examples/protocols/static_ip example cannot communicate with the outside (IDFGH-5523)

[nopnop2002]

Environment

freeRTOS version:V10.2.1
NEWLIB version:3.0.0
portTICK_RATE_MS:10 msec/tick
lwIP version:2-1-3-0
ESP-IDF version:v4.4-dev-1183-g9d34a1cd4-dirty
chip model is 2, chip with 1 CPU cores, WiFi, silicon revision 0, 2MB external flash
package is ESP32D0WDQ6
target is ESP32S2

Problem Description

This example turns off DHCP but doesn't set DNS.
Therefore, it cannot communicate with the NTP server.

Workaround

After stopping DHCP, set the DNS address.
I modiyied this

There may be better code.

static void example_set_static_ip(esp_netif_t *netif)
{
    if (esp_netif_dhcpc_stop(netif) != ESP_OK) {
        ESP_LOGE(TAG, "Failed to stop dhcp client");
        return;
    }
    esp_netif_ip_info_t ip;
    memset(&ip, 0 , sizeof(esp_netif_ip_info_t));
    ip.ip.addr = ipaddr_addr(CONFIG_STATIC_IP_ADDRESS);
    //ip.netmask.addr = ipaddr_addr(CONFIG_STATIC_NETMASK_ADDR);
    ip.netmask.addr = ipaddr_addr(CONFIG_STATIC_NM_ADDRESS);
    ip.gw.addr = ipaddr_addr(CONFIG_STATIC_GW_ADDRESS);
    if (esp_netif_set_ip_info(netif, &ip) != ESP_OK) {
        ESP_LOGE(TAG, "Failed to set ip info");
        return;
    }
    ESP_LOGD(TAG, "Success to set static ip: %s, netmask: %s, gw: %s",
        CONFIG_STATIC_IP_ADDRESS, CONFIG_STATIC_NM_ADDRESS, CONFIG_STATIC_GW_ADDRESS);

    ip_addr_t d;
    d.type = IPADDR_TYPE_V4;
    d.u_addr.ip4.addr = 0x08080808; //8.8.8.8 dns
    dns_setserver(0, &d);
    d.u_addr.ip4.addr = 0x08080404; //8.8.4.4 dns
    dns_setserver(1, &d);
}

[david-cermak]

Hi @nopnop2002

Thanks for letting us know about this and providing a working setup! The idea behind that example was just to demonstrate static IP configuration. I agree, though, that it might be a bit misleading if we cannot resolve hosts by default. We will add a menuconfig option to setup configurable global DNS server.