/* * Copyright (C) 2021 - 2022 Elytrium * * 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 . */ package net.elytrium.limboauth; import com.google.inject.Inject; import com.j256.ormlite.dao.Dao; import com.j256.ormlite.dao.DaoManager; import com.j256.ormlite.field.FieldType; import com.j256.ormlite.jdbc.JdbcPooledConnectionSource; import com.j256.ormlite.stmt.QueryBuilder; import com.j256.ormlite.table.TableUtils; import com.mojang.brigadier.tree.CommandNode; import com.velocitypowered.api.command.CommandManager; import com.velocitypowered.api.command.CommandMeta; import com.velocitypowered.api.command.CommandSource; import com.velocitypowered.api.command.SimpleCommand; import com.velocitypowered.api.event.Subscribe; import com.velocitypowered.api.event.proxy.ProxyInitializeEvent; import com.velocitypowered.api.plugin.Dependency; import com.velocitypowered.api.plugin.Plugin; import com.velocitypowered.api.plugin.PluginContainer; import com.velocitypowered.api.plugin.annotation.DataDirectory; import com.velocitypowered.api.proxy.Player; import com.velocitypowered.api.proxy.ProxyServer; import java.io.File; import java.io.IOException; import java.net.InetAddress; import java.net.URI; import java.net.URLEncoder; import java.net.http.HttpClient; import java.net.http.HttpRequest; import java.net.http.HttpResponse; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.sql.SQLException; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.List; import java.util.Locale; import java.util.Map; import java.util.Objects; import java.util.Set; import java.util.UUID; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; import java.util.function.Consumer; import java.util.regex.Pattern; import java.util.stream.Collectors; import net.elytrium.limboapi.api.Limbo; import net.elytrium.limboapi.api.LimboFactory; import net.elytrium.limboapi.api.chunk.Dimension; import net.elytrium.limboapi.api.chunk.VirtualWorld; import net.elytrium.limboapi.api.file.SchematicFile; import net.elytrium.limboapi.api.file.StructureFile; import net.elytrium.limboapi.api.file.WorldFile; import net.elytrium.limboauth.command.ChangePasswordCommand; import net.elytrium.limboauth.command.DestroySessionCommand; import net.elytrium.limboauth.command.ForceChangePasswordCommand; import net.elytrium.limboauth.command.ForceUnregisterCommand; import net.elytrium.limboauth.command.LimboAuthCommand; import net.elytrium.limboauth.command.PremiumCommand; import net.elytrium.limboauth.command.TotpCommand; import net.elytrium.limboauth.command.UnregisterCommand; import net.elytrium.limboauth.event.AuthPluginReloadEvent; import net.elytrium.limboauth.event.PreAuthorizationEvent; import net.elytrium.limboauth.event.PreEvent; import net.elytrium.limboauth.event.PreRegisterEvent; import net.elytrium.limboauth.event.TaskEvent; import net.elytrium.limboauth.floodgate.FloodgateApiHolder; import net.elytrium.limboauth.handler.AuthSessionHandler; import net.elytrium.limboauth.listener.AuthListener; import net.elytrium.limboauth.model.RegisteredPlayer; import net.elytrium.limboauth.utils.UpdatesChecker; import net.kyori.adventure.text.serializer.legacy.LegacyComponentSerializer; import net.kyori.adventure.title.Title; import org.bstats.charts.SimplePie; import org.bstats.charts.SingleLineChart; import org.bstats.velocity.Metrics; import org.checkerframework.checker.nullness.qual.Nullable; import org.slf4j.Logger; @Plugin( id = "limboauth", name = "LimboAuth", version = BuildConstants.AUTH_VERSION, url = "https://elytrium.net/", authors = { "hevav", "mdxd44" }, dependencies = { @Dependency(id = "limboapi"), @Dependency(id = "floodgate", optional = true) } ) public class LimboAuth { private final Map cachedAuthChecks = new ConcurrentHashMap<>(); private final Map premiumCache = new ConcurrentHashMap<>(); private final Map postLoginTasks = new ConcurrentHashMap<>(); private final Set unsafePasswords = new HashSet<>(); private final HttpClient client = HttpClient.newHttpClient(); private final ProxyServer server; private final Logger logger; private final Metrics.Factory metricsFactory; private final Path dataDirectory; private final LimboFactory factory; private final FloodgateApiHolder floodgateApi; private JdbcPooledConnectionSource connectionSource; private Dao playerDao; private Pattern nicknameValidationPattern; private Limbo authServer; @Inject public LimboAuth(ProxyServer server, Logger logger, Metrics.Factory metricsFactory, @DataDirectory Path dataDirectory) { this.server = server; this.logger = logger; this.metricsFactory = metricsFactory; this.dataDirectory = dataDirectory; this.factory = (LimboFactory) this.server.getPluginManager().getPlugin("limboapi").flatMap(PluginContainer::getInstance).orElseThrow(); if (this.server.getPluginManager().getPlugin("floodgate").isPresent()) { this.floodgateApi = new FloodgateApiHolder(); } else { this.floodgateApi = null; } } @Subscribe public void onProxyInitialization(ProxyInitializeEvent event) throws Exception { Metrics metrics = this.metricsFactory.make(this, 13700); System.setProperty("com.j256.simplelogging.level", "ERROR"); this.reload(); metrics.addCustomChart(new SimplePie("floodgate_auth", () -> String.valueOf(Settings.IMP.MAIN.FLOODGATE_NEED_AUTH))); metrics.addCustomChart(new SimplePie("premium_auth", () -> String.valueOf(Settings.IMP.MAIN.ONLINE_MODE_NEED_AUTH))); metrics.addCustomChart(new SimplePie("db_type", () -> Settings.IMP.DATABASE.STORAGE_TYPE)); metrics.addCustomChart(new SimplePie("load_world", () -> String.valueOf(Settings.IMP.MAIN.LOAD_WORLD))); metrics.addCustomChart(new SimplePie("totp_enabled", () -> String.valueOf(Settings.IMP.MAIN.ENABLE_TOTP))); metrics.addCustomChart(new SimplePie("dimension", () -> Settings.IMP.MAIN.DIMENSION)); metrics.addCustomChart(new SimplePie("save_uuid", () -> String.valueOf(Settings.IMP.MAIN.SAVE_UUID))); metrics.addCustomChart(new SingleLineChart("registered_players", () -> Math.toIntExact(this.playerDao.countOf()))); UpdatesChecker.checkForUpdates(this.getLogger()); } @SuppressWarnings("SwitchStatementWithTooFewBranches") public void reload() throws Exception { Settings.IMP.reload(new File(this.dataDirectory.toFile().getAbsoluteFile(), "config.yml")); if (this.floodgateApi == null && !Settings.IMP.MAIN.FLOODGATE_NEED_AUTH) { throw new IllegalStateException("If you don't need to auth floodgate players please install floodgate plugin."); } if (Settings.IMP.MAIN.CHECK_PASSWORD_STRENGTH) { this.unsafePasswords.clear(); Path unsafePasswordsPath = Paths.get(this.dataDirectory.toFile().getAbsolutePath(), Settings.IMP.MAIN.UNSAFE_PASSWORDS_FILE); if (!unsafePasswordsPath.toFile().exists()) { Files.copy(Objects.requireNonNull(this.getClass().getResourceAsStream("/unsafe_passwords.txt")), unsafePasswordsPath); } this.unsafePasswords.addAll(Files.lines(unsafePasswordsPath).collect(Collectors.toSet())); } this.cachedAuthChecks.clear(); Settings.DATABASE dbConfig = Settings.IMP.DATABASE; // requireNonNull prevents the shade plugin from excluding the drivers in minimized jar. switch (dbConfig.STORAGE_TYPE.toLowerCase(Locale.ROOT)) { case "h2": { Objects.requireNonNull(org.h2.Driver.class); Objects.requireNonNull(org.h2.engine.Engine.class); this.connectionSource = new JdbcPooledConnectionSource("jdbc:h2:" + this.dataDirectory.toFile().getAbsoluteFile() + "/limboauth"); break; } case "mysql": { Objects.requireNonNull(com.mysql.cj.jdbc.Driver.class); Objects.requireNonNull(com.mysql.cj.conf.url.SingleConnectionUrl.class); this.connectionSource = new JdbcPooledConnectionSource( "jdbc:mysql://" + dbConfig.HOSTNAME + "/" + dbConfig.DATABASE + dbConfig.CONNECTION_PARAMETERS, dbConfig.USER, dbConfig.PASSWORD ); break; } case "postgresql": { Objects.requireNonNull(org.postgresql.Driver.class); this.connectionSource = new JdbcPooledConnectionSource( "jdbc:postgresql://" + dbConfig.HOSTNAME + "/" + dbConfig.DATABASE + dbConfig.CONNECTION_PARAMETERS, dbConfig.USER, dbConfig.PASSWORD ); break; } default: { this.getLogger().error("WRONG DATABASE TYPE."); this.server.shutdown(); return; } } TableUtils.createTableIfNotExists(this.connectionSource, RegisteredPlayer.class); this.playerDao = DaoManager.createDao(this.connectionSource, RegisteredPlayer.class); this.nicknameValidationPattern = Pattern.compile(Settings.IMP.MAIN.ALLOWED_NICKNAME_REGEX); this.migrateDb(this.playerDao); CommandManager manager = this.server.getCommandManager(); manager.unregister("unregister"); manager.unregister("premium"); manager.unregister("forceunregister"); manager.unregister("changepassword"); manager.unregister("forcechangepassword"); manager.unregister("destroysession"); manager.unregister("2fa"); manager.unregister("limboauth"); manager.register("unregister", new UnregisterCommand(this, this.playerDao), "unreg"); manager.register("premium", new PremiumCommand(this, this.playerDao), "license"); manager.register("forceunregister", new ForceUnregisterCommand(this, this.server, this.playerDao), "forceunreg"); manager.register("changepassword", new ChangePasswordCommand(this.playerDao), "changepass"); manager.register("forcechangepassword", new ForceChangePasswordCommand(this.server, this.playerDao), "forcechangepass"); manager.register("destroysession", new DestroySessionCommand(this)); if (Settings.IMP.MAIN.ENABLE_TOTP) { manager.register("2fa", new TotpCommand(this.playerDao), "totp"); } manager.register("limboauth", new LimboAuthCommand(this), "la", "auth", "lauth"); Settings.MAIN.AUTH_COORDS authCoords = Settings.IMP.MAIN.AUTH_COORDS; VirtualWorld authWorld = this.factory.createVirtualWorld( Dimension.valueOf(Settings.IMP.MAIN.DIMENSION), authCoords.X, authCoords.Y, authCoords.Z, (float) authCoords.YAW, (float) authCoords.PITCH ); if (Settings.IMP.MAIN.LOAD_WORLD) { try { Path path = this.dataDirectory.resolve(Settings.IMP.MAIN.WORLD_FILE_PATH); WorldFile file; switch (Settings.IMP.MAIN.WORLD_FILE_TYPE) { case "schematic": { file = new SchematicFile(path); break; } case "structure": { file = new StructureFile(path); break; } default: { this.getLogger().error("Incorrect world file type."); this.server.shutdown(); return; } } Settings.MAIN.WORLD_COORDS coords = Settings.IMP.MAIN.WORLD_COORDS; file.toWorld(this.factory, authWorld, coords.X, coords.Y, coords.Z); } catch (IOException e) { e.printStackTrace(); } } this.authServer = this.factory .createLimbo(authWorld) .setName("LimboAuth") .registerCommand(new AuthCommandMeta(this, this.filterCommands(Settings.IMP.MAIN.REGISTER_COMMAND)), new AuthCommand()) .registerCommand(new AuthCommandMeta(this, this.filterCommands(Settings.IMP.MAIN.LOGIN_COMMAND)), new AuthCommand()) .registerCommand(new AuthCommandMeta(this, this.filterCommands(Settings.IMP.MAIN.TOTP_COMMAND)), new