esp-idf/examples/protocols/mdns/main/mdns_example_main.c

/* MDNS-SD Query and advertise Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#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 "tcpip_adapter.h"
#include "protocol_examples_common.h"
#include "mdns.h"
#include "driver/gpio.h"
#include <sys/socket.h>
#include <netdb.h>


#define EXAMPLE_MDNS_INSTANCE CONFIG_MDNS_INSTANCE
#define EXAMPLE_BUTTON_GPIO     0

static const char *TAG = "mdns-test";
static char* generate_hostname(void);

#if CONFIG_MDNS_RESOLVE_TEST_SERVICES == 1
static void  query_mdns_host_with_gethostbyname(char * host);
static void  query_mdns_host_with_getaddrinfo(char * host);
#endif

static void initialise_mdns(void)
{
    char* hostname = generate_hostname();
    //initialize mDNS
    ESP_ERROR_CHECK( mdns_init() );
    //set mDNS hostname (required if you want to advertise services)
    ESP_ERROR_CHECK( mdns_hostname_set(hostname) );
    ESP_LOGI(TAG, "mdns hostname set to: [%s]", hostname);
    //set default mDNS instance name
    ESP_ERROR_CHECK( mdns_instance_name_set(EXAMPLE_MDNS_INSTANCE) );

    //structure with TXT records
    mdns_txt_item_t serviceTxtData[3] = {
        {"board","esp32"},
        {"u","user"},
        {"p","password"}
    };

    //initialize service
    ESP_ERROR_CHECK( mdns_service_add("ESP32-WebServer", "_http", "_tcp", 80, serviceTxtData, 3) );
    //add another TXT item
    ESP_ERROR_CHECK( mdns_service_txt_item_set("_http", "_tcp", "path", "/foobar") );
    //change TXT item value
    ESP_ERROR_CHECK( mdns_service_txt_item_set("_http", "_tcp", "u", "admin") );
    free(hostname);
}

/* these strings match tcpip_adapter_if_t enumeration */
static const char * if_str[] = {"STA", "AP", "ETH", "MAX"};

/* these strings match mdns_ip_protocol_t enumeration */
static const char * ip_protocol_str[] = {"V4", "V6", "MAX"};

static void mdns_print_results(mdns_result_t * results){
    mdns_result_t * r = results;
    mdns_ip_addr_t * a = NULL;
    int i = 1, t;
    while(r){
        printf("%d: Interface: %s, Type: %s\n", i++, if_str[r->tcpip_if], ip_protocol_str[r->ip_protocol]);
        if(r->instance_name){
            printf("  PTR : %s\n", r->instance_name);
        }
        if(r->hostname){
            printf("  SRV : %s.local:%u\n", r->hostname, r->port);
        }
        if(r->txt_count){
            printf("  TXT : [%u] ", r->txt_count);
            for(t=0; t<r->txt_count; t++){
                printf("%s=%s; ", r->txt[t].key, r->txt[t].value?r->txt[t].value:"NULL");
            }
            printf("\n");
        }
        a = r->addr;
        while(a){
            if(a->addr.type == IPADDR_TYPE_V6){
                printf("  AAAA: " IPV6STR "\n", IPV62STR(a->addr.u_addr.ip6));
            } else {
                printf("  A   : " IPSTR "\n", IP2STR(&(a->addr.u_addr.ip4)));
            }
            a = a->next;
        }
        r = r->next;
    }

}

static void query_mdns_service(const char * service_name, const char * proto)
{
    ESP_LOGI(TAG, "Query PTR: %s.%s.local", service_name, proto);

    mdns_result_t * results = NULL;
    esp_err_t err = mdns_query_ptr(service_name, proto, 3000, 20,  &results);
    if(err){
        ESP_LOGE(TAG, "Query Failed: %s", esp_err_to_name(err));
        return;
    }
    if(!results){
        ESP_LOGW(TAG, "No results found!");
        return;
    }

    mdns_print_results(results);
    mdns_query_results_free(results);
}

static void query_mdns_host(const char * host_name)
{
    ESP_LOGI(TAG, "Query A: %s.local", host_name);

    struct ip4_addr addr;
    addr.addr = 0;

    esp_err_t err = mdns_query_a(host_name, 2000,  &addr);
    if(err){
        if(err == ESP_ERR_NOT_FOUND){
            ESP_LOGW(TAG, "%s: Host was not found!", esp_err_to_name(err));
            return;
        }
        ESP_LOGE(TAG, "Query Failed: %s", esp_err_to_name(err));
        return;
    }

