From 5465e58749ecf553839484f4a41ca94a1621bbb8 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Tue, 14 Feb 2017 02:19:31 +1300
Subject: Handle empty AT2000 message (fix #2662)

---
 src/org/traccar/protocol/At2000ProtocolDecoder.java      | 4 ++++
 test/org/traccar/protocol/At2000ProtocolDecoderTest.java | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/src/org/traccar/protocol/At2000ProtocolDecoder.java b/src/org/traccar/protocol/At2000ProtocolDecoder.java
index 00973f2aa..f990e05c2 100644
--- a/src/org/traccar/protocol/At2000ProtocolDecoder.java
+++ b/src/org/traccar/protocol/At2000ProtocolDecoder.java
@@ -102,6 +102,10 @@ public class At2000ProtocolDecoder extends BaseProtocolDecoder {
                 return null;
             }
 
+            if (buf.capacity() <= BLOCK_LENGTH) {
+                return null; // empty message
+            }
+
             byte[] data = new byte[buf.capacity() - BLOCK_LENGTH];
             buf.readBytes(data);
             buf = ChannelBuffers.wrappedBuffer(ByteOrder.LITTLE_ENDIAN, cipher.update(data));
diff --git a/test/org/traccar/protocol/At2000ProtocolDecoderTest.java b/test/org/traccar/protocol/At2000ProtocolDecoderTest.java
index 596d2870d..0b1a9f471 100644
--- a/test/org/traccar/protocol/At2000ProtocolDecoderTest.java
+++ b/test/org/traccar/protocol/At2000ProtocolDecoderTest.java
@@ -18,6 +18,14 @@ public class At2000ProtocolDecoderTest extends ProtocolTest {
 
         decoder = new At2000ProtocolDecoder(new At2000Protocol());
 
+        verifyNothing(decoder, binary(ByteOrder.LITTLE_ENDIAN,
+                "01012f00000000000000000000000000003335373435343037313632373539388b57ec3a6ec7e3310a1ceb0a70fd751b8f2e7be6df1d6dcd80129f66fff0ea1c"));
+
+        verifyNothing(decoder, binary(ByteOrder.LITTLE_ENDIAN,
+                "89000000000000000000000000000000"));
+
+        decoder = new At2000ProtocolDecoder(new At2000Protocol());
+
         verifyNothing(decoder, binary(ByteOrder.LITTLE_ENDIAN,
                 "01012f0000000000000000000000000000333537343534303731363036313936ddf189075add9a32d97b54073025963e65849a3a59940d05fd8db655fc84bc6d"));
 
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