[1.7.10] [Solved] io.netty.handler.codec.DecoderException

[xandayn]

Hey everyone, I have a question about an issue I'm having with netty, I've used it before and this is the first time I've ever encountered a bug quite like this.

 

io.netty.handler.codec.DecoderException: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:99) ~[MessageToMessageDecoder.class:?]
at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) ~[MessageToMessageCodec.class:?]
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:785) [DefaultChannelPipeline.class:?]
at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:169) [EmbeddedChannel.class:?]
at cpw.mods.fml.common.network.internal.FMLProxyPacket.processPacket(FMLProxyPacket.java:86) [FMLProxyPacket.class:?]
at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:241) [NetworkManager.class:?]
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:182) [NetworkSystem.class:?]
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:726) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:349) [DedicatedServer.class:?]
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752) [MinecraftServer$2.class:?]
Caused by: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:73) ~[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:?]
... 13 more
[00:27:35] [server thread/ERROR] [FML]: SimpleChannelHandlerWrapper exception
io.netty.handler.codec.DecoderException: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:99) ~[MessageToMessageDecoder.class:?]
at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) ~[MessageToMessageCodec.class:?]
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:785) [DefaultChannelPipeline.class:?]
at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:169) [EmbeddedChannel.class:?]
at cpw.mods.fml.common.network.internal.FMLProxyPacket.processPacket(FMLProxyPacket.java:86) [FMLProxyPacket.class:?]
at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:241) [NetworkManager.class:?]
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:182) [NetworkSystem.class:?]
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:726) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:349) [DedicatedServer.class:?]
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752) [MinecraftServer$2.class:?]
Caused by: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:73) ~[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:?]
... 13 more
[00:27:35] [server thread/ERROR] [FML]: SimpleChannelHandlerWrapper exception
io.netty.handler.codec.DecoderException: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:99) ~[MessageToMessageDecoder.class:?]
at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) ~[MessageToMessageCodec.class:?]
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323) [DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:785) [DefaultChannelPipeline.class:?]
at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:169) [EmbeddedChannel.class:?]
at cpw.mods.fml.common.network.internal.FMLProxyPacket.processPacket(FMLProxyPacket.java:86) [FMLProxyPacket.class:?]
at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:241) [NetworkManager.class:?]
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:182) [NetworkSystem.class:?]
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:726) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:349) [DedicatedServer.class:?]
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752) [MinecraftServer$2.class:?]
Caused by: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:73) ~[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:?]
... 13 more
[00:27:35] [server thread/ERROR] [FML]: There was a critical exception handling a packet on channel xan_prChannel
io.netty.handler.codec.DecoderException: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:99) ~[MessageToMessageDecoder.class:?]
at io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111) ~[MessageToMessageCodec.class:?]
at io.netty.channel.DefaultChannelHandlerContext.invokeChannelRead(DefaultChannelHandlerContext.java:337) ~[DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelHandlerContext.fireChannelRead(DefaultChannelHandlerContext.java:323) ~[DefaultChannelHandlerContext.class:?]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:785) ~[DefaultChannelPipeline.class:?]
at io.netty.channel.embedded.EmbeddedChannel.writeInbound(EmbeddedChannel.java:169) ~[EmbeddedChannel.class:?]
at cpw.mods.fml.common.network.internal.FMLProxyPacket.processPacket(FMLProxyPacket.java:86) [FMLProxyPacket.class:?]
at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:241) [NetworkManager.class:?]
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:182) [NetworkSystem.class:?]
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:726) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.updateTimeLightAndEntities(DedicatedServer.java:349) [DedicatedServer.class:?]
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752) [MinecraftServer$2.class:?]
Caused by: java.lang.NullPointerException: Undefined message for discriminator 21 in channel xan_prChannel
at cpw.mods.fml.common.network.FMLIndexedMessageToMessageCodec.decode(FMLIndexedMessageToMessageCodec.java:73) ~[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:?]
... 13 more

 

Clearly it has an issue with discriminator 21, which makes sense, because I have no discriminator 21 registered, here's my packet registration (and yes it is being called)

