text: void esp_struct_init(struct espconn *ec, u8 *remote_ip, int remote_port);
  void test(u8 *remote_ip);
  void conn_cb(void *arg);
  void dc_cb(void *arg);
  void reconn_cb(void *arg);
  void rcv_cb(void *arg, char *pdata, unsigned short len);
  void snd_cb(void *arg);
  void write_fin_cb(void *arg);
  