From a11be97deeba6d2b69a8870518bd47bdcd4dda64 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton@traccar.org>
Date: Wed, 2 Oct 2024 15:50:11 -0700
Subject: [PATCH] Fix Lantrix ACK (fix #5394)

---
 .../java/org/traccar/protocol/TaipProtocolDecoder.java   | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/traccar/protocol/TaipProtocolDecoder.java b/src/main/java/org/traccar/protocol/TaipProtocolDecoder.java
index c09888011a5..4211bc99c06 100644
--- a/src/main/java/org/traccar/protocol/TaipProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/TaipProtocolDecoder.java
@@ -301,11 +301,14 @@ private Position decodeAttributes(
                         response = ">SAK;ID=" + uniqueId + ";" + messageIndex + "<";
                     } else {
                         if (indexFirst) {
-                            response = ">ACK;" + messageIndex + ";ID=" + uniqueId + ";*";
+                            response = ">ACK;" + messageIndex + ";ID=" + uniqueId + ";";
                         } else {
-                            response = ">ACK;ID=" + uniqueId + ";" + messageIndex + ";*";
+                            response = ">ACK;ID=" + uniqueId + ";" + messageIndex + ";";
                         }
-                        response += String.format("%02X", Checksum.xor(response)) + "<";
+                        String model = getDeviceModel(deviceSession);
+                        boolean lantrix = model != null && model.toUpperCase().startsWith("LANTRIX");
+                        int checksum = Checksum.xor(lantrix ? response : response + "*");
+                        response += String.format("*%02X", checksum) + "<";
                     }
                     channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
                 } else {