/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.handler.codec.marshalling;

import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;
import io.netty.handler.codec.TooLongFrameException;
import org.jboss.marshalling.ByteInput;
import org.jboss.marshalling.Unmarshaller;

import java.io.ObjectStreamConstants;
import java.util.List;

ReplayingDecoder which use an Unmarshaller to read the Object out of the ByteBuf. If you can you should use MarshallingDecoder. /**
 * {@link ReplayingDecoder} which use an {@link Unmarshaller} to read the Object out of the {@link ByteBuf}.
 *
 * If you can you should use {@link MarshallingDecoder}.
 */
public class CompatibleMarshallingDecoder extends ReplayingDecoder<Void> {
    protected final UnmarshallerProvider provider;
    protected final int maxObjectSize;
    private boolean discardingTooLongFrame;

    
Create a new instance of CompatibleMarshallingDecoder. 
Params:
provider –  the UnmarshallerProvider which is used to obtain the Unmarshaller for the Channel
maxObjectSize –  the maximal size (in bytes) of the Object to unmarshal. Once the size is exceeded the Channel will get closed. Use a maxObjectSize of Integer.MAX_VALUE to disable this. You should only do this if you are sure that the received Objects will never be big and the sending side are trusted, as this opens the possibility for a DOS-Attack due an OutOfMemoryError./**
     * Create a new instance of {@link CompatibleMarshallingDecoder}.
     *
     * @param provider
     *        the {@link UnmarshallerProvider} which is used to obtain the {@link Unmarshaller}
     *        for the {@link Channel}
     * @param maxObjectSize
     *        the maximal size (in bytes) of the {@link Object} to unmarshal. Once the size is
     *        exceeded the {@link Channel} will get closed. Use a maxObjectSize of
     *        {@link Integer#MAX_VALUE} to disable this.  You should only do this if you are sure
     *        that the received Objects will never be big and the sending side are trusted, as this
     *        opens the possibility for a DOS-Attack due an {@link OutOfMemoryError}.
     */
    public CompatibleMarshallingDecoder(UnmarshallerProvider provider, int maxObjectSize) {
        this.provider = provider;
        this.maxObjectSize = maxObjectSize;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
        if (discardingTooLongFrame) {
            buffer.skipBytes(actualReadableBytes());
            checkpoint();
            return;
        }

        Unmarshaller unmarshaller = provider.getUnmarshaller(ctx);
        ByteInput input = new ChannelBufferByteInput(buffer);
        if (maxObjectSize != Integer.MAX_VALUE) {
            input = new LimitingByteInput(input, maxObjectSize);
        }
        try {
            unmarshaller.start(input);
            Object obj = unmarshaller.readObject();
            unmarshaller.finish();
            out.add(obj);
        } catch (LimitingByteInput.TooBigObjectException ignored) {
            discardingTooLongFrame = true;
            throw new TooLongFrameException();
        } finally {
            // Call close in a finally block as the ReplayingDecoder will throw an Error if not enough bytes are
            // readable. This helps to be sure that we do not leak resource
            unmarshaller.close();
        }
    }

    @Override
    protected void decodeLast(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
        switch (buffer.readableBytes()) {
        case 0:
            return;
        case 1:
            // Ignore the last TC_RESET
            if (buffer.getByte(buffer.readerIndex()) == ObjectStreamConstants.TC_RESET) {
                buffer.skipBytes(1);
                return;
            }
        }

        decode(ctx, buffer, out);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        if (cause instanceof TooLongFrameException) {
            ctx.close();
        } else {
            super.exceptionCaught(ctx, cause);
        }
    }
}