Merge remote-tracking branch 'upstream/dev/3.0.0'

This reverts commit 11834de220.

.github/workflows/gradle.yml

@@ -14,10 +14,10 @@ jobs:
         persist-credentials: false
     - name: Set up Gradle
       uses: gradle/actions/setup-gradle@v4
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v4
       with:
-        java-version: 17
-        distribution: 'temurin'
+        java-version: 21
+        distribution: 'zulu'
     - name: Build with Gradle
       run: ./gradlew build

api/src/main/java/com/velocitypowered/api/command/CommandManager.java

@@ -7,8 +7,10 @@
 
 package com.velocitypowered.api.command;
 
+import com.mojang.brigadier.suggestion.Suggestions;
 import com.velocitypowered.api.event.command.CommandExecuteEvent;
 import java.util.Collection;
+import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Predicate;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -116,6 +118,27 @@ public interface CommandManager {
    */
   CompletableFuture<Boolean> executeImmediatelyAsync(CommandSource source, String cmdLine);
 
+  /**
+   * Asynchronously collects suggestions to fill in the given command {@code cmdLine}.
+   * Returns only the raw completion suggestions without tooltips.
+   *
+   * @param source  the source to execute the command for
+   * @param cmdLine the partially completed command
+   * @return a {@link CompletableFuture} eventually completed with a {@link List}, possibly empty
+   */
+  CompletableFuture<List<String>> offerSuggestions(CommandSource source, String cmdLine);
+
+  /**
+   * Asynchronously collects suggestions to fill in the given command {@code cmdLine}.
+   * Returns the brigadier {@link Suggestions} with tooltips for each result.
+   *
+   * @param source  the source to execute the command for
+   * @param cmdLine the partially completed command
+   * @return a {@link CompletableFuture} eventually completed with {@link Suggestions}, possibly
+   *         empty
+   */
+  CompletableFuture<Suggestions> offerBrigadierSuggestions(CommandSource source, String cmdLine);
+
   /**
    * Returns an immutable collection of the case-insensitive aliases registered
    * on this manager.

api/src/main/java/com/velocitypowered/api/network/ProtocolVersion.java

@@ -90,7 +90,9 @@ public enum ProtocolVersion implements Ordered<ProtocolVersion> {
   MINECRAFT_1_21(767, "1.21", "1.21.1"),
   MINECRAFT_1_21_2(768, "1.21.2", "1.21.3"),
   MINECRAFT_1_21_4(769, "1.21.4"),
-  MINECRAFT_1_21_5(770, /*1073742067,*/ "1.21.5");
+  MINECRAFT_1_21_5(770, "1.21.5"),
+  MINECRAFT_1_21_6(771, "1.21.6"),
+  MINECRAFT_1_21_7(772, "1.21.7", "1.21.8");
 
   private static final int SNAPSHOT_BIT = 30;
 

api/src/main/java/com/velocitypowered/api/proxy/config/ProxyConfig.java

@@ -148,4 +148,59 @@ public interface ProxyConfig {
    * @return read timeout (in milliseconds)
    */
   int getReadTimeout();
+
+  /**
+   * Get the rate limit for how fast a player can execute commands.
+   *
+   * @return the command rate limit (in milliseconds)
+   */
+  int getCommandRatelimit();
+
+  /**
+   * Get whether we should forward commands to the backend if the player is rate limited.
+   *
+   * @return whether to forward commands if rate limited
+   */
+  boolean isForwardCommandsIfRateLimited();
+
+  /**
+   * Get the kick limit for commands that are rate limited.
+   * If this limit is 0 or less, the player will be not be kicked.
+   *
+   * @return the rate limited command rate limit
+   */
+  int getKickAfterRateLimitedCommands();
+
+  /**
+   * Get whether the proxy should kick players who are command rate limited.
+   *
+   * @return whether to kick players who are rate limited
+   */
+  default boolean isKickOnCommandRateLimit() {
+    return getKickAfterRateLimitedCommands() > 0;
+  }
+
+  /**
+   * Get the rate limit for how fast a player can tab complete.
+   *
+   * @return the tab complete rate limit (in milliseconds)
+   */
+  int getTabCompleteRatelimit();
+
+  /**
+   * Get the kick limit for tab completes that are rate limited.
+   * If this limit is 0 or less, the player will be not be kicked.
+   *
+   * @return the rate limited command rate limit
+   */
+  int getKickAfterRateLimitedTabCompletes();
+
+  /**
+   * Get whether the proxy should kick players who are tab complete rate limited.
+   *
+   * @return whether to kick players who are rate limited
+   */
+  default boolean isKickOnTabCompleteRateLimit() {
+    return getKickAfterRateLimitedTabCompletes() > 0;
+  }
 }

api/src/main/java/com/velocitypowered/api/proxy/messages/MinecraftChannelIdentifier.java

@@ -11,7 +11,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 
 import com.google.common.base.Strings;
 import java.util.Objects;
-import java.util.regex.Pattern;
 import net.kyori.adventure.key.Key;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -21,8 +20,6 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  */
 public final class MinecraftChannelIdentifier implements ChannelIdentifier {
 
-  private static final Pattern VALID_IDENTIFIER_REGEX = Pattern.compile("[a-z0-9/\\-_]*");
-
   private final String namespace;
   private final String name;
 
@@ -39,7 +36,7 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
    * @return a new channel identifier
    */
   public static MinecraftChannelIdentifier forDefaultNamespace(String name) {
-    return new MinecraftChannelIdentifier("minecraft", name);
+    return new MinecraftChannelIdentifier(Key.MINECRAFT_NAMESPACE, name);
   }
 
   /**
@@ -52,14 +49,10 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
   public static MinecraftChannelIdentifier create(String namespace, String name) {
     checkArgument(!Strings.isNullOrEmpty(namespace), "namespace is null or empty");
     checkArgument(name != null, "namespace is null or empty");
-    checkArgument(VALID_IDENTIFIER_REGEX.matcher(namespace).matches(),
-        "namespace is not valid, must match: %s got %s",
-        VALID_IDENTIFIER_REGEX.toString(),
-        namespace);
-    checkArgument(VALID_IDENTIFIER_REGEX.matcher(name).matches(),
-        "name is not valid, must match: %s got %s",
-        VALID_IDENTIFIER_REGEX.toString(),
-        name);
+    checkArgument(Key.parseableNamespace(namespace),
+        "namespace is not valid, must match: [a-z0-9_.-] got %s", namespace);
+    checkArgument(Key.parseableValue(name),
+        "name is not valid, must match: [a-z0-9/._-] got %s", name);
     return new MinecraftChannelIdentifier(namespace, name);
   }
 
