dnsupdate-install-hooks.in

#!/bin/sh
# Script to install the required DHCP hook for various known platforms.
# Copyright 2006 Quest Software, see the COPYING file for licencing
# Authors: Ted Percival <ted.percival@quest.com>
#
# (c) 2006 Quest Software, Inc.  All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of Quest Software, Inc. nor the names of its
#    contributors may be used to endorse or promote products derived from
#    this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

set -e
TMPSUFFIX='.quest-dhclient.tmp'

umask 022

#-- Display the program usage
usage () {
	echo "usage: $0 [-hiqrt] [platform]" >&2
        cat <<-. >&2
	  -h    Help (display this information)
	  -i    Installs a DHCP client hook to run dnsupdate on address changes.
	  -q    Quiet, no informational messages.
	  -r    Removes the last installed hook.
	  -t	Test if it looks like a hook is already installed

	  platform   DHCP client type to install hook. Auto-detected if missing.
		     One of:
			    aix hpux solaris macos
			    linux dhclient dhcpcd odhcpcd
	             (Note: 'linux' auto-detects dhclient, dhcpcd or odhcpcd.)

	  Warning: Running this hook installation script more than once
	           may insert multiple dnsupdate hooks, which is probably not
	           what you want.
.
}

#-- Write a verbose, error message to stderr and exit
die () {
        echo "$0: error $*" >&2
        exit 1
}

#-- Write a verbose, informational message to stderr unless QUIET is true
verbose () {
        $QUIET || echo "quest-dnsupdate: $*" >&2
}

#-- Clean up temporary files on exit
cleanup () {
    if test -n "$TMPHOOKFILE"; then
    	rm -f "$TMPHOOKFILE"
    	rm -f "$TMPHOOKFILE.2"
    fi
    return 0
}
trap cleanup 0 1 2

#------------------------------------------------------------
# hook-style platform helper

# These helper functions are for the common case where all we need to do
# is insert a shell fragment into a script file that is run by the DHCP
# client whenever it registers an IP address.

# Requiements for 'hookable' platform $PLAT:
#  - Set the following vars
#		$HOOKFILE	-- script file to create or append 
#                                  script fragment to
#		$TMPHOOKFILE	-- temporary place for building new hookfile
#  - Define a function "${PLAT}_script ()" that emits a script fragment
#       The output of the ${PLAT}_script must not contain '#!'
#  - Call "add_hook_platform ${PLAT}"

# hook_insert($PLAT)
# Installs the output of ${PLAT}_script into $HOOKFILE.
# $HOOKFILE is created executable with '#!/bin/sh' if it doesn't exist.
# $TMPHOOKFILE is created to store working data. It is deleted at exit.
hook_insert () {
	test $# -eq 1 || die "hook_insert: missing argument"
	test -n "$TMPHOOKFILE" || die "hook_insert $1: TMPHOOKFILE not set"
	test -n "$HOOKFILE" || die "hook_insert $1: HOOKFILE not set"

	if [ -f $HOOKFILE ]; then
		hook_script $1 >> $HOOKFILE
	else
		{ echo '#!/bin/sh'; hook_script $1; } > $HOOKFILE
		chmod 755 $HOOKFILE
	fi
	verbose "$1 hook installed into $HOOKFILE"
	return 0
}

# hook_remove($PLAT)
# Removes previously inserted output of ${PLAT}_script from $HOOKFILE.
# That is, reverses hook_insert($PLAT)
# $HOOKFILE is deleted if the result would be that it just contains '#!/bin/sh'
# $TMPHOOKFILE is used to store working data.
hook_remove () {
	test $# -eq 1 || die "hook_remove: missing argument"
	test -n "$TMPHOOKFILE" || die "hook_remove $1: TMPHOOKFILE not set"
	test -n "$HOOKFILE" || die "hook_remove $1: HOOKFILE not set"

	test -f $HOOKFILE || return 0

	if hook_test $1; then
	    # Make a regular expression for the tag text, which
	    # may include dots and slashes.
	    tagre=`echo "$hook_tag" | sed -e 's/[./]/[&]/g'`
	    sed -e "/^# $tagre BEGIN\$/,/^# $tagre END\$/d" \
		< $HOOKFILE > $TMPHOOKFILE
	    # If only the shebang is left, then delete the hookfile
	    echo '#!/bin/sh' > $TMPHOOKFILE.2
	    if cmp $TMPHOOKFILE.2 $TMPHOOKFILE >/dev/null 2>/dev/null; then
		rm -f $HOOKFILE
	    else
		cat $TMPHOOKFILE > $HOOKFILE
	    fi
	    rm -f $TMPHOOKFILE $TMPHOOKFILE.2
	    verbose "hook removed from $HOOKFILE"
	else
	    echo "$0: No hook found in $HOOKFILE" >&2
	    verbose "no changes made to $HOOKFILE"
	    verbose "manual editing of $HOOKFILE may be necessary."
	fi
	return 0
}

hook_tag='#quest-dnsupdate @VERSION@#'

