Add mavlink2 protocol support

Mavlink2 is a common protocol for unmanned vehicles and flight
controllers like Pixhawk devices.

2 files changed, 151 insertions, 0 deletions

diff --git a/src/main/java/org/traccar/protocol/Mavlink2Protocol.java b/src/main/java/org/traccar/protocol/Mavlink2Protocol.java
new file mode 100644
index 000000000..ba051a854
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/Mavlink2Protocol.java
@@ -0,0 +1,23 @@
+package org.traccar.protocol;
+
+import org.traccar.BaseProtocol;
+import org.traccar.PipelineBuilder;
+import org.traccar.TrackerServer;
+
+import io.netty.handler.codec.bytes.ByteArrayDecoder;
+import io.netty.handler.codec.bytes.ByteArrayEncoder;
+
+public class Mavlink2Protocol extends BaseProtocol {
+
+    public Mavlink2Protocol() {
+        addServer(new TrackerServer(true, getName()) {
+            @Override
+            protected void addProtocolHandlers(PipelineBuilder pipeline) {
+                pipeline.addLast(new ByteArrayEncoder());
+                pipeline.addLast(new ByteArrayDecoder());
+                pipeline.addLast(new Mavlink2ProtocolDecoder(Mavlink2Protocol.this));
+            }
+        });
+    }
+
+}
diff --git a/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java b/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java
new file mode 100644
index 000000000..d23398bce
--- /dev/null
+++ b/src/main/java/org/traccar/protocol/Mavlink2ProtocolDecoder.java
@@ -0,0 +1,128 @@
+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.model.Position;
+
+import io.netty.channel.Channel;
+
+public class Mavlink2ProtocolDecoder extends BaseProtocolDecoder {
+
+    public Mavlink2ProtocolDecoder(Protocol protocol) {
+        super(protocol);
+    }
+
+    @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) {
+            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;
+            }
+            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);
+            return position;
+        }
+        return null;
+    }
+
+}