esp_netif_is_netif_up returns false when running with WIFI_MODE_STA

[JohnOhl]

If you start wifi in WIFI_MODE_STA, and don't connect to a remote AP, the esp_netif_is_netif_up method always returns false, even though the interface has started. Essentially both netif_is_link_up and netif_is_up always return the same values when in STA mode and not connected to a remote AP.

This is inconsistent with both ethernet interfaces and WIFI_MODE_AP where the interface is considered up as long as the service has started, and it does not depend on whether or not a connection link is established.

Attached example, it should output wifi_init_sta interface status -- UP but instead outputs wifi_init_sta interface status -- DOWN

#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_event.h"
#include "esp_log.h"
#include "nvs_flash.h"

#include "lwip/err.h"
#include "lwip/sys.h"

#define EXAMPLE_ESP_WIFI_SSID      "Test SSID"
#define EXAMPLE_ESP_WIFI_PASS      "password"

static EventGroupHandle_t s_wifi_event_group;

#define WIFI_STARTED_BIT ( 1 << 0)

static const char *TAG = "wifi station";

static int s_retry_num = 0;

static void event_handler(void* arg, esp_event_base_t event_base,
                                int32_t event_id, void* event_data)
{
    if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
        xEventGroupSetBits(s_wifi_event_group, WIFI_STARTED_BIT);
    }
}

void wifi_init_sta(void)
{
    s_wifi_event_group = xEventGroupCreate();

    ESP_ERROR_CHECK(esp_netif_init());

    ESP_ERROR_CHECK(esp_event_loop_create_default());
    static esp_netif_t *netif = esp_netif_create_default_wifi_sta();

    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));

    esp_event_handler_instance_t instance_any_id;
    esp_event_handler_instance_t instance_got_ip;
    ESP_ERROR_CHECK(esp_event_handler_instance_register(WIFI_EVENT,
                                                        WIFI_EVENT_STA_START,
                                                        &event_handler,
                                                        NULL,
                                                        &instance_any_id));

    wifi_config_t wifi_config = {
        .sta = {
            .ssid = EXAMPLE_ESP_WIFI_SSID,
            .password = EXAMPLE_ESP_WIFI_PASS,
            .threshold.authmode = WIFI_AUTH_WPA2_PSK,
            .sae_pwe_h2e = 2,
        },
    };
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
    ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
    ESP_ERROR_CHECK(esp_wifi_start() );

    ESP_LOGI(TAG, "wifi_init_sta finished.");

    // Wait until the WiFi station interface starts
    xEventGroupWaitBits(s_wifi_event_group, WIFI_STARTED_BIT, pdFALSE, pdFALSE, portMAX_DELAY);
    ESP_LOGI(TAG, "wifi_init_sta started.");

    bool is_up = esp_netif_is_netif_up(netif);
    ESP_LOGI(TAG, "wifi_init_sta interface status -- %s", is_up ? "UP" : "DOWN");
}

void app_main(void)
{
    //Initialize NVS
    esp_err_t ret = nvs_flash_init();
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
      ESP_ERROR_CHECK(nvs_flash_erase());
      ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK(ret);

    ESP_LOGI(TAG, "ESP_WIFI_MODE_STA");
    wifi_init_sta();
}