HardenedBSD/sbin/dhclient/dhclient-script

#!/bin/sh
#
# $OpenBSD: dhclient-script,v 1.6 2004/05/06 18:22:41 claudio Exp $
# $FreeBSD$
#
# Copyright (c) 2003 Kenneth R Westerback <krw@openbsd.org>
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
#

ARP=/usr/sbin/arp
HOSTNAME=/bin/hostname
IFCONFIG='/sbin/ifconfig -n'

LOCALHOST=127.0.0.1

if [ -x /usr/bin/logger ]; then
	LOGGER="/usr/bin/logger -s -p user.notice -t dhclient"
else
	LOGGER=echo
fi

#
# Helper functions that implement common actions.
#

check_hostname() {
	current_hostname=`$HOSTNAME`
	if [ -z "$current_hostname" ]; then
		$LOGGER "New Hostname ($interface): $new_host_name"
		$HOSTNAME $new_host_name
	elif [ "$current_hostname" = "$old_host_name" -a \
	       "$new_host_name" != "$old_host_name" ]; then
		$LOGGER "New Hostname ($interface): $new_host_name"
		$HOSTNAME $new_host_name
	fi
}

arp_flush() {
	arp -an -i $interface | \
		sed -n -e 's/^.*(\(.*\)) at .*$/arp -d \1/p' | \
		sh >/dev/null 2>&1
}

delete_old_address() {
	eval "$IFCONFIG $interface inet -alias $old_ip_address $medium"
}

add_new_address() {
	eval "$IFCONFIG $interface \
		inet $new_ip_address \
		netmask $new_subnet_mask \
		broadcast $new_broadcast_address \
		$medium"

	$LOGGER "New IP Address ($interface): $new_ip_address"
	$LOGGER "New Subnet Mask ($interface): $new_subnet_mask"
	$LOGGER "New Broadcast Address ($interface): $new_broadcast_address"
	$LOGGER "New Routers ($interface): $new_routers"
}

delete_old_alias() {
	if [ -n "$alias_ip_address" ]; then
		$IFCONFIG $interface inet -alias $alias_ip_address > /dev/null 2>&1
		#route delete $alias_ip_address $LOCALHOST > /dev/null 2>&1
	fi
}

add_new_alias() {
	if [ -n "$alias_ip_address" ]; then
		$IFCONFIG $interface inet alias $alias_ip_address netmask \
		    $alias_subnet_mask
		#route add $alias_ip_address $LOCALHOST
	fi
}

fill_classless_routes() {
	set $1
	while [ $# -ge 5 ]; do
		if [ $1 -eq 0 ]; then
			route="default"
		elif [ $1 -le 8 ]; then
			route="$2.0.0.0/$1"
			shift
		elif [ $1 -le 16 ]; then
			route="$2.$3.0.0/$1"
			shift; shift
		elif [ $1 -le 24 ]; then
			route="$2.$3.$4.0/$1"
			shift; shift; shift
		else
			route="$2.$3.$4.$5/$1"
			shift; shift; shift; shift
		fi
		shift
		router="$1.$2.$3.$4"
		classless_routes="$classless_routes $route $router"
		shift; shift; shift; shift
	done
}

delete_old_routes() {
	#route delete "$old_ip_address" $LOCALHOST >/dev/null 2>&1
	if [ -n "$old_classless_routes" ]; then
		fill_classless_routes "$old_classless_routes"
		set $classless_routes
		while [ $# -gt 1 ]; do
			route delete "$1" "$2"
			shift; shift
		done
		return 0;
	fi

	# If we supported multiple default routes, we'd be removing each
	# one here.  We don't so just delete the default route if it's
	# through our interface.
	if is_default_interface; then
		route delete default >/dev/null 2>&1
	fi

	if [ -n "$old_static_routes" ]; then
		set $old_static_routes
		while [ $# -gt 1 ]; do
			route delete "$1" "$2"
			shift; shift
		done
	fi

	arp_flush
}

add_new_routes() {
	#route add $new_ip_address $LOCALHOST >/dev/null 2>&1

	# RFC 3442: If the DHCP server returns both a Classless Static
	# Routes option and a Router option, the DHCP client MUST ignore
	# the Router option.
	#
	# DHCP clients that support this option (Classless Static Routes)
	# MUST NOT install the routes specified in the Static Routes
	# option (option code 33) if both a Static Routes option and the
	# Classless Static Routes option are provided.

	if [ -n "$new_classless_routes" ]; then
		fill_classless_routes "$new_classless_routes"
		$LOGGER "New Classless Static Routes ($interface): $classless_routes"
		set $classless_routes
		while [ $# -gt 1 ]; do
			if [ "0.0.0.0" = "$2" ]; then
				route add "$1" -iface "$interface"
			else
				route add "$1" "$2"
			fi
			shift; shift
		done
		return
	fi

	for router in $new_routers; do
		if is_default_interface; then

			if [ "$new_ip_address" = "$router" ]; then
				route add default -iface $router >/dev/null 2>&1
			else
				route add default $router >/dev/null 2>&1
			fi
		fi
		# 2nd and subsequent default routers error out, so explicitly
		# stop processing the list after the first one.
		break
	done

	if [ -n "$new_static_routes" ]; then
		$LOGGER "New Static Routes ($interface): $new_static_routes"
		set $new_static_routes
		while [ $# -gt 1 ]; do
			route add $1 $2
			shift; shift
		done
	fi
}

add_new_resolv_conf() {
	# XXX Old code did not create/update resolv.conf unless both
	# $new_domain_name and $new_domain_name_servers were provided.  PR
	# #3135 reported some ISP's only provide $new_domain_name_servers and
	# thus broke the script. This code creates the resolv.conf if either
	# are provided.

