Java tutorial
/* * This file is part of LanternServer, licensed under the MIT License (MIT). * * Copyright (c) LanternPowered <https://www.lanternpowered.org> * Copyright (c) SpongePowered <https://www.spongepowered.org> * Copyright (c) contributors * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the Software), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ /* * Copyright (c) 2011-2014 Glowstone - Tad Hardesty * Copyright (c) 2010-2011 Lightstone - Graham Edgecombe * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package org.lanternpowered.server.network.rcon; import io.netty.buffer.ByteBuf; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.util.AttributeKey; import org.lanternpowered.server.game.Lantern; import org.spongepowered.api.Sponge; import org.spongepowered.api.event.SpongeEventFactory; import org.spongepowered.api.event.cause.Cause; import org.spongepowered.api.event.network.rcon.RconConnectionEvent; import java.nio.charset.StandardCharsets; final class RconHandler extends SimpleChannelInboundHandler<ByteBuf> { private static final AttributeKey<RconSource> SOURCE = AttributeKey.valueOf("rcon-source"); private static final byte FAILURE = -1; private static final byte TYPE_RESPONSE = 0; private static final byte TYPE_COMMAND = 2; private static final byte TYPE_LOGIN = 3; private final RconServer server; private final String password; RconHandler(RconServer server, String password) { this.password = password; this.server = server; } @Override protected void channelRead0(ChannelHandlerContext ctx, ByteBuf buf) throws Exception { if (buf.readableBytes() < 8) { return; } final int requestId = buf.readIntLE(); final int type = buf.readIntLE(); final byte[] payloadData = new byte[buf.readableBytes() - 2]; buf.readBytes(payloadData); final String payload = new String(payloadData, StandardCharsets.UTF_8); // Two byte padding buf.readBytes(2); if (type == TYPE_LOGIN) { handleLogin(ctx, payload, this.password, requestId); } else if (type == TYPE_COMMAND) { handleCommand(ctx, payload, requestId); } else { sendLargeResponse(ctx, requestId, "Unknown request " + Integer.toHexString(type)); } } @Override public void channelActive(ChannelHandlerContext ctx) { final Channel channel = ctx.channel(); final RconSource source = this.server.newSource(channel); final RconConnectionEvent.Connect event = SpongeEventFactory .createRconConnectionEventConnect(Cause.source(source).build(), source); Sponge.getEventManager().post(event); if (event.isCancelled()) { ctx.channel().close(); return; } if (!channel.attr(SOURCE).compareAndSet(null, source)) { throw new IllegalStateException("Rcon source may not be set more than once!"); } this.server.onChannelActive(source); } @Override public void channelInactive(ChannelHandlerContext ctx) { final Channel channel = ctx.channel(); final RconSource source = channel.attr(SOURCE).getAndSet(null); if (source == null) { return; } final RconConnectionEvent.Disconnect event = SpongeEventFactory .createRconConnectionEventDisconnect(Cause.source(source).build(), source); Sponge.getEventManager().post(event); this.server.onChannelInactive(source); } private static void handleLogin(ChannelHandlerContext ctx, String payload, String password, int requestId) { final RconSource source = ctx.channel().attr(SOURCE).get(); if (password.equals(payload)) { final RconConnectionEvent.Login event = SpongeEventFactory .createRconConnectionEventLogin(Cause.source(source).build(), source); if (!Sponge.getEventManager().post(event)) { source.setLoggedIn(true); sendResponse(ctx, requestId, TYPE_COMMAND, ""); Lantern.getLogger().info("Rcon connection from [" + ctx.channel().remoteAddress() + "]"); return; } } source.setLoggedIn(false); sendResponse(ctx, FAILURE, TYPE_COMMAND, ""); } private static void handleCommand(ChannelHandlerContext ctx, String payload, int requestId) { final RconSource source = ctx.channel().attr(SOURCE).get(); if (!source.getLoggedIn()) { sendResponse(ctx, FAILURE, TYPE_COMMAND, ""); return; } Sponge.getCommandManager().process(source, payload); sendLargeResponse(ctx, requestId, source.flush()); } private static void sendResponse(ChannelHandlerContext ctx, int requestId, int type, String payload) { final ByteBuf buf = ctx.alloc().buffer(); buf.writeIntLE(requestId); buf.writeIntLE(type); buf.writeBytes(payload.getBytes(StandardCharsets.UTF_8)); buf.writeByte(0); buf.writeByte(0); ctx.write(buf); } private static void sendLargeResponse(ChannelHandlerContext ctx, int requestId, String payload) { if (payload.length() == 0) { sendResponse(ctx, requestId, TYPE_RESPONSE, ""); return; } int start = 0; while (start < payload.length()) { final int length = payload.length() - start; final int truncated = length > 2048 ? 2048 : length; sendResponse(ctx, requestId, TYPE_RESPONSE, payload.substring(start, truncated)); start += truncated; } } }