mdns: Add support for registering custom netif

* Original commit: espressif/esp-idf@bec42ff85d

components/mdns/include/mdns.h

@@ -719,6 +719,11 @@ esp_err_t mdns_query_a(const char * host_name, uint32_t timeout, esp_ip4_addr_t
 esp_err_t mdns_query_aaaa(const char * host_name, uint32_t timeout, esp_ip6_addr_t * addr);
 #endif
 
+
+esp_err_t mdns_add_custom_netif(esp_netif_t *esp_netif);
+esp_err_t mdns_post_custom_action(esp_netif_t *esp_netif, mdns_event_actions_t event_action);
+esp_err_t mdns_delete_custom_netif(esp_netif_t *esp_netif);
+
 #ifdef __cplusplus
 }
 #endif

components/mdns/mdns.c

@@ -5086,6 +5086,52 @@ esp_err_t mdns_post_custom_action(esp_netif_t *esp_netif, mdns_event_actions_t e
     return mdns_post_custom_action_tcpip_if(_mdns_get_if_from_esp_netif(esp_netif), event_action);
 }
 
+esp_err_t mdns_add_custom_netif(esp_netif_t *esp_netif)
+{
+    if (!_mdns_server) {
+        return ESP_ERR_INVALID_STATE;
+    }
+
+    esp_err_t err = ESP_ERR_NO_MEM;
+    MDNS_SERVICE_LOCK();
+    for (mdns_if_t i=0; i<MDNS_MAX_INTERFACES; ++i) {
+        if (s_esp_netifs[i].netif == esp_netif) {
+            MDNS_SERVICE_UNLOCK();
+            return ESP_ERR_INVALID_STATE;
+        }
+    }
+
+    for (mdns_if_t i=0; i<MDNS_MAX_INTERFACES; ++i) {
+        if (!s_esp_netifs[i].predefined && s_esp_netifs[i].netif == NULL) {
+            s_esp_netifs[i].netif = esp_netif;
+            err = ESP_OK;
+            break;
+        }
+    }
+    MDNS_SERVICE_UNLOCK();
+    return err;
+}
+
+esp_err_t mdns_delete_custom_netif(esp_netif_t *esp_netif)
+{
+    if (!_mdns_server) {
+        return ESP_ERR_INVALID_STATE;
+    }
+
+    esp_err_t err = ESP_ERR_NOT_FOUND;
+    MDNS_SERVICE_LOCK();
+    for (mdns_if_t i=0; i<MDNS_MAX_INTERFACES; ++i) {
+        if (!s_esp_netifs[i].predefined && s_esp_netifs[i].netif == esp_netif) {
+            s_esp_netifs[i].netif = NULL;
+            err = ESP_OK;
+            break;
+        }
+    }
+    MDNS_SERVICE_UNLOCK();
+    return err;
+}
+
+
 esp_err_t mdns_init(void)
 {
     esp_err_t err = ESP_OK;
@@ -5133,7 +5179,9 @@ esp_err_t mdns_init(void)
     }
 #endif
 
+#if CONFIG_MDNS_PREDEF_NETIF_STA || CONFIG_MDNS_PREDEF_NETIF_AP || CONFIG_MDNS_PREDEF_NETIF_ETH
     set_default_duplicated_interfaces();
+#endif
 
     uint8_t i;
 #if CONFIG_LWIP_IPV6
@@ -5166,8 +5214,10 @@ free_all_and_disable_pcbs:
         _mdns_disable_pcb(i, MDNS_IP_PROTOCOL_V4);
         s_esp_netifs[i].duplicate = MDNS_MAX_INTERFACES;
     }
+#if CONFIG_MDNS_PREDEF_NETIF_STA || CONFIG_MDNS_PREDEF_NETIF_AP || CONFIG_MDNS_PREDEF_NETIF_ETH
 free_event_handlers:
     unregister_predefined_handlers();
+#endif
     vQueueDelete(_mdns_server->action_queue);
 free_lock:
     vSemaphoreDelete(_mdns_server->lock);

examples/protocols/mdns/main/Kconfig.projbuild

@@ -48,4 +48,13 @@ menu "Example Configuration"
         help
             Set the GPIO number used as mDNS test button
 
+    config MDNS_ADD_CUSTOM_NETIF
+        bool "Add user netif to mdns service"
+        default n
+        help
+            If enabled, we try to add a custom netif to mdns service.
+            Note that for using with common connection example code, we have to disable
+            all predefined interfaces in mdns component setup (since we're adding one
+            of the default interfaces)
+
 endmenu

examples/protocols/mdns/main/mdns_example_main.c

@@ -266,6 +266,14 @@ void app_main(void)
      */
     ESP_ERROR_CHECK(example_connect());
 
+#if defined(CONFIG_MDNS_ADD_CUSTOM_NETIF) && !defined(CONFIG_MDNS_PREDEF_NETIF_STA) && !defined(CONFIG_MDNS_PREDEF_NETIF_ETH)
+    /* Demonstration of adding a custom netif to mdns service, but we're adding the default example one,
+     * so we must disable all predefined interfaces (PREDEF_NETIF_STA, AP and ETH) first
+     */
+    ESP_ERROR_CHECK(mdns_add_custom_netif(EXAMPLE_INTERFACE));
+    ESP_ERROR_CHECK(mdns_post_custom_action(EXAMPLE_INTERFACE, MDNS_EVENT_ENABLE_IP4));
+    ESP_ERROR_CHECK(mdns_post_custom_action(EXAMPLE_INTERFACE, MDNS_EVENT_ANNOUNCE_IP4));
+#endif
     initialise_button();
     xTaskCreate(&mdns_example_task, "mdns_example_task", 2048, NULL, 5, NULL);
 }