    ESP_LOGI(TAG, "Query A: %s.local resolved to: " IPSTR, host_name, IP2STR(&addr));
}

static void initialise_button(void)
{
    gpio_config_t io_conf = {0};
    io_conf.intr_type = GPIO_PIN_INTR_DISABLE;
    io_conf.pin_bit_mask = BIT64(EXAMPLE_BUTTON_GPIO);
    io_conf.mode = GPIO_MODE_INPUT;
    io_conf.pull_up_en = 1;
    io_conf.pull_down_en = 0;
    gpio_config(&io_conf);
}

static void check_button(void)
{
    static bool old_level = true;
    bool new_level = gpio_get_level(EXAMPLE_BUTTON_GPIO);
    if (!new_level && old_level) {
        query_mdns_host("esp32");
        query_mdns_service("_arduino", "_tcp");
        query_mdns_service("_http", "_tcp");
        query_mdns_service("_printer", "_tcp");
        query_mdns_service("_ipp", "_tcp");
        query_mdns_service("_afpovertcp", "_tcp");
        query_mdns_service("_smb", "_tcp");
        query_mdns_service("_ftp", "_tcp");
        query_mdns_service("_nfs", "_tcp");
    }
    old_level = new_level;
}

static void mdns_example_task(void *pvParameters)
{
#if CONFIG_MDNS_RESOLVE_TEST_SERVICES == 1
    /* Send initial queries that are started by CI tester */
    query_mdns_host("tinytester");
    query_mdns_host_with_gethostbyname("tinytester-lwip.local");
    query_mdns_host_with_getaddrinfo("tinytester-lwip.local");
#endif

    while(1) {
        check_button();
        vTaskDelay(50 / portTICK_PERIOD_MS);
    }
}

void app_main(void)
{
    ESP_ERROR_CHECK(nvs_flash_init());
    tcpip_adapter_init();
    ESP_ERROR_CHECK(esp_event_loop_create_default());

    initialise_mdns();

    /* This helper function configures Wi-Fi or Ethernet, as selected in menuconfig.
     * Read "Establishing Wi-Fi or Ethernet Connection" section in
     * examples/protocols/README.md for more information about this function.
     */
    ESP_ERROR_CHECK(example_connect());

    initialise_button();
    xTaskCreate(&mdns_example_task, "mdns_example_task", 2048, NULL, 5, NULL);
}

/** Generate host name based on sdkconfig, optionally adding a portion of MAC address to it.
 *  @return host name string allocated from the heap
 */
static char* generate_hostname(void)
{
#ifndef CONFIG_MDNS_ADD_MAC_TO_HOSTNAME
    return strdup(CONFIG_MDNS_HOSTNAME);
#else
    uint8_t mac[6];
    char   *hostname;
    esp_read_mac(mac, ESP_MAC_WIFI_STA);
    if (-1 == asprintf(&hostname, "%s-%02X%02X%02X", CONFIG_MDNS_HOSTNAME, mac[3], mac[4], mac[5])) {
        abort();
    }
    return hostname;
#endif
}

#if CONFIG_MDNS_RESOLVE_TEST_SERVICES == 1
/**
 *  @brief Executes gethostbyname and displays list of resolved addresses.
 *  Note: This function is used only to test advertised mdns hostnames resolution
 */
static void  query_mdns_host_with_gethostbyname(char * host)
{
    struct hostent *res = gethostbyname(host);
    if (res) {
        unsigned int i = 0;
        while (res->h_addr_list[i] != NULL) {
            ESP_LOGI(TAG, "gethostbyname: %s resolved to: %s", host, inet_ntoa(*(struct in_addr *) (res->h_addr_list[i])));
            i++;
        }
    }
}

/**
 *  @brief Executes getaddrinfo and displays list of resolved addresses.
 *  Note: This function is used only to test advertised mdns hostnames resolution
 */
static void  query_mdns_host_with_getaddrinfo(char * host)
{
    struct addrinfo hints;
    struct addrinfo * res;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if (!getaddrinfo(host, NULL, &hints, &res)) {
        while (res) {
            ESP_LOGI(TAG, "getaddrinfo: %s resolved to: %s", host,
                     res->ai_family == AF_INET?
                     inet_ntoa(((struct sockaddr_in *) res->ai_addr)->sin_addr):
                     inet_ntoa(((struct sockaddr_in6 *) res->ai_addr)->sin6_addr));
            res = res->ai_next;
        }
    }
}
#endif