* proposal for 'Extended Trace' packets. Using 'flags' byte, lower 2 bits, for path hash size.

Author: Scott Powell

examples/companion_radio/MyMesh.cpp

@@ -670,6 +670,11 @@ void MyMesh::onRawDataRecv(mesh::Packet *packet) {
 
 void MyMesh::onTraceRecv(mesh::Packet *packet, uint32_t tag, uint32_t auth_code, uint8_t flags,
                          const uint8_t *path_snrs, const uint8_t *path_hashes, uint8_t path_len) {
+  uint8_t path_sz = flags & 0x03;  // NEW v1.11+
+  if (12 + path_len + (path_len >> path_sz) + 1 > sizeof(out_frame)) {
+    MESH_DEBUG_PRINTLN("onTraceRecv(), path_len is too long: %d", (uint32_t)path_len);
+    return;
+  }
   int i = 0;
   out_frame[i++] = PUSH_CODE_TRACE_DATA;
   out_frame[i++] = 0; // reserved
@@ -681,8 +686,9 @@ void MyMesh::onTraceRecv(mesh::Packet *packet, uint32_t tag, uint32_t auth_code,
   i += 4;
   memcpy(&out_frame[i], path_hashes, path_len);
   i += path_len;
-  memcpy(&out_frame[i], path_snrs, path_len);
-  i += path_len;
+
+  memcpy(&out_frame[i], path_snrs, path_len >> path_sz);
+  i += path_len >> path_sz;
   out_frame[i++] = (int8_t)(packet->getSNR() * 4); // extra/final SNR (to this node)
 
   if (_serial->isConnected()) {
@@ -1446,25 +1452,31 @@ void MyMesh::handleCmdFrame(size_t len) {
     } else {
       writeErrFrame(ERR_CODE_BAD_STATE);
     }
-  } else if (cmd_frame[0] == CMD_SEND_TRACE_PATH && len > 10 && len - 10 < MAX_PATH_SIZE) {
-    uint32_t tag, auth;
-    memcpy(&tag, &cmd_frame[1], 4);
-    memcpy(&auth, &cmd_frame[5], 4);
-    auto pkt = createTrace(tag, auth, cmd_frame[9]);
-    if (pkt) {
-      uint8_t path_len = len - 10;
-      sendDirect(pkt, &cmd_frame[10], path_len);
+  } else if (cmd_frame[0] == CMD_SEND_TRACE_PATH && len > 10 && len - 10 < MAX_PACKET_PAYLOAD-5) {
+    uint8_t path_len = len - 10;
+    uint8_t flags = cmd_frame[9];
+    uint8_t path_sz = flags & 0x03;  // NEW v1.11+ 
+    if ((path_len >> path_sz) > MAX_PATH_SIZE || (path_len % (1 << path_sz)) != 0) { // make sure is multiple of path_sz
+      writeErrFrame(ERR_CODE_ILLEGAL_ARG);
+    } else {
+      uint32_t tag, auth;
+      memcpy(&tag, &cmd_frame[1], 4);
+      memcpy(&auth, &cmd_frame[5], 4);
+      auto pkt = createTrace(tag, auth, flags);
+      if (pkt) {
+        sendDirect(pkt, &cmd_frame[10], path_len);
 
-      uint32_t t = _radio->getEstAirtimeFor(pkt->payload_len + pkt->path_len + 2);
-      uint32_t est_timeout = calcDirectTimeoutMillisFor(t, path_len);
+        uint32_t t = _radio->getEstAirtimeFor(pkt->payload_len + pkt->path_len + 2);
+        uint32_t est_timeout = calcDirectTimeoutMillisFor(t, path_len);
 
-      out_frame[0] = RESP_CODE_SENT;
-      out_frame[1] = 0;
-      memcpy(&out_frame[2], &tag, 4);
-      memcpy(&out_frame[6], &est_timeout, 4);
-      _serial->writeFrame(out_frame, 10);
-    } else {
-      writeErrFrame(ERR_CODE_TABLE_FULL);
+        out_frame[0] = RESP_CODE_SENT;
+        out_frame[1] = 0;
+        memcpy(&out_frame[2], &tag, 4);
+        memcpy(&out_frame[6], &est_timeout, 4);
+        _serial->writeFrame(out_frame, 10);
+      } else {
+        writeErrFrame(ERR_CODE_TABLE_FULL);
+      }
     }
   } else if (cmd_frame[0] == CMD_SET_DEVICE_PIN && len >= 5) {
 

src/Identity.h

@@ -23,6 +23,9 @@ class Identity {
   bool isHashMatch(const uint8_t* hash) const {
     return memcmp(hash, pub_key, PATH_HASH_SIZE) == 0;
   }
+  bool isHashMatch(const uint8_t* hash, uint8_t len) const {
+    return memcmp(hash, pub_key, len) == 0;
+  }
 
   /**
    * \brief  Performs Ed25519 signature verification.

src/Mesh.cpp

@@ -52,14 +52,15 @@ DispatcherAction Mesh::onRecvPacket(Packet* pkt) {
       uint32_t auth_code;
       memcpy(&auth_code, &pkt->payload[i], 4); i += 4;
       uint8_t flags = pkt->payload[i++];
+      uint8_t path_sz = flags & 0x03;  // NEW v1.11+: lower 2 bits is path hash size
 
       uint8_t len = pkt->payload_len - i;
-      if (pkt->path_len >= len) {   // TRACE has reached end of given path
+      uint8_t offset = pkt->path_len << path_sz;
+      if (offset >= len) {   // TRACE has reached end of given path
         onTraceRecv(pkt, trace_tag, auth_code, flags, pkt->path, &pkt->payload[i], len);
-      } else if (self_id.isHashMatch(&pkt->payload[i + pkt->path_len]) && allowPacketForward(pkt) && !_tables->hasSeen(pkt)) {
+      } else if (self_id.isHashMatch(&pkt->payload[i + offset], 1 << path_sz) && allowPacketForward(pkt) && !_tables->hasSeen(pkt)) {
         // append SNR (Not hash!)
-        pkt->path[pkt->path_len] = (int8_t) (pkt->getSNR()*4);
-        pkt->path_len += PATH_HASH_SIZE;
+        pkt->path[pkt->path_len++] = (int8_t) (pkt->getSNR()*4);
 
         uint32_t d = getDirectRetransmitDelay(pkt);
         return ACTION_RETRANSMIT_DELAYED(5, d);  // schedule with priority 5 (for now), maybe make configurable?