KeepAlive: Better session cleanup after KeepAlive failure

include/coap3/coap_session_internal.h

@@ -604,6 +604,16 @@ coap_session_t *coap_new_client_session_psk2_lkd(coap_context_t *ctx,
 coap_session_t *coap_session_new_dtls_session(coap_session_t *session,
                                               coap_tick_t now);
 
+/**
+ * Clear down a session following a keepalive failure.
+ * The event handler will get notified of the failure.
+ * Note: the @p session cannot be used after this function is called.
+ *
+ * @param session Session to clear down.
+ *
+ */
+void coap_session_server_keepalive_failed(coap_session_t *session);
+
 void coap_session_free(coap_session_t *session);
 void coap_session_mfree(coap_session_t *session);
 

include/coap3/coap_subscribe_internal.h

@@ -167,6 +167,18 @@ int coap_delete_observer_request(coap_resource_t *resource,
  */
 void coap_delete_observers(coap_context_t *context, coap_session_t *session);
 
+/**
+ * Removes specific subscription for @p session for @p resource and releases
+ * the allocated storage.
+ *
+ * @param resource The resource
+ * @param session  The observer's session.
+ * @param subscription  The observer's subscription.
+ */
+void coap_delete_observer_internal(coap_resource_t *resource,
+                                   coap_session_t *session,
+                                   coap_subscription_t *subscription);
+
 /**
  * Initiate the sending of an Observe packet for all observers of @p resource,
  * optionally matching @p query if not NULL

src/coap_io.c

@@ -1490,16 +1490,7 @@ coap_io_prepare_io_lkd(coap_context_t *ctx,
             /* Some issue - not safe to continue processing */
             continue;
           if (s->last_ping > 0 && s->last_pong < s->last_ping) {
-            coap_handle_event_lkd(s->context, COAP_EVENT_KEEPALIVE_FAILURE, s);
-            coap_session_reference_lkd(s);
-            RESOURCES_ITER(s->context->resources, r) {
-              coap_cancel_all_messages(s->context, s, NULL);
-              coap_delete_observer(r, s, NULL);
-            }
-            coap_session_release_lkd(s);
-            /* Force session to go away */
-            coap_session_set_type_client_lkd(s);
-            coap_session_release_lkd(s);
+            coap_session_server_keepalive_failed(s);
             /* check the next session */
             continue;
           }

src/coap_net.c

@@ -763,9 +763,9 @@ coap_free_context_lkd(coap_context_t *context) {
 #endif /* COAP_SERVER_SUPPORT */
 
   coap_delete_all(context->sendqueue);
+  context->sendqueue = NULL;
 
 #ifdef WITH_LWIP
-  context->sendqueue = NULL;
   if (context->timer_configured) {
     LOCK_TCPIP_CORE();
     sys_untimeout(coap_io_process_timeout, (void *)context);
@@ -2167,8 +2167,14 @@ coap_retransmit(coap_context_t *context, coap_queue_t *node) {
 #if COAP_SERVER_SUPPORT
   /* Check if subscriptions exist that should be canceled after
      COAP_OBS_MAX_FAIL */
-  if (COAP_RESPONSE_CLASS(node->pdu->code) >= 2) {
-    coap_handle_failed_notify(context, node->session, &node->pdu->actual_token);
+  if (COAP_RESPONSE_CLASS(node->pdu->code) >= 2 && node->session->ref_subscriptions) {
+    if (context->ping_timeout) {
+      coap_session_server_keepalive_failed(node->session);
+      coap_delete_node_lkd(node);
+      return COAP_INVALID_MID;
+    } else {
+      coap_handle_failed_notify(context, node->session, &node->pdu->actual_token);
+    }
   }
 #endif /* COAP_SERVER_SUPPORT */
   if (node->session->con_active) {

src/coap_resource.c

@@ -513,13 +513,7 @@ coap_free_resource(coap_resource_t *resource) {
 
   /* free all elements from resource->subscribers */
   LL_FOREACH_SAFE(resource->subscribers, obs, otmp) {
-    if (resource->context->observe_deleted)
-      resource->context->observe_deleted(obs->session, obs,
-                                         resource->context->observe_user_data);
-    coap_session_release_lkd(obs->session);
-    coap_delete_pdu_lkd(obs->pdu);
-    coap_delete_cache_key(obs->cache_key);
-    coap_free_type(COAP_SUBSCRIPTION, obs);
+    coap_delete_observer_internal(resource, obs->session, obs);
   }
   if (resource->proxy_name_count && resource->proxy_name_list) {
     size_t i;
@@ -996,7 +990,7 @@ coap_touch_observer(coap_context_t *context, coap_session_t *session,
   }
 }
 
-static void
+void
 coap_delete_observer_internal(coap_resource_t *resource, coap_session_t *session,
                               coap_subscription_t *s) {
   if (!s)
@@ -1022,9 +1016,9 @@ coap_delete_observer_internal(coap_resource_t *resource, coap_session_t *session
 
   if (resource->subscribers) {
     LL_DELETE(resource->subscribers, s);
-    coap_session_release_lkd(session);
     assert(session->ref_subscriptions > 0);
     session->ref_subscriptions--;
+    coap_session_release_lkd(session);
     coap_delete_pdu_lkd(s->pdu);
     coap_delete_cache_key(s->cache_key);
     coap_free_type(COAP_SUBSCRIPTION, s);

src/coap_session.c

@@ -601,6 +601,28 @@ coap_session_free(coap_session_t *session) {
   coap_free_type(COAP_SESSION, session);
 }
 
+#if COAP_SERVER_SUPPORT
+void
+coap_session_server_keepalive_failed(coap_session_t *session) {
+  coap_handle_event_lkd(session->context, COAP_EVENT_KEEPALIVE_FAILURE, session);
+  coap_session_reference_lkd(session);
+  coap_cancel_all_messages(session->context, session, NULL);
+  RESOURCES_ITER(session->context->resources, r) {
+    coap_delete_observer(r, session, NULL);
+  }
+  while (session->delayqueue) {
+    coap_queue_t *q = session->delayqueue;
+
+    session->delayqueue = q->next;
+    coap_delete_node_lkd(q);
+  }
+  coap_session_release_lkd(session);
+  /* Force session to go away */
+  coap_session_set_type_client_lkd(session);
+  coap_session_release_lkd(session);
+}
+#endif /* COAP_SERVER_SUPPORT */
+
 static size_t
 coap_session_max_pdu_size_internal(const coap_session_t *session,
                                    size_t max_with_header) {