,
|
||||
|
||||
<citerefentry>
|
||||
<refentrytitle>lwres_hstrerror</refentrytitle><manvolnum>3
|
||||
</manvolnum>
|
||||
</citerefentry>
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
<refsect1>
|
||||
<title>BUGS</title>
|
||||
<para>
|
||||
<function>lwres_gethostbyname()</function>,
|
||||
<function>lwres_gethostbyname2()</function>,
|
||||
<function>lwres_gethostbyaddr()</function>
|
||||
and
|
||||
<function>lwres_endhostent()</function>
|
||||
are not thread safe; they return pointers to static data and
|
||||
provide error codes through a global variable.
|
||||
Thread-safe versions for name and address lookup are provided by
|
||||
<function>lwres_gethostbyname_r()</function>,
|
||||
and
|
||||
<function>lwres_gethostbyaddr_r()</function>
|
||||
respectively.
|
||||
</para>
|
||||
<para>
|
||||
The resolver daemon does not currently support any non-DNS
|
||||
name services such as
|
||||
<filename>/etc/hosts</filename>
|
||||
or
|
||||
<type>NIS</type>,
|
||||
consequently the above functions don't, either.
|
||||
</para>
|
||||
</refsect1>
|
||||
</refentry>
|
||||
Reference in New Issue
Block a user