mwan3: fix empty gateway when creating routing table

Interfaces of some PtP protocols do not have a real gateway. In that
case ubus may fill them with '0.0.0.0' or even leave it blank. This
will cause error when adding new routing rule.

Signed-off-by: David Yang <mmyangfl@gmail.com>

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

@@ -26,24 +26,20 @@ if [ "$ACTION" == "ifup" ]; then
 	if [ "$family" = "ipv4" ]; then
 		ubus call network.interface.${INTERFACE}_4 status &>/dev/null
 		if [ "$?" -eq "0" ]; then
-			network_get_gateway gateway ${INTERFACE}_4
 			network_get_ipaddr src_ip ${INTERFACE}_4
 		else
-			network_get_gateway gateway $INTERFACE
 			network_get_ipaddr src_ip ${INTERFACE}
 		fi
 	elif [ "$family" = "ipv6" ]; then
 		ubus call network.interface.${INTERFACE}_6 status &>/dev/null
 		if [ "$?" -eq "0" ]; then
-			network_get_gateway6 gateway ${INTERFACE}_6
 			network_get_ipaddr6 src_ip ${INTERFACE}_6
 		else
-			network_get_gateway6 gateway ${INTERFACE}
 			network_get_ipaddr6 src_ip ${INTERFACE}
 		fi
 	fi
 
-	[ -n "$gateway" ] || exit 9
+	[ -n "$src_ip" ] || exit 9
 fi
 
 if [ "$initial_state" = "offline" ]; then

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

@@ -324,10 +324,14 @@ mwan3_create_iface_route()
 			network_get_gateway route_args $1
 		fi
 
-		route_args="via $route_args dev $2"
+		if [ -n "$route_args" -a "$route_args" != "0.0.0.0" ]; then
+			route_args="via $route_args"
+		else
+			route_args=""
+		fi
 
 		$IP4 route flush table $id
-		$IP4 route add table $id default $route_args
+		$IP4 route add table $id default $route_args dev $2
 	fi
 
 	if [ "$family" == "ipv6" ]; then
@@ -337,10 +341,14 @@ mwan3_create_iface_route()
 			network_get_gateway6 route_args $1
 		fi
 
-		route_args="via $route_args dev $2"
+		if [ -n "$route_args" -a "$route_args" != "::" ]; then
+			route_args="via $route_args"
+		else
+			route_args=""
+		fi
 
 		$IP6 route flush table $id
-		$IP6 route add table $id default $route_args
+		$IP6 route add table $id default $route_args dev $2
 	fi
 }