p2p/nat: use IP.IsPrivate (#26252)

p2p/nat/natpmp.go

@@ -95,13 +95,6 @@ func discoverPMP() Interface {
 	return nil
 }
 
-var (
-	// LAN IP ranges
-	_, lan10, _  = net.ParseCIDR("10.0.0.0/8")
-	_, lan176, _ = net.ParseCIDR("172.16.0.0/12")
-	_, lan192, _ = net.ParseCIDR("192.168.0.0/16")
-)
-
 // TODO: improve this. We currently assume that (on most networks)
 // the router is X.X.X.1 in a local LAN range.
 func potentialGateways() (gws []net.IP) {
@@ -116,7 +109,7 @@ func potentialGateways() (gws []net.IP) {
 		}
 		for _, addr := range ifaddrs {
 			if x, ok := addr.(*net.IPNet); ok {
-				if lan10.Contains(x.IP) || lan176.Contains(x.IP) || lan192.Contains(x.IP) {
+				if x.IP.IsPrivate() {
 					ip := x.IP.Mask(x.Mask).To4()
 					if ip != nil {
 						ip[3] = ip[3] | 0x01