diff options
Diffstat (limited to 'src/nss-myhostname')
| l--------- | src/nss-myhostname/GNUmakefile | 1 | ||||
| -rw-r--r--[l---------] | src/nss-myhostname/Makefile | 48 | ||||
| -rw-r--r-- | src/nss-myhostname/nss-myhostname.c | 16 | ||||
| -rw-r--r-- | src/nss-myhostname/nss-myhostname.xml | 149 |
4 files changed, 205 insertions, 9 deletions
diff --git a/src/nss-myhostname/GNUmakefile b/src/nss-myhostname/GNUmakefile new file mode 120000 index 0000000000..54fdd42278 --- /dev/null +++ b/src/nss-myhostname/GNUmakefile @@ -0,0 +1 @@ +../../GNUmakefile
\ No newline at end of file diff --git a/src/nss-myhostname/Makefile b/src/nss-myhostname/Makefile index d0b0e8e008..3f87158794 120000..100644 --- a/src/nss-myhostname/Makefile +++ b/src/nss-myhostname/Makefile @@ -1 +1,47 @@ -../Makefile
\ No newline at end of file +# -*- Mode: makefile; indent-tabs-mode: t -*- +# +# This file is part of systemd. +# +# Copyright 2010-2012 Lennart Poettering +# Copyright 2010-2012 Kay Sievers +# Copyright 2013 Zbigniew Jędrzejewski-Szmek +# Copyright 2013 David Strauss +# Copyright 2016 Luke Shumaker +# +# systemd is free software; you can redistribute it and/or modify it +# under the terms of the GNU Lesser General Public License as published by +# the Free Software Foundation; either version 2.1 of the License, or +# (at your option) any later version. +# +# systemd is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public License +# along with systemd; If not, see <http://www.gnu.org/licenses/>. +include $(dir $(lastword $(MAKEFILE_LIST)))/../../config.mk +include $(topsrcdir)/build-aux/Makefile.head.mk + +ifneq ($(HAVE_MYHOSTNAME),) +libnss_myhostname_la_SOURCES = \ + src/nss-myhostname/nss-myhostname.sym \ + src/nss-myhostname/nss-myhostname.c + +libnss_myhostname_la_LDFLAGS = \ + -module \ + -export-dynamic \ + -avoid-version \ + -shared \ + -shrext .so.2 \ + -Wl,--version-script=$(srcdir)/nss-myhostname.sym + +libnss_myhostname_la_LIBADD = \ + libsystemd-internal.la \ + libsystemd-basic.la + +rootlib_LTLIBRARIES += \ + libnss_myhostname.la +endif # HAVE_MYHOSTNAME + +include $(topsrcdir)/build-aux/Makefile.tail.mk diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c index 11c27575c0..862ad2fcb5 100644 --- a/src/nss-myhostname/nss-myhostname.c +++ b/src/nss-myhostname/nss-myhostname.c @@ -24,14 +24,14 @@ #include <stdlib.h> #include <string.h> -#include "alloc-util.h" -#include "hostname-util.h" -#include "local-addresses.h" -#include "macro.h" -#include "nss-util.h" -#include "signal-util.h" -#include "string-util.h" -#include "util.h" +#include "sd-netlink/local-addresses.h" +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/hostname-util.h" +#include "systemd-basic/macro.h" +#include "systemd-basic/nss-util.h" +#include "systemd-basic/signal-util.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/util.h" /* We use 127.0.0.2 as IPv4 address. This has the advantage over * 127.0.0.1 that it can be translated back to the local hostname. For diff --git a/src/nss-myhostname/nss-myhostname.xml b/src/nss-myhostname/nss-myhostname.xml new file mode 100644 index 0000000000..c25476ecc8 --- /dev/null +++ b/src/nss-myhostname/nss-myhostname.xml @@ -0,0 +1,149 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<!-- + This file is part of systemd. + + Copyright 2011 Lennart Poettering + Copyright 2013 Tom Gundersen + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +--> + +<refentry id="nss-myhostname" conditional='HAVE_MYHOSTNAME'> + + <refentryinfo> + <title>nss-myhostname</title> + <productname>systemd</productname> + + <authorgroup> + <author> + <contrib>Developer</contrib> + <firstname>Lennart</firstname> + <surname>Poettering</surname> + <email>lennart@poettering.net</email> + </author> + </authorgroup> + </refentryinfo> + + <refmeta> + <refentrytitle>nss-myhostname</refentrytitle> + <manvolnum>8</manvolnum> + </refmeta> + + <refnamediv> + <refname>nss-myhostname</refname> + <refname>libnss_myhostname.so.2</refname> + <refpurpose>Provide hostname resolution for the locally + configured system hostname.</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <para><filename>libnss_myhostname.so.2</filename></para> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><command>nss-myhostname</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of + the GNU C Library (<command>glibc</command>), primarily providing hostname resolution for the locally configured + system hostname as returned by + <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>. The precise + hostnames resolved by this module are:</para> + + <itemizedlist> + <listitem><para>The local, configured hostname is resolved to + all locally configured IP addresses ordered by their scope, or + — if none are configured — the IPv4 address 127.0.0.2 (which + is on the local loopback) and the IPv6 address ::1 (which is the + local host).</para></listitem> + + <listitem><para>The hostnames <literal>localhost</literal> and + <literal>localhost.localdomain</literal> (as well as any hostname + ending in <literal>.localhost</literal> or <literal>.localhost.localdomain</literal>) + are resolved to the IP addresses 127.0.0.1 and ::1.</para></listitem> + + <listitem><para>The hostname <literal>gateway</literal> is + resolved to all current default routing gateway addresses, + ordered by their metric. This assigns a stable hostname to the + current gateway, useful for referencing it independently of the + current network configuration state.</para></listitem> + </itemizedlist> + + <para>Various software relies on an always-resolvable local + hostname. When using dynamic hostnames, this is traditionally + achieved by patching <filename>/etc/hosts</filename> at the same + time as changing the hostname. This is problematic since it + requires a writable <filename>/etc</filename> file system and is + fragile because the file might be edited by the administrator at + the same time. With <command>nss-myhostname</command> enabled, + changing <filename>/etc/hosts</filename> is unnecessary, and on + many systems, the file becomes entirely optional.</para> + + <para>To activate the NSS modules, add <literal>myhostname</literal> to the line starting with + <literal>hosts:</literal> in <filename>/etc/nsswitch.conf</filename>.</para> + + <para>It is recommended to place <literal>myhostname</literal> last in the <filename>nsswitch.conf</filename>' + <literal>hosts:</literal> line to make sure that this mapping is only used as fallback, and that any DNS or + <filename>/etc/hosts</filename> based mapping takes precedence.</para> + </refsect1> + + <refsect1> + <title>Example</title> + + <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables + <command>nss-myhostname</command> correctly:</para> + +<programlisting>passwd: compat mymachines systemd +group: compat mymachines systemd +shadow: compat + +hosts: files mymachines resolve [!UNAVAIL=return] dns <command>myhostname</command> +networks: files + +protocols: db files +services: db files +ethers: db files +rpc: db files + +netgroup: nis</programlisting> + + <para>To test, use <command>glibc</command>'s <command>getent</command> tool:</para> + + <programlisting>$ getent ahosts `hostname` +::1 STREAM omega +::1 DGRAM +::1 RAW +127.0.0.2 STREAM +127.0.0.2 DGRAM +127.0.0.2 RAW</programlisting> + + <para>In this case, the local hostname is <varname>omega</varname>.</para> + + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |