* new PAYLOAD_TYPE_CONTROL (11)

* repeater: onControlDataRecv(), now responds to new CTL_TYPE_NODE_DISCOVER_REQ (zero hop only)
* node prefs: new discovery_mod_timestamp  (will be set to affect when node should respond to DISCOVERY_REQ's )

examples/simple_repeater/MyMesh.cpp

@@ -607,6 +607,38 @@ bool MyMesh::onPeerPathRecv(mesh::Packet *packet, int sender_idx, const uint8_t
   return false;
 }
 
+#define CTL_TYPE_NODE_DISCOVER_REQ   0x80
+#define CTL_TYPE_NODE_DISCOVER_RESP  0x90
+
+void MyMesh::onControlDataRecv(mesh::Packet* packet) {
+  uint8_t type = packet->payload[0] & 0xF0;    // just test upper 4 bits
+  if (type == CTL_TYPE_NODE_DISCOVER_REQ && packet->payload_len >= 6) {
+    // TODO: apply rate limiting to these!
+    int i = 1;
+    uint8_t  filter = packet->payload[i++];
+    uint32_t tag;
+    memcpy(&tag, &packet->payload[i], 4); i += 4;
+    uint32_t since;
+    if (packet->payload_len >= i+4) {   // optional since field
+      memcpy(&since, &packet->payload[i], 4); i += 4;
+    } else {
+      since = 0;
+    }
+
+    if ((filter & (1 << ADV_TYPE_REPEATER)) != 0 && _prefs.discovery_mod_timestamp >= since) {
+      uint8_t data[6 + PUB_KEY_SIZE];
+      data[0] = CTL_TYPE_NODE_DISCOVER_RESP | ADV_TYPE_REPEATER;   // low 4-bits for node type
+      data[1] = packet->_snr;   // let sender know the inbound SNR ( x 4)
+      memcpy(&data[2], &tag, 4);     // include tag from request, for client to match to
+      memcpy(&data[6], self_id.pub_key, PUB_KEY_SIZE);
+      auto resp = createControlData(data, sizeof(data));
+      if (resp) {
+        sendZeroHop(resp, getRetransmitDelay(resp));  // apply random delay, as multiple nodes can respond to this
+      }
+    }
+  }
+}
+
 MyMesh::MyMesh(mesh::MainBoard &board, mesh::Radio &radio, mesh::MillisecondClock &ms, mesh::RNG &rng,
                mesh::RTCClock &rtc, mesh::MeshTables &tables)
     : mesh::Mesh(radio, ms, rng, rtc, *new StaticPoolPacketManager(32), tables),

examples/simple_repeater/MyMesh.h

@@ -157,6 +157,7 @@ protected:
   void onAdvertRecv(mesh::Packet* packet, const mesh::Identity& id, uint32_t timestamp, const uint8_t* app_data, size_t app_data_len);
   void onPeerDataRecv(mesh::Packet* packet, uint8_t type, int sender_idx, const uint8_t* secret, uint8_t* data, size_t len) override;
   bool onPeerPathRecv(mesh::Packet* packet, int sender_idx, const uint8_t* secret, uint8_t* path, uint8_t path_len, uint8_t extra_type, uint8_t* extra, uint8_t extra_len) override;
+  void onControlDataRecv(mesh::Packet* packet) override;
 
 public:
   MyMesh(mesh::MainBoard& board, mesh::Radio& radio, mesh::MillisecondClock& ms, mesh::RNG& rng, mesh::RTCClock& rtc, mesh::MeshTables& tables);

src/Mesh.cpp

@@ -68,6 +68,14 @@ DispatcherAction Mesh::onRecvPacket(Packet* pkt) {
     return ACTION_RELEASE;
   }
 
+  if (pkt->isRouteDirect() && pkt->getPayloadType() == PAYLOAD_TYPE_CONTROL && (pkt->payload[0] & 0x80) != 0) {
+    if (pkt->path_len == 0) {
+      onControlDataRecv(pkt);
+    }
+    // just zero-hop control packets allowed (for this subset of payloads)
+    return ACTION_RELEASE;
+  }
+
   if (pkt->isRouteDirect() && pkt->path_len >= PATH_HASH_SIZE) {
     if (self_id.isHashMatch(pkt->path) && allowPacketForward(pkt)) {
       if (pkt->getPayloadType() == PAYLOAD_TYPE_MULTIPART) {
@@ -589,6 +597,22 @@ Packet* Mesh::createTrace(uint32_t tag, uint32_t auth_code, uint8_t flags) {
   return packet;
 }
 