@@ -72,10 +65,9 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
   public static MinecraftChannelIdentifier from(String identifier) {
     int colonPos = identifier.indexOf(':');
     if (colonPos == -1) {
-      throw new IllegalArgumentException("Identifier does not contain a colon.");
-    }
-    if (colonPos + 1 == identifier.length()) {
-      throw new IllegalArgumentException("Identifier is empty.");
+      return create(Key.MINECRAFT_NAMESPACE, identifier);
+    } else if (colonPos == 0) {
+      return create(Key.MINECRAFT_NAMESPACE, identifier.substring(1));
     }
     String namespace = identifier.substring(0, colonPos);
     String name = identifier.substring(colonPos + 1);

api/src/main/java/com/velocitypowered/api/proxy/server/ServerPing.java

@@ -517,6 +517,10 @@ public final class ServerPing {
    */
   public static final class SamplePlayer {
 
+    public static final SamplePlayer ANONYMOUS = new SamplePlayer(
+        "Anonymous Player",
+        new UUID(0L, 0L)
+    );
     private final String name;
     private final UUID id;
 

api/src/test/java/com/velocitypowered/api/proxy/messages/MinecraftChannelIdentifierTest.java

@@ -47,17 +47,25 @@ class MinecraftChannelIdentifierTest {
     create("velocity", "test/test2");
   }
 
+  @Test
+  void fromIdentifierDefaultNamespace() {
+    assertEquals("minecraft", from("test").getNamespace());
+    assertEquals("minecraft", from(":test").getNamespace());
+  }
+
+  @Test
+  void fromIdentifierAllowsEmptyName() {
+    from("minecraft:");
+    from(":");
+    from("");
+  }
+
   @Test
   void fromIdentifierThrowsOnBadValues() {
     assertAll(
-        () -> assertThrows(IllegalArgumentException.class, () -> from("")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from(":")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from(":a")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from("a:")),
         () -> assertThrows(IllegalArgumentException.class, () -> from("hello:$$$$$$")),
+        () -> assertThrows(IllegalArgumentException.class, () -> from("he/llo:wor/ld")),
         () -> assertThrows(IllegalArgumentException.class, () -> from("hello::"))
     );
   }
-
-
 }

build-logic/src/main/kotlin/velocity-init-manifest.gradle.kts

@@ -2,8 +2,15 @@ import org.gradle.jvm.tasks.Jar
 import org.gradle.kotlin.dsl.withType
 import java.io.ByteArrayOutputStream
 
+// This interface is needed as a workaround to get an instance of ExecOperations
+interface Injected {
+    @get:Inject
+    val execOps: ExecOperations
+}
+
 val currentShortRevision = ByteArrayOutputStream().use {
-    exec {
+    val execOps = objects.newInstance<Injected>().execOps
+    execOps.exec {
         executable = "git"
         args = listOf("rev-parse", "HEAD")
         standardOutput = it

build-logic/src/main/kotlin/velocity-publish.gradle.kts

@@ -8,7 +8,7 @@ extensions.configure<PublishingExtension> {
         maven {
             credentials(PasswordCredentials::class.java)
 
-            name = "paper"
+            name = if (version.toString().endsWith("SNAPSHOT")) "paperSnapshots" else "paper" // "paper" is seemingly not defined
             val base = "https://repo.papermc.io/repository/maven"
             val releasesRepoUrl = "$base-releases/"
             val snapshotsRepoUrl = "$base-snapshots/"

build.gradle.kts

@@ -20,11 +20,11 @@ subprojects {
         testImplementation(rootProject.libs.junit)
     }
 
-    tasks {
-        test {
-            useJUnitPlatform()
-            reports {
-                junitXml.required.set(true)
+    testing.suites.named<JvmTestSuite>("test") {
+        useJUnitJupiter()
+        targets.all {
+            testTask.configure {
+                reports.junitXml.required = true
             }
         }
     }

gradle/libs.versions.toml

@@ -2,19 +2,20 @@
 configurate3 = "3.7.3"
 configurate4 = "4.1.2"
 flare = "2.0.1"
-log4j = "2.24.1"
-netty = "4.1.119.Final"
+log4j = "2.24.3"
+netty = "4.2.1.Final"
 
 [plugins]
+fill = "io.papermc.fill.gradle:1.0.3"
 indra-publishing = "net.kyori.indra.publishing:2.0.6"
-shadow = "io.github.goooler.shadow:8.1.5"
+shadow = "com.gradleup.shadow:8.3.6"
 spotless = "com.diffplug.spotless:6.25.0"
 
 [libraries]
-adventure-bom = "net.kyori:adventure-bom:4.19.0"
-adventure-text-serializer-json-legacy-impl = "net.kyori:adventure-text-serializer-json-legacy-impl:4.19.0"
+adventure-bom = "net.kyori:adventure-bom:4.23.0"
+adventure-text-serializer-json-legacy-impl = "net.kyori:adventure-text-serializer-json-legacy-impl:4.23.0"
 adventure-facet = "net.kyori:adventure-platform-facet:4.3.4"
-asm = "org.ow2.asm:asm:9.7.1"
+asm = "org.ow2.asm:asm:9.8"
 auto-service = "com.google.auto.service:auto-service:1.0.1"
 auto-service-annotations = "com.google.auto.service:auto-service-annotations:1.0.1"
 brigadier = "com.velocitypowered:velocity-brigadier:1.0.0-SNAPSHOT"
@@ -33,7 +34,7 @@ disruptor = "com.lmax:disruptor:4.0.0"
 fastutil = "it.unimi.dsi:fastutil:8.5.15"
 flare-core = { module = "space.vectrix.flare:flare", version.ref = "flare" }
 flare-fastutil = { module = "space.vectrix.flare:flare-fastutil", version.ref = "flare" }
-jline = "org.jline:jline-terminal-jansi:3.27.1"
+jline = "org.jline:jline-terminal-jansi:3.30.2"
 jopt = "net.sf.jopt-simple:jopt-simple:5.0.4"
 junit = "org.junit.jupiter:junit-jupiter:5.10.2"
 jspecify = "org.jspecify:jspecify:0.3.0"
@@ -53,10 +54,10 @@ netty-codec-haproxy = { module = "io.netty:netty-codec-haproxy", version.ref = "
 netty-codec-http = { module = "io.netty:netty-codec-http", version.ref = "netty" }
 netty-handler = { module = "io.netty:netty-handler", version.ref = "netty" }
 netty-transport-native-epoll = { module = "io.netty:netty-transport-native-epoll", version.ref = "netty" }
-netty-transport-native-iouring = { module = "io.netty.incubator:netty-incubator-transport-native-io_uring", version = "0.0.25.Final" }
 netty-transport-native-kqueue = { module = "io.netty:netty-transport-native-kqueue", version.ref = "netty" }
+netty-transport-native-iouring = { module = "io.netty:netty-transport-native-io_uring", version.ref = "netty" }
 nightconfig = "com.electronwill.night-config:toml:3.6.7"
-slf4j = "org.slf4j:slf4j-api:2.0.12"
+slf4j = "org.slf4j:slf4j-api:2.0.17"
 snakeyaml = "org.yaml:snakeyaml:1.33"
 spotbugs-annotations = "com.github.spotbugs:spotbugs-annotations:4.7.3"
 terminalconsoleappender = "net.minecrell:terminalconsoleappender:1.3.0"

