nut: Fix procd crashloop no interfaces

Fix a crashloop under procd when attempting to bind
to any address when no interfaces are yet available.

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>

net/nut/files/nut-monitor.init

@@ -163,12 +163,39 @@ build_config() {
 	[ -s "$UPSMON_C" ] && chgrp $(id -gn ${runas:-root}) "$UPSMON_C"
 }
 
+interface_triggers() {
+	local action="$1"
+	local triggerlist trigger
+
+	config_get triggerlist "upsmon" triggerlist
+
+	. /lib/functions/network.sh
+
+	if [ -n "$triggerlist" ]; then
+		for trigger in $triggerlist; do
+			if [ "$action" = "add_trigger" ]; then
+				procd_add_interface_trigger "interface.*" "$trigger" /etc/init.d/nut-monitor reload
+			else
+				network_is_up "$trigger" && return 0
+			fi
+		done
+	else
+		if [ "$action" = "add_trigger" ]; then
+			procd_add_raw_trigger "interface.*.up" 2000 /etc/init.d/nut-monitor reload
+		else
+			ubus call network.device status | grep -q '"up": true' && return 0
+		fi
+	fi
+	[ "$action" = "add_trigger" ] || return 1
+}
+
 start_service() {
 	local havemon havems
 	build_config
 
 	[ "$havemon" != 1 ] && return
 	[ "$havems" != 1 ] && return
+	interface_triggers "check_interface_up" || return
 
 	procd_open_instance "upsmon"
 	procd_set_param respawn
@@ -190,5 +217,7 @@ reload_service() {
 }
 
 service_triggers() {
+	confg_load nut_monitor
+	interface_triggers "add_trigger"
 	procd_add_reload_trigger "nut_monitor"
 }