Bridge connection state doesn't update locally when `notifications_local_only` is set to true

[matesh]

I'm trying to use an LED on a device to indicate the bridge broker status using mosquitto V1.6.7. I found an issue, where the bridge connection status is not getting updated under certain circumstances.

I have set notifications and notifications_local_only to true (I don't want the status notification to be sent to the bridged broker). When mosquitto starts up with a broken bridge connection, the state 0 is published in $SYS/broker/connection/*id*/state and as soon as the connection is restored, state 1 is published in the same topic, as expected. However, if the connection breaks again, status 0 is no longer published in the above topic. When mosquitto starts up and establishes the connection straight away but the connection is broken later, status 0 is not published into the status topic. I tried re-subscribing but the retained message received at subscribe has the payload 1.

This doesn't seem to be an issue at all, when notifications_local_only is commented out from the configuration, in which case the status of the bridge connection is updated as expected, every time when there is a change in the bridge connection status.

[karlp]

I think this is what I commented on when it was initially added, that only the 1 is published: https://github.com/eclipse/mosquitto/issues/233#issuecomment-371149796

[timothyfroehlich]

I just fought with this problem, it's frustrating to know that this is a known issue. Confirmed on v1.5.8 (Rpi3, Yocto Warrior)

[karlp]

I've just retested this on 1.6.12. As before, the "1" is published locally when the connection is made, but the "0" is never published locally when the connection goes down.

[jason416]

I've just retested this on 1.6.12. As before, the "1" is published locally when the connection is made, but the "0" is never published locally when the connection goes down.

Yes, I met this problem this days. It should publish state 0 locally, and here is my patch for that.

diff --git a/src/bridge.c b/src/bridge.c
index c951c8c..54936bd 100644
--- a/src/bridge.c
+++ b/src/bridge.c
@@ -355,13 +355,11 @@ int bridge__connect(struct mosquitto_db *db, struct mosquitto *context)
                                context->bridge->initial_notification_done = true;
                        }
 
-                       if (!context->bridge->notifications_local_only) {
-                               notification_payload = '0';
-                               rc = will__set(context, context->bridge->notification_topic, 1, &notification_payload, 1, true, NULL);
-                               if(rc != MOSQ_ERR_SUCCESS){
-                                       return rc;
-                               }
-                       }
+                       notification_payload = '0';
+                       rc = will__set(context, context->bridge->notification_topic, 1, &notification_payload, 1, true, NULL);
+                       if(rc != MOSQ_ERR_SUCCESS){
+                               return rc;
+                       }
                }else{
                        notification_topic_len = strlen(context->bridge->remote_clientid)+strlen("$SYS/broker/connection//state");
                        notification_topic = mosquitto__malloc(sizeof(char)*(notification_topic_len+1));
@@ -375,14 +373,12 @@ int bridge__connect(struct mosquitto_db *db, struct mosquitto *context)
                                context->bridge->initial_notification_done = true;
                        }
 
-                       if (!context->bridge->notifications_local_only) {
-                               notification_payload = '0';
-                               rc = will__set(context, notification_topic, 1, &notification_payload, 1, true, NULL);
-                               mosquitto__free(notification_topic);
-                               if(rc != MOSQ_ERR_SUCCESS){
-                                       return rc;
-                               }
-                       }
+                       notification_payload = '0';
+                       rc = will__set(context, notification_topic, 1, &notification_payload, 1, true, NULL);
+                       mosquitto__free(notification_topic);
+                       if(rc != MOSQ_ERR_SUCCESS){
+                               return rc;
+                       }
                }
        }

[cimplart]

The above patch is not correct, the 'state = 0' is still published remotely after bridge disconnected.

[jason416]

The above patch is not correct, the 'state = 0' is still published remotely after bridge disconnected.

No, Above patch is not well tested for you situation, More see #1902, it should work fine!

[cimplart]

The above patch is not correct, the 'state = 0' is still published remotely after bridge disconnected.

No, Above patch is not well tested for you situation, More see #1902, it should work fine!

I see, I was not aware of the change in send_connect.c.

As a side comment I would like to add that the notification_topic is not mapped by the bridge according to the topic mapping rules, when set as LW&T topic by the bridge. So to avoid problems it is best to keep it the same on the local and remote brokers.

[ralight]

Please give the develop branch a try if you are able.