Implement AIS protocol decoder

3 files changed, 275 insertions, 0 deletions

diff --git a/src/org/traccar/helper/BitBuffer.java b/src/org/traccar/helper/BitBuffer.java
new file mode 100644
index 000000000..7626988cc
--- /dev/null
+++ b/src/org/traccar/helper/BitBuffer.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2016 Anton Tananaev (anton@traccar.org)
+ *
+ * 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.helper;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.jboss.netty.buffer.ChannelBuffers;
+
+public class BitBuffer {
+
+    private ChannelBuffer buffer = ChannelBuffers.dynamicBuffer();
+
+    private int writeByte;
+    private int writeCount;
+
+    private int readByte;
+    private int readCount;
+
+    public void writeEncoded(byte[] bytes) {
+        for (byte b : bytes) {
+            b -= 48;
+            if (b > 40) {
+                b -= 8;
+            }
+            write(b);
+        }
+    }
+
+    public void write(int b) {
+        if (writeCount == 0) {
+            writeByte |= b;
+            writeCount = 6;
+        } else {
+            int remaining = 8 - writeCount;
+            writeByte <<= remaining;
+            writeByte |= b >> (6 - remaining);
+            buffer.writeByte(writeByte);
+            writeByte = b & ((1 << (6 - remaining)) - 1);
+            writeCount = 6 - remaining;
+        }
+    }
+
+    public int readUnsigned(int length) {
+        int result = 0;
+
+        while (length > 0) {
+            if (readCount == 0) {
+                readByte = buffer.readUnsignedByte();
+                readCount = 8;
+            }
+            if (readCount >= length) {
+                result <<= length;
+                result |= readByte >> (readCount - length);
+                readByte &= (1 << (readCount - length)) - 1;
+                readCount -= length;
+                length = 0;
+            } else {
+                result <<= readCount;
+                result |= readByte;
+                length -= readCount;
+                readByte = 0;
+                readCount = 0;
+            }
+        }
+
+        return result;
+    }
+
+    public int readSigned(int length) {
+        int result = readUnsigned(length);
+        int signBit = 1 << (length - 1);
+        if ((result & signBit) == 0) {
+            return result;
+        } else {
+            result &= signBit - 1;
+            result += ~(signBit - 1);
+            return result;
+        }
+    }
+
+}
diff --git a/src/org/traccar/protocol/AisProtocol.java b/src/org/traccar/protocol/AisProtocol.java
new file mode 100644
index 000000000..4b2e1719e
--- /dev/null
+++ b/src/org/traccar/protocol/AisProtocol.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2016 Anton Tananaev (anton@traccar.org)
+ *
+ * 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 org.jboss.netty.bootstrap.ConnectionlessBootstrap;
+import org.jboss.netty.channel.ChannelPipeline;
+import org.jboss.netty.handler.codec.string.StringDecoder;
+import org.traccar.BaseProtocol;
+import org.traccar.TrackerServer;
+
+import java.util.List;
+
+public class AisProtocol extends BaseProtocol {
+
+    public AisProtocol() {
+        super("ais");
+    }
+
+    @Override
+    public void initTrackerServers(List<TrackerServer> serverList) {
+        serverList.add(new TrackerServer(new ConnectionlessBootstrap(), getName()) {
+            @Override
+            protected void addSpecificHandlers(ChannelPipeline pipeline) {
+                pipeline.addLast("stringDecoder", new StringDecoder());
+                pipeline.addLast("objectDecoder", new AisProtocolDecoder(AisProtocol.this));
+            }
+        });
+    }
+
+}
diff --git a/src/org/traccar/protocol/AisProtocolDecoder.java b/src/org/traccar/protocol/AisProtocolDecoder.java
new file mode 100644
index 000000000..3ccca6dd3
--- /dev/null
+++ b/src/org/traccar/protocol/AisProtocolDecoder.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2016 Anton Tananaev (anton@traccar.org)
+ *
+ * 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 org.jboss.netty.channel.Channel;
+import org.traccar.BaseProtocolDecoder;
+import org.traccar.DeviceSession;
+import org.traccar.helper.BitBuffer;
+import org.traccar.helper.Parser;
+import org.traccar.helper.PatternBuilder;
+import org.traccar.model.Position;
+
+import java.net.SocketAddress;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+public class AisProtocolDecoder extends BaseProtocolDecoder {
+
+    public AisProtocolDecoder(AisProtocol protocol) {
+        super(protocol);
+    }
+
+    private static final Pattern PATTERN = new PatternBuilder()
+            .text("!AIVDM,")
+            .number("(d+),")                     // count
+            .number("(d+),")                     // index
+            .number("(d+)?,")                    // id
+            .expression(".,")                    // radio channel
+            .expression("([^,]+),")              // payload
+            .any()
+            .compile();
+
+    private Position decodePayload(Channel channel, SocketAddress remoteAddress, BitBuffer buf) {
+
+        int type = buf.readUnsigned(6);
+        if (type == 1 || type == 2 || type == 3 || type == 18) {
+
+            buf.readUnsigned(2);
+            int mmsi = buf.readUnsigned(30);
+
+            DeviceSession deviceSession = getDeviceSession(channel, remoteAddress, String.valueOf(mmsi));
+            if (deviceSession == null) {
+                return null;
+            }
+
+            Position position = new Position();
+            position.setProtocol(getProtocolName());
+            position.setDeviceId(deviceSession.getDeviceId());
+
+            position.setTime(new Date());
+
+            if (type == 18) {
+                buf.readUnsigned(8); // reserved
+            } else {
+                position.set(Position.KEY_STATUS, buf.readUnsigned(4));
+                position.set("turn", buf.readSigned(8));
+            }
+
+            position.setSpeed(buf.readUnsigned(10) * 0.1);
+            position.setValid(buf.readUnsigned(1) != 0);
+            position.setLongitude(buf.readSigned(28) * 0.0001 / 60.0);
+            position.setLatitude(buf.readSigned(27) * 0.0001 / 60.0);
+            position.setCourse(buf.readUnsigned(12) * 0.1);
+
+            position.set("heading", buf.readUnsigned(9));
+
+            return position;
+
+        }
+
+        return null;
+    }
+
+    @Override
+    protected Object decode(
+            Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {
+
+        String[] sentences = ((String) msg).split("\\r\\n");
+
+        List<Position> positions = new ArrayList<>();
+        Map<Integer, BitBuffer> buffers = new HashMap<>();
+
+        for (String sentence : sentences) {
+            if (!sentence.isEmpty()) {
+                Parser parser = new Parser(PATTERN, sentence);
+                if (parser.matches()) {
+
+                    int count = parser.nextInt();
+                    int index = parser.nextInt();
+                    int id = parser.nextInt();
+
+                    Position position = null;
+
+                    if (count == 1) {
+                        BitBuffer bits = new BitBuffer();
+                        bits.writeEncoded(parser.next().getBytes());
+                        position = decodePayload(channel, remoteAddress, bits);
+                    } else {
+                        BitBuffer bits = buffers.get(id);
+                        if (bits == null) {
+                            bits = new BitBuffer();
+                            buffers.put(id, bits);
+                        }
+                        bits.writeEncoded(parser.next().getBytes());
+                        if (count == index) {
+                            position = decodePayload(channel, remoteAddress, bits);
+                            buffers.remove(id);
+                        }
+                    }
+
+                    if (position != null) {
+                        positions.add(position);
+                    }
+
+                }
+            }
+        }
+
+        return positions;
+    }
+
+}