# hook_script($PLAT)
# Writes the platforms-specific script fragment to standard output
# preceeded by a tag that hook_test will look for
hook_script () {
	echo "# $hook_tag BEGIN"
	${1}_script
	echo "# $hook_tag END"
}

# hook_test($PLAT)
# Tests to see if the hook has already been installed. 
# Relies on the tag written by hook_script.
# Exits abnormally if it hasn't.
hook_test () {
	test $# -eq 1 || die "hook_test: missing argument"
	test -n "$HOOKFILE" || die "hook_remove $1: HOOKFILE not set"

	test -f $HOOKFILE || return 1
	fgrep "# $hook_tag BEGIN" $HOOKFILE > /dev/null
}

#-- marks platform as using hook_insert/hook_remove
add_hook_platform () {
	eval "${1}_insert () { hook_insert $1; }"
	eval "${1}_remove () { hook_remove $1; }"
	eval "${1}_test ()   { hook_test $1; }"
}

#------------------------------------------------------------
# AIX

aix_init () {
	REALFILE=/etc/dhcpcd.ini
	TMPHOOKFILE=/etc/dhcpcd.ini$TMPSUFFIX
}

aix_insert () {
	sed -e '/^updateDNS/s/^/##quest-dnsupdate##/' \
	    < $REALFILE > $TMPHOOKFILE
	echo "updateDNS \"@sbindir@/dnsupdate '%.0s%.0s%s%.0s'\"" \
	    >> $TMPHOOKFILE
	cat < $TMPHOOKFILE > $REALFILE
	verbose "Installed dnsupdate hook into $REALFILE"
	return 0
}

aix_remove () {
	grep -v '^updateDNS "@sbindir@/dnsupdate' < $REALFILE | 
	    sed -e 's/^##quest-dnsupdate##//' > $TMPHOOKFILE
	cat < $TMPHOOKFILE > $REALFILE
	verbose "Removed dnsupdate hook from $REALFILE"
	return 0
}

aix_test () {
	grep '^updateDNS "@sbindir@/dnsupdate' < $REALFILE > /dev/null
}

#------------------------------------------------------------
# Solaris

add_hook_platform solaris

solaris_init () {
	case `uname -r` in
	    5.[6789])	
	       die "DHCP event hooks only became available in Solaris 10"
	       ;;
	esac
	HOOKFILE=/etc/dhcp/eventhook
	TMPHOOKFILE=${HOOKFILE}${TMPSUFFIX}
}

solaris_script () {
	cat <<-'.'
		# usage: eventhook <interface> <event>
		case "$2" in
			BOUND|EXTEND)
				addr=`/sbin/dhcpinfo -i "$1" Yiaddr`
				@sbindir@/dnsupdate $addr
			;;
		esac
.
}

#------------------------------------------------------------
# HP-UX

add_hook_platform hpux

hpux_init () {
	HOOKFILE=/sbin/rc1.d/S321dnsupdate
	TMPHOOKFILE=$HOOKFILE$TMPSUFFIX
}

hpux_script () {
	cat <<-'.'
		if test 0 -ne 0`/usr/sbin/ch_rc -l -p 'DHCP_ENABLE[0]'`
		then
			addr=`/usr/sbin/ch_rc -l -p 'IP_ADDRESS[0]'`
			case "$addr" in
				*.*.*.*) @sbindir@/dnsupdate $addr;;
			esac
		fi
.
}

#------------------------------------------------------------
# Linux

#-- detects the kind of DHCP client in use.
# Mostly useful for Linux distros; Standards and consistency are a good thing.
# Possible values of $dhc are: dhclient dhcpcd odhcpcd unknown
detect_linux_platform () {
	if [ -x /sbin/dhclient ]; then
		echo dhclient
	elif [ -x /sbin/dhcpcd ]; then
		if [ -d /etc/sysconfig/network/if-up.d ]; then
			echo dhcpcd
		else
			echo odhcpcd
		fi
	else
		echo "unknown"
		return 1
	fi
}

#------------------------------------------------------------
# Linux dhclient

add_hook_platform dhclient

dhclient_init () {
	if [ -d /etc/dhcp3/dhclient-exit-hooks.d ]; then
		HOOKFILE=/etc/dhcp3/dhclient-exit-hooks.d/dnsupdate
	else
		HOOKFILE=/etc/dhclient-exit-hooks
	fi
	TMPHOOKFILE=$HOOKFILE$TMPSUFFIX
}

