Merge branch 'master' into tab-complete

.gitignore

@@ -102,7 +102,7 @@ hs_err_pid*
 
 ### Gradle ###
 .gradle
-/build/
+build/
 
 # Ignore Gradle GUI config
 gradle-app.setting
@@ -122,3 +122,4 @@ gradle-app.setting
 # Other trash
 logs/
 /velocity.toml
+server-icon.png

README.md

@@ -34,8 +34,6 @@ page.
 
 ## Status
 
-Velocity is far from finished, but most of the essential pieces are in place:
-you can switch between two servers running Minecraft 1.8-1.13. More versions
-and functionality is planned.
-
-You should join us on **irc.spi.gt** `#velocity` or send us a pull request.
+Velocity is far from finished, but most of the essential pieces you would
+expect are in place. Velocity supports Minecraft 1.8-1.13. More functionality
+is planned.

api/src/main/java/com/velocitypowered/api/server/Favicon.java

@@ -0,0 +1,88 @@
+package com.velocitypowered.api.server;
+
+import com.google.common.base.Preconditions;
+
+import javax.annotation.Nonnull;
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Base64;
+import java.util.Objects;
+
+/**
+ * Represents a Minecraft server favicon. A Minecraft server favicon is a 64x64 image that can be displayed to a remote
+ * client that sends a Server List Ping packet, and is automatically displayed in the Minecraft client.
+ */
+public final class Favicon {
+    private final String base64Url;
+
+    /**
+     * Directly create a favicon using its Base64 URL directly. You are generally better served by the create() series
+     * of functions.
+     * @param base64Url the url for use with this favicon
+     */
+    public Favicon(@Nonnull String base64Url) {
+        this.base64Url = Preconditions.checkNotNull(base64Url, "base64Url");
+    }
+
+    /**
+     * Returns the Base64-encoded URI for this image.
+     * @return a URL representing this favicon
+     */
+    public String getBase64Url() {
+        return base64Url;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Favicon favicon = (Favicon) o;
+        return Objects.equals(base64Url, favicon.base64Url);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(base64Url);
+    }
+
+    @Override
+    public String toString() {
+        return "Favicon{" +
+                "base64Url='" + base64Url + '\'' +
+                '}';
+    }
+
+    /**
+     * Creates a new {@code Favicon} from the specified {@code image}.
+     * @param image the image to use for the favicon
+     * @return the created {@link Favicon} instance
+     */
+    public static Favicon create(@Nonnull BufferedImage image) {
+        Preconditions.checkNotNull(image, "image");
+        Preconditions.checkArgument(image.getWidth() == 64 && image.getHeight() == 64, "Image does not have" +
+                " 64x64 dimensions (found %sx%s)", image.getWidth(), image.getHeight());
+        ByteArrayOutputStream os = new ByteArrayOutputStream();
+        try {
+            ImageIO.write(image, "PNG", os);
+        } catch (IOException e) {
+            throw new AssertionError(e);
+        }
+        return new Favicon("data:image/png;base64," + Base64.getEncoder().encodeToString(os.toByteArray()));
+    }
+
+    /**
+     * Creates a new {@code Favicon} by reading the image from the specified {@code path}.
+     * @param path the path to the image to create a favicon for
+     * @return the created {@link Favicon} instance
+     */
+    public static Favicon create(@Nonnull Path path) throws IOException {
+        try (InputStream stream = Files.newInputStream(path)) {
+            return create(ImageIO.read(stream));
+        }
+    }
+}

proxy/build.gradle

@@ -28,6 +28,7 @@ dependencies {
     compile "io.netty:netty-handler:${nettyVersion}"
     compile "io.netty:netty-transport-native-epoll:${nettyVersion}"
     compile "io.netty:netty-transport-native-epoll:${nettyVersion}:linux-x86_64"
+    compile "io.netty:netty-transport-native-kqueue:${nettyVersion}:osx-x86_64"
 
     compile "org.apache.logging.log4j:log4j-api:${log4jVersion}"
     compile "org.apache.logging.log4j:log4j-core:${log4jVersion}"

proxy/src/main/java/com/velocitypowered/network/ConnectionManager.java

@@ -24,6 +24,7 @@ import io.netty.channel.epoll.EpollDatagramChannel;
 import io.netty.channel.epoll.EpollEventLoopGroup;
 import io.netty.channel.epoll.EpollServerSocketChannel;
 import io.netty.channel.epoll.EpollSocketChannel;
+import io.netty.channel.kqueue.*;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.DatagramChannel;
 import io.netty.channel.socket.ServerSocketChannel;
@@ -37,6 +38,7 @@ import org.apache.logging.log4j.Logger;
 
 import java.net.InetSocketAddress;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
@@ -53,46 +55,25 @@ import static com.velocitypowered.network.Connections.READ_TIMEOUT;
 public final class ConnectionManager {
     private static final Logger logger = LogManager.getLogger(ConnectionManager.class);
 
-    private static final String DISABLE_EPOLL_PROPERTY = "velocity.connection.disable-epoll";
-    private static final boolean DISABLE_EPOLL = Boolean.getBoolean(DISABLE_EPOLL_PROPERTY);
     private final Set<Channel> endpoints = new HashSet<>();
-    private final Class<? extends ServerSocketChannel> serverSocketChannelClass;
-    private final Class<? extends SocketChannel> socketChannelClass;
-    private final Class<? extends DatagramChannel> datagramChannelClass;
+    private final TransportType transportType;
     private final EventLoopGroup bossGroup;
     private final EventLoopGroup workerGroup;
 
     public ConnectionManager() {
-        final boolean epoll = canUseEpoll();
-        if (epoll) {
-            this.serverSocketChannelClass = EpollServerSocketChannel.class;
-            this.socketChannelClass = EpollSocketChannel.class;
-            this.datagramChannelClass = EpollDatagramChannel.class;
-            this.bossGroup = new EpollEventLoopGroup(0, createThreadFactory("Netty Epoll Boss #%d"));
-            this.workerGroup = new EpollEventLoopGroup(0, createThreadFactory("Netty Epoll Worker #%d"));
-        } else {
-            this.serverSocketChannelClass = NioServerSocketChannel.class;
-            this.socketChannelClass = NioSocketChannel.class;
-            this.datagramChannelClass = NioDatagramChannel.class;
-            this.bossGroup = new NioEventLoopGroup(0, createThreadFactory("Netty Nio Boss #%d"));
-            this.workerGroup = new NioEventLoopGroup(0, createThreadFactory("Netty Nio Worker #%d"));
-        }
-        this.logChannelInformation(epoll);
+        this.transportType = TransportType.bestType();
+        this.bossGroup = transportType.createEventLoopGroup(true);
+        this.workerGroup = transportType.createEventLoopGroup(false);
+        this.logChannelInformation();
     }
 
-    private void logChannelInformation(final boolean epoll) {
-        final StringBuilder sb = new StringBuilder();
-        sb.append("Using channel type ");
-        sb.append(epoll ? "epoll": "nio");
-        if(DISABLE_EPOLL) {
-            sb.append(String.format(" - epoll explicitly disabled using -D%s=true", DISABLE_EPOLL_PROPERTY));
-        }
-        logger.info(sb.toString()); // TODO: move to logger
+    private void logChannelInformation() {
+        logger.info("Using channel type {}", transportType);
     }
 
     public void bind(final InetSocketAddress address) {
         final ServerBootstrap bootstrap = new ServerBootstrap()
-                .channel(this.serverSocketChannelClass)
+                .channel(this.transportType.serverSocketChannelClass)
                 .group(this.bossGroup, this.workerGroup)
                 .childHandler(new ChannelInitializer<Channel>() {
                     @Override
@@ -129,7 +110,7 @@ public final class ConnectionManager {
 
     public void queryBind(final String hostname, final int port) {
         Bootstrap bootstrap = new Bootstrap()
-                .channel(datagramChannelClass)
+                .channel(transportType.datagramChannelClass)
                 .group(this.workerGroup)
                 .handler(new GS4QueryHandler())
                 .localAddress(hostname, port);
@@ -147,7 +128,7 @@ public final class ConnectionManager {
 
     public Bootstrap createWorker() {
         return new Bootstrap()
-                .channel(this.socketChannelClass)
+                .channel(this.transportType.socketChannelClass)
                 .group(this.workerGroup);
     }
 
