Change frame to have prefix showing origin. Tested and all units received from the other tree. I should have committed then, but forgot. Here, the blocking has been activated, but not tested.

exercises/204_established_identities/platformio.ini

@@ -50,6 +50,8 @@ build_flags =
   -D LORA_SYNC_WORD=0x12
   -D LORA_TX_POWER_DBM=14
   -D USTORE_MAX_VALUE_LEN=1200
+  -D SIM_PHY_ENVELOPE=1
+  -D SIM_PHY_BLOCK_BOB_CY=1
 ; Live announces are enough for this single-hop field exercise. Do not define
 ; RNS_PERSIST_PATHS here: the LittleFS-backed path_store compactor can leave an
 ; active segment FD open while unlinking /path_store_*.dat on ESP32.

exercises/204_established_identities/src/TBeamSupremeLoRaInterface.cpp

@@ -17,6 +17,15 @@
 #ifndef LORA_BUSY
 #error "LORA_BUSY not defined"
 #endif
+#ifndef NODE_SLOT_INDEX
+#define NODE_SLOT_INDEX 255
+#endif
+#ifndef SIM_PHY_ENVELOPE
+#define SIM_PHY_ENVELOPE 0
+#endif
+#ifndef SIM_PHY_BLOCK_BOB_CY
+#define SIM_PHY_BLOCK_BOB_CY 0
+#endif
 
 using namespace RNS;
 
@@ -24,7 +33,7 @@ TBeamSupremeLoRaInterface::TBeamSupremeLoRaInterface(const char* name) : Interfa
   _IN = true;
   _OUT = true;
   _bitrate = (double)LORA_SF * ((4.0 / LORA_CR) / (pow(2, LORA_SF) / LORA_BW_KHZ)) * 1000.0;
-  _HW_MTU = 508;
+  _HW_MTU = (uint16_t)(LORA_MAX_PAYLOAD * 2);
 }
 
 TBeamSupremeLoRaInterface::~TBeamSupremeLoRaInterface() {
@@ -82,13 +91,23 @@ void TBeamSupremeLoRaInterface::loop() {
   }
 
   int len = _radio->getPacketLength();
-  uint8_t rx_buf[255];
+  uint8_t rx_buf[RADIO_MAX_PAYLOAD];
   int state = _radio->readData(rx_buf, len);
 
-  if (state == RADIOLIB_ERR_NONE && len > 1) {
+  if (state == RADIOLIB_ERR_NONE) {
     _last_rssi = _radio->getRSSI();
     _last_snr = _radio->getSNR();
 
+    uint8_t physical_tx = 255;
+    if (!unpack_frame(rx_buf, len, physical_tx)) {
+      _radio->startReceive();
+      return;
+    }
+    if (len <= 1) {
+      _radio->startReceive();
+      return;
+    }
+
     uint8_t header = rx_buf[0];
     uint8_t seq = packet_sequence(header);
 
@@ -118,19 +137,71 @@ void TBeamSupremeLoRaInterface::loop() {
   _radio->startReceive();
 }
 
+int TBeamSupremeLoRaInterface::transmit_frame(uint8_t header, const uint8_t* payload, size_t payload_len) {
+  uint8_t tx_buf[RADIO_MAX_PAYLOAD];
+#if SIM_PHY_ENVELOPE
+  tx_buf[0] = PHY_MAGIC_0;
+  tx_buf[1] = PHY_MAGIC_1;
+  tx_buf[2] = PHY_VERSION;
+  tx_buf[3] = (uint8_t)NODE_SLOT_INDEX;
+  tx_buf[PHY_ENVELOPE_LEN] = header;
+  memcpy(tx_buf + PHY_ENVELOPE_LEN + 1, payload, payload_len);
+  return _radio->transmit(tx_buf, PHY_ENVELOPE_LEN + 1 + payload_len);
+#else
+  tx_buf[0] = header;
+  memcpy(tx_buf + 1, payload, payload_len);
+  return _radio->transmit(tx_buf, 1 + payload_len);
+#endif
+}
+
+bool TBeamSupremeLoRaInterface::unpack_frame(uint8_t* frame, int& len, uint8_t& physical_tx) {
+#if SIM_PHY_ENVELOPE
+  if (len < PHY_ENVELOPE_LEN + 1) {
+    DEBUGF("SIM PHY malformed: short frame len=%d", len);
+    return false;
+  }
+  if (frame[0] != PHY_MAGIC_0 || frame[1] != PHY_MAGIC_1 || frame[2] != PHY_VERSION) {
+    DEBUGF("SIM PHY malformed: bad envelope len=%d", len);
+    return false;
+  }
+  physical_tx = frame[3];
+  if (should_drop_physical_tx(physical_tx)) {
+    DEBUGF("SIM PHY DROP: rx=%u tx=%u len=%d",
+           (unsigned)NODE_SLOT_INDEX,
+           (unsigned)physical_tx,
+           len);
+    return false;
+  }
+  len -= PHY_ENVELOPE_LEN;
+  memmove(frame, frame + PHY_ENVELOPE_LEN, len);
+  return true;
+#else
+  (void)frame;
+  physical_tx = 255;
+  return true;
+#endif
+}
+
+bool TBeamSupremeLoRaInterface::should_drop_physical_tx(uint8_t physical_tx) {
+#if SIM_PHY_BLOCK_BOB_CY
+  const uint8_t local = (uint8_t)NODE_SLOT_INDEX;
+  return (local == 1U && physical_tx == 2U) || (local == 2U && physical_tx == 1U);
+#else
+  (void)physical_tx;
+  return false;
+#endif
+}
+
 void TBeamSupremeLoRaInterface::send_outgoing(const Bytes& data) {
   if (!_online || !_radio) {
     return;
   }
 