# Linux dhclient hook based on dhclient-script(8) manpage
# This function being called dhclient_script is accidental coincidence
dhclient_script () {
	# Hook is sourced (not executed)
	# Return value is to be passed in exit_status var
	cat <<-'.'
		# This file is sourced by dhclient-script.
		# It doesn't matter if there is a bang (#!/bin/sh) above.
		case "$reason" in
		BOUND|RENEW|REBIND|REBOOT)
			@sbindir@/dnsupdate "$new_ip_address"
		;;
		esac
.
}

#------------------------------------------------------------
# Linux odhcpcd

add_hook_platform odhcpcd

odhcpcd_init () {
	if [ -d /etc/sysconfig/network/scripts ]; then
		HOOKFILE=/etc/sysconfig/network/scripts/dhcpcd-hook
	else
		HOOKFILE=/etc/dhcpc/dhcpcd.exe
	fi
	TMPHOOKFILE=$HOOKFILE$TMPSUFFIX
}

# Based on dhcpcd(8) manpage
odhcpcd_script () {
	# TODO: The script is called with [ "$3" = '-d' ] for debug mode.
	# dnsupdate should be called with '-v' if that's the case.
	cat <<-'.'
		. $1
		case $2 in
			new)
				@sbindir@/dnsupdate "$IPADDR"
			;;
		esac
.
}

#------------------------------------------------------------
# Linux odhcpcd

add_hook_platform dhcpcd

dhcpcd_init () {
	HOOKFILE=/etc/sysconfig/network/if-up.d/quest-dnsupdate
	TMPHOOKFILE=$HOOKFILE$TMPSUFFIX
}

dhcpcd_script () {
	cat <<'.'
		test -f /etc/sysconfig/network/ifcfg-$1 &&
		      . /etc/sysconfig/network/ifcfg-$1
		test x"$BOOTPROTO" = x"dhcp" || exit 0
		. /var/lib/dhcpcd/dhcpcd-$2.info || exit
		@sbindir@/dnsupdate "$IPADDR"
.
}

#------------------------------------------------------------
# Macos

macos_init () {
	IPWATCH_PLIST=/Library/LaunchDaemons/com.quest.rc.ipwatchd.plist
	PLIST_SRC=@datadir@/ipwatchd/com.quest.rc.ipwatchd.plist
}

macos_insert () {
	test -r $IPWATCH_PLIST ||
		/usr/bin/install -o root -m 644 $PLIST_SRC $IPWATCH_PLIST
	/bin/launchctl load $IPWATCH_PLIST
}

macos_remove () {
	/bin/launchctl unload $IPWATCH_PLIST
	if cmp $IPWATCH_PLIST $PLIST_SRC >/dev/null 2>/dev/null; then
	    rm -f $IPWATCH_PLIST
	fi
	return 0
}

macos_test () {
	test -r $IPWATCH_PLIST &&
	/bin/launchctl list | fgrep com.quest.rc.ipwatchd > /dev/null
}

#------------------------------------------------------------
# Command line processing

QUIET=false
ERROR=false
ACTION=unset
while getopts hiqrt f; do
    case "$f" in
	h) ACTION=help;;
	i) ACTION=insert;;
	q) QUIET=true;;
	r) ACTION=remove;;
	t) ACTION=test;;
	*) ERROR=true;;
    esac
done
shift `expr $OPTIND - 1`

case $ACTION in
    unset)  ERROR=true;;
    help)   usage help; exit 0;;
esac

#-- platform is the DHCP client type.
#   Most of the time, the DHCP client is directly tied to the operating
#   system, so its name will match the OS name. On Linux, however,
#   there are at least three DHCP client implementations.
if test $# -ge 1; then
    platform="$1"
    shift
else
    case `uname -s` in
	AIX)    platform=aix;;
	SunOS)  platform=solaris;;
	Darwin) platform=macos;;
	Linux)  platform=linux;;
	HP-UX)  platform=hpux;;
	*)      echo "Cannot auto-detect hook style (platform `uname -s`)" >&2
	        ERROR=true
	        ;;
    esac
fi

#-- Convert ambiguous platform names into specific DHCP client types
case "$platform" in
    linux)
	platform=`detect_linux_platform` || die "unknown Linux platform"
	;;
    hpux|aix|solaris|macos|dhclient|dhcpcd|odhcpcd)
	: no change
	;;
    *)
	echo "$0: Unrecognised platform '$platform'" >&2
	ERROR=true
	;;
esac

if $ERROR; then
    usage
    exit 1
fi

${platform}_init
${platform}_${ACTION}