#!/sbin/openrc-run

extra_commands="checkconfig panic save"
extra_started_commands="reload reset"

description="Manage nftable based firewall."
description_checkconfig="Check validity of rulesets on disk without applying changes."
description_panic="Immediately drop all packets on all interfaces."
description_reload="Clear current rulesets and load rulesets from the ruleset files."
description_save="Save nftables state or ruleset to disk."
description_reset="Reset stateful objects (counters and quotas)."

# Uppercase variables are there for backward compatibility (Alpine <3.8).
: ${rules_file:=${NFTABLES_SAVE:-"/etc/nftables.nft"}}
: ${save_objects:="ruleset"}  # "ruleset" is for backward compatibility (Alpine <3.17)
: ${save_options:=${SAVE_OPTIONS:-}}
: ${save_on_stop:=${SAVE_ON_STOP:-"no"}}
: ${enable_forwarding:="no"}

if [ "$save_objects" = 'ruleset' ]; then
	: ${save_file:="$rules_file"}
else
	: ${save_file:="/var/lib/nftables/state.nft"}
fi

depend() {
	need localmount
	after sysctl
	before net
	provide firewall
}

start_pre() {
	checkkernel && checkconfig
}

start() {
	ebegin "Loading nftables rules and starting firewall"

	nft -f "$rules_file"
	eend $? || return 1

	if yesno "$enable_forwarding"; then
		ebegin "Enabling forwarding"
		forwarding 1
		eend $? || return 1
	fi
}

stop() {
	if yesno "$save_on_stop"; then
		save || return 1
	fi

	if yesno "$enable_forwarding"; then
		ebegin "Disabling forwarding"
		forwarding 0
		eend $?
	fi

	ebegin "Stopping firewall"
	nft flush ruleset
	eend $?
}

reload() {
	# This condition is mainly for backward compatibility (Alpine <3.17).
	if yesno "$save_on_stop" && [ "$save_objects" != 'ruleset' ]; then
		save || return 1
	fi
	start
}

panic() {
	checkkernel || return 1

	if service_started "$RC_SVCNAME"; then
		rc-service "$RC_SVCNAME" stop
	fi

	ebegin "Dropping all packets"
	nft -f /dev/stdin <<-EOF
		flush ruleset
		table inet filter {
		    chain input { type filter hook input priority 0; policy drop; }
		    chain forward { type filter hook forward priority 0; policy drop; }
		    chain output { type filter hook output priority 0; policy drop; }
		}
	EOF
	eend $?
}

save() {
	[ "$RC_CMD" = 'save' ] && ebegin "Saving nftables state"

	checkpath -q -d "${save_file%/*}"
	checkpath -q -m 0600 -F -f "$save_file.tmp"

	local rc=0
	local type; for type in $save_objects; do
		[ "$type" = 'ruleset' ] && echo 'flush ruleset' >> "$save_file.tmp"
		nft $save_options list $type >> "$save_file.tmp" || rc=$?
	done

	[ $rc -eq 0 ] && mv "$save_file.tmp" "$save_file"

	[ "$RC_CMD" = 'save' ] && eend $rc

	return $rc
}

reset() {
	ebegin "Resetting stateful objects"

	local rc=0 type
	for type in counters quotas; do
		nft reset $type >/dev/null || rc=$?
	done

	eend $rc
}

checkconfig() {
	if [ ! -f "$rules_file" ]; then
		eerror "Rules files $rules_file does not exist!"
		return 1
	fi
	nft -c -f "$rules_file"
}

checkkernel() {
	if ! nft list tables >/dev/null 2>&1; then
		eerror "Your kernel lacks nftables support, please load"
		eerror "appropriate modules and try again."
		return 1
	fi
	return 0
}

forwarding() {
	/sbin/sysctl -qw net.ipv4.ip_forward=$1 || return 1

	if /sbin/sysctl -eq net.ipv6.conf.all.forwarding >/dev/null; then
		/sbin/sysctl -qw \
			net.ipv6.conf.default.forwarding=$1 \
			net.ipv6.conf.all.forwarding=$1 || return 1
	fi
	return 0
}