   try {
-    uint8_t tx_buf[255];
     uint8_t rand_nibble = (uint8_t)(Cryptography::randomnum(256)) & 0xF0;
 
     if ((int)data.size() <= LORA_MAX_PAYLOAD) {
-      tx_buf[0] = rand_nibble;
-      memcpy(tx_buf + 1, data.data(), data.size());
-      int state = _radio->transmit(tx_buf, 1 + data.size());
+      int state = transmit_frame(rand_nibble, data.data(), data.size());
       if (state != RADIOLIB_ERR_NONE) {
         ERRORF("LoRa transmit failed, code %d", state);
       }
@@ -138,17 +209,13 @@ void TBeamSupremeLoRaInterface::send_outgoing(const Bytes& data) {
       uint8_t seq = (_tx_seq_ctr++) & HEADER_SEQ_MASK;
       uint8_t split_header = rand_nibble | HEADER_SPLIT | seq;
 
-      tx_buf[0] = split_header;
-      memcpy(tx_buf + 1, data.data(), LORA_MAX_PAYLOAD);
-      int state = _radio->transmit(tx_buf, 1 + LORA_MAX_PAYLOAD);
+      int state = transmit_frame(split_header, data.data(), LORA_MAX_PAYLOAD);
       if (state != RADIOLIB_ERR_NONE) {
         ERRORF("LoRa transmit part 1 failed, code %d", state);
       }
 
       size_t remainder = data.size() - LORA_MAX_PAYLOAD;
-      tx_buf[0] = split_header;
-      memcpy(tx_buf + 1, data.data() + LORA_MAX_PAYLOAD, remainder);
-      state = _radio->transmit(tx_buf, 1 + remainder);
+      state = transmit_frame(split_header, data.data() + LORA_MAX_PAYLOAD, remainder);
       if (state != RADIOLIB_ERR_NONE) {
         ERRORF("LoRa transmit part 2 failed, code %d", state);
       }

exercises/204_established_identities/src/TBeamSupremeLoRaInterface.h

@@ -22,11 +22,24 @@ public:
 private:
   void send_outgoing(const RNS::Bytes& data) override;
   void on_incoming(const RNS::Bytes& data);
+  int transmit_frame(uint8_t header, const uint8_t* payload, size_t payload_len);
+  bool unpack_frame(uint8_t* frame, int& len, uint8_t& physical_tx);
+  static bool should_drop_physical_tx(uint8_t physical_tx);
 
   static constexpr uint8_t HEADER_SPLIT = 0x08;
   static constexpr uint8_t HEADER_SEQ_MASK = 0x07;
   static constexpr uint8_t SEQ_UNSET = 0xFF;
-  static constexpr int LORA_MAX_PAYLOAD = 254;
+  static constexpr int RADIO_MAX_PAYLOAD = 255;
+#if defined(SIM_PHY_ENVELOPE) && SIM_PHY_ENVELOPE
+  static constexpr uint8_t PHY_MAGIC_0 = 0xC2;
+  static constexpr uint8_t PHY_MAGIC_1 = 0x04;
+  static constexpr uint8_t PHY_VERSION = 0x01;
+  static constexpr int PHY_ENVELOPE_LEN = 4;
+  static constexpr int LORA_MAX_PAYLOAD = RADIO_MAX_PAYLOAD - PHY_ENVELOPE_LEN - 1;
+#else
+  static constexpr int PHY_ENVELOPE_LEN = 0;
+  static constexpr int LORA_MAX_PAYLOAD = RADIO_MAX_PAYLOAD - 1;
+#endif
 
   static bool is_split_packet(uint8_t header) { return (header & HEADER_SPLIT) != 0; }
   static uint8_t packet_sequence(uint8_t header) { return header & HEADER_SEQ_MASK; }