auto act = _auth->next();
			while (act != SUCCESS && act != FAILURE) {
				if (act == SEND) {
					size_t len;
					auto p = _auth->construct_send(len);
					_socket.send(boost::asio::buffer(p.get(), len));
					_auth->sent();
				}
				else if (act == RECV) {
					size_t len;
					auto p = _auth->construct_receive(len);
					_socket.receive(boost::asio::buffer(p.get(), len));
					_auth->received(p.get(), len);
				}
                                   
                                   **//act = _auth->next(); 缺这句？？？**
			}

inline static tcp_pcb* tcp_listen_any() {
			auto pcb = lwip_tcp_new();
			auto any = ip_addr_any;
			lwip_tcp_bind(pcb, &any, 0);
			return lwip_tcp_listen(pcb);
		}

/** Return true if the current input packet should be accepted on this netif */
static int
ip4_input_accept(struct netif *netif)
{
  LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
                         ip4_addr_get_u32(ip4_current_dest_addr()), ip4_addr_get_u32(netif_ip4_addr(netif)),
                         ip4_addr_get_u32(ip4_current_dest_addr()) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
                         ip4_addr_get_u32(netif_ip4_addr(netif)) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
                         ip4_addr_get_u32(ip4_current_dest_addr()) & ~ip4_addr_get_u32(netif_ip4_netmask(netif))));

  /* interface is up and configured? */
  if ((netif_is_up(netif)) && (!ip4_addr_isany_val(*netif_ip4_addr(netif)))) {
    /* unicast to this interface address? */
    if (ip4_addr_eq(ip4_current_dest_addr(), netif_ip4_addr(netif)) ||
        /* or broadcast on this interface network address? */
        ip4_addr_isbroadcast(ip4_current_dest_addr(), netif)
#if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
        || (ip4_addr_get_u32(ip4_current_dest_addr()) == PP_HTONL(IPADDR_LOOPBACK))
#endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
       ) {
      LWIP_DEBUGF(IP_DEBUG, ("ip4_input: packet accepted on interface %c%c\n",
                             netif->name[0], netif->name[1]));
      /* accept on this netif */
      return 1;
    }
#if LWIP_AUTOIP
    /* connections to link-local addresses must persist after changing
        the netif's address (RFC3927 ch. 1.9) */
    if (autoip_accept_packet(netif, ip4_current_dest_addr())) {
      LWIP_DEBUGF(IP_DEBUG, ("ip4_input: LLA packet accepted on interface %c%c\n",
                             netif->name[0], netif->name[1]));
      /* accept on this netif */
      return 1;
    }
#endif /* LWIP_AUTOIP */
  }
  return 0;
}