add: message when host not define && fix: host

src/parsing.c

@@ -23,7 +23,7 @@ static struct param *get_parameter(struct param parameters[], const char *str)
 
 char *parsing(char * const *av, struct param parameters[])
 {
-    char *host;
+    char *host = NULL;
     for (size_t i = 0; av[i]; i++)
     {
         struct param *parameter = get_parameter(parameters, av[i]);
@@ -46,5 +46,7 @@ char *parsing(char * const *av, struct param parameters[])
             host = (char*) av[i];
         }
     }
+    if (host == NULL)
+        print_err("usage error: Destination address required");
     return host;
 }