netty ByteBuf corruption

Question

I am using ByteToMessageDecoder

decode(ChannelHandlerContext ctx, ByteBuf bytebuf, List<Object> out) {
...
}

I want to perform some validation on incoming bytebuffer and then send bytebuf.nioBuffer() to out

1. do i have to make a copy of the bytebuf.nioBuffer() and add to output. if so what is the best way to do it
2. if I just add bytebuf.nioBuffer() to output will there be a chance of corruption
3. best way to extract ByteBuffer from netty ByteBuf, are there any utils available

Answer 1

If not enough data to read the complete message then call the reset method.

You don't need to copy bytebuf. That is not good for performance.

public class MyComplexByteToMessageDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf byteBuf, List<Object> out) throws Exception {
        // Mark the current read position
        byteBuf.markReaderIndex();

        // Check if there are enough bytes to read the length field (e.g., 4 bytes for an integer length)
        if (byteBuf.readableBytes() < 4) {
            byteBuf.resetReaderIndex();
            return; // Not enough data to read the length field
        }

        // Read the length field
        int length = byteBuf.readInt();

        // Check if enough bytes are available to read the complete message
        if (byteBuf.readableBytes() < length) {
            byteBuf.resetReaderIndex();
            return; // Not enough data to read the complete message
        }

        // Read the complete message (assuming it is a byte array)
        byte[] messageBytes = new byte[length];
        byteBuf.readBytes(messageBytes);

        // Decode the message and add to the output list
        String message = new String(messageBytes); // Example: decoding as a string
        out.add(message);
    }
}