ESP32 Forum

Posted: **Sat Dec 19, 2020 6:33 am**

Hi

I am trying to set DNS primary and secondary IP of ESP32, but i didn't see any API function for the same.
I am using esp-idf 4.0, I need to know the function to read and set DNS IP.

regards
vaibhav

Posted: **Sat Dec 19, 2020 8:55 am**

Hello @ht_main1

I don't have esp-idf 4.0 installed, but I've searched a bit through the Espressif github repository. How about dns_setserver() used here https://github.com/espressif/esp-idf/bl ... test_dns.c? And most likely there is a dns_getserver() as well.

Thanks
Felix

Posted: **Sat Dec 19, 2020 9:49 am**

tcpip_adapter_set_dns_info() and tcpip_adapter_get_dns_info()

Posted: **Sun Dec 20, 2020 7:10 am**

tcpip_adapter_set_dns_info() and tcpip_adapter_get_dns_info()

Thanks this helped

Posted: **Sun Dec 20, 2020 7:58 am**

tcpip_adapter_set_dns_info() and tcpip_adapter_get_dns_info()

Hi i tried your method, i am setting Static IP, and dns, but when i read back DNS , i get 0.0.0.0

Code: Select all

tcpip_adapter_init();

	if(userData.eth_host_cfg.dhcp_en){
			
		tcpip_adapter_dns_info_t dns_info = {0};
		dhcps_offer_t dhcps_dns_value = OFFER_DNS;
		//dns_info.ip.u_addr.ip4.addr = addr;
		dns_info.ip.type = IPADDR_TYPE_V4;
		
		memset (&dns_info, 8, sizeof(dns_info));
		
		//IP4_ADDR(&dns_info.ip.u_addr.ip4, 8, 8, 8, 8);
		IP_ADDR4(&dns_info.ip, 4, 4, 4, 4);
		
  /*  static esp_err_t set_dhcps_dns(esp_netif_t *netif, uint32_t addr)
{
    esp_netif_dns_info_t dns;
    dns.ip.u_addr.ip4.addr = addr;
    dns.ip.type = IPADDR_TYPE_V4;
    dhcps_offer_t dhcps_dns_value = OFFER_DNS;
    ESP_ERROR_CHECK(esp_netif_dhcps_option(netif, ESP_NETIF_OP_SET, 
				ESP_NETIF_DOMAIN_NAME_SERVER, &dhcps_dns_value, sizeof(dhcps_dns_value)));
    ESP_ERROR_CHECK(esp_netif_set_dns_info(netif, ESP_NETIF_DNS_MAIN, &dns));
    return ESP_OK;
}*/
   // dhcps_offer_t opt_val = OFFER_DNS; // supply a dns server via dhcps
   // tcpip_adapter_dhcps_option(TCPIP_ADAPTER_OP_SET, TCPIP_ADAPTER_DOMAIN_NAME_SERVER, &opt_val, 1);
   // tcpip_adapter_dhcps_start(TCPIP_ADAPTER_IF_AP);
	
	
		tcpip_adapter_ip_info_t ipInfo;
		memset(&ipInfo, 0x00, sizeof(ipInfo));

		IP4_ADDR(&ipInfo.ip, userData.eth_host_cfg.server.IP[0],userData.eth_host_cfg.server.IP[1],userData.eth_host_cfg.server.IP[2],userData.eth_host_cfg.server.IP[3]);
		IP4_ADDR(&ipInfo.gw, userData.eth_host_cfg.network.GW[0],userData.eth_host_cfg.network.GW[1],userData.eth_host_cfg.network.GW[2],userData.eth_host_cfg.network.GW[3]);
		IP4_ADDR(&ipInfo.netmask , userData.eth_host_cfg.network.SNM[0],userData.eth_host_cfg.network.SNM[1],userData.eth_host_cfg.network.SNM[2],userData.eth_host_cfg.network.SNM[3]);

		printf("[app_main]ETHIP: " IPSTR "\r\n", IP2STR(&ipInfo.ip));
		printf("[app_main]ETHMASK: " IPSTR "\r\n", IP2STR(&ipInfo.netmask));
		printf("[app_main]ETHGW: " IPSTR "\r\n", IP2STR(&ipInfo.gw));
		
		tcpip_adapter_dhcpc_stop(TCPIP_ADAPTER_IF_ETH); // ret=0x5000 -> tcpip_adapter_invalid_params, //
		//very old esp-idf didn't implementated this yet.

		ESP_LOGI(TAG, "dhcp client stop RESULT:");
		ESP_ERROR_CHECK(tcpip_adapter_dhcps_option(TCPIP_ADAPTER_OP_SET , 
				TCPIP_ADAPTER_DOMAIN_NAME_SERVER , &dhcps_dns_value, sizeof(dhcps_dns_value)));
		ESP_ERROR_CHECK(tcpip_adapter_set_dns_info(TCPIP_ADAPTER_IF_ETH, TCPIP_ADAPTER_DNS_MAIN, &dns_info));
		tcpip_adapter_set_ip_info(TCPIP_ADAPTER_IF_ETH, &ipInfo);
		//tcpip_adapter_dhcps_start(TCPIP_ADAPTER_IF_AP);
	}

Code: Select all

void monitoring_task(void *pvParameter)
{
	ST_QUERY vTmp_q = {0};
	uint32_t lu32Cnt = 0;
	uint32_t lu32Index = 0;
	tcpip_adapter_dns_info_t dns_info = {0};
	for(;;){
		ESP_LOGI(TAG, "free heap: %d",esp_get_free_heap_size());
		//tcpip_adapter_get_dns_info(TCPIP_ADAPTER_IF_ETH, TCPIP_ADAPTER_DNS_MAIN, &dns_info);
		tcpip_adapter_get_dns_info(TCPIP_ADAPTER_IF_ETH, 0, &dns_info);
        ESP_LOGI(TAG, "Name Server1: " IPSTR, IP2STR(&dns_info.ip.u_addr.ip4));
        tcpip_adapter_get_dns_info(TCPIP_ADAPTER_IF_ETH, 1, &dns_info);
        ESP_LOGI(TAG, "Name Server2: " IPSTR, IP2STR(&dns_info.ip.u_addr.ip4));
		vTaskDelay( 5000 / portTICK_PERIOD_MS);		// task delay 5s
	}
}

As you can see from following log , static IP is set but dns server are empty

Code: Select all

[app_main]ETHIP: 192.168.2.10

[app_main]ETHMASK: 255.255.255.0

[app_main]ETHGW: 192.168.2.1
[0;32mI (17523) eth_example: free heap: 167480[0m
[0;32mI (17523) eth_example: Name Server1: 0.0.0.0[0m
[0;32mI (17523) eth_example: Name Server2: 0.0.0.0[0m
[0;32mI (22523) eth_example: free heap: 167480[0m
[0;32mI (22523) eth_example: Name Server1: 0.0.0.0[0m
[0;32mI (22523) eth_example: Name Server2: 0.0.0.0[0m

Posted: **Thu Apr 03, 2025 2:49 pm**

Example here: https://github.com/espressif/esp-idf/bl ... ple_main.c

Posted: **Fri Apr 04, 2025 6:25 pm**

It looks like ESP-IDF 4.0 doesn’t have a direct function for setting DNS, but you can manage it through the network interface settings in the LWIP stack. DNS is typically assigned via DHCP, but if you need to set it manually, you’ll need to adjust the network configuration accordingly. Have you looked into LWIP’s DNS handling?

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