NTP_CONF=/etc/ntp.conf
NTP_DHCP_CONF=/var/lib/ntp/ntp.conf.dhcp


ntp_server_restart() {
	invoke-rc.d ntp try-restart
}


ntp_servers_setup_remove() {
	if [ ! -e $NTP_DHCP_CONF ]; then
		return
	fi
	rm -f $NTP_DHCP_CONF
	ntp_server_restart
}


ntp_servers_setup_add() {
	if [ -e $NTP_DHCP_CONF ] && [ "$new_ntp_servers" = "$old_ntp_servers" ]; then
		return
	fi

	if [ -z "$new_ntp_servers" ]; then
		ntp_servers_setup_remove
		return
	fi

	tmp=$(mktemp "$NTP_DHCP_CONF.XXXXXX") || return
	chmod --reference=$NTP_CONF $tmp
	chown --reference=$NTP_CONF $tmp

	(
	  echo "# This file was copied from $NTP_CONF with the server options changed"
	  echo "# to reflect the information sent by the DHCP server.  Any changes made"
	  echo "# here will be lost at the next DHCP event.  Edit $NTP_CONF instead."
	  echo
	  echo "# NTP server entries received from DHCP server"
	  for server in $new_ntp_servers; do
		echo "server $server iburst"
	  done
	  echo
	  sed '/^[[:space:]]*\(server\|peer\|pool\)[[:space:]]/d' $NTP_CONF
	) >>$tmp
	
	mv $tmp $NTP_DHCP_CONF

	ntp_server_restart
}


ntp_servers_setup() {
	case $reason in
		BOUND|RENEW|REBIND|REBOOT)
			ntp_servers_setup_add
			;;
		EXPIRE|FAIL|RELEASE|STOP)
			ntp_servers_setup_remove
			;;
	esac
}


ntp_servers_setup