fix(mdns): Fix API races when removing all services

Author: david-cermak

components/mdns/mdns.c

@@ -5148,8 +5148,6 @@ static void _mdns_free_action(mdns_action_t *action)
  */
 static void _mdns_execute_action(mdns_action_t *action)
 {
-    mdns_srv_item_t *a = NULL;
-
     switch (action->type) {
     case ACTION_SYSTEM_EVENT:
         perform_event_action(action->data.sys_event.interface, action->data.sys_event.event_action);
@@ -5169,19 +5167,6 @@ static void _mdns_execute_action(mdns_action_t *action)
         _mdns_server->instance = action->data.instance;
         _mdns_restart_all_pcbs_no_instance();
 
-        break;
-    case ACTION_SERVICES_CLEAR:
-        _mdns_send_final_bye(false);
-        a = _mdns_server->services;
-        _mdns_server->services = NULL;
-        while (a) {
-            mdns_srv_item_t *s = a;
-            a = a->next;
-            _mdns_remove_scheduled_service_packets(s->service);
-            _mdns_free_service(s->service);
-            free(s);
-        }
-
         break;
     case ACTION_SEARCH_ADD:
         _mdns_search_add(action->data.search_add.search);
@@ -5226,6 +5211,7 @@ static void _mdns_execute_action(mdns_action_t *action)
             free((char *)action->data.delegate_hostname.hostname);
             free_address_list(action->data.delegate_hostname.address_list);
         }
+        xSemaphoreGive(_mdns_server->action_sema);
         break;
     case ACTION_DELEGATE_HOSTNAME_SET_ADDR:
         if (!_mdns_delegate_hostname_set_address(action->data.delegate_hostname.hostname,
@@ -5789,6 +5775,7 @@ esp_err_t mdns_delegate_hostname_add(const char *hostname, const mdns_ip_addr_t
         free(action);
         return ESP_ERR_NO_MEM;
     }
+    xSemaphoreTake(_mdns_server->action_sema, portMAX_DELAY);
     return ESP_OK;
 }
 
@@ -6465,27 +6452,27 @@ esp_err_t mdns_service_remove(const char *service_type, const char *proto)
 
 esp_err_t mdns_service_remove_all(void)
 {
-    if (!_mdns_server) {
-        return ESP_ERR_INVALID_ARG;
-    }
     MDNS_SERVICE_LOCK();
+    esp_err_t ret = ESP_OK;
+    ESP_GOTO_ON_FALSE(_mdns_server, ESP_ERR_INVALID_ARG, done, TAG, "Invalid state");
     if (!_mdns_server->services) {
-        MDNS_SERVICE_UNLOCK();
-        return ESP_OK;
+        goto done;
     }
-    MDNS_SERVICE_UNLOCK();
 
-    mdns_action_t *action = (mdns_action_t *)malloc(sizeof(mdns_action_t));
-    if (!action) {
-        HOOK_MALLOC_FAILED;
-        return ESP_ERR_NO_MEM;
-    }
-    action->type = ACTION_SERVICES_CLEAR;
-    if (xQueueSend(_mdns_server->action_queue, &action, (TickType_t)0) != pdPASS) {
-        free(action);
-        return ESP_ERR_NO_MEM;
+    _mdns_send_final_bye(false);
+    mdns_srv_item_t *services = _mdns_server->services;
+    _mdns_server->services = NULL;
+    while (services) {
+        mdns_srv_item_t *s = services;
+        services = services->next;
+        _mdns_remove_scheduled_service_packets(s->service);
+        _mdns_free_service(s->service);
+        free(s);
     }
-    return ESP_OK;
+
+done:
+    MDNS_SERVICE_UNLOCK();
+    return ret;
 }
 
 /*

components/mdns/private_include/mdns_private.h

@@ -187,7 +187,6 @@ typedef enum {
     ACTION_SYSTEM_EVENT,
     ACTION_HOSTNAME_SET,
     ACTION_INSTANCE_SET,
-    ACTION_SERVICES_CLEAR,
     ACTION_SEARCH_ADD,
     ACTION_SEARCH_SEND,
     ACTION_SEARCH_END,