#!/bin/ash

UUID=$( dmidecode -q -s system-uuid | grep -v '^#' | head -n 1 | tr 'a-z' 'A-Z' )
if [ "${#UUID}" -ne "36" ]; then
	echo "Determined UUID (${UUID}) has not expected length of 36, falling back to MAC..."
	UUID=
else
	# Got UUID, check blacklist
	DIR="/opt/openslx/bad-uuid.d"
	TMPLIST=$(mktemp)
	BADLIST=$(mktemp)
	for file in "$DIR"/*; do
		[ -f "$file" ] || continue
		# 11111111-2222-3333-4444-555555555555
		< "$file" tr 'a-z' 'A-Z' | grep -Eo '[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}'
	done | tee "$TMPLIST" > "$BADLIST"
	# Also add flipped version of bad uuids. Found some of them through googling and discovered that sometimes
	# users report them in a different order. UUIDs use different endianness for the first three blocks than
	# the remaining two, but some tools seem to ignore that fact.
	< "$BADLIST" sed -r 's/^(..)(..)(..)(..)\-(..)(..)\-(..)(..)\-([0-9A-F]{4}\-[0-9A-F]{12})$/\4\3\2\1-\6\5-\8\7-\9/' >> "$TMPLIST"
	# Finally make unique
	sort -u "$TMPLIST" > "$BADLIST"
	if grep -Fxq "$UUID" "$BADLIST"; then
		echo "WARNING: UUID is blacklisted as potentially not being unique, using MAC fallback"
		UUID=
	fi
	rm -f -- "$TMPLIST" "$BADLIST"
fi
if [ -z "$UUID" ]; then
	if [ "${#MAC}" -ne 17 ]; then
		MAC="$( grep -Po '(?<=ipv4.if=)\S+' /proc/cmdline )"
	fi
	if [ "${#MAC}" -ne 17 ]; then
		MAC="$( grep -Po '(?<=BOOTIF=01-)\S+' /proc/cmdline )"
	fi
	if [ "${#MAC}" -ne 17 ]; then
		echo "Getting MAC from /proc/cmdline failed, using 'ip a'..."
		MAC="$( ip a | grep -A 1 ': br0' | grep -o 'ether ..:..:..:..:..:..' | cut -d' ' -f2 )"
	fi
	if [ "${#MAC}" -ne 17 ]; then
		echo "FAIL FAIL FAIL"
		MAC="88-77-66-55-44-33"
	fi
	UUID=$( echo "$MAC" | sed -r 's/[^0-9A-Fa-f]//g' )
	if [ "${#UUID}" -eq 12 ]; then
		UUID="baad1d00-9491-4716-b98b-$UUID"
	else
		UUID="baad1d00-9491-4716-b98b-000000000000"
	fi
fi
UUID=$( echo "$UUID" | tr 'a-z' 'A-Z' )
readonly UUID

echo "$UUID" > "/run/system-uuid"