1 files changed, 18 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;
             }
         }