@@ -162,14 +143,61 @@ public final class ConnectionManager {
         }
     }
 
-    private static boolean canUseEpoll() {
-        return Epoll.isAvailable() && !DISABLE_EPOLL;
-    }
-
     private static ThreadFactory createThreadFactory(final String nameFormat) {
         return new ThreadFactoryBuilder()
                 .setNameFormat(nameFormat)
                 .setDaemon(true)
                 .build();
     }
+
+    private enum TransportType {
+        NIO(NioServerSocketChannel.class, NioSocketChannel.class, NioDatagramChannel.class) {
+            @Override
+            public EventLoopGroup createEventLoopGroup(boolean boss) {
+                String name = "Netty NIO " + (boss ? "Boss" : "Worker") + " #%d";
+                return new NioEventLoopGroup(0, createThreadFactory(name));
+            }
+        },
+        EPOLL(EpollServerSocketChannel.class, EpollSocketChannel.class, EpollDatagramChannel.class) {
+            @Override
+            public EventLoopGroup createEventLoopGroup(boolean boss) {
+                String name = "Netty Epoll " + (boss ? "Boss" : "Worker") + " #%d";
+                return new EpollEventLoopGroup(0, createThreadFactory(name));
+            }
+        },
+        KQUEUE(KQueueServerSocketChannel.class, KQueueSocketChannel.class, KQueueDatagramChannel.class) {
+            @Override
+            public EventLoopGroup createEventLoopGroup(boolean boss) {
+                String name = "Netty Kqueue " + (boss ? "Boss" : "Worker") + " #%d";
+                return new KQueueEventLoopGroup(0, createThreadFactory(name));
+            }
+        };
+
+        private final Class<? extends ServerSocketChannel> serverSocketChannelClass;
+        private final Class<? extends SocketChannel> socketChannelClass;
+        private final Class<? extends DatagramChannel> datagramChannelClass;
+
+        TransportType(Class<? extends ServerSocketChannel> serverSocketChannelClass, Class<? extends SocketChannel> socketChannelClass, Class<? extends DatagramChannel> datagramChannelClass) {
+            this.serverSocketChannelClass = serverSocketChannelClass;
+            this.socketChannelClass = socketChannelClass;
+            this.datagramChannelClass = datagramChannelClass;
+        }
+
+        @Override
+        public String toString() {
+            return name().toLowerCase(Locale.US);
+        }
+
+        public abstract EventLoopGroup createEventLoopGroup(boolean boss);
+
+        public static TransportType bestType() {
+            if (Epoll.isAvailable()) {
+                return EPOLL;
+            } else if (KQueue.isAvailable()) {
+                return KQUEUE;
+            } else {
+                return NIO;
+            }
+        }
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/Velocity.java

@@ -3,6 +3,12 @@ package com.velocitypowered.proxy;
 import com.velocitypowered.proxy.console.VelocityConsole;
 
 public class Velocity {
+    static {
+        // We use BufferedImage for favicons, and on macOS this puts the Java application in the dock. How inconvenient.
+        // Force AWT to work with its head chopped off.
+        System.setProperty("java.awt.headless", "true");
+    }
+
     public static void main(String... args) {
         final VelocityServer server = VelocityServer.getServer();
         server.start();

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -7,6 +7,7 @@ import com.google.gson.GsonBuilder;
 import com.velocitypowered.api.command.CommandInvoker;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.api.server.Favicon;
 import com.velocitypowered.natives.util.Natives;
 import com.velocitypowered.network.ConnectionManager;
 import com.velocitypowered.proxy.command.ServerCommand;
@@ -17,8 +18,10 @@ import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.connection.http.NettyHttpClient;
 import com.velocitypowered.api.server.ServerInfo;
 import com.velocitypowered.proxy.command.CommandManager;
+import com.velocitypowered.proxy.protocol.util.FaviconSerializer;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.proxy.util.EncryptionUtils;
+import com.velocitypowered.proxy.util.Ratelimiter;
 import com.velocitypowered.proxy.util.ServerMap;
 import io.netty.bootstrap.Bootstrap;
 import net.kyori.text.Component;
@@ -44,6 +47,7 @@ public class VelocityServer implements ProxyServer {
     private static final VelocityServer INSTANCE = new VelocityServer();
     public static final Gson GSON = new GsonBuilder()
             .registerTypeHierarchyAdapter(Component.class, new GsonComponentSerializer())
+            .registerTypeHierarchyAdapter(Favicon.class, new FaviconSerializer())
             .create();
 
     private final ConnectionManager cm = new ConnectionManager();
@@ -68,6 +72,7 @@ public class VelocityServer implements ProxyServer {
             return true;
         }
     };
+    private final Ratelimiter ipAttemptLimiter = new Ratelimiter(3000); // TODO: Configurable.
 
