adacam-odc: internet check before forwarder cycle (DNS probe, exponential backoff when offline)

services/adacam-odc/adacam_odc.py

@@ -901,6 +901,17 @@ def forwarder_process_cycle() -> Tuple[int, int]:
 # =============================================================================
 
 
+
+def is_internet_available(host: str = "8.8.8.8", port: int = 53, timeout: int = 3) -> bool:
+    """Quick internet connectivity check — DNS port probe, no HTTP overhead."""
+    import socket
+    try:
+        socket.setdefaulttimeout(timeout)
+        socket.socket(socket.AF_INET, socket.SOCK_STREAM).connect((host, port))
+        return True
+    except Exception:
+        return False
+
 def forwarder_thread_main():
     """Main function for forwarder thread."""
     fwd_logger.info("╔════════════════════════════════════════════════════════════╗")
@@ -920,6 +931,15 @@ def forwarder_thread_main():
 
     while not shutdown_event.is_set():
         try:
+            if not is_internet_available():
+                fwd_logger.debug("No internet connectivity — skipping cycle, will retry")
+                for _ in range(min(backoff_seconds, max_backoff)):
+                    if shutdown_event.is_set():
+                        break
+                    time.sleep(1)
+                backoff_seconds = min(backoff_seconds * 2, max_backoff)
+                continue
+
             det_sent, img_uploaded = forwarder_process_cycle()
 
             if det_sent > 0 or img_uploaded > 0: