From b7bd2ce8416a4b7bbc8a5e5171f0891d894e6bc7 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton@traccar.org>
Date: Sat, 3 Feb 2024 08:29:43 -0800
Subject: Implement FleetGuide acknowledgement

---
 .../protocol/FleetGuideProtocolDecoder.java        | 68 ++++++++++++++++++++--
 .../protocol/FleetGuideProtocolDecoderTest.java    |  3 +
 2 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/traccar/protocol/FleetGuideProtocolDecoder.java b/src/main/java/org/traccar/protocol/FleetGuideProtocolDecoder.java
index 9fddec922..ba4d9cfae 100644
--- a/src/main/java/org/traccar/protocol/FleetGuideProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/FleetGuideProtocolDecoder.java
@@ -19,8 +19,10 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.Channel;
 import org.traccar.BaseProtocolDecoder;
+import org.traccar.NetworkMessage;
 import org.traccar.Protocol;
 import org.traccar.helper.BitUtil;
+import org.traccar.helper.Checksum;
 import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Position;
 import org.traccar.session.DeviceSession;
@@ -38,9 +40,13 @@ public class FleetGuideProtocolDecoder extends BaseProtocolDecoder {
         super(protocol);
     }
 
-    public static final int MSG_DATA = 0x10;
-    public static final int MSG_HEARTBEAT = 0x1A;
-    public static final int MSG_RESPONSE = 0x1C;
+    public static final int MSG_EMPTY = 0;
+    public static final int MSG_SYNC_REQ = 1;
+    public static final int MSG_SYNC_ACK = 2;
+    public static final int MSG_DATA_R_ACK = 3;
+    public static final int MSG_DATA_N_ACK = 4;
+    public static final int MSG_REP_R_ACK = 5;
+    public static final int MSG_REP_N_ACK = 6;
 
     @Override
     protected Object decode(
@@ -53,9 +59,12 @@ public class FleetGuideProtocolDecoder extends BaseProtocolDecoder {
         int length = BitUtil.to(options, 11);
 
         DeviceSession deviceSession;
+        Long deviceId;
         if (BitUtil.check(options, 11)) {
-            deviceSession = getDeviceSession(channel, remoteAddress, String.valueOf(buf.readUnsignedIntLE()));
+            deviceId = buf.readUnsignedIntLE();
+            deviceSession = getDeviceSession(channel, remoteAddress, String.valueOf(deviceId));
         } else {
+            deviceId = null;
             deviceSession = getDeviceSession(channel, remoteAddress);
         }
         if (deviceSession == null) {
@@ -63,12 +72,24 @@ public class FleetGuideProtocolDecoder extends BaseProtocolDecoder {
         }
 
         int type;
+        Integer index;
         if (BitUtil.check(options, 12)) {
-            type = BitUtil.to(buf.readUnsignedByte(), 4);
+            int value = buf.readUnsignedByte();
+            type = BitUtil.to(value, 4);
+            index = BitUtil.from(value, 4);
         } else {
             type = 0;
+            index = null;
         }
 
+        Integer responseType;
+        if (type == MSG_SYNC_REQ) {
+            responseType = MSG_SYNC_ACK;
+        } else {
+            responseType = null;
+        }
+        sendResponse(channel, remoteAddress, deviceId, responseType, index);
+
         if (BitUtil.check(options, 13)) {
             buf.readUnsignedShortLE(); // acknowledgement
         }
@@ -153,6 +174,43 @@ public class FleetGuideProtocolDecoder extends BaseProtocolDecoder {
         return position;
     }
 
+
+    private void sendResponse(
+            Channel channel, SocketAddress remoteAddress, Long deviceId, Integer type, Integer index) {
+        if (channel != null) {
+
+            ByteBuf response = Unpooled.buffer();
+            response.writeByte(0x53); // signature
+
+            int options = 0;
+            if (deviceId != null) {
+                options |= 1 << 11;
+            }
+            if (type != null) {
+                options |= 1 << 12;
+            }
+            if (index != null) {
+                options |= 1 << 13;
+            }
+            response.writeShortLE(options);
+
+            if (deviceId != null) {
+                response.writeIntLE(deviceId.intValue());
+            }
+            if (type != null) {
+                response.writeByte(type);
+            }
+            if (index != null) {
+                int mask = (1 << (index + 1)) - 1;
+                response.writeShortLE(mask);
+            }
+            response.writeShortLE(Checksum.crc16(
+                    Checksum.CRC16_CCITT_FALSE, response.nioBuffer(1, response.writerIndex() - 1)));
+
+            channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
+        }
+    }
+
     private int readVarSize(ByteBuf buf) {
         int b;
         int y = 0;
diff --git a/src/test/java/org/traccar/protocol/FleetGuideProtocolDecoderTest.java b/src/test/java/org/traccar/protocol/FleetGuideProtocolDecoderTest.java
index 34b15d14b..363f33c5b 100644
--- a/src/test/java/org/traccar/protocol/FleetGuideProtocolDecoderTest.java
+++ b/src/test/java/org/traccar/protocol/FleetGuideProtocolDecoderTest.java
@@ -10,6 +10,9 @@ public class FleetGuideProtocolDecoderTest extends ProtocolTest {
 
         var decoder = inject(new FleetGuideProtocolDecoder(null));
 
+        verifyNull(decoder, binary(
+                "5300188f8a020001f36a"));
+
         verifyPositions(decoder, binary(
                 "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"));
 
-- 
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