net/mwan3: registrate SIGUSR1 trap on interface down event

If interface is getting down by netifd (unplug ethernet cable)
mwan3track will not recognize this change. It will also generate an
additional down event when he notice does his tracking interface is offline.

Mwan3track will now be informed by a signal (trap) USR1 during down event
that the interface is already down. An additional down event will not be
generated.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>

net/mwan3/files/etc/hotplug.d/iface/15-mwan3

@@ -64,6 +64,7 @@ case "$ACTION" in
 		mwan3_delete_iface_iptables $INTERFACE
 		mwan3_delete_iface_route $INTERFACE
 		mwan3_delete_iface_ipset_entries $INTERFACE
+		mwan3_track_signal $INTERFACE $DEVICE
 		mwan3_set_policies_iptables
 		mwan3_set_user_rules
 		mwan3_flush_conntrack $INTERFACE $DEVICE "ifdown"

net/mwan3/files/lib/mwan3/mwan3.sh

@@ -399,6 +399,23 @@ mwan3_track()
 	fi
 }
 
+mwan3_track_signal()
+{
+	local pid status
+
+	if [ -f "/var/run/mwan3track-${1}.pid" ]; then
+		pid="$(cat "/var/run/mwan3track-${1}.pid")"
+		status="$(pgrep -f mwan3track | grep "${pid}")"
+		if [ "${status}" != "" ]; then
+			kill -USR1 "${pid}"
+		else
+			$LOG warn "Unable to send signal USR1 to mwan3track on interface $1 with pid ${pid}"
+		fi
+	else
+		$LOG warn "Unable to find \"/var/run/mwan3track-${1}.pid\" file for mwan3track on interface $1"
+	fi
+}
+
 mwan3_set_policy()
 {
 	local iface_count id iface family metric probability weight

net/mwan3/files/usr/sbin/mwan3track

@@ -4,6 +4,9 @@
 
 LOG="/usr/bin/logger -t $(basename "$0")[$$] -p"
 INTERFACE=""
+DEVICE=""
+
+IFDOWN_EVENT=0
 
 clean_up() {
 	$LOG notice "Stopping mwan3track for interface \"${INTERFACE}\""
@@ -15,6 +18,11 @@ clean_up() {
 	exit 0
 }
 
+if_down() {
+	$LOG info "Detect ifdown event on interface ${INTERFACE} (${DEVICE})"
+	IFDOWN_EVENT=1
+}
+
 main() {
 	local reliability count timeout interval failure_interval
 	local recovery_interval down up size
@@ -22,9 +30,11 @@ main() {
 	[ -z "$3" ] && echo "Error: should not be started manually" && exit 0
 
 	INTERFACE=$1
+	DEVICE=$2
 	echo "$$" > /var/run/mwan3track-$1.pid
 	mkdir -p /var/run/mwan3track/$1
 	trap clean_up SIGINT SIGTERM
+	trap if_down SIGUSR1
 
 	config_load mwan3
 	config_get reliability $1 reliability 1
@@ -106,6 +116,12 @@ main() {
 
 		host_up_count=0
 		sleep $sleep_time
+
+		if [ "${IFDOWN_EVENT}" -eq 1 ]; then
+			score=0
+			echo "offline" > /var/run/mwan3track/$1/STATUS
+			IFDOWN_EVENT=0
+		fi
 	done
 }