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jsync.io is a non-blocking, event-driven networking framework for Java

There is a newer version: 1.10.13

package io.jsync.http.impl.cgbystrom;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

/**
 * A Flash policy file handler
 * Will detect connection attempts made by Adobe Flash clients and return a policy file response
 * 
 * After the policy has been sent, it will instantly close the connection.
 * If the first bytes sent are not a policy file request the handler will simply remove itself
 * from the pipeline.
 * 

 * Read more at http://www.adobe.com/devnet/articles/crossdomain_policy_file_spec.html
 * 

 * Example usage:
 * 
 * ChannelPipeline pipeline = Channels.pipeline();
 * pipeline.addLast("flashPolicy", new FlashPolicyHandler());
 * pipeline.addLast("decoder", new MyProtocolDecoder());
 * pipeline.addLast("encoder", new MyProtocolEncoder());
 * pipeline.addLast("handler", new MyBusinessLogicHandler());
 * 
 * 
 * For license see LICENSE file in this directory
 */
public class FlashPolicyHandler extends ChannelInboundHandlerAdapter {
    private static final String XML = "";
    private ParseState state = ParseState.MAGIC1;

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf buffer = (ByteBuf) msg;
        int index = buffer.readerIndex();
        switch (state) {
            case MAGIC1:
                if (!buffer.isReadable()) {
                    return;
                }
                final int magic1 = buffer.getUnsignedByte(index++);
                state = ParseState.MAGIC2;
                if (magic1 != '<') {
                    ctx.fireChannelRead(buffer);
                    ctx.pipeline().remove(this);
                    return;
                }
                // fall through
            case MAGIC2:
                if (!buffer.isReadable()) {
                    return;
                }
                final int magic2 = buffer.getUnsignedByte(index);
                if (magic2 != 'p') {
                    ctx.fireChannelRead(buffer);
                    ctx.pipeline().remove(this);
                } else {
                    ctx.writeAndFlush(Unpooled.copiedBuffer(XML, CharsetUtil.UTF_8)).addListener(ChannelFutureListener.CLOSE);
                }
        }
    }

    enum ParseState {
        MAGIC1,
        MAGIC2
    }
}