add some validation code

persistence.go

@@ -119,15 +119,14 @@ func checkUserAvailable(username string) bool {
 	conn := globalPool.Get()
 	defer conn.Close()
 
-	_, err := conn.Do("HGETALL", userPrefix+username)
-	if err == redis.ErrNil {
-		logit("User does not exist and is therefore available:" + username)
+	exists, _ := redis.Bool(conn.Do("EXISTS", userPrefix+username))
+	if !exists {
+		logit("checkUserAvailable: User does not exist, so it is available: " + username)
 		return true
-	} else if err != nil {
-		logit("checkUserAvailable: Error to query Key Value Store")
+	} else {
+		logit("checkUserAvailable: User exist, so it is not available: " + username)
 		return false
 	}
-	return false
 }
 
 func getMyDevs(username string) []string {