2 files changed, 22 insertions, 9 deletions
diff --git a/src/main/java/org/traccar/protocol/ItsFrameDecoder.java b/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
index b28d6e96f..cebfdca5f 100644
--- a/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
+++ b/src/main/java/org/traccar/protocol/ItsFrameDecoder.java
@@ -25,16 +25,28 @@ public class ItsFrameDecoder extends BaseFrameDecoder {
 
     private static final int MINIMUM_LENGTH = 20;
 
+    private ByteBuf readFrame(ByteBuf buf, int delimiterIndex, int skip) {
+        int headerIndex = buf.indexOf(buf.readerIndex() + 1, buf.writerIndex(), (byte) '$');
+        if (headerIndex > 0 && headerIndex < delimiterIndex) {
+            return buf.readRetainedSlice(headerIndex - buf.readerIndex());
+        } else {
+            ByteBuf frame = buf.readRetainedSlice(delimiterIndex - buf.readerIndex());
+            buf.skipBytes(skip);
+            return frame;
+        }
+    }
+
     @Override
     protected Object decode(
             ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
 
-        ByteBuf frame;
+        while (buf.isReadable() && buf.getByte(buf.readerIndex()) != '$') {
+            buf.skipBytes(1);
+        }
+
         int delimiterIndex = BufferUtil.indexOf("\r\n", buf);
         if (delimiterIndex > MINIMUM_LENGTH) {
-            frame = buf.readRetainedSlice(delimiterIndex - buf.readerIndex());
-            buf.skipBytes(2);
-            return frame;
+            return readFrame(buf, delimiterIndex, 2);
         } else {
             delimiterIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*');
             if (delimiterIndex > MINIMUM_LENGTH) {
@@ -42,13 +54,10 @@ public class ItsFrameDecoder extends BaseFrameDecoder {
                     delimiterIndex += 1;
                 }
                 if (buf.getByte(delimiterIndex - 2) == ',') {
-                    frame = buf.readRetainedSlice(delimiterIndex - 1 - buf.readerIndex());
-                    buf.skipBytes(1); // binary checksum
+                    return readFrame(buf, delimiterIndex - 1, 2); // skip binary checksum
                 } else {
-                    frame = buf.readRetainedSlice(delimiterIndex - buf.readerIndex());
+                    return readFrame(buf, delimiterIndex, 1);
                 }
-                buf.skipBytes(1); // delimiter
-                return frame;
             }
         }
 
diff --git a/src/test/java/org/traccar/protocol/ItsFrameDecoderTest.java b/src/test/java/org/traccar/protocol/ItsFrameDecoderTest.java
index 6112f773b..f5c98b1aa 100644
--- a/src/test/java/org/traccar/protocol/ItsFrameDecoderTest.java
+++ b/src/test/java/org/traccar/protocol/ItsFrameDecoderTest.java
@@ -11,6 +11,10 @@ public class ItsFrameDecoderTest extends ProtocolTest {
         ItsFrameDecoder decoder = new ItsFrameDecoder();
 
         verifyFrame(
+                binary("242c2c3836383732383033373731373434312c312e3444335f4149533134305f312e302c56455253494f4e312e302c32382e3633333731372c4e2c37372e3232323730322c45"),
+                decoder.decode(null, null, binary("242c2c3836383732383033373731373434312c312e3444335f4149533134305f312e302c56455253494f4e312e302c32382e3633333731372c4e2c37372e3232323730322c45242c43502c41544c2c312e3444335f4149533134305f312e302c49462c30382c4c2c3836383732383033373731373434312c2c312c31373034323031392c3133313830392c32382e3633333731352c4e2c37372e3232323730322c452c302e302c342e30302c302c3231312e302c312e312c362e362c496465612c302c312c31322e362c332e392c302c4f2c31322c3430342c31312c3430612c3564332c326464642c3430612c30392c3438622c3430612c30362c3564342c3430612c30352c6165392c3430612c30352c303131312c30302c3236303831342c662a")));
+
+        verifyFrame(
                 binary("244865616465722c69547269616e676c65312c4b41303147313233342c3836343439353033343433343631302c315f333654303242303136344d4149535f362c4149533134302c302e3030303030302c4e2c302e3030303030302c452a3545"),
                 decoder.decode(null, null, binary("244865616465722c69547269616e676c65312c4b41303147313233342c3836343439353033343433343631302c315f333654303242303136344d4149535f362c4149533134302c302e3030303030302c4e2c302e3030303030302c452a35450d0a")));