HardenedBSD/sbin/dhclient/dhclient-script

#!/bin/sh
#
# $OpenBSD: dhclient-script,v 1.6 2004/05/06 18:22:41 claudio Exp $
#
# 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.
#
#

#
# Helper functions that implement common actions.
#

delete_old_address() {
	if [ -n "$old_ip_address" ]; then
		ifconfig $interface inet -alias $old_ip_address $medium
		route delete "$old_ip_address" 127.0.0.1 >/dev/null 2>&1
	fi
}

add_new_address() {
	ifconfig $interface \
		inet $new_ip_address \
		netmask $new_subnet_mask \
		broadcast $new_broadcast_address \
		$medium

	# XXX Original TIMEOUT code did not do this unless $new_routers was set?
	route add $new_ip_address 127.0.0.1 >/dev/null 2>&1
}

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 127.0.0.1 > /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 127.0.0.1
	fi
}

delete_old_routes() {
	# Delete existing default route. We only allow one, so no need to
	# process $old_routers list.
	route delete default >/dev/null 2>&1

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

	arp -dan
}

add_new_routes() {
	route delete default >/dev/null 2>&1
	for router in $new_routers; do
		if [ "$new_ip_address" = "$router" ]; then
			route add default -iface $router >/dev/null 2>&1
		else
			route add default $router >/dev/null 2>&1
		fi
		# 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
		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.

	rm -f /etc/resolv.conf.std

	if [ -n "$new_domain_name" ]; then
		echo "search $new_domain_name" >>/etc/resolv.conf.std
	fi

	if [ -n "$new_domain_name_servers" ]; then
		for nameserver in $new_domain_name_servers; do
			echo "nameserver $nameserver" >>/etc/resolv.conf.std
		done
	fi

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

		# 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 /etc/resolv.conf.std > /etc/resolv.conf
		rm -f /etc/resolv.conf.std

		# 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
}

#
# Start of active code.
#

if [ -n "$new_network_number" ]; then
	echo "New Network Number: $new_network_number"
fi

if [ -n "$new_broadcast_address" ]; then
	echo "New Broadcast Address: $new_broadcast_address"
fi

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

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

ARPCHECK|ARPSEND)
	;;

BOUND|RENEW|REBIND|REBOOT)
	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
	add_new_resolv_conf
	;;

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

TIMEOUT)
	delete_old_alias
	add_new_address
	sleep 1
	if [ -n "$new_routers" ]; then
		set "$new_routers"
		if ping -q -c 1 -w 1 "$1"; then
			if [ "$new_ip_address" != "$alias_ip_address" ]; then
				add_new_alias
			fi
			add_new_routes
			if add_new_resolv_conf; then
				exit 0
			fi
		fi
	fi
	ifconfig $interface inet -alias $new_ip_address $medium
	# XXX Why not a delete_old_address as before all other invocations of
	#     delete_old_routes?
	delete_old_routes
	exit 1
	;;
esac

exit 0