2 files changed, 37 insertions, 2 deletions
diff --git a/src/main/java/org/traccar/helper/BufferUtil.java b/src/main/java/org/traccar/helper/BufferUtil.java
index bbf12d738..9485c17c6 100644
--- a/src/main/java/org/traccar/helper/BufferUtil.java
+++ b/src/main/java/org/traccar/helper/BufferUtil.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2018 - 2021 Anton Tananaev (anton@traccar.org)
+ * Copyright 2018 - 2022 Anton Tananaev (anton@traccar.org)
  * Copyright 2018 Andrey Kunitsyn (andrey@traccar.org)
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -50,7 +50,7 @@ public final class BufferUtil {
             wrappedHaystack.writerIndex(endIndex - haystack.readerIndex());
         }
         int result = ByteBufUtil.indexOf(needle, wrappedHaystack);
-        return result < 0 ? result : haystack.readerIndex() + startIndex + result;
+        return result < 0 ? result : startIndex + result;
     }
 
 }
diff --git a/src/test/java/org/traccar/helper/BufferUtilTest.java b/src/test/java/org/traccar/helper/BufferUtilTest.java
new file mode 100644
index 000000000..b539b5b28
--- /dev/null
+++ b/src/test/java/org/traccar/helper/BufferUtilTest.java
@@ -0,0 +1,35 @@
+package org.traccar.helper;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import org.junit.Test;
+
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.Assert.assertEquals;
+
+public class BufferUtilTest {
+
+    @Test
+    public void test1() {
+        ByteBuf buf = Unpooled.copiedBuffer("abcdef", StandardCharsets.US_ASCII);
+        assertEquals(2, BufferUtil.indexOf("cd", buf));
+    }
+
+    @Test
+    public void test2() {
+        ByteBuf buf = Unpooled.copiedBuffer("abcdef", StandardCharsets.US_ASCII);
+        buf.readerIndex(1);
+        buf.writerIndex(5);
+        assertEquals(2, BufferUtil.indexOf("cd", buf));
+    }
+
+    @Test
+    public void test3() {
+        ByteBuf buf = Unpooled.copiedBuffer("abcdefgh", StandardCharsets.US_ASCII);
+        buf.readerIndex(1);
+        buf.writerIndex(7);
+        assertEquals(3, BufferUtil.indexOf("de", buf, 2, 6));
+    }
+
+}