Mark packets received via MQTT and add option to ignore them (#3117)

* Mark packets received via MQTT and add option to ignore them

* Don't send packets received via MQTT back into MQTT
Generate implicit ACK for packets we as an MQTT gateway sent

---------

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

src/mesh/NodeDB.cpp

@@ -173,6 +173,7 @@ void NodeDB::installDefaultConfig()
     config.lora.region = meshtastic_Config_LoRaConfig_RegionCode_UNSET;
     config.lora.modem_preset = meshtastic_Config_LoRaConfig_ModemPreset_LONG_FAST;
     config.lora.hop_limit = HOP_RELIABLE;
+    config.lora.ignore_mqtt = false;
 #ifdef PIN_GPS_EN
     config.position.gps_en_gpio = PIN_GPS_EN;
 #endif

src/mesh/RadioInterface.cpp

@@ -287,15 +287,14 @@ void printPacket(const char *prefix, const meshtastic_MeshPacket *p)
         out += " encrypted";
     }
 
-    if (p->rx_time != 0) {
+    if (p->rx_time != 0)
         out += DEBUG_PORT.mt_sprintf(" rxtime=%u", p->rx_time);
-    }
-    if (p->rx_snr != 0.0) {
+    if (p->rx_snr != 0.0)
         out += DEBUG_PORT.mt_sprintf(" rxSNR=%g", p->rx_snr);
-    }
-    if (p->rx_rssi != 0) {
+    if (p->rx_rssi != 0)
         out += DEBUG_PORT.mt_sprintf(" rxRSSI=%i", p->rx_rssi);
-    }
+    if (p->via_mqtt != 0)
+        out += DEBUG_PORT.mt_sprintf(" via MQTT");
     if (p->priority != 0)
         out += DEBUG_PORT.mt_sprintf(" priority=%d", p->priority);
 
@@ -554,7 +553,7 @@ size_t RadioInterface::beginSending(meshtastic_MeshPacket *p)
         LOG_WARN("hop limit %d is too high, setting to %d\n", p->hop_limit, HOP_RELIABLE);
         p->hop_limit = HOP_RELIABLE;
     }
-    h->flags = p->hop_limit | (p->want_ack ? PACKET_FLAGS_WANT_ACK_MASK : 0);
+    h->flags = p->hop_limit | (p->want_ack ? PACKET_FLAGS_WANT_ACK_MASK : 0) | (p->via_mqtt ? PACKET_FLAGS_VIA_MQTT_MASK : 0);
 
     // if the sender nodenum is zero, that means uninitialized
     assert(h->from);
@@ -563,4 +562,4 @@ size_t RadioInterface::beginSending(meshtastic_MeshPacket *p)
 
     sendingPacket = p;
     return p->encrypted.size + sizeof(PacketHeader);
-}
+}

src/mesh/RadioInterface.h

@@ -12,6 +12,7 @@
 
 #define PACKET_FLAGS_HOP_MASK 0x07
 #define PACKET_FLAGS_WANT_ACK_MASK 0x08
+#define PACKET_FLAGS_VIA_MQTT_MASK 0x10
 
 /**
  * This structure has to exactly match the wire layout when sent over the radio link.  Used to keep compatibility
@@ -223,4 +224,4 @@ class RadioInterface
 };
 
 /// Debug printing for packets
-void printPacket(const char *prefix, const meshtastic_MeshPacket *p);
+void printPacket(const char *prefix, const meshtastic_MeshPacket *p);

src/mesh/RadioLibInterface.cpp

@@ -362,6 +362,7 @@ void RadioLibInterface::handleReceiveInterrupt()
             assert(HOP_MAX <= PACKET_FLAGS_HOP_MASK); // If hopmax changes, carefully check this code
             mp->hop_limit = h->flags & PACKET_FLAGS_HOP_MASK;
             mp->want_ack = !!(h->flags & PACKET_FLAGS_WANT_ACK_MASK);
+            mp->via_mqtt = !!(h->flags & PACKET_FLAGS_VIA_MQTT_MASK);
 
             addReceiveMetadata(mp);
 
@@ -406,4 +407,4 @@ void RadioLibInterface::startSend(meshtastic_MeshPacket *txp)
         // bits
         enableInterrupt(isrTxLevel0);
     }
-}
+}

src/mesh/Router.cpp

@@ -467,10 +467,10 @@ void Router::handleReceived(meshtastic_MeshPacket *p, RxSource src)
 void Router::perhapsHandleReceived(meshtastic_MeshPacket *p)
 {
     // assert(radioConfig.has_preferences);
-    bool ignore = is_in_repeated(config.lora.ignore_incoming, p->from);
+    bool ignore = is_in_repeated(config.lora.ignore_incoming, p->from) || (config.lora.ignore_mqtt && p->via_mqtt);
 
     if (ignore) {
-        LOG_DEBUG("Ignoring incoming message, 0x%x is in our ignore list\n", p->from);
+        LOG_DEBUG("Ignoring incoming message, 0x%x is in our ignore list or came via MQTT\n", p->from);
     } else if (ignore |= shouldFilterReceived(p)) {
         LOG_DEBUG("Incoming message was filtered 0x%x\n", p->from);
     }
@@ -481,4 +481,4 @@ void Router::perhapsHandleReceived(meshtastic_MeshPacket *p)
         handleReceived(p);
 
     packetPool.release(p);
-}
+}

src/modules/TraceRouteModule.cpp

@@ -85,4 +85,4 @@ TraceRouteModule::TraceRouteModule()
     : ProtobufModule("traceroute", meshtastic_PortNum_TRACEROUTE_APP, &meshtastic_RouteDiscovery_msg)
 {
     ourPortNum = meshtastic_PortNum_TRACEROUTE_APP;
-}
+}

src/mqtt/MQTT.cpp

@@ -7,6 +7,7 @@
 #include "mesh/Router.h"
 #include "mesh/generated/meshtastic/mqtt.pb.h"
 #include "mesh/generated/meshtastic/telemetry.pb.h"
+#include "modules/RoutingModule.h"
 #if defined(ARCH_ESP32)
 #include "../mesh/generated/meshtastic/paxcount.pb.h"
 #endif
@@ -142,6 +143,7 @@ void MQTT::onReceive(char *topic, byte *payload, size_t length)
                 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);
+                    p->via_mqtt = true; // Mark that the packet was received via MQTT
 
                     if (p->which_payload_variant == meshtastic_MeshPacket_decoded_tag) {
                         p->channel = ch.index;
@@ -463,6 +465,9 @@ void MQTT::publishQueuedMessages()
 
 void MQTT::onSend(const meshtastic_MeshPacket &mp, ChannelIndex chIndex)
 {
+    if (mp.via_mqtt)
+        return; // Don't send messages that came from MQTT back into MQTT
+
     auto &ch = channels.getByIndex(chIndex);
 
     if (&mp.decoded && strcmp(moduleConfig.mqtt.address, default_mqtt_address) == 0 &&
@@ -501,6 +506,12 @@ void MQTT::onSend(const meshtastic_MeshPacket &mp, ChannelIndex chIndex)
                     publish(topicJson.c_str(), jsonString.c_str(), false);
                 }
             }
+
+            // 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) {