From 74ead779cd0b275620ffd399bac7b57f4bc02deb Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton@traccar.org>
Date: Wed, 25 Oct 2023 20:42:52 -0700
Subject: Support Teltonika DSM camera

---
 .../traccar/protocol/DualcamProtocolDecoder.java   | 30 ++++++++++++++--------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/main/java/org/traccar/protocol/DualcamProtocolDecoder.java b/src/main/java/org/traccar/protocol/DualcamProtocolDecoder.java
index f6712d7f2..b0e793a43 100644
--- a/src/main/java/org/traccar/protocol/DualcamProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/DualcamProtocolDecoder.java
@@ -46,11 +46,15 @@ public class DualcamProtocolDecoder extends BaseProtocolDecoder {
     public static final int MSG_PATH_RESPONSE = 0x000D;
 
     private String uniqueId;
-    private int packetCount;
-    private int currentPacket;
+    private int dataSize;
+    private int dataCurrent;
     private boolean video;
     private ByteBuf media;
 
+    private boolean isPacketData() {
+        return dataSize < 100;
+    }
+
     @Override
     protected Object decode(
             Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {
@@ -97,21 +101,29 @@ public class DualcamProtocolDecoder extends BaseProtocolDecoder {
                 break;
             case MSG_START:
                 buf.readUnsignedShort(); // length
-                packetCount = buf.readInt();
-                currentPacket = 1;
+                dataSize = buf.readInt();
+                dataCurrent = isPacketData() ? 1 : 0;
                 media = Unpooled.buffer();
                 if (channel != null) {
                     ByteBuf response = Unpooled.buffer();
                     response.writeShort(MSG_RESUME);
                     response.writeShort(4);
-                    response.writeInt(currentPacket);
+                    response.writeInt(dataCurrent);
                     channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
                 }
                 break;
             case MSG_DATA:
-                buf.readUnsignedShort(); // length
-                media.writeBytes(buf, buf.readableBytes() - 2);
-                if (currentPacket == packetCount) {
+                int length = buf.readUnsignedShort();
+                media.writeBytes(buf, length);
+                boolean finished;
+                if (isPacketData()) {
+                    finished = dataCurrent == dataSize;
+                    dataCurrent += 1;
+                } else {
+                    finished = dataCurrent + length == dataSize;
+                    dataCurrent += length;
+                }
+                if (finished) {
                     deviceSession = getDeviceSession(channel, remoteAddress);
                     Position position = new Position(getProtocolName());
                     position.setDeviceId(deviceSession.getDeviceId());
@@ -132,8 +144,6 @@ public class DualcamProtocolDecoder extends BaseProtocolDecoder {
                         channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
                     }
                     return position;
-                } else {
-                    currentPacket += 1;
                 }
                 break;
             case MSG_PATH_RESPONSE:
-- 
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