133 lines
4.3 KiB
Java
133 lines
4.3 KiB
Java
/*
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* ProtocolLib - Bukkit server library that allows access to the Minecraft protocol.
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* Copyright (C) 2012 Kristian S. Stangeland
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*
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* This program is free software; you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with this program;
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* if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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* 02111-1307 USA
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*/
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package com.comphenix.protocol.injector.player;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.util.ArrayList;
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import java.util.Set;
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import com.comphenix.protocol.injector.player.NetworkFieldInjector.FakePacket;
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import net.minecraft.server.Packet;
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import net.sf.cglib.proxy.Enhancer;
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import net.sf.cglib.proxy.MethodInterceptor;
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import net.sf.cglib.proxy.MethodProxy;
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/**
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* The array list that notifies when packets are sent by the server.
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*
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* @author Kristian
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*/
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class InjectedArrayList extends ArrayList<Packet> {
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/**
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* Silly Eclipse.
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*/
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private static final long serialVersionUID = -1173865905404280990L;
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private PlayerInjector injector;
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private Set<Packet> ignoredPackets;
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private ClassLoader classLoader;
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public InjectedArrayList(ClassLoader classLoader, PlayerInjector injector, Set<Packet> ignoredPackets) {
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this.classLoader = classLoader;
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this.injector = injector;
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this.ignoredPackets = ignoredPackets;
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}
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@Override
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public boolean add(Packet packet) {
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Packet result = null;
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// Check for fake packets and ignored packets
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if (packet instanceof FakePacket) {
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return true;
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} else if (ignoredPackets.contains(packet)) {
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ignoredPackets.remove(packet);
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} else {
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result = injector.handlePacketRecieved(packet);
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}
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// A NULL packet indicate cancelling
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try {
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if (result != null) {
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super.add(result);
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} else {
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// We'll use the FakePacket marker instead of preventing the filters
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injector.sendServerPacket(createNegativePacket(packet), true);
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}
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// Collection.add contract
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return true;
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} catch (InvocationTargetException e) {
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throw new RuntimeException("Reverting cancelled packet failed.", e.getTargetException());
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}
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}
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/**
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* Used by a hack that reverses the effect of a cancelled packet. Returns a packet
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* whereby every int method's return value is inverted (a => -a).
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*
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* @param source - packet to invert.
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* @return The inverted packet.
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*/
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Packet createNegativePacket(Packet source) {
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Enhancer ex = new Enhancer();
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Class<?> type = source.getClass();
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// We want to subtract the byte amount that were added to the running
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// total of outstanding packets. Otherwise, cancelling too many packets
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// might cause a "disconnect.overflow" error.
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//
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// We do that by constructing a special packet of the same type that returns
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// a negative integer for all zero-parameter integer methods. This includes the
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// size() method, which is used by the queue method to count the number of
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// bytes to add.
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//
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// Essentially, we have:
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//
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// public class NegativePacket extends [a packet] {
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// @Override
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// public int size() {
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// return -super.size();
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// }
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// ect.
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// }
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ex.setInterfaces(new Class[] { FakePacket.class } );
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ex.setUseCache(true);
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ex.setClassLoader(classLoader);
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ex.setSuperclass(type);
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ex.setCallback(new MethodInterceptor() {
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@Override
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public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
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if (method.getReturnType().equals(int.class) && args.length == 0) {
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Integer result = (Integer) proxy.invokeSuper(obj, args);
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return -result;
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} else {
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return proxy.invokeSuper(obj, args);
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}
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}
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});
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return (Packet) ex.create();
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}
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}
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