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.2-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

proxy/build.gradle.kts

@@ -1,9 +1,11 @@
 import com.github.jengelman.gradle.plugins.shadow.transformers.Log4j2PluginsCacheFileTransformer
+import io.papermc.fill.model.BuildChannel
 
 plugins {
     application
     id("velocity-init-manifest")
     alias(libs.plugins.shadow)
+    alias(libs.plugins.fill)
 }
 
 application {
@@ -100,6 +102,7 @@ tasks {
     runShadow {
         workingDir = file("run").also(File::mkdirs)
         standardInput = System.`in`
+        jvmArgs("-Dvelocity.packet-decode-logging=true")
     }
     named<JavaExec>("run") {
         workingDir = file("run").also(File::mkdirs)
@@ -107,6 +110,24 @@ tasks {
     }
 }
 
+val projectVersion = version as String
+fill {
+    project("velocity")
+
+    build {
+        channel = BuildChannel.STABLE
+        versionFamily("3.0.0")
+        version(projectVersion)
+
+        downloads {
+            register("server:default") {
+                file = tasks.shadowJar.flatMap { it.archiveFile }
+                nameResolver.set { project, _, version, build -> "$project-$version-$build.jar" }
+            }
+        }
+    }
+}
+
 dependencies {
     implementation(project(":velocity-api"))
     implementation(project(":velocity-native"))

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

@@ -47,6 +47,11 @@ public class Velocity {
       System.setProperty("io.netty.native.workdir", System.getProperty("velocity.natives-tmpdir"));
     }
 
+    // Restore allocator used before Netty 4.2 due to oom issues with the adaptive allocator
+    if (System.getProperty("io.netty.allocator.type") == null) {
+      System.setProperty("io.netty.allocator.type", "pooled");
+    }
+
     // Disable the resource leak detector by default as it reduces performance. Allow the user to
     // override this if desired.
     if (!VelocityProperties.hasProperty("io.netty.leakDetection.level")) {

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

@@ -75,11 +75,13 @@ import io.netty.channel.ChannelInitializer;
 import io.netty.channel.EventLoopGroup;
 import java.io.IOException;
 import java.io.InputStream;
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.http.HttpClient;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.security.KeyPair;
+import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -103,7 +105,7 @@ import net.kyori.adventure.audience.ForwardingAudience;
 import net.kyori.adventure.key.Key;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.translation.GlobalTranslator;
-import net.kyori.adventure.translation.TranslationRegistry;
+import net.kyori.adventure.translation.TranslationStore;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.bstats.MetricsBase;
@@ -162,7 +164,9 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
   private final Map<UUID, ConnectedPlayer> connectionsByUuid = new ConcurrentHashMap<>();
   private final Map<String, ConnectedPlayer> connectionsByName = new ConcurrentHashMap<>();
   private final VelocityConsole console;
-  private @MonotonicNonNull Ratelimiter ipAttemptLimiter;
+  private @MonotonicNonNull Ratelimiter<InetAddress> ipAttemptLimiter;
+  private @MonotonicNonNull Ratelimiter<UUID> commandRateLimiter;
+  private @MonotonicNonNull Ratelimiter<UUID> tabCompleteRateLimiter;
   private final VelocityEventManager eventManager;
   private final VelocityScheduler scheduler;
   private final VelocityChannelRegistrar channelRegistrar = new VelocityChannelRegistrar();
@@ -295,6 +299,8 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
     }
 
     ipAttemptLimiter = Ratelimiters.createWithMilliseconds(configuration.getLoginRatelimit());
+    commandRateLimiter = Ratelimiters.createWithMilliseconds(configuration.getCommandRatelimit());
+    tabCompleteRateLimiter = Ratelimiters.createWithMilliseconds(configuration.getTabCompleteRatelimit());
     loadPlugins();
 
     // Go ahead and fire the proxy initialization event. We block since plugins should have a chance
@@ -332,8 +338,8 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
   }
 
   private void registerTranslations() {
-    final TranslationRegistry translationRegistry = TranslationRegistry
-        .create(Key.key("velocity", "translations"));
+    final TranslationStore.StringBased<MessageFormat> translationRegistry =
+            TranslationStore.messageFormat(Key.key("velocity", "translations"));
     translationRegistry.defaultLocale(Locale.US);
     try {
       ResourceUtils.visitResources(VelocityServer.class, path -> {
@@ -654,10 +660,18 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
     return cm.createHttpClient();
   }
 
-  public Ratelimiter getIpAttemptLimiter() {
+  public @MonotonicNonNull Ratelimiter<InetAddress> getIpAttemptLimiter() {
     return ipAttemptLimiter;
   }
 
+  public @MonotonicNonNull Ratelimiter<UUID> getCommandRateLimiter() {
+    return commandRateLimiter;
+  }
+
+  public @MonotonicNonNull Ratelimiter<UUID> getTabCompleteRateLimiter() {
+    return tabCompleteRateLimiter;
+  }
+
   /**
    * Checks if the {@code connection} can be registered with the proxy.
    *

proxy/src/main/java/com/velocitypowered/proxy/command/VelocityCommandManager.java

@@ -300,27 +300,14 @@ public class VelocityCommandManager implements CommandManager {
     );
   }
 