	local tmpres=/var/run/resolv.conf.${interface}
	rm -f $tmpres

	if [ -n "$new_domain_name" ]; then
		echo "search $new_domain_name" >>$tmpres
	fi

	if [ -n "$new_domain_name_servers" ]; then
		for nameserver in $new_domain_name_servers; do
			echo "nameserver $nameserver" >>$tmpres
		done
	fi

	if [ -f $tmpres ]; then
		if [ -f /etc/resolv.conf.tail ]; then
			cat /etc/resolv.conf.tail >>$tmpres
		fi

		# When resolv.conf is not changed actually, we don't
		# need to update it.
		# If /usr is not mounted yet, we cannot use cmp, then
		# the following test fails.  In such case, we simply
		# ignore an error and do update resolv.conf.
		if cmp -s $tmpres /etc/resolv.conf; then
			rm -f $tmpres
			return 0
		fi 2>/dev/null

		# In case (e.g. during OpenBSD installs) /etc/resolv.conf
		# is a symbolic link, take care to preserve the link and write
		# the new data in the correct location.

		if [ -f /etc/resolv.conf ]; then
			cat /etc/resolv.conf > /etc/resolv.conf.save
		fi
		cat $tmpres > /etc/resolv.conf
		rm -f $tmpres

		# Try to ensure correct ownership and permissions.
		chown -RL root:wheel /etc/resolv.conf
		chmod -RL 644 /etc/resolv.conf

		return 0
	fi

	return 1
}

# Must be used on exit.   Invokes the local dhcp client exit hooks, if any.
exit_with_hooks() {
	exit_status=$1
	if [ -f /etc/dhclient-exit-hooks ]; then
		. /etc/dhclient-exit-hooks
	fi
	# probably should do something with exit status of the local script
	exit $exit_status
}

# Get the interface with the current ipv4 default route on it using only
# commands that are available prior to /usr being mounted.
is_default_interface()
{
	routeget="`route -n get -inet default`"
	oldifs="$IFS"
	IFS="
"
	defif=
	for line in $routeget ; do
		case $line in
		*interface:*)
			defif=${line##*: }
			;;
		esac
	done
	IFS=${oldifs}

	if [ -z "$defif" -o "$defif" = "$interface" ]; then
		return 0
	else
		return 1
	fi
}

#
# Start of active code.
#

# Invoke the local dhcp client enter hooks, if they exist.
if [ -f /etc/dhclient-enter-hooks ]; then
	exit_status=0
	. /etc/dhclient-enter-hooks
	# allow the local script to abort processing of this state
	# local script must set exit_status variable to nonzero.
	if [ $exit_status -ne 0 ]; then
		exit $exit_status
	fi
fi

case $reason in
MEDIUM)
	eval "$IFCONFIG $interface $medium"
	eval "$IFCONFIG $interface inet -alias 0.0.0.0 $medium" >/dev/null 2>&1
	sleep 1
	;;

PREINIT)
	delete_old_alias
	$IFCONFIG $interface inet alias 0.0.0.0 netmask 0.0.0.0 broadcast 255.255.255.255 up
	;;

ARPCHECK|ARPSEND)
	;;

BOUND|RENEW|REBIND|REBOOT)
	check_hostname
	if [ -n "$old_ip_address" ]; then
		if [ "$old_ip_address" != "$alias_ip_address" ]; then
			delete_old_alias
		fi
		if [ "$old_ip_address" != "$new_ip_address" ]; then
			delete_old_address
			delete_old_routes
		fi
	fi
	if [ "$reason" = BOUND ] || \
	   [ "$reason" = REBOOT ] || \
	   [ -z "$old_ip_address" ] || \
	   [ "$old_ip_address" != "$new_ip_address" ]; then
		add_new_address
		add_new_routes
	fi
	if [ "$new_ip_address" != "$alias_ip_address" ]; then
		add_new_alias
	fi
	if is_default_interface; then
		add_new_resolv_conf
	fi
	;;

EXPIRE|FAIL)
	delete_old_alias
	if [ -n "$old_ip_address" ]; then
		delete_old_address
		delete_old_routes
	fi
	if [ -x $ARP ]; then
		$ARP -d -a -i $interface
	fi
	# XXX Why add alias we just deleted above?
	add_new_alias
	if is_default_interface; then
		if [ -f /etc/resolv.conf.save ]; then
			cat /etc/resolv.conf.save > /etc/resolv.conf
		fi
	fi
	;;

TIMEOUT)
	delete_old_alias
	add_new_address
	sleep 1
	if [ -n "$new_routers" ]; then
		$LOGGER "New Routers ($interface): $new_routers"
		set "$new_routers"
		if ping -q -c 1 -t 1 "$1"; then
			if [ "$new_ip_address" != "$alias_ip_address" ]; then
				add_new_alias
			fi
			add_new_routes
			if ! is_default_interface; then
				exit_with_hooks 0
			fi
			if add_new_resolv_conf; then
				exit_with_hooks 0
			fi
		fi
	fi
	eval "$IFCONFIG $interface inet -alias $new_ip_address $medium"
	delete_old_routes
	exit_with_hooks 1
	;;
esac

exit_with_hooks 0