fix: pcap_dispatch is non blocking

feature: no response handle

src/thread.c

@@ -80,7 +80,7 @@ error:
 int create_threads(const struct option_lst *options, char *ip_addr,
                    struct response *responses)
 {
-	uint16_t port_start, port_end;
+	uint16_t port_start = 0, port_end = 0;
 	const char *ports = get_option_arg(options, FL_PORTS);
 	if (parse_ports(ports, &port_start, &port_end) < 0)
 		return -1;