From 6eb1837b796f51bd2a84d091b706a7ae1d4952a0 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Tue, 7 Jul 2015 15:20:48 +1200
Subject: Improve Aplicom id parsing

---
 src/org/traccar/helper/Crc.java                    | 30 +++++----
 .../traccar/protocol/AplicomProtocolDecoder.java   | 72 ++++++++--------------
 .../traccar/protocol/MeiligaoProtocolDecoder.java  |  2 +-
 3 files changed, 42 insertions(+), 62 deletions(-)

(limited to 'src/org/traccar')

diff --git a/src/org/traccar/helper/Crc.java b/src/org/traccar/helper/Crc.java
index 213d1192a..418ec3132 100644
--- a/src/org/traccar/helper/Crc.java
+++ b/src/org/traccar/helper/Crc.java
@@ -154,21 +154,25 @@ public class Crc {
         return String.format("*%02x", checksum).toUpperCase();
     }
 
-    public static String luhnChecksum(String s) {
-        int sum = 0;
-        boolean evenPosition = true;
-        for (int i = s.length() - 1; i >= 0; i--) {
-            int n = Integer.parseInt(s.substring(i, i + 1));
-            if (evenPosition) {
-                n *= 2;
-                if (n > 9) {
-                    n = (n % 10) + 1;
+    public static long luhnChecksum(long imei) {
+        long checksum = 0;
+        long remain = imei;
+
+        for (int i = 0; remain != 0; i++) {
+            long digit = remain % 10;
+
+            if ((i % 2) == 0) {
+                digit *= 2;
+                if (digit >= 10) {
+                    digit = 1 + (digit % 10);
                 }
             }
-            sum += n;
-            evenPosition = !evenPosition;
+
+            checksum += digit;
+            remain /= 10;
         }
-        return String.valueOf(10 - sum % 10);
-    }    
+
+        return 10 - (checksum % 10);
+    }
     
 }
diff --git a/src/org/traccar/protocol/AplicomProtocolDecoder.java b/src/org/traccar/protocol/AplicomProtocolDecoder.java
index 045eb2adc..573cccecf 100644
--- a/src/org/traccar/protocol/AplicomProtocolDecoder.java
+++ b/src/org/traccar/protocol/AplicomProtocolDecoder.java
@@ -26,6 +26,7 @@ import org.jboss.netty.channel.ChannelHandlerContext;
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.Context;
 import org.traccar.helper.ChannelBufferTools;
+import org.traccar.helper.Crc;
 import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Event;
 import org.traccar.model.Position;
@@ -40,68 +41,41 @@ public class AplicomProtocolDecoder extends BaseProtocolDecoder {
     private static final long IMEI_BASE_TC65_V28 = 358244010000000L;
     private static final long IMEI_BASE_TC65I_V11 = 0x14143B4000000L;
 
+    private static boolean validateImei(long imei) {
+        return Crc.luhnChecksum(imei / 10) == imei % 10;
+    }
+
     private static long imeiFromUnitId(long unitId) {
-        if(unitId == 0) {
-            return 0L;
-        } else if(unitId < 0x1000000) {
-            // Assume TC65i.
+
+        if (unitId == 0) {
+
+            return 0;
+
+        } else {
+
+            // Try TC65i
             long imei = IMEI_BASE_TC65I_V11 + unitId;
-            if(validateImei(imei)) {
+            if (validateImei(imei)) {
                 return imei;
             }
             
-            // No? Maybe it's TC65 v2.8?
+            // Try TC65 v2.8
             imei = IMEI_BASE_TC65_V28 + ((unitId + 0xA8180) & 0xFFFFFF);
-            if(validateImei(imei)) {
+            if (validateImei(imei)) {
                 return imei;
             }
             
-            // Still no match? How about TC65 v2.0?
+            // Try TC65 v2.0
             imei = IMEI_BASE_TC65_V20 + unitId;
-            if(validateImei(imei)) {
+            if (validateImei(imei)) {
                 return imei;
             }
-        } else {
-            // Unit ID is full IMEI, just check it.
-            if(validateImei(unitId)) {
-                return unitId;
-            }
+
         }
         
         return unitId;
     }
-    
-    private static boolean validateImei(long imei2) {
-
-        int checksum = 0;
-        long remain = imei2;
-
-        // Iterate through all meaningful digits.
-        for (int i = 0; remain != 0; i++) {
-            // Extract the rightmost digit, that is, compute
-            // imei modulo 10 (or remainder of imei / 10).
-            int digit = (int) (remain % 10);
-
-            // For each even-positioned digit, calculate the value
-            // to be added to sum: Double the digit and then sum up
-            // the digits of the result.
-            // Example: 7 -> 2*7 = 14 -> 1 + 4 = 5
-            if (0 != (i % 2)) {
-                digit = digit * 2;
-                if (digit >= 10) {
-                    digit = digit - 9;
-                }
-            }
-            checksum = checksum + digit;
-
-            // Remove the rightmost digit as it's already processed.
-            remain = remain / 10;
-        }
 
-        // The IMEI is valid if the calculated checksum is dividable by 10.
-        return 0 == (checksum % 10);
-    }
-    
     private static final int DEFAULT_SELECTOR = 0x0002FC;
 
     private static final int EVENT_DATA = 119;
@@ -115,12 +89,14 @@ public class AplicomProtocolDecoder extends BaseProtocolDecoder {
 
         buf.readUnsignedByte(); // marker
         int version = buf.readUnsignedByte();
+
+        String imei;
         if ((version & 0x80) != 0) {
-            buf.skipBytes(4); // unit id high
+            imei = String.valueOf((buf.readUnsignedInt() << (3 * 8)) | buf.readUnsignedMedium());
+        } else {
+            imei = String.valueOf(imeiFromUnitId(buf.readUnsignedMedium()));
         }
 
-        String imei = String.valueOf(imeiFromUnitId(buf.readUnsignedMedium()));
-
         buf.readUnsignedShort(); // length
 
         // Selector
diff --git a/src/org/traccar/protocol/MeiligaoProtocolDecoder.java b/src/org/traccar/protocol/MeiligaoProtocolDecoder.java
index f17d2e168..faa2f122e 100644
--- a/src/org/traccar/protocol/MeiligaoProtocolDecoder.java
+++ b/src/org/traccar/protocol/MeiligaoProtocolDecoder.java
@@ -89,7 +89,7 @@ public class MeiligaoProtocolDecoder extends BaseProtocolDecoder {
         }
 
         if (id.length() == 14) {
-            id += Crc.luhnChecksum(id); // IMEI checksum
+            id += Crc.luhnChecksum(Long.valueOf(id)); // IMEI checksum
         }
         return id;
     }
-- 
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