Add Promiscuous mode for serial

src/main.cpp

@@ -218,6 +218,8 @@ bool eink_found = true;
 
 uint32_t serialSinceMsec;
 bool pauseBluetoothLogging = false;
+// Global control flag for encrypted-only promiscuous forwarding to FromRadio
+bool serialPromiscuousEnabled = false;
 
 bool pmu_found;
 

src/main.h

@@ -90,6 +90,10 @@ extern bool runASAP;
 
 extern bool pauseBluetoothLogging;
 
+// When true, forward all received LoRa packets to FromRadio as encrypted MeshPacket payloads
+// and avoid sending decrypted duplicates to FromRadio. Reset to false on serial connect/disconnect.
+extern bool serialPromiscuousEnabled;
+
 void nrf52Setup(), esp32Setup(), nrf52Loop(), esp32Loop(), rp2040Setup(), clearBonds(), enterDfuMode();
 
 meshtastic_DeviceMetadata getDeviceMetadata();

src/mesh/MeshService.cpp

@@ -109,7 +109,10 @@ int MeshService::handleFromRadio(const meshtastic_MeshPacket *mp)
     }
 
     printPacket("Forwarding to phone", mp);
-    sendToPhone(packetPool.allocCopy(*mp));
+    // If promiscuous mode is enabled, suppress duplicate to phone.
+    if (!serialPromiscuousEnabled) {
+        sendToPhone(packetPool.allocCopy(*mp));
+    }
 
     return 0;
 }
@@ -184,7 +187,10 @@ void MeshService::handleToRadio(meshtastic_MeshPacket &p)
         return;
     }
 #endif
-    p.from = 0;                          // We don't let clients assign nodenums to their sent messages
+    // Allow any encrypted packet as-is in promiscuous mode
+    if (!(serialPromiscuousEnabled && p.which_payload_variant == meshtastic_MeshPacket_encrypted_tag)) {
+        p.from = 0; // We don't let clients assign nodenums to their sent messages
+    }
     p.next_hop = NO_NEXT_HOP_PREFERENCE; // We don't let clients assign next_hop to their sent messages
     p.relay_node = NO_RELAY_NODE;        // We don't let clients assign relay_node to their sent messages
 
@@ -292,7 +298,10 @@ bool MeshService::trySendPosition(NodeNum dest, bool wantReplies)
 
 void MeshService::sendToPhone(meshtastic_MeshPacket *p)
 {
-    perhapsDecode(p);
+    // In promiscuous mode, prefer to forward encrypted packets as-is and avoid decoding duplicates
+    if (!serialPromiscuousEnabled) {
+        perhapsDecode(p);
+    }
 
 #ifdef ARCH_ESP32
 #if !MESHTASTIC_EXCLUDE_STOREFORWARD
@@ -306,8 +315,9 @@ void MeshService::sendToPhone(meshtastic_MeshPacket *p)
 #endif
 
     if (toPhoneQueue.numFree() == 0) {
-        if (p->decoded.portnum == meshtastic_PortNum_TEXT_MESSAGE_APP ||
-            p->decoded.portnum == meshtastic_PortNum_RANGE_TEST_APP) {
+        if (p->which_payload_variant == meshtastic_MeshPacket_decoded_tag &&
+            (p->decoded.portnum == meshtastic_PortNum_TEXT_MESSAGE_APP ||
+             p->decoded.portnum == meshtastic_PortNum_RANGE_TEST_APP)) {
             LOG_WARN("ToPhone queue is full, discard oldest");
             meshtastic_MeshPacket *d = toPhoneQueue.dequeuePtr(0);
             if (d)

src/mesh/PhoneAPI.cpp

@@ -127,6 +127,7 @@ void PhoneAPI::close()
         config_state = 0;
         pauseBluetoothLogging = false;
         heartbeatReceived = false;
+        serialPromiscuousEnabled = false;
     }
 }
 
