JSONAPIChannelDecoder.java

package com.alecgorge.minecraft.jsonapi.packets.netty;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;

import java.util.List;
import java.util.NoSuchElementException;

import com.alecgorge.minecraft.jsonapi.JSONAPI;

public class JSONAPIChannelDecoder extends ByteToMessageDecoder {
	private JSONAPI						api;

	public JSONAPIChannelDecoder(JSONAPI api) {
		this.api = api;
	}
	
	@Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buf, List<Object> list) throws Exception {
        // use 4 bytes to detect HTTP or abort
        if (buf.readableBytes() < 4) {
            return;
        }
        buf.retain(2);

        final int magic1 = buf.getUnsignedByte(buf.readerIndex());
        final int magic2 = buf.getUnsignedByte(buf.readerIndex() + 1);
        final int magic3 = buf.getUnsignedByte(buf.readerIndex() + 2);
        final int magic4 = buf.getUnsignedByte(buf.readerIndex() + 3);
        ChannelPipeline p = ctx.channel().pipeline();
        
        if (isHttp(magic1, magic2, magic3, magic4)) {
            ByteBuf copy = buf.copy();
            ctx.channel().config().setOption(ChannelOption.TCP_NODELAY, true);

            try {
                while (p.removeLast() != null);
            } catch (NoSuchElementException e) {

            }
            
            p.addLast("codec-http", new HttpServerCodec());
            p.addLast("aggregator", new HttpObjectAggregator(65536));
            p.addLast("handler", new JSONAPIHandler(api));
           
            p.fireChannelRead(copy);
            buf.release();
            buf.release();
        } else {
            try {
                p.remove(this);
            } catch (NoSuchElementException e) {
                // probably okay, it just needs to be off
                System.out.println("NoSuchElementException");
            }

            buf.release();
            buf.release();
        }
    }

    private boolean isHttp(int magic1, int magic2, int magic3, int magic4) {
        return magic1 == 'G' && magic2 == 'E' && magic3 == 'T' && magic4 == ' ' || // GET
                magic1 == 'P' && magic2 == 'O' && magic3 == 'S' && magic4 == 'T' || // POST
                magic1 == 'P' && magic2 == 'U' && magic3 == 'T' && magic4 == ' ' || // PUT
                magic1 == 'H' && magic2 == 'E' && magic3 == 'A' && magic4 == 'D' || // HEAD
                magic1 == 'O' && magic2 == 'P' && magic3 == 'T' && magic4 == 'I' || // OPTIONS
                magic1 == 'P' && magic2 == 'A' && magic3 == 'T' && magic4 == 'C' || // PATCH
                magic1 == 'D' && magic2 == 'E' && magic3 == 'L' && magic4 == 'E' || // DELETE
                magic1 == 'T' && magic2 == 'R' && magic3 == 'C' && magic4 == 'C' || // TRACE
                magic1 == 'C' && magic2 == 'O' && magic3 == 'N' && magic4 == 'N'; // CONNECT
    }
}