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[1.7.2-1083] Netty Truncating Packets?


shadowking97

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Upon upgrading my dynamic link panels mod to 1.7.2, it appears my packets are being truncated by netty.

 

I am using slightly modified versions of the simpleimpl packet handlers, only modified gain access to playerentity.

 

This is the code I'm using in my packet:

 

   public void toBytes(ByteBuf buffer, ChannelHandlerContext ctx)
    {
    	if (this.compressedChunkData == null)
        {
            deflateGate.acquireUninterruptibly();
            if (this.compressedChunkData == null)
            {
                deflate();
            }
            deflateGate.release();
        }
    	buffer.writeInt(dimension);
        buffer.writeInt(this.xPos);
        buffer.writeInt(this.zPos);
        buffer.writeBoolean(this.includeInitialize);
        buffer.writeShort((short)(this.yPos & 65535));
        buffer.writeShort((short)(this.yMSBPos & 65535));
        buffer.writeInt(this.compressedChunkData.length);
        int i = buffer.writableBytes();
        buffer.ensureWritable(this.compressedChunkData.length);
        buffer.writeBytes(this.compressedChunkData);
    }

@Override
public void fromBytes(ByteBuf in, ChannelHandlerContext ctx) {
	this.dimension = in.readInt();
	this.xPos = in.readInt();
        this.zPos = in.readInt();
        this.includeInitialize = in.readBoolean();
        this.yPos = in.readShort();
        this.yMSBPos = in.readShort();
        int len = in.readInt();

        if (field_149286_i.length < len)
        {
            field_149286_i = new byte[len];
        }
        
        in.readBytes(field_149286_i, 0, len);
        int i = 0;
        int j;
        int msb = 0; //BugFix: MC does not read the MSB array from the packet properly, causing issues for servers that use blocks > 256

        for (j = 0; j < 16; ++j)
        {
            i += this.yPos >> j & 1;
            msb += this.yPos >> j & 1;
        }

        j = 12288 * i;
        j += 2048 * msb;

        if (this.includeInitialize)
        {
            j += 256;
        }

        this.chunkData = new byte[j];
        Inflater inflater = new Inflater();
        inflater.setInput(field_149286_i, 0, len);

        try
        {
            inflater.inflate(this.chunkData);
        }
        catch (DataFormatException dataformatexception)
        {
            error = true;
        }
        finally
        {
            inflater.end();
        }
}

 

And this is the crash I'm getting on the client side:

 

Caused by: java.lang.IndexOutOfBoundsException: readerIndex(21) + length(2879) exceeds writerIndex(36): SlicedByteBuf(ridx: 21, widx: 36, cap: 36/36, unwrapped: UnpooledHeapByteBuf(ridx: 1, widx: 37, cap: 37/37))
at io.netty.buffer.AbstractByteBuf.checkReadableBytes(AbstractByteBuf.java:1160) ~[AbstractByteBuf.class:?]
at io.netty.buffer.AbstractByteBuf.readBytes(AbstractByteBuf.java:668) ~[AbstractByteBuf.class:?]
at com.shadowking97.mystcraftplugin.dynamicLinkPanels.network.packets.ChunkInfoPacket.fromBytes(ChunkInfoPacket.java:131) ~[ChunkInfoPacket.class:?]
at com.shadowking97.mystcraftplugin.dynamicLinkPanels.network.impl.DLPIndexedCodec.decodeInto(DLPIndexedCodec.java:17) ~[DLPIndexedCodec.class:?]
at com.shadowking97.mystcraftplugin.dynamicLinkPanels.network.impl.DLPIndexedCodec.decodeInto(DLPIndexedCodec.java:1) ~[DLPIndexedCodec.class:?]
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:77) ~[FMLIndexedMessageToMessageCodec.class:?]
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:17) ~[FMLIndexedMessageToMessageCodec.class:?]
at io.netty.handler.codec.MessageToMessageCodec$2.decode(MessageToMessageCodec.java:81) ~[MessageToMessageCodec$2.class:?]
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:89) ~[MessageToMessageDecoder.class:?]
... 18 more

 

The server isn't reporting any errors, so it *appears* buffer.ensureWritable is passing, allowing the packet to send the full chunkData... but the client isn't receiving the 2879 bytes that it's supposed to.

 

If I can just be pointed in the right direction to ensure my packets are being sent and received completely, that would be lovely. Thank you!

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Well, it is probably just a programming mistake.  Honestly you're probably making the payload processing a little more complicated than necessary, although your general approach seems workable.  Generally you shouldn't need to access the bytes in the buffer directly, but use ByteBuf and ByteBufUtils to access it.

Check out my tutorials here: http://jabelarminecraft.blogspot.com/

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Why not simply store the inflated length (in addition to the deflated size) in the send packet instead of trying such odd computations?

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They're not odd computations, they're how vanilla minecraft compresses the chunk data that I'm sending to my second dimension renderer. This is a converted vanilla minecraft packet so I can redirected to my instance of theWorld instead of the normal one.

 

Here's my problem:

 

I'm writing to the packet, both the length of the data and the data itself:

 

        buffer.writeInt(this.compressedChunkData.length);
        int i = buffer.writableBytes();
        buffer.ensureWritable(this.compressedChunkData.length);
        buffer.writeBytes(this.compressedChunkData);

 

And then I'm attempting to read it:

 

int len = in.readInt();

        if (field_149286_i.length < len)
        {
            field_149286_i = new byte[len];
        }
        
        in.readBytes(field_149286_i, 0, len);

 

But when I try to read it:

 

Caused by: java.lang.IndexOutOfBoundsException: readerIndex(21) + length(2879) exceeds writerIndex(36): SlicedByteBuf(ridx: 21, widx: 36, cap: 36/36, unwrapped: UnpooledHeapByteBuf(ridx: 1, widx: 37, cap: 37/37))

 

So it SHOULD be sending a packet with the size of 21+2879, but it's only receiving a packet with the size of 36. The server isn't giving me any warnings or errors about the packet being too big when I try to send it (using simpleimpl), but the client isn't receiving it.

 

 

In other notes: I have just switched my packet pipeline to one of the tutorial ones that doesn't use simpleimpl, editing it so I didn't have to mess with my packets (other than switching which classes everything extends), and it started working fine. Other than the fact that the tutorial I used was marked as having horrible memory leaks. But at least now I know it's not anything wrong with my code, but some error or limitation within simpleimpl. At least in 1083.

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They're not odd computations, they're how vanilla minecraft compresses the chunk data that I'm sending to my second dimension renderer.

 

On the contrary; they are odd in the sense that they are useless and out of place where they are. The uncompressed size is readily available to the sender (and when encoded as an integer) to the receiver as well. Computing it is a futile effort that just wastes cycles. See?

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