+Packet* Mesh::createControlData(const uint8_t* data, size_t len) {
+  if (len > sizeof(Packet::payload)) return NULL;  // invalid arg
+
+  Packet* packet = obtainNewPacket();
+  if (packet == NULL) {
+    MESH_DEBUG_PRINTLN("%s Mesh::createControlData(): error, packet pool empty", getLogDateTime());
+    return NULL;
+  }
+  packet->header = (PAYLOAD_TYPE_CONTROL << PH_TYPE_SHIFT);  // ROUTE_TYPE_* set later
+
+  memcpy(packet->payload, data, len);
+  packet->payload_len = len;
+
+  return packet;
+}
+
 void Mesh::sendFlood(Packet* packet, uint32_t delay_millis) {
   if (packet->getPayloadType() == PAYLOAD_TYPE_TRACE) {
     MESH_DEBUG_PRINTLN("%s Mesh::sendFlood(): TRACE type not suspported", getLogDateTime());

src/Mesh.h

@@ -133,6 +133,11 @@ protected:
   */
   virtual void onPathRecv(Packet* packet, Identity& sender, uint8_t* path, uint8_t path_len, uint8_t extra_type, uint8_t* extra, uint8_t extra_len) { }
 
+  /**
+   * \brief  A control packet has been received.
+  */
+  virtual void onControlDataRecv(Packet* packet) { }
+
   /**
    * \brief  A packet with PAYLOAD_TYPE_RAW_CUSTOM has been received.
   */
@@ -185,6 +190,7 @@ public:
   Packet* createPathReturn(const Identity& dest, const uint8_t* secret, const uint8_t* path, uint8_t path_len, uint8_t extra_type, const uint8_t*extra, size_t extra_len);
   Packet* createRawData(const uint8_t* data, size_t len);
   Packet* createTrace(uint32_t tag, uint32_t auth_code, uint8_t flags = 0);
+  Packet* createControlData(const uint8_t* data, size_t len);
 
   /**
    * \brief  send a locally-generated Packet with flood routing

src/Packet.h

@@ -27,6 +27,7 @@ namespace mesh {
 #define PAYLOAD_TYPE_PATH        0x08    // returned path (prefixed with dest/src hashes, MAC) (enc data: path, extra)
 #define PAYLOAD_TYPE_TRACE       0x09    // trace a path, collecting SNI for each hop
 #define PAYLOAD_TYPE_MULTIPART   0x0A    // packet is one of a set of packets
+#define PAYLOAD_TYPE_CONTROL     0x0B    // a control/discovery packet
 //...
 #define PAYLOAD_TYPE_RAW_CUSTOM   0x0F    // custom packet as raw bytes, for applications with custom encryption, payloads, etc
 

src/helpers/CommonCLI.cpp

@@ -69,7 +69,8 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
     file.read((uint8_t *)&_prefs->gps_enabled, sizeof(_prefs->gps_enabled));                       // 156
     file.read((uint8_t *)&_prefs->gps_interval, sizeof(_prefs->gps_interval));                     // 157
     file.read((uint8_t *)&_prefs->advert_loc_policy, sizeof (_prefs->advert_loc_policy));          // 161
-    // 162
+    file.read((uint8_t *)&_prefs->discovery_mod_timestamp, sizeof(_prefs->discovery_mod_timestamp)); // 162
+    // 166
 
     // sanitise bad pref values
     _prefs->rx_delay_base = constrain(_prefs->rx_delay_base, 0, 20.0f);
@@ -146,7 +147,8 @@ void CommonCLI::savePrefs(FILESYSTEM* fs) {
     file.write((uint8_t *)&_prefs->gps_enabled, sizeof(_prefs->gps_enabled));                       // 156
     file.write((uint8_t *)&_prefs->gps_interval, sizeof(_prefs->gps_interval));                     // 157
     file.write((uint8_t *)&_prefs->advert_loc_policy, sizeof(_prefs->advert_loc_policy));           // 161
-    // 162
+    file.write((uint8_t *)&_prefs->discovery_mod_timestamp, sizeof(_prefs->discovery_mod_timestamp)); // 162
+    // 166
 
     file.close();
   }

src/helpers/CommonCLI.h

@@ -46,6 +46,7 @@ struct NodePrefs { // persisted to file
   uint8_t gps_enabled;
   uint32_t gps_interval; // in seconds
   uint8_t advert_loc_policy;
+  uint32_t discovery_mod_timestamp;
 };
 
 class CommonCLICallbacks {