-  /**
-   * Returns suggestions to fill in the given command.
-   *
-   * @param source  the source to execute the command for
-   * @param cmdLine the partially completed command
-   * @return a {@link CompletableFuture} eventually completed with a {@link List}, possibly empty
-   */
+  @Override
   public CompletableFuture<List<String>> offerSuggestions(final CommandSource source,
       final String cmdLine) {
     return offerBrigadierSuggestions(source, cmdLine)
         .thenApply(suggestions -> Lists.transform(suggestions.getList(), Suggestion::getText));
   }
 
-  /**
-   * Returns suggestions to fill in the given command.
-   *
-   * @param source  the source to execute the command for
-   * @param cmdLine the partially completed command
-   * @return a {@link CompletableFuture} eventually completed with {@link Suggestions}, possibly
-   *         empty
-   */
+  @Override
   public CompletableFuture<Suggestions> offerBrigadierSuggestions(
       final CommandSource source, final String cmdLine) {
     Preconditions.checkNotNull(source, "source");

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

@@ -78,6 +78,8 @@ public class VelocityConfiguration implements ProxyConfig {
   private boolean onlineModeKickExistingPlayers = false;
   @Expose
   private PingPassthroughMode pingPassthrough = PingPassthroughMode.DISABLED;
+  @Expose
+  private boolean samplePlayersInPing = false;
   private final Servers servers;
   private final ForcedHosts forcedHosts;
   @Expose
@@ -105,8 +107,9 @@ public class VelocityConfiguration implements ProxyConfig {
       boolean preventClientProxyConnections, boolean announceForge,
       PlayerInfoForwarding playerInfoForwardingMode, byte[] forwardingSecret,
       boolean onlineModeKickExistingPlayers, PingPassthroughMode pingPassthrough,
-      boolean enablePlayerAddressLogging, Servers servers, ForcedHosts forcedHosts,
-      Advanced advanced, Query query, Metrics metrics, boolean forceKeyAuthentication) {
+      boolean samplePlayersInPing, boolean enablePlayerAddressLogging, Servers servers,
+      ForcedHosts forcedHosts, Advanced advanced, Query query, Metrics metrics,
+      boolean forceKeyAuthentication) {
     this.bind = bind;
     this.motd = motd;
     this.showMaxPlayers = showMaxPlayers;
@@ -117,6 +120,7 @@ public class VelocityConfiguration implements ProxyConfig {
     this.forwardingSecret = forwardingSecret;
     this.onlineModeKickExistingPlayers = onlineModeKickExistingPlayers;
     this.pingPassthrough = pingPassthrough;
+    this.samplePlayersInPing = samplePlayersInPing;
     this.enablePlayerAddressLogging = enablePlayerAddressLogging;
     this.servers = servers;
     this.forcedHosts = forcedHosts;
@@ -230,6 +234,11 @@ public class VelocityConfiguration implements ProxyConfig {
       valid = false;
     }
 
+    if (advanced.commandRateLimit < 0) {
+      logger.error("Invalid command rate limit {}", advanced.commandRateLimit);
+      valid = false;
+    }
+
     loadFavicon();
 
     return valid;
@@ -351,6 +360,31 @@ public class VelocityConfiguration implements ProxyConfig {
     return advanced.getReadTimeout();
   }
 
+  @Override
+  public int getCommandRatelimit() {
+    return advanced.getCommandRateLimit();
+  }
+
+  @Override
+  public int getTabCompleteRatelimit() {
+    return advanced.getTabCompleteRateLimit();
+  }
+
+  @Override
+  public int getKickAfterRateLimitedTabCompletes() {
+    return advanced.getKickAfterRateLimitedTabCompletes();
+  }
+
+  @Override
+  public boolean isForwardCommandsIfRateLimited() {
+    return advanced.isForwardCommandsIfRateLimited();
+  }
+
+  @Override
+  public int getKickAfterRateLimitedCommands() {
+    return advanced.getKickAfterRateLimitedCommands();
+  }
+
   public boolean isProxyProtocol() {
     return advanced.isProxyProtocol();
   }
@@ -371,6 +405,10 @@ public class VelocityConfiguration implements ProxyConfig {
     return pingPassthrough;
   }
 
+  public boolean getSamplePlayersInPing() {
+    return samplePlayersInPing;
+  }
+
   public boolean isPlayerAddressLoggingEnabled() {
     return enablePlayerAddressLogging;
   }
@@ -507,6 +545,8 @@ public class VelocityConfiguration implements ProxyConfig {
       final PingPassthroughMode pingPassthroughMode = config.getEnumOrElse("ping-passthrough",
               PingPassthroughMode.DISABLED);
 
+      final boolean samplePlayersInPing = config.getOrElse("sample-players-in-ping", false);
+
       final String bind = config.getOrElse("bind", "0.0.0.0:25565");
       final int maxPlayers = config.getIntOrElse("show-max-players", 500);
       final boolean onlineMode = config.getOrElse("online-mode", true);
@@ -537,6 +577,7 @@ public class VelocityConfiguration implements ProxyConfig {
               forwardingSecret,
               kickExisting,
               pingPassthroughMode,
+              samplePlayersInPing,
               enablePlayerAddressLogging,
               new Servers(serversConfig),
               new ForcedHosts(forcedHostsConfig),
@@ -722,6 +763,16 @@ public class VelocityConfiguration implements ProxyConfig {
     private boolean acceptTransfers = false;
     @Expose
     private boolean enableReusePort = false;
+    @Expose
+    private int commandRateLimit = 50;
+    @Expose
+    private boolean forwardCommandsIfRateLimited = true;
+    @Expose
+    private int kickAfterRateLimitedCommands = 5;
+    @Expose
+    private int tabCompleteRateLimit = 50;
+    @Expose
+    private int kickAfterRateLimitedTabCompletes = 10;
 
     private Advanced() {
     }
@@ -748,6 +799,11 @@ public class VelocityConfiguration implements ProxyConfig {
         this.logPlayerConnections = config.getOrElse("log-player-connections", true);
         this.acceptTransfers = config.getOrElse("accepts-transfers", false);
         this.enableReusePort = config.getOrElse("enable-reuse-port", false);
+        this.commandRateLimit = config.getIntOrElse("command-rate-limit", 25);
+        this.forwardCommandsIfRateLimited = config.getOrElse("forward-commands-if-rate-limited", true);
+        this.kickAfterRateLimitedCommands = config.getIntOrElse("kick-after-rate-limited-commands", 0);
+        this.tabCompleteRateLimit = config.getIntOrElse("tab-complete-rate-limit", 10); // very lenient
+        this.kickAfterRateLimitedTabCompletes = config.getIntOrElse("kick-after-rate-limited-tab-completes", 0);
       }
     }
 
