Use FTP instead of SMB

cmd/utils.go

@@ -163,29 +163,60 @@ func runVM(passthroughArg string, fn func(context.Context, *vm.VM, *vm.FileManag
 	}
 }
 
-func getClosestAvailPort(port uint16) (uint16, error) {
-	for i := port; i < 65535; i++ {
-		ln, err := net.Listen("tcp", ":"+fmt.Sprint(i))
+func checkPortAvailable(port uint16, subsequent uint16) (bool, error) {
+	if port+subsequent < port {
+		return false, fmt.Errorf("subsequent ports exceed allowed port range")
+	}
+
+	if subsequent == 0 {
+		ln, err := net.Listen("tcp", ":"+fmt.Sprint(port))
 		if err != nil {
 			if opErr, ok := err.(*net.OpError); ok {
 				if sysErr, ok := opErr.Err.(*os.SyscallError); ok {
 					if sysErr.Err == syscall.EADDRINUSE {
 						// The port is in use.
-						continue
+						return false, nil
 					}
 				}
 			}
 
-			return 0, errors.Wrapf(err, "net listen (port %v)", port)
+			return false, errors.Wrapf(err, "net listen (port %v)", port)
 		}
 
 		err = ln.Close()
 		if err != nil {
-			return 0, errors.Wrap(err, "close ephemeral listener")
+			return false, errors.Wrap(err, "close ephemeral listener")
 		}
 
-		return i, nil
+		return true, nil
 	}
 
-	return 0, fmt.Errorf("no available port found")
+	for i := uint16(0); i < subsequent; i++ {
+		ok, err := checkPortAvailable(port+i, 0)
+		if err != nil {
+			return false, errors.Wrapf(err, "check subsequent port available (base: %v, seq: %v)", port, i)
+		}
+
+		if !ok {
+			return false, nil
+		}
+	}
+
+	return true, nil
+}
+
+func getClosestAvailPortWithSubsequent(port uint16, subsequent uint16) (uint16, error) {
+	// We use 10 as port range
+	for i := port; i < 65535; i += subsequent {
+		ok, err := checkPortAvailable(i, subsequent)
+		if err != nil {
+			return 0, errors.Wrapf(err, "check port available (%v)", i)
+		}
+
+		if ok {
+			return i, nil
+		}
+	}
+
+	return 0, fmt.Errorf("no available port (with %v subsequent ones) found", subsequent)
 }