     private VelocityServer() {
         commandManager.registerCommand("velocity", new VelocityCommand());
@@ -159,6 +164,10 @@ public class VelocityServer implements ProxyServer {
         return httpClient;
     }
 
+    public Ratelimiter getIpAttemptLimiter() {
+        return ipAttemptLimiter;
+    }
+
     public boolean registerConnection(ConnectedPlayer connection) {
         String lowerName = connection.getUsername().toLowerCase(Locale.US);
         if (connectionsByName.putIfAbsent(lowerName, connection) != null) {

proxy/src/main/java/com/velocitypowered/proxy/config/PlayerInfoForwarding.java

@@ -1,6 +1,6 @@
 package com.velocitypowered.proxy.config;
 
-public enum IPForwardingMode {
+public enum PlayerInfoForwarding {
     NONE,
     LEGACY,
     MODERN

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -2,8 +2,10 @@ package com.velocitypowered.proxy.config;
 
 import com.google.common.collect.ImmutableMap;
 import com.moandjiezana.toml.Toml;
+import com.velocitypowered.api.server.Favicon;
 import com.velocitypowered.proxy.util.AddressUtil;
 import com.velocitypowered.api.util.LegacyChatColorUtils;
+import io.netty.buffer.ByteBufUtil;
 import net.kyori.text.Component;
 import net.kyori.text.serializer.ComponentSerializers;
 import org.apache.logging.log4j.LogManager;
@@ -15,6 +17,7 @@ import java.net.InetSocketAddress;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -26,7 +29,7 @@ public class VelocityConfiguration {
     private final String motd;
     private final int showMaxPlayers;
     private final boolean onlineMode;
-    private final IPForwardingMode ipForwardingMode;
+    private final PlayerInfoForwarding playerInfoForwardingMode;
     private final Map<String, String> servers;
     private final List<String> attemptConnectionOrder;
     private final int compressionThreshold;
@@ -36,22 +39,27 @@ public class VelocityConfiguration {
     private final int queryPort;
 
     private Component motdAsComponent;
+    private Favicon favicon;
+
+    private final byte[] forwardingSecret;
 
     private VelocityConfiguration(String bind, String motd, int showMaxPlayers, boolean onlineMode,
-                                  IPForwardingMode ipForwardingMode, Map<String, String> servers,
+                                  PlayerInfoForwarding playerInfoForwardingMode, Map<String, String> servers,
                                   List<String> attemptConnectionOrder, int compressionThreshold,
-                                  int compressionLevel, boolean queryEnabled, int queryPort) {
+                                  int compressionLevel, boolean queryEnabled, int queryPort,
+                                  byte[] forwardingSecret) {
         this.bind = bind;
         this.motd = motd;
         this.showMaxPlayers = showMaxPlayers;
         this.onlineMode = onlineMode;
-        this.ipForwardingMode = ipForwardingMode;
+        this.playerInfoForwardingMode = playerInfoForwardingMode;
         this.servers = servers;
         this.attemptConnectionOrder = attemptConnectionOrder;
         this.compressionThreshold = compressionThreshold;
         this.compressionLevel = compressionLevel;
         this.queryEnabled = queryEnabled;
         this.queryPort = queryPort;
+        this.forwardingSecret = forwardingSecret;
     }
 
     public boolean validate() {
@@ -73,9 +81,15 @@ public class VelocityConfiguration {
             logger.info("Proxy is running in offline mode!");
         }
 
-        switch (ipForwardingMode) {
+        switch (playerInfoForwardingMode) {
             case NONE:
-                logger.info("IP forwarding is disabled! All players will appear to be connecting from the proxy and will have offline-mode UUIDs.");
+                logger.info("Player info forwarding is disabled! All players will appear to be connecting from the proxy and will have offline-mode UUIDs.");
+                break;
+            case MODERN:
+                if (forwardingSecret.length == 0) {
+                    logger.error("You don't have a forwarding secret set.");
+                    valid = false;
+                }
                 break;
         }
 
@@ -124,9 +138,22 @@ public class VelocityConfiguration {
             logger.warn("ALL packets going through the proxy are going to be compressed. This may hurt performance.");
         }
 