@@ -815,6 +871,26 @@ public class VelocityConfiguration implements ProxyConfig {
       return enableReusePort;
     }
 
+    public int getCommandRateLimit() {
+      return commandRateLimit;
+    }
+
+    public boolean isForwardCommandsIfRateLimited() {
+      return forwardCommandsIfRateLimited;
+    }
+
+    public int getKickAfterRateLimitedCommands() {
+      return kickAfterRateLimitedCommands;
+    }
+
+    public int getTabCompleteRateLimit() {
+      return tabCompleteRateLimit;
+    }
+
+    public int getKickAfterRateLimitedTabCompletes() {
+      return kickAfterRateLimitedTabCompletes;
+    }
+
     @Override
     public String toString() {
       return "Advanced{"

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftConnection.java

@@ -46,6 +46,7 @@ import com.velocitypowered.proxy.protocol.netty.MinecraftCompressDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftCompressorAndLengthEncoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
+import com.velocitypowered.proxy.protocol.netty.MinecraftVarintFrameDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftVarintLengthEncoder;
 import com.velocitypowered.proxy.protocol.netty.PlayPacketQueueInboundHandler;
 import com.velocitypowered.proxy.protocol.netty.PlayPacketQueueOutboundHandler;
@@ -84,6 +85,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
   private static final Logger logger = LogManager.getLogger(MinecraftConnection.class);
 
   private final Channel channel;
+  public boolean pendingConfigurationSwitch = false;
   private SocketAddress remoteAddress;
   private StateRegistry state;
   private Map<StateRegistry, MinecraftSessionHandler> sessionHandlers;
@@ -367,6 +369,11 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     ensureInEventLoop();
 
     this.state = state;
+    final MinecraftVarintFrameDecoder frameDecoder = this.channel.pipeline()
+        .get(MinecraftVarintFrameDecoder.class);
+    if (frameDecoder != null) {
+      frameDecoder.setState(state);
+    }
     // If the connection is LEGACY (<1.6), the decoder and encoder are not set.
     final MinecraftEncoder minecraftEncoder = this.channel.pipeline()
         .get(MinecraftEncoder.class);

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

@@ -49,6 +49,7 @@ import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
+import com.velocitypowered.proxy.protocol.netty.MinecraftVarintFrameDecoder;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommandsPacket;
 import com.velocitypowered.proxy.protocol.packet.BossBarPacket;
 import com.velocitypowered.proxy.protocol.packet.BundleDelimiterPacket;
@@ -151,6 +152,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
     MinecraftConnection smc = serverConn.ensureConnected();
     smc.setAutoReading(false);
     // Even when not auto reading messages are still decoded. Decode them with the correct state
+    smc.getChannel().pipeline().get(MinecraftVarintFrameDecoder.class).setState(StateRegistry.CONFIG);
     smc.getChannel().pipeline().get(MinecraftDecoder.class).setState(StateRegistry.CONFIG);
     serverConn.getPlayer().switchToConfigState();
     return true;

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

@@ -20,6 +20,7 @@ package com.velocitypowered.proxy.connection.backend;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ServerConnection;
+import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
@@ -316,9 +317,9 @@ public class BungeeCordMessageResponder {
     });
   }
 
-  static String getBungeeCordChannel(ProtocolVersion version) {
-    return version.noLessThan(ProtocolVersion.MINECRAFT_1_13) ? MODERN_CHANNEL.getId()
-        : LEGACY_CHANNEL.getId();
+  static ChannelIdentifier getBungeeCordChannel(ProtocolVersion version) {
+    return version.noLessThan(ProtocolVersion.MINECRAFT_1_13) ? MODERN_CHANNEL
+        : LEGACY_CHANNEL;
   }
 
   // Note: this method will always release the buffer!
@@ -329,8 +330,8 @@ public class BungeeCordMessageResponder {
   // Note: this method will always release the buffer!
   private static void sendServerResponse(ConnectedPlayer player, ByteBuf buf) {
     MinecraftConnection serverConnection = player.ensureAndGetCurrentServer().ensureConnected();
-    String chan = getBungeeCordChannel(serverConnection.getProtocolVersion());
-    PluginMessagePacket msg = new PluginMessagePacket(chan, buf);
+    ChannelIdentifier chan = getBungeeCordChannel(serverConnection.getProtocolVersion());
+    PluginMessagePacket msg = new PluginMessagePacket(chan.getId(), buf);
     serverConnection.write(msg);
   }
 

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

@@ -40,6 +40,7 @@ import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
+import com.velocitypowered.proxy.protocol.netty.MinecraftVarintFrameDecoder;
 import com.velocitypowered.proxy.protocol.packet.ClientboundCookieRequestPacket;
 import com.velocitypowered.proxy.protocol.packet.ClientboundStoreCookiePacket;
 import com.velocitypowered.proxy.protocol.packet.DisconnectPacket;
@@ -232,6 +233,7 @@ public class ConfigSessionHandler implements MinecraftSessionHandler {
     final ConnectedPlayer player = serverConn.getPlayer();
     final ClientConfigSessionHandler configHandler = (ClientConfigSessionHandler) player.getConnection().getActiveSessionHandler();
 
+    smc.getChannel().pipeline().get(MinecraftVarintFrameDecoder.class).setState(StateRegistry.PLAY);
     smc.getChannel().pipeline().get(MinecraftDecoder.class).setState(StateRegistry.PLAY);
     //noinspection DataFlowIssue
     configHandler.handleBackendFinishUpdate(serverConn).thenRunAsync(() -> {

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

@@ -170,7 +170,11 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
   @Override
   public boolean handle(KnownPacksPacket packet) {
     callConfigurationEvent().thenRun(() -> {
-      player.getConnectionInFlightOrConnectedServer().ensureConnected().write(packet);
+      VelocityServerConnection targetServer =
+          player.getConnectionInFlightOrConnectedServer();
+      if (targetServer != null) {
+        targetServer.ensureConnected().write(packet);
+      }
     }).exceptionally(ex -> {
       logger.error("Error forwarding known packs response to backend:", ex);
       return null;

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

@@ -74,6 +74,7 @@ import com.velocitypowered.proxy.protocol.packet.config.FinishedUpdatePacket;
 import com.velocitypowered.proxy.protocol.packet.title.GenericTitlePacket;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import com.velocitypowered.proxy.util.CharacterUtil;
+import com.velocitypowered.proxy.util.except.QuietRuntimeException;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
@@ -113,6 +114,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
   private CompletableFuture<Void> configSwitchFuture;
 
