lib/beacon, lib/discover: Send IPv4 limited broadcast when address listing fails (fixes #1628) (#9087)

lib/beacon/broadcast.go

@@ -46,8 +46,9 @@ func writeBroadcasts(ctx context.Context, inbox <-chan []byte, port int) error {
 
 		intfs, err := net.Interfaces()
 		if err != nil {
-			l.Debugln(err)
-			return err
+			l.Debugln("Failed to list interfaces:", err)
+			// net.Interfaces() is broken on Android. see https://github.com/golang/go/issues/40569
+			// Use the general broadcast address 255.255.255.255 instead.
 		}
 
 		var dsts []net.IP
@@ -58,8 +59,9 @@ func writeBroadcasts(ctx context.Context, inbox <-chan []byte, port int) error {
 
 			addrs, err := intf.Addrs()
 			if err != nil {
-				l.Debugln(err)
-				return err
+				l.Debugln("Failed to list interface addresses:", err)
+				// Interface discovery might work while retrieving the addresses doesn't. So log the error and carry on.
+				continue
 			}
 
 			for _, addr := range addrs {