+        loadFavicon();
+
         return valid;
     }
 
+    private void loadFavicon() {
+        Path faviconPath = Paths.get("server-icon.png");
+        if (Files.exists(faviconPath)) {
+            try {
+                this.favicon = Favicon.create(faviconPath);
+            } catch (Exception e) {
+                logger.info("Unable to load your server-icon.png, continuing without it.", e);
+            }
+        }
+    }
+
     public InetSocketAddress getBind() {
         return AddressUtil.parseAddress(bind);
     }
@@ -162,8 +189,8 @@ public class VelocityConfiguration {
         return onlineMode;
     }
 
-    public IPForwardingMode getIpForwardingMode() {
-        return ipForwardingMode;
+    public PlayerInfoForwarding getPlayerInfoForwardingMode() {
+        return playerInfoForwardingMode;
     }
 
     public Map<String, String> getServers() {
@@ -182,6 +209,14 @@ public class VelocityConfiguration {
         return compressionLevel;
     }
 
+    public Favicon getFavicon() {
+        return favicon;
+    }
+
+    public byte[] getForwardingSecret() {
+        return forwardingSecret;
+    }
+
     @Override
     public String toString() {
         return "VelocityConfiguration{" +
@@ -189,7 +224,7 @@ public class VelocityConfiguration {
                 ", motd='" + motd + '\'' +
                 ", showMaxPlayers=" + showMaxPlayers +
                 ", onlineMode=" + onlineMode +
-                ", ipForwardingMode=" + ipForwardingMode +
+                ", playerInfoForwardingMode=" + playerInfoForwardingMode +
                 ", servers=" + servers +
                 ", attemptConnectionOrder=" + attemptConnectionOrder +
                 ", compressionThreshold=" + compressionThreshold +
@@ -197,6 +232,8 @@ public class VelocityConfiguration {
                 ", queryEnabled=" + queryEnabled +
                 ", queryPort=" + queryPort +
                 ", motdAsComponent=" + motdAsComponent +
+                ", favicon=" + favicon +
+                ", forwardingSecret=" + ByteBufUtil.hexDump(forwardingSecret) +
                 '}';
     }
 
@@ -215,18 +252,22 @@ public class VelocityConfiguration {
                 }
             }
 
+            byte[] forwardingSecret = toml.getString("player-info-forwarding-secret", "5up3r53cr3t")
+                    .getBytes(StandardCharsets.UTF_8);
+
             return new VelocityConfiguration(
-                    toml.getString("bind"),
-                    toml.getString("motd"),
-                    toml.getLong("show-max-players").intValue(),
-                    toml.getBoolean("online-mode"),
-                    IPForwardingMode.valueOf(toml.getString("ip-forwarding").toUpperCase()),
+                    toml.getString("bind", "0.0.0.0:25577"),
+                    toml.getString("motd", "&3A Velocity Server"),
+                    toml.getLong("show-max-players", 500L).intValue(),
+                    toml.getBoolean("online-mode", true),
+                    PlayerInfoForwarding.valueOf(toml.getString("player-info-forwarding", "MODERN").toUpperCase()),
                     ImmutableMap.copyOf(servers),
                     toml.getTable("servers").getList("try"),
                     toml.getTable("advanced").getLong("compression-threshold", 1024L).intValue(),
                     toml.getTable("advanced").getLong("compression-level", -1L).intValue(),
-                    toml.getTable("query").getBoolean("enabled"),
-                    toml.getTable("query").getLong("port", 25577L).intValue());
+                    toml.getTable("query").getBoolean("enabled", false),
+                    toml.getTable("query").getLong("port", 25577L).intValue(),
+                    forwardingSecret);
         }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/LoginSessionHandler.java

@@ -2,7 +2,8 @@ package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.config.IPForwardingMode;
+import com.velocitypowered.proxy.config.PlayerInfoForwarding;
+import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
@@ -17,6 +18,11 @@ import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelPipeline;
 import net.kyori.text.TextComponent;
 
+import javax.crypto.Mac;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
@@ -30,7 +36,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
 
