UDP transport with broadcast support, -udp and -iface flags on info

cmd/picomap/main.go

@@ -73,12 +73,16 @@ func printInfo(dev string, info *client.ResponseInfo) {
 func cmdInfo(args []string) error {
 	fs := flag.NewFlagSet("info", flag.ExitOnError)
 	udpAddr := fs.String("udp", "", "connect via UDP to this IP address")
+	iface := fs.String("iface", "", "bind to this network interface (for broadcast)")
 	fs.Parse(args)
 
 	if *udpAddr != "" {
 		log := slog.With("addr", *udpAddr)
+		if *iface != "" {
+			log = log.With("iface", *iface)
+		}
 		log.Info("connecting via UDP")
-		c, err := client.NewUDP(*udpAddr, 2*time.Second)
+		c, err := client.NewUDP(*udpAddr, *iface, 2*time.Second)
 		if err != nil {
 			return err
 		}