#!/bin/sh
# Install into /etc/dhcp and symlink to /etc/dhcp/dhclient-{enter,exit}-hooks.d

IFACE=enp9s0f1.4
VRID=4
PRIO=100
DUMMYIP_OLD=192.168.254.254
DUMMYIP_NEW=192.168.254.253

PIDFILE=/var/run/"vrrpd_${IFACE}_${VRID}.pid"
HOOKDIR="$(basename "$dir")"

## Debugging
#set -x
#exec >> /tmp/dhcp.log 2>&1
echo $HOOKDIR $reason $interface >>/tmp/dhcp.log
set | grep 'ip_address\|route' | sort >>/tmp/dhcp.log
printf '\n\n' >>/tmp/dhcp.log

killvrrp () {
	echo "killvrrp $PIDFILE" >>/tmp/dhcp.log
	[ -n $old_ip_address ] || return
	if [ -e "$PIDFILE" ]; then
		kill "$(cat $PIDFILE)" || true
	fi
}

startvrrp () {
	echo "startvrrp $new_ip_address\n" >>/tmp/dhcp.log
	[ -n $new_ip_address ] || return
	echo vrrpd -D -n -i "$interface" -v "$VRID" -p "$PRIO" "$new_ip_address"
	vrrpd -D -n -i "$interface" -v "$VRID" -p "$PRIO" "$new_ip_address" ||
		exit_status=1
}

# dhclient-script insists on fucking with the IP address, we don't want any
# of that since vrrpd will do it.
neutralize_ip_change () {
	ip () neutered_ip "$@"
}

neutered_ip () {
	[ $# -ge 3 ] || { ip "$@"; return; }
	if
		[ "$1" = "-4" -a "$2" = addr -a "$3" = flush ] ||
		[ "$1" = "-4" -a "$2" = addr -a "$3" = add ] ||
		[ "$1" = "-4" -a "$2" = addr -a "$3" = change ]
	then
		echo ignored "$@"
		return
	else
		echo =ip "$@"
		command ip "$@"
	fi
}

do_vrrp () {

if [ "$HOOKDIR" = "dhclient-enter-hooks.d" ]; then
	case $reason in
		BOUND | REBOOT | TIMEOUT) ;; # Just started shouldn't be running
		RENEW | REBIND)
			[ $new_ip_address = $old_ip_address] || killvrrp ;;
		EXPIRE | FAIL | RELEASE | STOP | TIMEOUT)
			killvrrp ;;
	esac

	neutralize_ip_change
elif [ "$HOOKDIR" = "dhclient-exit-hooks.d" ]; then
	case $reason in
		# Note: TIMEOUT is when we can't reach a dhcp server during
		# startup but have a valid lease still that we're going to
		# use.
		BOUND | REBOOT | TIMEOUT)
			startvrrp ;;
		RENEW | REBIND)
			[ $new_ip_address = $old_ip_address] || startvrrp ;;
		EXPIRE | FAIL | RELEASE) ;;
	esac
fi
}

if [ "$interface" = $IFACE ]; then
	do_vrrp
fi