+  private int failedTabCompleteAttempts;
+
   /**
    * Constructs a client play session handler.
    *
@@ -160,7 +163,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
   @Override
   public void activated() {
     configSwitchFuture = new CompletableFuture<>();
-    Collection<String> channels =
+    Collection<ChannelIdentifier> channels =
         server.getChannelRegistrar().getChannelsForProtocol(player.getProtocolVersion());
     if (!channels.isEmpty()) {
       PluginMessagePacket register = constructChannelsPacket(player.getProtocolVersion(), channels);
@@ -308,20 +311,17 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         logger.warn("A plugin message was received while the backend server was not "
             + "ready. Channel: {}. Packet discarded.", packet.getChannel());
       } else if (PluginMessageUtil.isRegister(packet)) {
-        List<String> channels = PluginMessageUtil.getChannels(packet);
-        List<ChannelIdentifier> channelIdentifiers = new ArrayList<>();
-        for (String channel : channels) {
-          try {
-            channelIdentifiers.add(MinecraftChannelIdentifier.from(channel));
-          } catch (IllegalArgumentException e) {
-            channelIdentifiers.add(new LegacyChannelIdentifier(channel));
-          }
-        }
+        List<ChannelIdentifier> channels =
+            PluginMessageUtil.getChannels(this.player.getClientsideChannels().size(), packet,
+                this.player.getProtocolVersion());
+        player.getClientsideChannels().addAll(channels);
         server.getEventManager()
             .fireAndForget(
-                new PlayerChannelRegisterEvent(player, ImmutableList.copyOf(channelIdentifiers)));
+                new PlayerChannelRegisterEvent(player, ImmutableList.copyOf(channels)));
         backendConn.write(packet.retain());
       } else if (PluginMessageUtil.isUnregister(packet)) {
+        player.getClientsideChannels()
+            .removeAll(PluginMessageUtil.getChannels(0, packet, this.player.getProtocolVersion()));
         backendConn.write(packet.retain());
       } else if (PluginMessageUtil.isMcBrand(packet)) {
         String brand = PluginMessageUtil.readBrandMessage(packet.content());
@@ -377,10 +377,14 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(FinishedUpdatePacket packet) {
+    if (!player.getConnection().pendingConfigurationSwitch) {
+      throw new QuietRuntimeException("Not expecting reconfiguration");
+    }
     // Complete client switch
     player.getConnection().setActiveSessionHandler(StateRegistry.CONFIG);
     VelocityServerConnection serverConnection = player.getConnectedServer();
-    server.getEventManager().fireAndForget(new PlayerEnteredConfigurationEvent(player, serverConnection));
+    server.getEventManager()
+        .fireAndForget(new PlayerEnteredConfigurationEvent(player, serverConnection));
     if (serverConnection != null) {
       MinecraftConnection smc = serverConnection.ensureConnected();
       CompletableFuture.runAsync(() -> {
@@ -567,11 +571,15 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
     // Tell the server about the proxy's plugin message channels.
     ProtocolVersion serverVersion = serverMc.getProtocolVersion();
-    final Collection<String> channels = server.getChannelRegistrar()
+    final Collection<ChannelIdentifier> channels = server.getChannelRegistrar()
         .getChannelsForProtocol(serverMc.getProtocolVersion());
     if (!channels.isEmpty()) {
       serverMc.delayedWrite(constructChannelsPacket(serverVersion, channels));
     }
+    // Tell the server about this client's plugin message channels.
+    if (!player.getClientsideChannels().isEmpty()) {
+      serverMc.delayedWrite(constructChannelsPacket(serverVersion, player.getClientsideChannels()));
+    }
 
     // If we had plugin messages queued during login/FML handshake, send them now.
     PluginMessagePacket pm;
@@ -653,6 +661,17 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       return false;
     }
 
+    if (!server.getTabCompleteRateLimiter().attempt(player.getUniqueId())) {
+      if (server.getConfiguration().isKickOnTabCompleteRateLimit()
+              && failedTabCompleteAttempts++ >= server.getConfiguration().getKickAfterRateLimitedTabCompletes()) {
+        player.disconnect(Component.translatable("velocity.kick.tab-complete-rate-limit"));
+      }
+
+      return true;
+    }
+
+    failedTabCompleteAttempts = 0;
+
     server.getCommandManager().offerBrigadierSuggestions(player, command)
         .thenAcceptAsync(suggestions -> {
           if (suggestions.isEmpty()) {

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

@@ -99,6 +99,7 @@ import com.velocitypowered.proxy.tablist.VelocityTabListLegacy;
 import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
 import com.velocitypowered.proxy.util.DurationUtils;
 import com.velocitypowered.proxy.util.TranslatableMapper;
+import com.velocitypowered.proxy.util.collect.CappedSet;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import java.net.InetSocketAddress;
@@ -122,6 +123,7 @@ import net.kyori.adventure.permission.PermissionChecker;
 import net.kyori.adventure.platform.facet.FacetPointers;
 import net.kyori.adventure.platform.facet.FacetPointers.Type;
 import net.kyori.adventure.pointer.Pointers;
+import net.kyori.adventure.pointer.PointersSupplier;
 import net.kyori.adventure.resource.ResourcePackInfoLike;
 import net.kyori.adventure.resource.ResourcePackRequest;
 import net.kyori.adventure.resource.ResourcePackRequestLike;
@@ -144,13 +146,23 @@ import org.jetbrains.annotations.NotNull;
 public class ConnectedPlayer implements MinecraftConnectionAssociation, Player, KeyIdentifiable,
     VelocityInboundConnection {
 
+  public static final int MAX_CLIENTSIDE_PLUGIN_CHANNELS = Integer.getInteger("velocity.max-clientside-plugin-channels", 1024);
   private static final PlainTextComponentSerializer PASS_THRU_TRANSLATE =
       PlainTextComponentSerializer.builder().flattener(TranslatableMapper.FLATTENER).build();
   static final PermissionProvider DEFAULT_PERMISSIONS = s -> PermissionFunction.ALWAYS_UNDEFINED;
 
   private static final ComponentLogger logger = ComponentLogger.logger(ConnectedPlayer.class);
 