@@ -165,6 +166,10 @@ bool PhoneAPI::handleToRadio(const uint8_t *buf, size_t bufLength)
             LOG_INFO("Disconnect from phone");
             close();
             break;
+        case meshtastic_ToRadio_set_promiscuous_tag:
+            LOG_INFO("Set serial promiscuous: %s", toRadioScratch.set_promiscuous ? "true" : "false");
+            serialPromiscuousEnabled = toRadioScratch.set_promiscuous;
+            break;
         case meshtastic_ToRadio_xmodemPacket_tag:
             LOG_INFO("Got xmodem packet");
 #ifdef FSCom

src/mesh/Router.cpp

@@ -758,6 +758,13 @@ void Router::handleReceived(meshtastic_MeshPacket *p, RxSource src)
 
 void Router::perhapsHandleReceived(meshtastic_MeshPacket *p)
 {
+    if (serialPromiscuousEnabled) {
+        // If serial promiscuous mode is enabled, forward the encrypted form to the phone now
+        service->sendToPhone(packetPool.allocCopy(*p));
+    }
+    LOG_DEBUG("serialPromiscuousEnabled: %d Encrypted: %d", serialPromiscuousEnabled,
+              p->which_payload_variant == meshtastic_MeshPacket_encrypted_tag);
+
 #if ENABLE_JSON_LOGGING
     // Even ignored packets get logged in the trace
     p->rx_time = getValidTime(RTCQualityFromNet); // store the arrival timestamp for the phone

src/mesh/StreamAPI.cpp

@@ -3,6 +3,7 @@
 #include "RTC.h"
 #include "Throttle.h"
 #include "configuration.h"
+#include "main.h"
 
 #define START1 0x94
 #define START2 0xc3
@@ -219,9 +220,13 @@ void StreamAPI::onConnectionChanged(bool connected)
 
     if (connected) { // To prevent user confusion, turn off bluetooth while using the serial port api
         powerFSM.trigger(EVENT_SERIAL_CONNECTED);
+        // Reset promiscuous mode on connect
+        serialPromiscuousEnabled = false;
     } else {
         // FIXME, we get no notice of serial going away, we should instead automatically generate this event if we haven't
         // received a packet in a while
         powerFSM.trigger(EVENT_SERIAL_DISCONNECTED);
+        // Reset promiscuous mode on disconnect
+        serialPromiscuousEnabled = false;
     }
 }

src/mesh/generated/meshtastic/mesh.pb.h

@@ -1218,6 +1218,10 @@ typedef struct _meshtastic_ToRadio {
         meshtastic_MqttClientProxyMessage mqttClientProxyMessage;
         /* Heartbeat message (used to keep the device connection awake on serial) */
         meshtastic_Heartbeat heartbeat;
+        /* Set or clear promiscuous capture mode for LoRa RX.
+     If true, the device will forward all received LoRa packets to FromRadio as encrypted MeshPacket payloads,
+     and will avoid additionally sending the decrypted copies. This is primarily intended for serial sniffing. */
+        bool set_promiscuous;
     };
 } meshtastic_ToRadio;
 
@@ -1605,6 +1609,7 @@ extern "C" {
 #define meshtastic_ToRadio_xmodemPacket_tag      5
 #define meshtastic_ToRadio_mqttClientProxyMessage_tag 6
 #define meshtastic_ToRadio_heartbeat_tag         7
+#define meshtastic_ToRadio_set_promiscuous_tag   8
 #define meshtastic_NodeRemoteHardwarePin_node_num_tag 1
 #define meshtastic_NodeRemoteHardwarePin_pin_tag 2
 #define meshtastic_ChunkedPayload_payload_id_tag 1
@@ -1883,7 +1888,8 @@ X(a, STATIC,   ONEOF,    UINT32,   (payload_variant,want_config_id,want_config_i
 X(a, STATIC,   ONEOF,    BOOL,     (payload_variant,disconnect,disconnect),   4) \
 X(a, STATIC,   ONEOF,    MESSAGE,  (payload_variant,xmodemPacket,xmodemPacket),   5) \
 X(a, STATIC,   ONEOF,    MESSAGE,  (payload_variant,mqttClientProxyMessage,mqttClientProxyMessage),   6) \
-X(a, STATIC,   ONEOF,    MESSAGE,  (payload_variant,heartbeat,heartbeat),   7)
+X(a, STATIC,   ONEOF,    MESSAGE,  (payload_variant,heartbeat,heartbeat),   7) \
+X(a, STATIC,   ONEOF,    BOOL,     (payload_variant,set_promiscuous,set_promiscuous),   8)
 #define meshtastic_ToRadio_CALLBACK NULL
 #define meshtastic_ToRadio_DEFAULT NULL
 #define meshtastic_ToRadio_payload_variant_packet_MSGTYPE meshtastic_MeshPacket