Fix: mark packet sent to MQTT as ACKed only after we sent it out via …

…LoRa (meshtastic#3155)

* Fix: mark packet via MQTT as ACKed only after we sent it out via LoRa

* Don't need to check for broadcast, DMs also get implicit ACKs

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/mqtt/MQTT.cpp

@@ -127,11 +127,17 @@ void MQTT::onReceive(char *topic, byte *payload, size_t length)
             LOG_ERROR("Invalid MQTT service envelope, topic %s, len %u!\n", topic, length);
             return;
         } else {
-            if (strcmp(e.gateway_id, owner.id) == 0)
-                LOG_INFO("Ignoring downlink message we originally sent.\n");
-            else {
+            meshtastic_Channel ch = channels.getByName(e.channel_id);
+            if (strcmp(e.gateway_id, owner.id) == 0) {
+                // Generate an implicit ACK towards ourselves (handled and processed only locally!) for this message.
+                // We do this because packets are not rebroadcasted back into MQTT anymore and we assume that at least one node
+                // receives it when we get our own packet back. Then we'll stop our retransmissions.
+                if (e.packet && getFrom(e.packet) == nodeDB.getNodeNum())
+                    routingModule->sendAckNak(meshtastic_Routing_Error_NONE, getFrom(e.packet), e.packet->id, ch.index);
+                else
+                    LOG_INFO("Ignoring downlink message we originally sent.\n");
+            } else {
                 // Find channel by channel_id and check downlink_enabled
-                meshtastic_Channel ch = channels.getByName(e.channel_id);
                 if (strcmp(e.channel_id, channels.getGlobalId(ch.index)) == 0 && e.packet && ch.settings.downlink_enabled) {
                     LOG_INFO("Received MQTT topic %s, len=%u\n", topic, length);
                     meshtastic_MeshPacket *p = packetPool.allocCopy(*e.packet);
@@ -505,11 +511,6 @@ void MQTT::onSend(const meshtastic_MeshPacket &mp, const meshtastic_MeshPacket &
                 }
             }
 
-            // Generate an implicit ACK towards ourselves (handled and processed only locally!) for this message.
-            // We do this because packets are not rebroadcasted back into MQTT anymore and we assume that at least one node
-            // receives it when we're connected to the broker. Then we'll stop our retransmissions.
-            if (getFrom(&mp) == nodeDB.getNodeNum())
-                routingModule->sendAckNak(meshtastic_Routing_Error_NONE, getFrom(&mp), mp.id, chIndex);
         } else {
             LOG_INFO("MQTT not connected, queueing packet\n");
             if (mqttQueue.numFree() == 0) {