Opportunistic clock sync from verified advert timestamps

examples/simple_repeater/MyMesh.h

@@ -157,6 +157,8 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
     return _prefs.multi_acks;
   }
 
+  bool shouldSyncClockFromMesh() const override { return true; }
+
 #if ENV_INCLUDE_GPS == 1
   void applyGpsPrefs() {
     sensors.setSettingValue("gps", _prefs.gps_enabled?"1":"0");
@@ -252,4 +254,4 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
 #if defined(USE_SX1262) || defined(USE_SX1268)
   void setRxBoostedGain(bool enable) override;
 #endif
-};
+};

src/Mesh.cpp

@@ -267,6 +267,18 @@ DispatcherAction Mesh::onRecvPacket(Packet* pkt) {
         }
         if (is_ok) {
           MESH_DEBUG_PRINTLN("%s Mesh::onRecvPacket(): valid advertisement received!", getLogDateTime());
+
+       // sync clock from verified advert if local clock is clearly wrong (for repeaters without hardware RTC)
+          if (shouldSyncClockFromMesh()) {
+            uint32_t local_time = _rtc->getCurrentTime();
+            if (local_time < 1735689600UL          // local clock before Jan 2025 (clearly wrong)
+                && timestamp > 1735689600UL         // advert after Jan 2025
+                && timestamp < 2082758400UL) {      // advert before Jan 2036
+              _rtc->setCurrentTime(timestamp);
+              MESH_DEBUG_PRINTLN("  clock synced from advert: %lu", (unsigned long)timestamp);
+            }
+          }
+
           onAdvertRecv(pkt, id, timestamp, app_data, app_data_len);
           action = routeRecvPacket(pkt);
         } else {

src/Mesh.h

@@ -49,6 +49,9 @@ class Mesh : public Dispatcher {
    */
   virtual bool filterRecvFloodPacket(Packet* packet) { return false; }
 
+  // sync clock from verified advert if local clock is clearly wrong
+  virtual bool shouldSyncClockFromMesh() const { return false; }
+
   /**
    * \brief  Check whether this packet should be forwarded (re-transmitted) or not.
    *     Is sub-classes responsibility to make sure given packet is only transmitted ONCE (by this node)
@@ -222,4 +225,4 @@ class Mesh : public Dispatcher {
 
 };
 
-}
+}