SteamWarBungeeTeamserver/src/de/steamwar/listener/SteamwarConnectionListener.java

/*
 * This file is a part of the SteamWar software.
 *
 * Copyright (C) 2021  SteamWar.de-Serverteam
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package de.steamwar.listener;

import de.steamwar.ConfigSystem;
import de.steamwar.utils.BungeeTabListPlusFixer;
import io.netty.buffer.ByteBuf;
import net.md_5.bungee.BungeeCord;
import net.md_5.bungee.api.chat.TextComponent;
import net.md_5.bungee.api.event.PostLoginEvent;
import net.md_5.bungee.api.event.PreLoginEvent;
import net.md_5.bungee.api.plugin.Listener;
import net.md_5.bungee.connection.InitialHandler;
import net.md_5.bungee.connection.LoginResult;
import net.md_5.bungee.event.EventHandler;
import net.md_5.bungee.netty.ChannelWrapper;
import net.md_5.bungee.protocol.Protocol;
import net.md_5.bungee.protocol.ProtocolConstants;
import net.md_5.bungee.protocol.packet.Handshake;

import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.InetSocketAddress;
import java.util.Arrays;
import java.util.Set;
import java.util.UUID;
import java.util.function.Supplier;

public class SteamwarConnectionListener implements Listener {

    private Field chField;

    private Field loginProfile;

    private static class SteamwarHandshake extends Handshake {
        public void read(ByteBuf buf) {
            setProtocolVersion(readVarInt(buf));
            setHost(readString(buf));
            setPort(buf.readUnsignedShort());
            setRequestedProtocol(readVarInt(buf));
        }
    }

    {
        try {
            Method mapMethod = Protocol.class.getDeclaredMethod("map", int.class, int.class);
            mapMethod.setAccessible(true);
            Object protocolMapping = mapMethod.invoke(null, ProtocolConstants.MINECRAFT_1_8, 0x00);
            Class<?> directionDataClazz = Class.forName("net.md_5.bungee.protocol.Protocol$DirectionData");
            Class<?> protocolMappingClazz = Class.forName("net.md_5.bungee.protocol.Protocol$ProtocolMapping");
            Field field = Protocol.class.getDeclaredField("TO_SERVER");
            field.setAccessible(true);
            Object o = field.get(Protocol.HANDSHAKE);
            Method method = Arrays.stream(directionDataClazz.getDeclaredMethods())
                    .filter(m -> m.getName().equals("registerPacket"))
                    .filter(m -> m.getParameterCount() == 3)
                    .filter(m -> m.getParameterTypes()[0] == Class.class)
                    .filter(m -> m.getParameterTypes()[1] == Supplier.class)
                    .filter(m -> m.getParameterTypes()[2].isArray())
                    .findFirst()
                    .orElseThrow(() -> new RuntimeException("Could not find registerPacket method"));
            method.setAccessible(true);
            Object protocolMappingArray = Array.newInstance(protocolMappingClazz, 1);
            Array.set(protocolMappingArray, 0, protocolMapping);
            method.invoke(o, Handshake.class, new Supplier<Handshake>() {
                @Override
                public Handshake get() {
                    return new SteamwarHandshake();
                }
            }, protocolMappingArray);

            chField = InitialHandler.class.getDeclaredField("ch");
            chField.setAccessible(true);

            loginProfile = InitialHandler.class.getDeclaredField("loginProfile");
            loginProfile.setAccessible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @EventHandler
    public void preLoginEvent(PreLoginEvent preLoginEvent) {
        if (!ConfigSystem.isEnabled()) return;

        String address = preLoginEvent.getConnection().getSocketAddress().toString();
        if (address.startsWith("/78.31.71.136:")) {
            InitialHandler initialHandler = (InitialHandler) preLoginEvent.getConnection();
            String extraData = initialHandler.getExtraDataInHandshake();
            String[] split = extraData.split("\0");

            StringBuilder uuidStringBuilder = new StringBuilder(split[2]);
            uuidStringBuilder.insert(8, '-');
            uuidStringBuilder.insert(13, '-');
            uuidStringBuilder.insert(18, '-');
            uuidStringBuilder.insert(23, '-');

            if (ConfigSystem.isWhitelistEnabled()) {
                Set<String> whitelist = ConfigSystem.getWhitelist();
                if (!whitelist.contains(uuidStringBuilder.toString()) && !whitelist.contains(preLoginEvent.getConnection().getName())) {
                    preLoginEvent.setCancelled(true);
                    preLoginEvent.setCancelReason(new TextComponent());
                    return;
                }
            }

            try {
                ChannelWrapper channelWrapper = ((ChannelWrapper) chField.get(initialHandler));
                channelWrapper.setRemoteAddress(new InetSocketAddress(split[1], ((InetSocketAddress) channelWrapper.getRemoteAddress()).getPort()));
            } catch (IllegalAccessException e) {
                e.printStackTrace();
                return;
            }

            // 0: host, 1: address, 2: uuid, (3): mojangProfile (properties, so skin data)
            preLoginEvent.getConnection().setOnlineMode(false);

            initialHandler.setUniqueId(UUID.fromString(uuidStringBuilder.toString()));

            if (split.length > 3) {
                LoginResult loginResult = BungeeCord.getInstance().gson.fromJson("{\"properties\":" + split[3] + ", \"id\":\"\", \"name\":\"\"}", LoginResult.class);
                try {
                    loginProfile.set(initialHandler, loginResult);
                } catch (IllegalArgumentException | IllegalAccessException e) {
                    // Ignore
                }
            }
        } else if (ConfigSystem.isOnlySteamWarJoin()) {
            preLoginEvent.setCancelled(true);
            preLoginEvent.setCancelReason(ConfigSystem.getNotFromSteamWarMessage());
        }
    }

    @EventHandler
    public void postLoginEvent(PostLoginEvent postLoginEvent) {
        if (!ConfigSystem.isEnabled()) return;

        String address = postLoginEvent.getPlayer().getPendingConnection().getSocketAddress().toString();
        if (!address.startsWith("/127.127.127.127:")) {
            return;
        }

        if (BungeeCord.getInstance().getPluginManager().getPlugin("BungeeTabListPlus") != null) {
            BungeeTabListPlusFixer.remove(postLoginEvent.getPlayer());
        }
    }
}