-  private final Identity identity = new IdentityImpl();
+  private static final @NotNull PointersSupplier<ConnectedPlayer> POINTERS_SUPPLIER =
+          PointersSupplier.<ConnectedPlayer>builder()
+                  .resolving(Identity.UUID, Player::getUniqueId)
+                  .resolving(Identity.NAME, Player::getUsername)
+                  .resolving(Identity.DISPLAY_NAME, player -> Component.text(player.getUsername()))
+                  .resolving(Identity.LOCALE, Player::getEffectiveLocale)
+                  .resolving(PermissionChecker.POINTER, Player::getPermissionChecker)
+                  .resolving(FacetPointers.TYPE, player -> Type.PLAYER)
+                  .build();
+
   /**
    * The actual Minecraft connection. This is actually a wrapper object around the Netty channel.
    */
@@ -173,19 +185,12 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
   private final InternalTabList tabList;
   private final VelocityServer server;
   private ClientConnectionPhase connectionPhase;
+  private final Collection<ChannelIdentifier> clientsideChannels;
   private final CompletableFuture<Void> teardownFuture = new CompletableFuture<>();
   private @MonotonicNonNull List<String> serversToTry = null;
   private final ResourcePackHandler resourcePackHandler;
   private final BundleDelimiterHandler bundleHandler = new BundleDelimiterHandler(this);
 
-  private final @NotNull Pointers pointers =
-      Player.super.pointers().toBuilder()
-          .withDynamic(Identity.UUID, this::getUniqueId)
-          .withDynamic(Identity.NAME, this::getUsername)
-          .withDynamic(Identity.DISPLAY_NAME, () -> Component.text(this.getUsername()))
-          .withDynamic(Identity.LOCALE, this::getEffectiveLocale)
-          .withStatic(PermissionChecker.POINTER, getPermissionChecker())
-          .withStatic(FacetPointers.TYPE, Type.PLAYER).build();
   private @Nullable String clientBrand;
   private @Nullable Locale effectiveLocale;
   private final @Nullable IdentifiedKey playerKey;
@@ -205,6 +210,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     this.permissionFunction = PermissionFunction.ALWAYS_UNDEFINED;
     this.connectionPhase = connection.getType().getInitialClientPhase();
     this.onlineMode = onlineMode;
+    this.clientsideChannels = CappedSet.create(MAX_CLIENTSIDE_PLUGIN_CHANNELS);
 
     if (connection.getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_19_3)) {
       this.tabList = new VelocityTabList(this);
@@ -253,7 +259,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
 
   @Override
   public @NonNull Identity identity() {
-    return this.identity;
+    return Identity.identity(this.getUniqueId());
   }
 
   @Override
@@ -359,7 +365,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
 
   @Override
   public @NotNull Pointers pointers() {
-    return this.pointers;
+    return POINTERS_SUPPLIER.view(this);
   }
 
   @Override
@@ -392,14 +398,20 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
   }
 
   /**
-   * Translates the message in the user's locale.
+   * Translates the message in the user's locale, falling back to the default locale if not set.
    *
    * @param message the message to translate
    * @return the translated message
    */
   public Component translateMessage(Component message) {
-    Locale locale = ClosestLocaleMatcher.INSTANCE
-        .lookupClosest(getEffectiveLocale() == null ? Locale.getDefault() : getEffectiveLocale());
+    Locale locale = this.getEffectiveLocale();
+    if (locale == null && settings != null) {
+      locale = settings.getLocale();
+    }
+    if (locale == null) {
+      locale = Locale.getDefault();
+    }
+    locale = ClosestLocaleMatcher.INSTANCE.lookupClosest(locale);
     return GlobalTranslator.render(message, locale);
   }
 
@@ -1314,6 +1326,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
             connection.write(BundleDelimiterPacket.INSTANCE);
           }
           connection.write(StartUpdatePacket.INSTANCE);
+          connection.pendingConfigurationSwitch = true;
           connection.getChannel().pipeline().get(MinecraftEncoder.class).setState(StateRegistry.CONFIG);
           // Make sure we don't send any play packets to the player after update start
           connection.addPlayPacketQueueHandler();
@@ -1342,19 +1355,20 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     this.connectionPhase = connectionPhase;
   }
 
+  /**
+   * Return all the plugin message channels that registered by client.
+   *
+   * @return the channels
+   */
+  public Collection<ChannelIdentifier> getClientsideChannels() {
+    return clientsideChannels;
+  }
+
   @Override
   public @Nullable IdentifiedKey getIdentifiedKey() {
     return playerKey;
   }
 
-  private class IdentityImpl implements Identity {
-
-    @Override
-    public @NonNull UUID uuid() {
-      return ConnectedPlayer.this.getUniqueId();
-    }
-  }
-
   @Override
   public ProtocolState getProtocolState() {
     return connection.getState().toProtocolState();

proxy/src/main/java/com/velocitypowered/proxy/connection/util/ServerListPingHandler.java

@@ -30,10 +30,12 @@ import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
 
 /**
  * Common utilities for handling server list ping results.
@@ -51,11 +53,27 @@ public class ServerListPingHandler {
       version = ProtocolVersion.MAXIMUM_VERSION;
     }
     VelocityConfiguration configuration = server.getConfiguration();
+    List<ServerPing.SamplePlayer> samplePlayers;
+    if (configuration.getSamplePlayersInPing()) {
+      List<ServerPing.SamplePlayer> unshuffledPlayers = server.getAllPlayers().stream()
+              .map(p -> {
+                if (p.getPlayerSettings().isClientListingAllowed()) {
+                  return new ServerPing.SamplePlayer(p.getUsername(), p.getUniqueId());
+                } else {
+                  return ServerPing.SamplePlayer.ANONYMOUS;
+                }
+              })
+              .collect(Collectors.toList());
+      Collections.shuffle(unshuffledPlayers);
+      samplePlayers = unshuffledPlayers.subList(0, Math.min(12, server.getPlayerCount()));
+    } else {
+      samplePlayers = ImmutableList.of();
+    }
     return new ServerPing(
         new ServerPing.Version(version.getProtocol(),
             "Velocity " + ProtocolVersion.SUPPORTED_VERSION_STRING),
         new ServerPing.Players(server.getPlayerCount(), configuration.getShowMaxPlayers(),
-            ImmutableList.of()),
+            samplePlayers),
         configuration.getMotd(),
         configuration.getFavicon().orElse(null),
         configuration.isAnnounceForge() ? ModInfo.DEFAULT : null

