-type -t host &>/dev/null || apt-get -y install dnsutils
-ip=$(host $host | sed -rn 's/^\S+ has address //p;T;q')
-gateway_ip=$(route -n | sed -rn 's/^0\.0\.0\.0\s+(\S+).*/\1/p')
-my_ip=$(host faiserver $gateway_ip | sed -rn 's/^\S+ has address //p;T;q')
+rm -f /srv/tftp/fai/pxelinux.cfg/*
+if [[ ! $1 ]]; then
+ echo "$0: clearing pxe config and exiting"
+ exit 0
+fi
+
+# assuming ipv4, or else we might need to deal with multiple addresses
+# in an ipv4 + ipv6 network.
+my_ip=$(ip -4 route get 8.8.8.8 | sed -nr 's,^.*src\s+(\S+).*,\1,p')
+if [[ ! $my_ip || $my_ip =~ [[:space:]] ]]; then
+ echo "$0: error: failed to get \$my_ip, got: $my_ip"
+ exit 1
+fi
+
+if [[ $host == default ]]; then
+ ip='*'
+elif [[ $host == [0-9]*.[0-9]*.[0-9]*.[0-9]* ]]; then
+ ip=$host/32
+else
+ type -t host &>/dev/null || apt-get -y install dnsutils
+ ip=$(host $host | sed -rn 's/^\S+ has address //p;T;q' ||:)
+ if [[ ! $ip || $ip =~ [[:space:]] ]]; then
+ echo "$0: error: failed to get \$ip, got: $ip"
+ exit 1
+ fi
+ ip=$ip/32
+ echo "$0: found ip of $host: $ip"
+fi