From 2b34bc4162b279288e4a15990890df5b642bd831 Mon Sep 17 00:00:00 2001
From: Janez T <hey@dz0ny.dev>
Date: Thu, 5 Mar 2026 20:12:09 +0100
Subject: [PATCH] fix: stop lpp zero tail

ref:
---
 lib/services/cayenne_lpp_parser.dart       | 16 ++++++++++++++++
 test/services/cayenne_lpp_parser_test.dart | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/lib/services/cayenne_lpp_parser.dart b/lib/services/cayenne_lpp_parser.dart
index 60379d2..0d69fc9 100644
--- a/lib/services/cayenne_lpp_parser.dart
+++ b/lib/services/cayenne_lpp_parser.dart
@@ -25,6 +25,14 @@ class CayenneLppParser {
 
     int fieldCount = 0;
     while (reader.hasRemaining) {
+      if (fieldCount > 0 && _isZeroPaddedTail(data, reader.remainingBytesCount)) {
+        debugPrint(
+          '    Detected zero-padded telemetry tail, stopping parse at position '
+          '${data.length - reader.remainingBytesCount}',
+        );
+        break;
+      }
+
       try {
         fieldCount++;
         debugPrint(
@@ -250,6 +258,14 @@ class CayenneLppParser {
     return ((voltage - 3.0) / 1.2) * 100.0;
   }
 
+  static bool _isZeroPaddedTail(Uint8List data, int remainingBytes) {
+    final start = data.length - remainingBytes;
+    for (int i = start; i < data.length; i++) {
+      if (data[i] != 0) return false;
+    }
+    return remainingBytes > 0;
+  }
+
   /// Create Cayenne LPP data for GPS location
   /// Standard Cayenne LPP GPS format (type 0x88):
   /// - Latitude: 3 bytes, signed 24-bit, big-endian, × 10000
diff --git a/test/services/cayenne_lpp_parser_test.dart b/test/services/cayenne_lpp_parser_test.dart
index 2ee41bc..1a45ae2 100644
--- a/test/services/cayenne_lpp_parser_test.dart
+++ b/test/services/cayenne_lpp_parser_test.dart
@@ -410,6 +410,24 @@ void main() {
       expect(decoded.batteryMilliVolts, closeTo(3850, 1));
     });
 
+    test('stops parsing at zero-padded telemetry tail', () {
+      final payload = Uint8List.fromList([
+        0x01, 0x74, 0x01, 0x5F, // voltage 3.51V
+        0x01, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00,
+      ]);
+
+      final decoded = CayenneLppParser.parse(payload);
+
+      expect(decoded.batteryMilliVolts, closeTo(3510, 1));
+      expect(decoded.batteryPercentage, closeTo(42.5, 0.1));
+      expect(decoded.gpsLocation, isNotNull);
+      expect(decoded.gpsLocation!.latitude, 0.0);
+      expect(decoded.gpsLocation!.longitude, 0.0);
+      expect(decoded.extraSensorData?['digital_input_0'], isNull);
+    });
+
     test('empty data returns empty telemetry', () {
       final empty = Uint8List(0);
       final decoded = CayenneLppParser.parse(empty);