From 358b591bc457786927ac1466e10181bbffbcf56b Mon Sep 17 00:00:00 2001
From: Ivan Muratov <binakot@gmail.com>
Date: Thu, 13 Jul 2017 08:42:17 +0300
Subject: Replace MODULO256 checksum method. Added covering tests.

---
 src/org/traccar/helper/Checksum.java                 |  8 ++++++++
 src/org/traccar/protocol/Arnavi4ProtocolDecoder.java | 11 ++---------
 2 files changed, 10 insertions(+), 9 deletions(-)

(limited to 'src/org')

diff --git a/src/org/traccar/helper/Checksum.java b/src/org/traccar/helper/Checksum.java
index 43ba6a689..7a0151d36 100644
--- a/src/org/traccar/helper/Checksum.java
+++ b/src/org/traccar/helper/Checksum.java
@@ -243,4 +243,12 @@ public final class Checksum {
         return (10 - (checksum % 10)) % 10;
     }
 
+    public static int modulo256(byte... bytes) {
+        int sum = 0;
+        for (byte b : bytes) {
+            sum = (sum + b) & 0xFF;
+        }
+        return sum;
+    }
+
 }
diff --git a/src/org/traccar/protocol/Arnavi4ProtocolDecoder.java b/src/org/traccar/protocol/Arnavi4ProtocolDecoder.java
index caa8dd28f..46caebb71 100644
--- a/src/org/traccar/protocol/Arnavi4ProtocolDecoder.java
+++ b/src/org/traccar/protocol/Arnavi4ProtocolDecoder.java
@@ -5,6 +5,7 @@ import org.jboss.netty.buffer.ChannelBuffers;
 import org.jboss.netty.channel.Channel;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.DeviceSession;
+import org.traccar.helper.Checksum;
 import org.traccar.model.Position;
 
 import java.net.SocketAddress;
@@ -35,14 +36,6 @@ public class Arnavi4ProtocolDecoder extends BaseProtocolDecoder {
         super(protocol);
     }
 
-    private static int modulo256Checksum(byte[] bytes) {
-        int sum = 0;
-        for (byte b : bytes) {
-            sum = (sum + b) & 0xFF;
-        }
-        return sum;
-    }
-
     private Position decodePosition(DeviceSession deviceSession, ChannelBuffer buf, long timestamp) {
 
         final Position position = new Position();
@@ -107,7 +100,7 @@ public class Arnavi4ProtocolDecoder extends BaseProtocolDecoder {
                     response = ChannelBuffers.dynamicBuffer(ByteOrder.LITTLE_ENDIAN, 9);
                     response.writeBytes(new byte[]{0x7B, 0x04, 0x00});
                     byte[] timestampBytes = ByteBuffer.allocate(4).putInt((int) (System.currentTimeMillis() / 1000)).array();
-                    response.writeByte(modulo256Checksum(timestampBytes));
+                    response.writeByte(Checksum.modulo256(timestampBytes));
                     response.writeBytes(timestampBytes);
                     response.writeByte(0x7D);
 
-- 
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