 

    public static void initialize() {
        NETWORK = NetworkRegistry.INSTANCE.newSimpleChannel(References.MOD_CHANNEL_ID);
        NETWORK.registerMessage(ServerReceiveNewRecipe.Handler.class, ServerReceiveNewRecipe.class, 0, Side.SERVER);
        NETWORK.registerMessage(ServerRemoveOldRecipe.Handler.class, ServerRemoveOldRecipe.class, 1, Side.SERVER);
        NETWORK.registerMessage(ClientReceiveAllRecipesFromServer.Handler.class, ClientReceiveAllRecipesFromServer.class, 2, Side.CLIENT);
        NETWORK.registerMessage(ClientReceiveNewRecipeFromServer.Handler.class, ClientReceiveNewRecipeFromServer.class, 3, Side.CLIENT);
        NETWORK.registerMessage(ClientReceiveRecipeRemovalFromServer.Handler.class, ClientReceiveRecipeRemovalFromServer.class, 4, Side.CLIENT);
    }

 

All of the packets seem to work fine minus the ServerRemoveOldRecipe packet

 

//Imports removed to save space
public class ServerRemoveOldRecipe implements IMessage {

    private int handlerID = 0;
    private int recipeID = 0;

    public ServerRemoveOldRecipe() {}

    public ServerRemoveOldRecipe(int handlerID, int recipeID){
        this.handlerID = handlerID;
        this.recipeID = recipeID;
    }

    @Override
    public void fromBytes(ByteBuf byteBuf) {
        handlerID = byteBuf.getInt(0);
        recipeID = byteBuf.getInt(1);
    }

    @Override
    public void toBytes(ByteBuf byteBuf) {
        byteBuf.setInt(0, handlerID);
        byteBuf.setInt(1, recipeID);
    }

    public static class Handler implements IMessageHandler<ServerRemoveOldRecipe, IMessage> {

        @Override
        public IMessage onMessage(ServerRemoveOldRecipe message, MessageContext ctx) {
            if(ctx.side.isServer()) {
                RecipeRegistry.INSTANCE.removeRecipe(message.handlerID, message.recipeID);
                NetworkHandler.NETWORK.sendToAll(new ClientReceiveRecipeRemovalFromServer(message.handlerID, message.recipeID));
            }
            return null;
        }
    }
}

 

Here is the ClientReceiveRecipeRemovalFromServer class, although we never get this far as the crash happens before it, but for the sake of completeness.

 

//imports and package info removed to save space
public class ClientReceiveRecipeRemovalFromServer implements IMessage {

    private int handlerID = 0, position = 0;

    public ClientReceiveRecipeRemovalFromServer() {}

    public ClientReceiveRecipeRemovalFromServer(int handlerID, int position) {
        this.handlerID = handlerID;
        this.position = position;
    }

    @Override
    public void fromBytes(ByteBuf byteBuf) {
        handlerID = byteBuf.getInt(0);
        position = byteBuf.getInt(1);
    }

    @Override
    public void toBytes(ByteBuf byteBuf) {
        byteBuf.setInt(0, handlerID);
        byteBuf.setInt(1, position);
    }

    public static class Handler implements IMessageHandler<ClientReceiveRecipeRemovalFromServer, IMessage> {

        @Override
        public IMessage onMessage(ClientReceiveRecipeRemovalFromServer message, MessageContext ctx) {
            if(ctx.side.isClient()) {
                RecipeRegistry.INSTANCE.removeRecipe(message.handlerID, message.position);
            }
            return null;
        }
    }

}

 

And finally here's the code that actually sends the packet to the server

 

                //Some context for this code: It's within a GUI screen under actionPerformed(GuiButton) so this code is called from a client telling the server to remove a recipe, the server then tells all the clients to remove the same recipe.
                if(FMLCommonHandler.instance().getMinecraftServerInstance() == null) { 
                    //getMinecraftServerInstance() is null only if you're a client connected to a remote server I've found, which is when I want to send the packet, if theres a better way to detect that please let me know.
                    NetworkHandler.NETWORK.sendToServer(new ServerRemoveOldRecipe(RecipeRegistry.INSTANCE.getAliasIntID(handler.getID()), selected));
                } else {
                    handler.deleteRecipe(selected);
                }

 

I really have absolutely no idea why this is happening and I've spent probably 5 hours trying to figure it out now. Some help would be greatly appreciated, and if I've made a dumb mistake that I'm just blind to then I apologize but I really can't see one.

 

[larsgerrits]

Remove the integers from the

byteBuf.getInt();[code]

[TheGreyGhost]

Hi

 

Your setInt(0) is overwriting the discriminator, which is placed into the buffer before the call to toBytes

 

I suggest you use readInt() and writeInt() instead of getInt() and setInt()..

 

-TGG

[xandayn]

Thank you very much, I didn't realize it was something so simple, like I said I don't have a lot of experience with netty but I have done a bit in the past and i used get and set int with no problems so i assumed that was the correct way to do things.