AuthCommand()); this.server.getEventManager().unregisterListeners(this); this.server.getEventManager().register(this, new AuthListener(this, this.playerDao, this.floodgateApi)); Executors.newScheduledThreadPool(1, task -> new Thread(task, "purge-cache")).scheduleAtFixedRate(() -> this.checkCache(this.cachedAuthChecks, Settings.IMP.MAIN.PURGE_CACHE_MILLIS), Settings.IMP.MAIN.PURGE_CACHE_MILLIS, Settings.IMP.MAIN.PURGE_CACHE_MILLIS, TimeUnit.MILLISECONDS ); Executors.newScheduledThreadPool(1, task -> new Thread(task, "purge-premium-cache")).scheduleAtFixedRate(() -> this.checkCache(this.premiumCache, Settings.IMP.MAIN.PURGE_PREMIUM_CACHE_MILLIS), Settings.IMP.MAIN.PURGE_PREMIUM_CACHE_MILLIS, Settings.IMP.MAIN.PURGE_PREMIUM_CACHE_MILLIS, TimeUnit.MILLISECONDS ); this.server.getEventManager().fireAndForget(new AuthPluginReloadEvent()); } private List filterCommands(List commands) { return commands.stream().filter(e -> e.startsWith("/")).map(e -> e.substring(1)).collect(Collectors.toList()); } public void migrateDb(Dao dao) { Set tables = new HashSet<>(); Collections.addAll(tables, dao.getTableInfo().getFieldTypes()); String findSql; switch (Settings.IMP.DATABASE.STORAGE_TYPE) { case "h2": { findSql = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '" + dao.getTableInfo().getTableName() + "';"; break; } case "postgresql": { findSql = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_CATALOG = '" + Settings.IMP.DATABASE.DATABASE + "' AND TABLE_NAME = '" + dao.getTableInfo().getTableName() + "';"; break; } case "mysql": { findSql = "SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = '" + Settings.IMP.DATABASE.DATABASE + "' AND TABLE_NAME = '" + dao.getTableInfo().getTableName() + "';"; break; } default: { this.getLogger().error("WRONG DATABASE TYPE."); this.server.shutdown(); return; } } try { dao.queryRaw(findSql).forEach(e -> tables.removeIf(q -> q.getColumnName().equalsIgnoreCase(e[0]))); tables.forEach(t -> { try { String columnDefinition = t.getColumnDefinition(); StringBuilder builder = new StringBuilder("ALTER TABLE \"" + dao.getTableInfo().getTableName() + "\" ADD "); List dummy = new ArrayList<>(); if (columnDefinition == null) { dao.getConnectionSource().getDatabaseType().appendColumnArg(t.getTableName(), builder, t, dummy, dummy, dummy, dummy); } else { dao.getConnectionSource().getDatabaseType().appendEscapedEntityName(builder, t.getColumnName()); builder.append(" ").append(columnDefinition).append(" "); } dao.executeRawNoArgs(builder.toString()); } catch (SQLException e) { e.printStackTrace(); } }); } catch (SQLException e) { e.printStackTrace(); } } public void cacheAuthUser(Player player) { String username = player.getUsername(); String lowercaseUsername = username.toLowerCase(Locale.ROOT); this.cachedAuthChecks.remove(lowercaseUsername); this.cachedAuthChecks.put(lowercaseUsername, new CachedSessionUser(player.getRemoteAddress().getAddress(), username, System.currentTimeMillis())); } public void removePlayerFromCache(String username) { this.cachedAuthChecks.remove(username.toLowerCase(Locale.ROOT)); } public boolean needAuth(Player player) { String username = player.getUsername(); String lowercaseUsername = username.toLowerCase(Locale.ROOT); if (!this.cachedAuthChecks.containsKey(lowercaseUsername)) { return true; } else { CachedSessionUser sessionUser = this.cachedAuthChecks.get(lowercaseUsername); return !sessionUser.getInetAddress().equals(player.getRemoteAddress().getAddress()) || !sessionUser.getUsername().equals(username); } } public void authPlayer(Player player) { String nickname = player.getUsername(); boolean isFloodgate = !Settings.IMP.MAIN.FLOODGATE_NEED_AUTH && this.floodgateApi.isFloodgatePlayer(player.getUniqueId()); String validatorNickname = (isFloodgate) ? nickname.substring(this.floodgateApi.getPrefixLength()) : nickname; if (!this.nicknameValidationPattern.matcher(validatorNickname).matches()) { player.disconnect(LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.NICKNAME_INVALID_KICK)); return; } RegisteredPlayer registeredPlayer = AuthSessionHandler.fetchInfo(this.playerDao, nickname); boolean onlineMode = player.isOnlineMode(); TaskEvent.Result result = TaskEvent.Result.NORMAL; if (onlineMode || isFloodgate) { if (registeredPlayer == null || registeredPlayer.getHash().isEmpty()) { registeredPlayer = AuthSessionHandler.fetchInfo(this.playerDao, player.getUniqueId()); if (registeredPlayer == null || registeredPlayer.getHash().isEmpty()) { // Due to the current connection state, which is set to LOGIN there, we cannot send the packets. // We need to wait for the PLAY connection state to set. this.postLoginTasks.put(player.getUniqueId(), () -> { if (onlineMode) { if (!Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM.isEmpty()) { player.sendMessage(LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM)); } if (!Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM_TITLE.isEmpty() && !Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM_SUBTITLE.isEmpty()) { player.showTitle( Title.title( LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM_TITLE), LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_PREMIUM_SUBTITLE), Settings.IMP.MAIN.PREMIUM_TITLE_SETTINGS.toTimes() ) ); } } else { if (!Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE.isEmpty()) { player.sendMessage(LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE)); } if (!Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE_TITLE.isEmpty() && !Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE_SUBTITLE.isEmpty()) { player.showTitle( Title.title( LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE_TITLE), LegacyComponentSerializer.legacyAmpersand().deserialize(Settings.IMP.MAIN.STRINGS.LOGIN_FLOODGATE_SUBTITLE), Settings.IMP.MAIN.PREMIUM_TITLE_SETTINGS.toTimes() ) ); } } }); result = TaskEvent.Result.BYPASS; } } } if (registeredPlayer == null) { Consumer eventConsumer = (event) -> this.sendPlayer(event, null); this.server.getEventManager().fire(new PreRegisterEvent(result, player, eventConsumer)).thenAcceptAsync(eventConsumer); } else { Consumer eventConsumer = (event) -> this.sendPlayer(event, ((PreAuthorizationEvent) event).getPlayerInfo()); this.server.getEventManager().fire(new PreAuthorizationEvent(result, player, registeredPlayer, eventConsumer)).thenAcceptAsync(eventConsumer); } } private void sendPlayer(TaskEvent event, RegisteredPlayer registeredPlayer) { Player player = ((PreEvent) event).getPlayer(); switch (event.getResult()) { case BYPASS: { this.factory.passLoginLimbo(player); break; } case CANCEL: { player.disconnect(event.getReason()); break; } case WAIT: { return; } case NORMAL: default: { try { this.authServer.spawnPlayer(player, new AuthSessionHandler(this.playerDao, player, this, registeredPlayer)); } catch (Throwable t) { this.getLogger().error("Error", t); } break; } } } public boolean isPremiumExternal(String nickname) { String lowercaseNickname = nickname.toLowerCase(Locale.ROOT); if (this.premiumCache.containsKey(lowercaseNickname)) { return this.premiumCache.get(lowercaseNickname).isPremium(); } try { int statusCode = this.client.send( HttpRequest.newBuilder() .uri(URI.create( String.format( Settings.IMP.MAIN.ISPREMIUM_AUTH_URL, URLEncoder.encode(lowercaseNickname, StandardCharsets.UTF_8)))) .build(), HttpResponse.BodyHandlers.ofString() ).statusCode(); boolean isPremium = statusCode == 200; // 429 Too Many Requests if (statusCode != 429) { this.premiumCache.put(lowercaseNickname, new CachedPremiumUser(isPremium, System.currentTimeMillis())); } else { return Settings.IMP.MAIN.ON_RATE_LIMIT_PREMIUM; } return isPremium; } catch (IOException | InterruptedException e) { this.getLogger().error("Unable to authenticate with Mojang", e); return Settings.IMP.MAIN.ON_RATE_LIMIT_PREMIUM; } } public boolean isPremium(String nickname) { if (Settings.IMP.MAIN.FORCE_OFFLINE_MODE) { return false; } try { if (this.isPremiumExternal(nickname)) { QueryBuilder premiumRegisteredQuery = this.playerDao.queryBuilder(); premiumRegisteredQuery.where() .eq("LOWERCASENICKNAME", nickname.toLowerCase(Locale.ROOT)) .and() .ne("HASH", ""); premiumRegisteredQuery.setCountOf(true); QueryBuilder premiumUnregisteredQuery = this.playerDao.queryBuilder(); premiumUnregisteredQuery.where() .eq("LOWERCASENICKNAME", nickname.toLowerCase(Locale.ROOT)) .and() .eq("HASH", ""); premiumUnregisteredQuery.setCountOf(true); if (Settings.IMP.MAIN.ONLINE_MODE_NEED_AUTH) { return this.playerDao.countOf(premiumRegisteredQuery.prepare()) == 0 && this.playerDao.countOf(premiumUnregisteredQuery.prepare()) != 0; } else { return this.playerDao.countOf(premiumRegisteredQuery.prepare()) == 0; } } else { return false; } } catch (SQLException e) { this.getLogger().error("Unable to authenticate with Mojang", e); return true; } } private void checkCache(Map userMap, long time) { userMap.entrySet().stream() .filter(u -> u.getValue().getCheckTime() + time <= System.currentTimeMillis()) .map(Map.Entry::getKey) .forEach(userMap::remove); } public JdbcPooledConnectionSource getConnectionSource() { return this.connectionSource; } public Dao getPlayerDao() { return this.playerDao; } public Set getUnsafePasswords() { return this.unsafePasswords; } public Map getPostLoginTasks() { return this.postLoginTasks; } public Logger getLogger() { return this.logger; } public ProxyServer getServer() { return this.server; } private static class CachedUser { private final long checkTime; public CachedUser(long checkTime) { this.checkTime = checkTime; } public long getCheckTime() { return this.checkTime; } } private static class CachedSessionUser extends CachedUser { private final InetAddress inetAddress; private final String username; public CachedSessionUser(InetAddress inetAddress, String username, long checkTime) { super(checkTime); this.inetAddress = inetAddress; this.username = username; } public InetAddress getInetAddress() { return this.inetAddress; } public String getUsername() { return this.username; } } private static class CachedPremiumUser extends CachedUser { private final boolean isPremium; public CachedPremiumUser(boolean isPremium, long checkTime) { super(checkTime); this.isPremium = isPremium; } public boolean isPremium() { return this.isPremium; } } private static class AuthCommandMeta implements CommandMeta { private final LimboAuth plugin; private final Collection aliases; AuthCommandMeta(LimboAuth plugin, Collection aliases) { this.plugin = plugin; this.aliases = aliases; } @Override public Collection getAliases() { return this.aliases; } @Override public Collection> getHints() { return Collections.emptyList(); } @Override public @Nullable Object getPlugin() { return this.plugin; } } private static class AuthCommand implements SimpleCommand { @Override public void execute(Invocation invocation) { } } }