     @Override
     public void activated() {
-        if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.MODERN) {
+        if (VelocityServer.getServer().getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN) {
             forwardingCheckTask = connection.getMinecraftConnection().getChannel().eventLoop().schedule(() -> {
                 connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(),
                         TextComponent.of("Your server did not send the forwarding request in time. Is it set up correctly?"));
@@ -44,12 +50,14 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
             throw new IllegalStateException("Backend server is online-mode!");
         } else if (packet instanceof LoginPluginMessage) {
             LoginPluginMessage message = (LoginPluginMessage) packet;
-            if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.MODERN &&
+            VelocityConfiguration configuration = VelocityServer.getServer().getConfiguration();
+            if (configuration.getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN &&
                     message.getChannel().equals(VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL)) {
                 LoginPluginResponse response = new LoginPluginResponse();
                 response.setSuccess(true);
                 response.setId(message.getId());
-                response.setData(createForwardingData(connection.getProxyPlayer().getRemoteAddress().getHostString(),
+                response.setData(createForwardingData(configuration.getForwardingSecret(),
+                        connection.getProxyPlayer().getRemoteAddress().getHostString(),
                         connection.getProxyPlayer().getProfile()));
                 connection.getMinecraftConnection().write(response);
                 cancelForwardingCheck();
@@ -122,23 +130,43 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         }
     }
 
-    private static ByteBuf createForwardingData(String address, GameProfile profile) {
-        ByteBuf buf = Unpooled.buffer();
-        ProtocolUtils.writeString(buf, address);
-        ProtocolUtils.writeUuid(buf, profile.idAsUuid());
-        ProtocolUtils.writeString(buf, profile.getName());
-        ProtocolUtils.writeVarInt(buf, profile.getProperties().size());
+    static ByteBuf createForwardingData(byte[] hmacSecret, String address, GameProfile profile) {
+        ByteBuf dataToForward = Unpooled.buffer();
+        ByteBuf finalData = Unpooled.buffer();
+        try {
+            ProtocolUtils.writeString(dataToForward, address);
+            ProtocolUtils.writeUuid(dataToForward, profile.idAsUuid());
+            ProtocolUtils.writeString(dataToForward, profile.getName());
+            ProtocolUtils.writeVarInt(dataToForward, profile.getProperties().size());
             for (GameProfile.Property property : profile.getProperties()) {
-            ProtocolUtils.writeString(buf, property.getName());
-            ProtocolUtils.writeString(buf, property.getValue());
+                ProtocolUtils.writeString(dataToForward, property.getName());
+                ProtocolUtils.writeString(dataToForward, property.getValue());
                 String signature = property.getSignature();
                 if (signature != null) {
-                buf.writeBoolean(true);
-                ProtocolUtils.writeString(buf, signature);
+                    dataToForward.writeBoolean(true);
+                    ProtocolUtils.writeString(dataToForward, signature);
                 } else {
-                buf.writeBoolean(false);
+                    dataToForward.writeBoolean(false);
                 }
             }
-        return buf;
+
+            SecretKey key = new SecretKeySpec(hmacSecret, "HmacSHA256");
+            Mac mac = Mac.getInstance("HmacSHA256");
+            mac.init(key);
+            mac.update(dataToForward.array(), dataToForward.arrayOffset(), dataToForward.readableBytes());
+            byte[] sig = mac.doFinal();
+            finalData.writeBytes(sig);
+            finalData.writeBytes(dataToForward);
+            return finalData;
+        } catch (InvalidKeyException e) {
+            finalData.release();
+            throw new RuntimeException("Unable to authenticate data", e);
+        } catch (NoSuchAlgorithmException e) {
+            // Should never happen
+            finalData.release();
+            throw new AssertionError(e);
+        } finally {
+            dataToForward.release();
+        }
     }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/ServerConnection.java

@@ -1,7 +1,7 @@
 package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
-import com.velocitypowered.proxy.config.IPForwardingMode;
+import com.velocitypowered.proxy.config.PlayerInfoForwarding;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
@@ -97,7 +97,7 @@ public class ServerConnection implements MinecraftConnectionAssociation {
         Handshake handshake = new Handshake();
         handshake.setNextStatus(StateRegistry.LOGIN_ID);
         handshake.setProtocolVersion(proxyPlayer.getConnection().getProtocolVersion());
-        if (VelocityServer.getServer().getConfiguration().getIpForwardingMode() == IPForwardingMode.LEGACY) {
+        if (VelocityServer.getServer().getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.LEGACY) {
             handshake.setServerAddress(createBungeeForwardingAddress());
         } else {
             handshake.setServerAddress(serverInfo.getAddress().getHostString());
@@ -111,7 +111,7 @@ public class ServerConnection implements MinecraftConnectionAssociation {
 
