busybox: sysntpd: add trigger to reload server

sysntpd server becomes unavailable if the index of the bound
interface changes. So let's add an interface trigger to reload sysntpd.

This patch also adds the ability for the sysntpd script to handle
uci interface name from configuration.

Fixes: 4da60500ebd2 ("busybox: sysntpd: option to bind server to iface")
Signed-off-by: Alexey Dobrovolsky <dobrovolskiy.alexey@gmail.com>
Reviewed-by: Philip Prindeville <philipp@redfish-solutions.com>

package/utils/busybox/files/sysntpd

@@ -56,7 +56,14 @@ start_ntpd_instance() {
 	procd_set_param command "$PROG" -n -N
 	if [ "$enable_server" = "1" ]; then
 		procd_append_param command -l
-		[ -n "$interface" ] && procd_append_param command -I $interface
+		[ -n "$interface" ] && {
+			local ifname
+
+			network_get_device ifname "$interface" || \
+				ifname="$interface"
+			procd_append_param command -I "$ifname"
+			procd_append_param netdev "$ifname"
+		}
 	fi
 	[ -x "$HOTPLUG_SCRIPT" ] && procd_append_param command -S "$HOTPLUG_SCRIPT"
 	for peer in $server; do
@@ -74,11 +81,12 @@ start_ntpd_instance() {
 }
 
 start_service() {
+	. /lib/functions/network.sh
 	validate_ntp_section ntp start_ntpd_instance
 }
 
 service_triggers() {
-	local script name use_dhcp
+	local script name use_dhcp enable_server interface
 
 	script=$(readlink -f "$initscript")
 	name=$(basename ${script:-$initscript})
@@ -101,5 +109,17 @@ service_triggers() {
 		fi
 	}
 
+	config_get_bool enable_server ntp enable_server 0
+	config_get interface ntp interface
+
+	[ $enable_server -eq 1 ] && [ -n "$interface" ] && {
+		local ifname
+
+		network_get_device ifname "$interface" || \
+			ifname="$interface"
+		procd_add_interface_trigger "interface.*" "$ifname" \
+			/etc/init.d/"$name" reload
+	}
+
 	procd_add_validation validate_ntp_section
 }