使用at_socket 怎么完成的创建socket

int (*at_socket)(struct at_device *device, enum at_socket_type type);

at_socket(int domain, int type, int protocol)----> sock = alloc_socket(socket_type);---->alloc_socket_by_device(device, type);----> idx = device->class->socket_ops->at_socket(device, type);

static const struct at_socket_ops esp8266_socket_ops =
{
    esp8266_socket_connect,
    esp8266_socket_close,
    esp8266_socket_send,
    esp8266_domain_resolve,
    esp8266_socket_set_event_cb,
#if defined(AT_SW_VERSION_NUM) && AT_SW_VERSION_NUM > 0x10300
    RT_NULL, /*at_socket为空*/
#endif
};

/* AT socket operations function */
struct at_socket_ops
{
    int (*at_connect)(struct at_socket *socket, char *ip, int32_t port, enum at_socket_type type, rt_bool_t is_client);
    int (*at_closesocket)(struct at_socket *socket);
    int (*at_send)(struct at_socket *socket, const char *buff, size_t bfsz, enum at_socket_type type);
    int (*at_domain_resolve)(const char *name, char ip[16]);
    void (*at_set_event_cb)(at_socket_evt_t event, at_evt_cb_t cb);
    int (*at_socket)(struct at_device *device, enum at_socket_type type);
};

int esp8266_socket_class_register(struct at_device_class *class)
{
    RT_ASSERT(class);
    class->socket_num = AT_DEVICE_ESP8266_SOCKETS_NUM;
    class->socket_ops = &esp8266_socket_ops;
    return RT_EOK;
}