         // Send the server login packet for <=1.12.2 and for 1.13+ servers not using "modern" forwarding.
         if (protocolVersion <= ProtocolConstants.MINECRAFT_1_12_2 ||
-                VelocityServer.getServer().getConfiguration().getIpForwardingMode() != IPForwardingMode.MODERN) {
+                VelocityServer.getServer().getConfiguration().getPlayerInfoForwardingMode() != PlayerInfoForwarding.MODERN) {
             ServerLogin login = new ServerLogin();
             login.setUsername(proxyPlayer.getUsername());
             minecraftConnection.write(login);

proxy/src/main/java/com/velocitypowered/proxy/connection/client/HandshakeSessionHandler.java

@@ -15,6 +15,7 @@ import net.kyori.text.TextComponent;
 import net.kyori.text.TranslatableComponent;
 import net.kyori.text.format.TextColor;
 
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 
 public class HandshakeSessionHandler implements MinecraftSessionHandler {
@@ -50,6 +51,11 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
                     connection.closeWith(Disconnect.create(TranslatableComponent.of("multiplayer.disconnect.outdated_client")));
                     return;
                 } else {
+                    InetAddress address = ((InetSocketAddress) connection.getChannel().remoteAddress()).getAddress();
+                    if (!VelocityServer.getServer().getIpAttemptLimiter().attempt(address)) {
+                        connection.closeWith(Disconnect.create(TextComponent.of("You are logging in too fast, try again later.")));
+                        return;
+                    }
                     connection.setSessionHandler(new LoginSessionHandler(connection));
                 }
                 break;

proxy/src/main/java/com/velocitypowered/proxy/connection/client/LoginSessionHandler.java

@@ -91,6 +91,11 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
                 VelocityServer.getServer().getHttpClient()
                         .get(new URL(String.format(MOJANG_SERVER_AUTH_URL, login.getUsername(), serverId, playerIp)))
                         .thenAcceptAsync(profileResponse -> {
+                            if (inbound.isClosed()) {
+                                // The player disconnected after we authenticated them.
+                                return;
+                            }
+
                             try {
                                 inbound.enableEncryption(decryptedSharedSecret);
                             } catch (GeneralSecurityException e) {

proxy/src/main/java/com/velocitypowered/proxy/connection/client/StatusSessionHandler.java

@@ -41,7 +41,7 @@ public class StatusSessionHandler implements MinecraftSessionHandler {
                 new ServerPing.Version(shownVersion, "Velocity " + ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING),
                 new ServerPing.Players(VelocityServer.getServer().getPlayerCount(), configuration.getShowMaxPlayers()),
                 configuration.getMotdComponent(),
-                null
+                configuration.getFavicon()
         );
         StatusResponse response = new StatusResponse();
         response.setStatus(VelocityServer.GSON.toJson(ping));

proxy/src/main/java/com/velocitypowered/proxy/data/ServerPing.java

@@ -1,14 +1,15 @@
 package com.velocitypowered.proxy.data;
 
+import com.velocitypowered.api.server.Favicon;
 import net.kyori.text.Component;
 
 public class ServerPing {
     private final Version version;
     private final Players players;
     private final Component description;
-    private final String favicon;
+    private final Favicon favicon;
 
-    public ServerPing(Version version, Players players, Component description, String favicon) {
+    public ServerPing(Version version, Players players, Component description, Favicon favicon) {
         this.version = version;
         this.players = players;
         this.description = description;
@@ -27,7 +28,7 @@ public class ServerPing {
         return description;
     }
 
-    public String getFavicon() {
+    public Favicon getFavicon() {
         return favicon;
     }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/util/FaviconSerializer.java

@@ -0,0 +1,18 @@
+package com.velocitypowered.proxy.protocol.util;
+
+import com.google.gson.*;
+import com.velocitypowered.api.server.Favicon;
+
+import java.lang.reflect.Type;
+
+public class FaviconSerializer implements JsonSerializer<Favicon>, JsonDeserializer<Favicon> {
+    @Override
+    public Favicon deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+        return new Favicon(json.getAsString());
+    }
+
+    @Override
+    public JsonElement serialize(Favicon src, Type typeOfSrc, JsonSerializationContext context) {
+        return new JsonPrimitive(src.getBase64Url());
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/util/Ratelimiter.java

