ReplayingDecoder throws exception on decode

Question

I have created an decoder to process bytes that client sends. Here is it

import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;

public class MessageDecoder extends ReplayingDecoder<DecoderState> {

    private int length;

    public MessageDecoder()
    {
        super(DecoderState.READ_LENGTH);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buf, List<Object> out) throws Exception{
        System.out.println(buf.readableBytes());
        switch(state()){
            case READ_LENGTH:
                length=buf.readInt();
                System.out.println("length is: "+length);
                checkpoint(DecoderState.READ_CONTENT);
            case READ_CONTENT:
                ByteBuf frame = buf.readBytes(length);
                checkpoint(DecoderState.READ_LENGTH);
                out.add(frame);
                break;
            default:
                throw new Error("Shouldn't reach here");
        }
    }
}

And it throws next error when the client sends the bytes

io.netty.handler.codec.DecoderException: java.lang.IllegalArgumentException: minimumReadableBytes: -603652096 (expected: >= 0) at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:431) at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:245) at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:292) at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:278) at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:962) at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:131) at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:528) at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:485) at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:399) at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:371) at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:112) at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137) at java.lang.Thread.run(Unknown Source)

That code is from official documentation http://netty.io/4.0/api/io/netty/handler/codec/ReplayingDecoder.html so i really don't understand why it does not work

btw when I send 4 bytes it says me that I sent 2147483647 bytes — user2686299

Norman Maurer Norman Maurer · Accepted Answer · 2016-05-31T06:34:37

Probably the remote peer does write the int as unsigned. Maybe what you want is using readUnsignedInt() ?

ReplayingDecoder throws exception on decode

1 Answers