From 094a9acabf8f0b94d1c62f77a409dbf7e3b137f6 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Tue, 27 Mar 2018 00:49:29 +1300
Subject: Improve Watch frame decoding

---
 src/org/traccar/protocol/WatchFrameDecoder.java      | 14 +++++++++-----
 test/org/traccar/protocol/WatchFrameDecoderTest.java |  4 ++++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/org/traccar/protocol/WatchFrameDecoder.java b/src/org/traccar/protocol/WatchFrameDecoder.java
index 9adea2843..f6b5ef12c 100644
--- a/src/org/traccar/protocol/WatchFrameDecoder.java
+++ b/src/org/traccar/protocol/WatchFrameDecoder.java
@@ -37,11 +37,6 @@ public class WatchFrameDecoder extends FrameDecoder {
         int lengthIndex = buf.indexOf(idIndex, buf.writerIndex(), (byte) '*') + 1;
         if (lengthIndex <= 0) {
             return null;
-        } else if (lengthIndex - idIndex > 10 + 1) {
-            lengthIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*') + 1;
-            if (lengthIndex <= 0) {
-                return null;
-            }
         }
 
         int payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');
@@ -49,6 +44,15 @@ public class WatchFrameDecoder extends FrameDecoder {
             return null;
         }
 
+        if (payloadIndex + 5 < buf.writerIndex() && buf.getByte(payloadIndex + 5) == '*'
+                && buf.toString(payloadIndex + 1, 4, StandardCharsets.US_ASCII).matches("[0-9A-F]+")) {
+            lengthIndex = payloadIndex + 1;
+            payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');
+            if (payloadIndex < 0) {
+                return null;
+            }
+        }
+
         int length = Integer.parseInt(
                 buf.toString(lengthIndex, payloadIndex - lengthIndex, StandardCharsets.US_ASCII), 16);
         if (buf.readableBytes() >= payloadIndex + 1 + length + 1) {
diff --git a/test/org/traccar/protocol/WatchFrameDecoderTest.java b/test/org/traccar/protocol/WatchFrameDecoderTest.java
index a1eca30bc..741807de2 100644
--- a/test/org/traccar/protocol/WatchFrameDecoderTest.java
+++ b/test/org/traccar/protocol/WatchFrameDecoderTest.java
@@ -10,6 +10,10 @@ public class WatchFrameDecoderTest extends ProtocolTest {
 
         WatchFrameDecoder decoder = new WatchFrameDecoder();
 
+        verifyFrame(
+                binary("5b33472a3335323636313039303134333135302a303030412a4c4b2c302c302c3130305d"),
+                decoder.decode(null, null, binary("5b33472a3335323636313039303134333135302a303030412a4c4b2c302c302c3130305d")));
+
         verifyFrame(
                 binary("5b33472a383330383430363237392a303030382a72636170747572655d"),
                 decoder.decode(null, null, binary("5b33472a383330383430363237392a303030382a72636170747572655d")));
-- 
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