@@ -0,0 +1,41 @@
+package com.velocitypowered.proxy.util;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Ticker;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+
+import java.net.InetAddress;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+public class Ratelimiter {
+    private final Cache<InetAddress, Long> expiringCache;
+    private final long timeoutNanos;
+
+    public Ratelimiter(long timeoutMs) {
+        this(timeoutMs, Ticker.systemTicker());
+    }
+
+    @VisibleForTesting
+    Ratelimiter(long timeoutMs, Ticker ticker) {
+        this.timeoutNanos = TimeUnit.MILLISECONDS.toNanos(timeoutMs);
+        this.expiringCache = CacheBuilder.newBuilder()
+                .ticker(ticker)
+                .concurrencyLevel(Runtime.getRuntime().availableProcessors())
+                .expireAfterWrite(timeoutMs, TimeUnit.MILLISECONDS)
+                .build();
+    }
+
+    public boolean attempt(InetAddress address) {
+        long expectedNewValue = System.nanoTime() + timeoutNanos;
+        long last;
+        try {
+            last = expiringCache.get(address, () -> expectedNewValue);
+        } catch (ExecutionException e) {
+            // It should be impossible for this to fail.
+            throw new AssertionError(e);
+        }
+        return expectedNewValue == last;
+    }
+}

proxy/src/main/resources/velocity.toml

@@ -19,7 +19,10 @@ online-mode = true
 #             servers using Minecraft 1.12 or lower.
 # - "modern": Forward player IPs and UUIDs as part of the login process using Velocity's native
 #             forwarding. Only applicable for Minecraft 1.13 or higher.
-ip-forwarding = "modern"
+player-info-forwarding = "modern"
+
+# If you are using modern IP forwarding, configure an unique secret here.
+player-info-forwarding-secret = "5up3r53cr3t"
 
 [servers]
 # Configure your servers here.

proxy/src/test/java/com/velocitypowered/proxy/util/RatelimiterTest.java

@@ -0,0 +1,30 @@
+package com.velocitypowered.proxy.util;
+
+import com.google.common.base.Ticker;
+import org.junit.jupiter.api.Test;
+
+import java.net.InetAddress;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class RatelimiterTest {
+
+    @Test
+    void attempt() {
+        long base = System.nanoTime();
+        AtomicLong extra = new AtomicLong();
+        Ticker testTicker = new Ticker() {
+            @Override
+            public long read() {
+                return base + extra.get();
+            }
+        };
+        Ratelimiter ratelimiter = new Ratelimiter(1000, testTicker);
+        assertTrue(ratelimiter.attempt(InetAddress.getLoopbackAddress()));
+        assertFalse(ratelimiter.attempt(InetAddress.getLoopbackAddress()));
+        extra.addAndGet(TimeUnit.SECONDS.toNanos(2));
+        assertTrue(ratelimiter.attempt(InetAddress.getLoopbackAddress()));
+    }
+}

proxy/src/test/java/com/velocitypowered/proxy/util/ServerMapTest.java

@@ -0,0 +1,35 @@
+package com.velocitypowered.proxy.util;
+
+import com.velocitypowered.api.server.ServerInfo;
+import org.junit.jupiter.api.Test;
+
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ServerMapTest {
+    private static final InetSocketAddress TEST_ADDRESS = new InetSocketAddress(InetAddress.getLoopbackAddress(), 25565);
+
+    @Test
+    void respectsCaseInsensitivity() {
+        ServerMap map = new ServerMap();
+        ServerInfo info = new ServerInfo("TestServer", TEST_ADDRESS);
+        map.register(info);
+
+        assertEquals(Optional.of(info), map.getServer("TestServer"));
+        assertEquals(Optional.of(info), map.getServer("testserver"));
+        assertEquals(Optional.of(info), map.getServer("TESTSERVER"));
+    }
+
+    @Test
+    void rejectsRepeatedRegisterAttempts() {
+        ServerMap map = new ServerMap();
+        ServerInfo info = new ServerInfo("TestServer", TEST_ADDRESS);
+        map.register(info);
+
+        ServerInfo willReject = new ServerInfo("TESTSERVER", TEST_ADDRESS);
+        assertThrows(IllegalArgumentException.class, () -> map.register(willReject));
+    }
+}