Make the code more compatible with Traccar's standards

1 files changed, 43 insertions, 96 deletions

diff --git a/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java b/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java
index d23398bce..666538479 100644
--- a/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java
@@ -1,17 +1,31 @@
+/*
+ * Copyright 2021 Chipeng Li (chplee@gmail.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.traccar.protocol;
 
 import java.net.SocketAddress;
-import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
 import java.time.Instant;
-import java.util.Arrays;
 import java.util.Date;
 
 import org.traccar.BaseProtocolDecoder;
 import org.traccar.DeviceSession;
 import org.traccar.Protocol;
+import org.traccar.helper.UnitsConverter;
 import org.traccar.model.Position;
 
+import io.netty.buffer.ByteBuf;
 import io.netty.channel.Channel;
 
 public class Mavlink2ProtocolDecoder extends BaseProtocolDecoder {
@@ -21,105 +35,38 @@ public class Mavlink2ProtocolDecoder extends BaseProtocolDecoder {
     }
 
     @Override
-    protected Object decode(Channel channel, SocketAddress remoteAddress, Object pkt) throws Exception {
-        byte[] packet = (byte[]) pkt;
-        /*
-         * 0 uint8_t magic Packet start marker 0xFD Protocol-specific start-of-text
-         * (STX) marker used to indicate the beginning of a new packet. Any system that
-         * does not understand protocol version will skip the packet.
-         * *
-         * 1 uint8_t len Payload length 0 - 255 Indicates length of the following
-         * payload section. This may be affected by payload truncation.
-         * *
-         * 2 uint8_t incompat_flags Incompatibility Flags Flags that must be understood
-         * for MAVLink compatibility (implementation discards packet if it does not
-         * understand flag).
-         * *
-         * 3 uint8_t compat_flags Compatibility Flags Flags that can be ignored if not
-         * understood (implementation can still handle packet even if it does not
-         * understand flag).
-         * *
-         * 4 uint8_t seq Packet sequence number 0 - 255 Used to detect packet loss.
-         * Components increment value for each message sent.
-         * *
-         * 5 uint8_t sysid System ID (sender) 1 - 255 ID of system (vehicle) sending the
-         * message. Used to differentiate systems on network. Note that the broadcast
-         * address 0 may not be used in this field as it is an invalid source address.
-         * *
-         * 6 uint8_t compid Component ID (sender) 1 - 255 ID of component sending the
-         * message. Used to differentiate components in a system (e.g. autopilot and a
-         * camera). Use appropriate values in MAV_COMPONENT. Note that the broadcast
-         * address MAV_COMP_ID_ALL may not be used in this field as it is an invalid
-         * source address.
-         * *
-         * 7 to 9 uint32_t msgid:24 Message ID (low, middle, high bytes) 0 - 16777215 ID
-         * of message type in payload. Used to decode data back into message object.
-         * *
-         * 10 to (n+10) uint8_t payload[max 255] Payload Message data. Depends on
-         * message type (i.e. Message ID) and contents.
-         * *
-         * (n+10) to (n+11) uint16_t checksum Checksum (low byte, high byte)
-         * CRC-16/MCRF4XX for message (excluding magic byte). Includes CRC_EXTRA byte.
-         * *
-         * (n+12) to (n+25) uint8_t signature[13] Signature (Optional) Signature to
-         * ensure the link is tamper-proof.
-         */
-
-        if (packet[0] != (byte) 0xfd) {
+    protected Object decode(Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {
+        ByteBuf buf = (ByteBuf) msg;
+        if (buf.readUnsignedByte() != 0xFD) { //Packet start marker
             return null;
         }
-
-        int msgid = (packet[7] & 0xff) | ((packet[8] & 0xff) << 8) | ((packet[9] & 0x0f) << 16);
-        int len = packet[1] & 0xff;
-        int sysid = packet[5] & 0xff;
-        // GLOBAL_POSITION_INT ( #33 )
