From 7bf00894ad47ef47ce4c9ccc84b560956f3b41f8 Mon Sep 17 00:00:00 2001
From: Anton Tananaev <anton.tananaev@gmail.com>
Date: Fri, 9 Mar 2018 15:07:57 +1300
Subject: Extend Watch frame decoder

---
 src/org/traccar/protocol/WatchFrameDecoder.java | 85 +++++++++++++++----------
 1 file changed, 50 insertions(+), 35 deletions(-)

(limited to 'src')

diff --git a/src/org/traccar/protocol/WatchFrameDecoder.java b/src/org/traccar/protocol/WatchFrameDecoder.java
index 826a8b4d0..9adea2843 100644
--- a/src/org/traccar/protocol/WatchFrameDecoder.java
+++ b/src/org/traccar/protocol/WatchFrameDecoder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 Anton Tananaev (anton@traccar.org)
+ * Copyright 2017 - 2018 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.
@@ -25,47 +25,62 @@ import java.nio.charset.StandardCharsets;
 
 public class WatchFrameDecoder extends FrameDecoder {
 
-    public static final int MESSAGE_HEADER = 20;
-
     @Override
     protected Object decode(
             ChannelHandlerContext ctx, Channel channel, ChannelBuffer buf) throws Exception {
 
-        if (buf.readableBytes() >= MESSAGE_HEADER) {
-            ChannelBuffer lengthBuffer = ChannelBuffers.dynamicBuffer();
-            buf.getBytes(buf.readerIndex() + MESSAGE_HEADER - 4 - 1, lengthBuffer, 4);
-            int length = Integer.parseInt(lengthBuffer.toString(StandardCharsets.US_ASCII), 16) + MESSAGE_HEADER + 1;
-            if (buf.readableBytes() >= length) {
-                ChannelBuffer frame = ChannelBuffers.dynamicBuffer();
-                int endIndex = buf.readerIndex() + length;
-                while (buf.readerIndex() < endIndex) {
-                    byte b = buf.readByte();
-                    if (b == 0x7D) {
-                        switch (buf.readByte()) {
-                            case 0x01:
-                                frame.writeByte(0x7D);
-                                break;
-                            case 0x02:
-                                frame.writeByte(0x5B);
-                                break;
-                            case 0x03:
-                                frame.writeByte(0x5D);
-                                break;
-                            case 0x04:
-                                frame.writeByte(0x2C);
-                                break;
-                            case 0x05:
-                                frame.writeByte(0x2A);
-                                break;
-                            default:
-                                throw new IllegalArgumentException();
-                        }
-                    } else {
-                        frame.writeByte(b);
+        int idIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*') + 1;
+        if (idIndex <= 0) {
+            return null;
+        }
+
+        int lengthIndex = buf.indexOf(idIndex, buf.writerIndex(), (byte) '*') + 1;
+        if (lengthIndex <= 0) {
+            return null;
+        } else if (lengthIndex - idIndex > 10 + 1) {
+            lengthIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*') + 1;
+            if (lengthIndex <= 0) {
+                return null;
+            }
+        }
+
+        int payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');
+        if (payloadIndex < 0) {
+            return null;
+        }
+
+        int length = Integer.parseInt(
+                buf.toString(lengthIndex, payloadIndex - lengthIndex, StandardCharsets.US_ASCII), 16);
+        if (buf.readableBytes() >= payloadIndex + 1 + length + 1) {
+            ChannelBuffer frame = ChannelBuffers.dynamicBuffer();
+            int endIndex = buf.readerIndex() + payloadIndex + 1 + length + 1;
+            while (buf.readerIndex() < endIndex) {
+                byte b = buf.readByte();
+                if (b == 0x7D) {
+                    switch (buf.readByte()) {
+                        case 0x01:
+                            frame.writeByte(0x7D);
+                            break;
+                        case 0x02:
+                            frame.writeByte(0x5B);
+                            break;
+                        case 0x03:
+                            frame.writeByte(0x5D);
+                            break;
+                        case 0x04:
+                            frame.writeByte(0x2C);
+                            break;
+                        case 0x05:
+                            frame.writeByte(0x2A);
+                            break;
+                        default:
+                            throw new IllegalArgumentException();
                     }
+                } else {
+                    frame.writeByte(b);
                 }
-                return frame;
             }
+            return frame;
         }
 
         return null;
-- 
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