Fix handling of outgoing QoS>0 messages for bridges.

Fix handling of outgoing QoS>0 messages for bridges that could not be
sent because the bridge connection was down.

ChangeLog.txt

@@ -3,6 +3,8 @@ Broker:
 - Build fixes for OpenBSD.
 - Fix incorrect behaviour for autosave_interval, most noticable for
   autosave_interval=1. Closes #465438.
+- Fix handling of outgoing QoS>0 messages for bridges that could not be sent
+  because the bridge connection was down.
 
 Client library:
 - Add missing error strings to mosquitto_strerror.

src/database.c

@@ -195,6 +195,9 @@ void mosquitto__db_msg_store_deref(struct mosquitto_db *db, struct mosquitto_msg
 
 static void _message_remove(struct mosquitto_db *db, struct mosquitto *context, struct mosquitto_client_msg **msg, struct mosquitto_client_msg *last)
 {
+	int i;
+	struct mosquitto_client_msg *tail;
+
 	if(!context || !msg || !(*msg)){
 		return;
 	}
@@ -223,6 +226,29 @@ static void _message_remove(struct mosquitto_db *db, struct mosquitto *context,
 	}else{
 		*msg = context->msgs;
 	}
+	tail = context->msgs;
+	i = 0;
+	while(tail && tail->state == mosq_ms_queued && i<max_inflight){
+		if(tail->direction == mosq_md_out){
+			switch(tail->qos){
+				case 0:
+					tail->state = mosq_ms_publish_qos0;
+					break;
+				case 1:
+					tail->state = mosq_ms_publish_qos1;
+					break;
+				case 2:
+					tail->state = mosq_ms_publish_qos2;
+					break;
+			}
+		}else{
+			if(tail->qos == 2){
+				tail->state = mosq_ms_send_pubrec;
+			}
+		}
+
+		tail = tail->next;
+	}
 }
 
 int mqtt3_db_message_delete(struct mosquitto_db *db, struct mosquitto *context, uint16_t mid, enum mosquitto_msg_direction dir)