CustomHttpObjectAggregator.java

/*
 * Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
 *
 * WSO2 Inc. 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 org.wso2.carbon.transport.http.netty.listener;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.HttpObject;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.wso2.carbon.transport.http.netty.common.Constants;
import org.wso2.carbon.transport.http.netty.config.RequestSizeValidationConfiguration;

import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * Custom Http Object Aggregator to validate the message size.
 */
public class CustomHttpObjectAggregator extends HttpObjectAggregator {

    private static final Logger log = LoggerFactory.getLogger(CustomHttpObjectAggregator.class);

    public CustomHttpObjectAggregator() {
        super(RequestSizeValidationConfiguration.getInstance().getRequestMaxSize());
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, HttpObject msg, List<Object> out) throws Exception {
        try {
            super.decode(ctx, msg, out);
        } catch (Exception e) {
            log.warn("Message length validation failed");

            Iterator<Map.Entry<String, ChannelHandler>> iterator = ctx.pipeline().iterator();

            boolean canRemove = false;
            while (iterator.hasNext()) {
                Map.Entry<String, ChannelHandler> channelHandlerEntry = iterator.next();
                if (channelHandlerEntry.getKey().equalsIgnoreCase(ctx.name())) {
                    canRemove = true;
                }
                if (canRemove && !channelHandlerEntry.getKey().equalsIgnoreCase(ctx.name())) {
                    ctx.pipeline().remove(channelHandlerEntry.getKey());
                }
            }

            String rejectMessage = RequestSizeValidationConfiguration.getInstance().getRequestRejectMessage();
            byte[] errorMessageBytes = rejectMessage.getBytes(Charset.defaultCharset());
            ByteBuf content = Unpooled.wrappedBuffer(errorMessageBytes);
            DefaultFullHttpResponse rejectResponse = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,
                    HttpResponseStatus
                            .valueOf(RequestSizeValidationConfiguration.getInstance().getRequestRejectStatusCode()),
                    content);
            rejectResponse.headers().set(Constants.HTTP_CONTENT_LENGTH, errorMessageBytes.length);
            rejectResponse.headers().set(Constants.HTTP_CONTENT_TYPE,
                    RequestSizeValidationConfiguration.getInstance().getRequestRejectMsgContentType());

            ctx.writeAndFlush(rejectResponse);
        }
    }

}