-        if (msgid == 33) {
-            byte[] message = Arrays.copyOfRange(packet, 10, 10 + len);
-            /*
-             * time_boot_ms uint32_t ms Timestamp (time since system boot).
-             * *
-             * lat int32_t degE7 Latitude, expressed
-             * *
-             * lon int32_t degE7 Longitude, expressed
-             * *
-             * alt int32_t mm Altitude (MSL). Note that virtually all GPS modules provide
-             * both WGS84 and MSL.
-             * *
-             * relative_alt int32_t mm Altitude above ground
-             * *
-             * vx int16_t cm/s Ground X Speed (Latitude, positive north)
-             * *
-             * vy int16_t cm/s Ground Y Speed (Longitude, positive east)
-             * *
-             * vz int16_t cm/s Ground Z Speed (Altitude, positive down)
-             * *
-             * hdg uint16_t cdeg Vehicle heading (yaw angle), 0.0..359.99 degrees. If
-             * unknown, set to: UINT16_MAX
-             */
-
-            // int timeBootms = ByteBuffer.wrap(message, 0, 4).order(ByteOrder.LITTLE_ENDIAN).getInt();
-            int lat = ByteBuffer.wrap(message, 4, 4).order(ByteOrder.LITTLE_ENDIAN).getInt();
-            int lon = ByteBuffer.wrap(message, 8, 4).order(ByteOrder.LITTLE_ENDIAN).getInt();
-            int alt = ByteBuffer.wrap(message, 12, 4).order(ByteOrder.LITTLE_ENDIAN).getInt();
-            int vx = ByteBuffer.wrap(message, 20, 2).order(ByteOrder.LITTLE_ENDIAN).getShort();
-            int vy = ByteBuffer.wrap(message, 22, 2).order(ByteOrder.LITTLE_ENDIAN).getShort();
-            int hdg = ByteBuffer.wrap(message, 26, 2).order(ByteOrder.LITTLE_ENDIAN).getShort();
-            DeviceSession deviceSession = getDeviceSession(channel, remoteAddress, Integer.toString(sysid));
-            if (deviceSession == null) {
-                return null;
-            }
+        buf.readUnsignedByte(); // Payload length
+        buf.readUnsignedByte(); // Incompatibility Flags
+        buf.readUnsignedByte(); // Compatibility Flags
+        buf.readUnsignedByte(); // Packet sequence number
+        int senderSystemId = buf.readUnsignedByte(); // System ID (sender)
+        DeviceSession deviceSession = getDeviceSession(channel, remoteAddress, Integer.toString(senderSystemId));
+        buf.readUnsignedByte(); // Component ID (sender)
+        if (deviceSession == null) {
+            return null;
+        }
+        int messageId = buf.readUnsignedMediumLE(); // Message ID (low, middle, high bytes)
+        if (messageId == 33) {
             Position position = new Position(getProtocolName());
             position.setDeviceId(deviceSession.getDeviceId());
             position.setValid(true);
-            // position.setTime(Date.from(Instant.ofEpochMilli(timeBootms)));
             position.setTime(Date.from(Instant.now()));
-            position.setLatitude(lat / 1e7);
-            position.setLongitude(lon / 1e7);
-            position.setAltitude(alt / 1e3);
-            double speed = Math.sqrt(Math.pow(vx, 2) + Math.pow(vy, 2));
-            // cm/s to kn
-            position.setSpeed(speed * 0.01943844);
-            position.setCourse(hdg / 1e2);
+            position.set("timeBootms", buf.readUnsignedIntLE()); // Timestamp (time since system boot).
+            position.setLatitude(buf.readIntLE() / 10000000.0);
+            position.setLongitude(buf.readIntLE() / 10000000.0);
+            position.setAltitude(buf.readIntLE() / 1000.0); // Altitude (MSL).
+            position.set("relativeAltitude", buf.readIntLE() / 1000.0); // Altitude above ground
+            int groundSpeedX = buf.readShortLE();
+            int groundSpeedY = buf.readShortLE();
+            buf.readShortLE(); // Ground Z Speed
+            double speed = Math.sqrt(Math.pow(groundSpeedX, 2) + Math.pow(groundSpeedY, 2));
+            position.setSpeed(UnitsConverter.knotsFromCps(speed));
+            position.setCourse(buf.readUnsignedShortLE() / 100.0);
             return position;
         }
         return null;