From eaa2f12d6761710d2633b4934fe09f6f45e20f4f Mon Sep 17 00:00:00 2001
From: David Cermak <cermak@espressif.com>
Date: Mon, 9 Dec 2019 11:29:19 +0100
Subject: [PATCH] mdns: fixed crash on event during deinit

mdns library deinitialization destroys internal structures including action queue. if an event (e.g. network update) received
after some essential stucture is destoyed, an unexpected behavour might be introduced (e.g. crash of adding the event notification
to the action queue which was already destroyed

Closes WIFI-1485
---
 components/mdns/mdns.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/components/mdns/mdns.c b/components/mdns/mdns.c
index 83e9be71a1..f04d4d1922 100644
--- a/components/mdns/mdns.c
+++ b/components/mdns/mdns.c
@@ -4301,6 +4301,14 @@ void mdns_free(void)
     if (!_mdns_server) {
         return;
     }
+
+    // Unregister handlers before destoying the mdns internals to avoid receiving asyc events while deinit
+    esp_event_handler_unregister(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler);
+    esp_event_handler_unregister(IP_EVENT, ESP_EVENT_ANY_ID, &event_handler);
+#if CONFIG_ETH_ENABLED
+    esp_event_handler_unregister(ETH_EVENT, ESP_EVENT_ANY_ID, &event_handler);
+#endif
+
     mdns_service_remove_all();
     _mdns_service_task_stop();
     for (i=0; i<MDNS_IF_MAX; i++) {
@@ -4331,11 +4339,6 @@ void mdns_free(void)
         free(h);
     }
     vSemaphoreDelete(_mdns_server->lock);
-    esp_event_handler_unregister(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler);
-    esp_event_handler_unregister(IP_EVENT, ESP_EVENT_ANY_ID, &event_handler);
-#if CONFIG_ETH_ENABLED
-    esp_event_handler_unregister(ETH_EVENT, ESP_EVENT_ANY_ID, &event_handler);
-#endif
     free(_mdns_server);
     _mdns_server = NULL;
 }