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

@@ -51,7 +51,7 @@ public class BackendChannelInitializer extends ChannelInitializer<Channel> {
   @Override
   protected void initChannel(Channel ch) {
     ch.pipeline()
-        .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
+        .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder(ProtocolUtils.Direction.CLIENTBOUND))
         .addLast(READ_TIMEOUT,
             new ReadTimeoutHandler(server.getConfiguration().getReadTimeout(),
                 TimeUnit.MILLISECONDS))

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

@@ -104,7 +104,7 @@ public final class ConnectionManager {
         .childOption(ChannelOption.IP_TOS, 0x18)
         .localAddress(address);
 
-    if (transportType.supportsTcpFastOpenServer() && server.getConfiguration().useTcpFastOpen()) {
+    if (server.getConfiguration().useTcpFastOpen()) {
       bootstrap.option(ChannelOption.TCP_FASTOPEN, 3);
     }
 
@@ -197,7 +197,7 @@ public final class ConnectionManager {
             this.server.getConfiguration().getConnectTimeout())
         .group(group == null ? this.workerGroup : group)
         .resolver(this.resolver.asGroup());
-    if (transportType.supportsTcpFastOpenClient() && server.getConfiguration().useTcpFastOpen()) {
+    if (server.getConfiguration().useTcpFastOpen()) {
       bootstrap.option(ChannelOption.TCP_FASTOPEN_CONNECT, true);
     }
     return bootstrap;

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

@@ -58,7 +58,7 @@ public class ServerChannelInitializer extends ChannelInitializer<Channel> {
   protected void initChannel(final Channel ch) {
     ch.pipeline()
         .addLast(LEGACY_PING_DECODER, new LegacyPingDecoder())
-        .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
+        .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder(ProtocolUtils.Direction.SERVERBOUND))
         .addLast(READ_TIMEOUT,
             new ReadTimeoutHandler(this.server.getConfiguration().getReadTimeout(),
                 TimeUnit.MILLISECONDS))

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

@@ -20,27 +20,32 @@ package com.velocitypowered.proxy.network;
 import com.velocitypowered.proxy.util.concurrent.VelocityNettyThreadFactory;
 import io.netty.channel.ChannelFactory;
 import io.netty.channel.EventLoopGroup;
+import io.netty.channel.IoHandlerFactory;
+import io.netty.channel.MultiThreadIoEventLoopGroup;
 import io.netty.channel.epoll.Epoll;
 import io.netty.channel.epoll.EpollDatagramChannel;
-import io.netty.channel.epoll.EpollEventLoopGroup;
+import io.netty.channel.epoll.EpollIoHandler;
 import io.netty.channel.epoll.EpollServerSocketChannel;
 import io.netty.channel.epoll.EpollSocketChannel;
 import io.netty.channel.kqueue.KQueue;
 import io.netty.channel.kqueue.KQueueDatagramChannel;
-import io.netty.channel.kqueue.KQueueEventLoopGroup;
+import io.netty.channel.kqueue.KQueueIoHandler;
 import io.netty.channel.kqueue.KQueueServerSocketChannel;
 import io.netty.channel.kqueue.KQueueSocketChannel;
-import io.netty.channel.nio.NioEventLoopGroup;
+import io.netty.channel.nio.NioIoHandler;
 import io.netty.channel.socket.DatagramChannel;
 import io.netty.channel.socket.ServerSocketChannel;
 import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioDatagramChannel;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
 import io.netty.channel.socket.nio.NioSocketChannel;
-import io.netty.incubator.channel.uring.*;
-
+import io.netty.channel.uring.IoUring;
+import io.netty.channel.uring.IoUringDatagramChannel;
+import io.netty.channel.uring.IoUringIoHandler;
+import io.netty.channel.uring.IoUringServerSocketChannel;
+import io.netty.channel.uring.IoUringSocketChannel;
 import java.util.concurrent.ThreadFactory;
-import java.util.function.BiFunction;
+import java.util.function.Supplier;
 
 /**
  * Enumerates the supported transports for Velocity.
@@ -49,50 +54,36 @@ public enum TransportType {
   NIO("NIO", NioServerSocketChannel::new,
       NioSocketChannel::new,
       NioDatagramChannel::new,
-      (name, type) -> new NioEventLoopGroup(0, createThreadFactory(name, type)),
-      false,
-      false),
+      NioIoHandler::newFactory),
   EPOLL("epoll", EpollServerSocketChannel::new,
       EpollSocketChannel::new,
       EpollDatagramChannel::new,
-      (name, type) -> new EpollEventLoopGroup(0, createThreadFactory(name, type)),
-      Epoll.isTcpFastOpenServerSideAvailable(),
-      Epoll.isTcpFastOpenClientSideAvailable()),
-  IO_URING("io_uring", IOUringServerSocketChannel::new,
-      IOUringSocketChannel::new,
-      IOUringDatagramChannel::new,
-      (name, type) -> new IOUringEventLoopGroup(0, createThreadFactory(name, type)),
-      IOUring.isTcpFastOpenServerSideAvailable(),
-      IOUring.isTcpFastOpenClientSideAvailable()),
+      EpollIoHandler::newFactory),
   KQUEUE("kqueue", KQueueServerSocketChannel::new,
       KQueueSocketChannel::new,
       KQueueDatagramChannel::new,
-      (name, type) -> new KQueueEventLoopGroup(0, createThreadFactory(name, type)),
-      KQueue.isTcpFastOpenServerSideAvailable(),
-      KQueue.isTcpFastOpenClientSideAvailable());
+      KQueueIoHandler::newFactory),
+  IO_URING("io_uring", IoUringServerSocketChannel::new,
+      IoUringSocketChannel::new,
+      IoUringDatagramChannel::new,
+      IoUringIoHandler::newFactory);
 
   final String name;
   final ChannelFactory<? extends ServerSocketChannel> serverSocketChannelFactory;
   final ChannelFactory<? extends SocketChannel> socketChannelFactory;
   final ChannelFactory<? extends DatagramChannel> datagramChannelFactory;
-  final BiFunction<String, Type, EventLoopGroup> eventLoopGroupFactory;
-  final boolean supportsTcpFastOpenServer;
-  final boolean supportsTcpFastOpenClient;
+  final Supplier<IoHandlerFactory> ioHandlerFactorySupplier;
 
   TransportType(final String name,
       final ChannelFactory<? extends ServerSocketChannel> serverSocketChannelFactory,
       final ChannelFactory<? extends SocketChannel> socketChannelFactory,
       final ChannelFactory<? extends DatagramChannel> datagramChannelFactory,
-      final BiFunction<String, Type, EventLoopGroup> eventLoopGroupFactory,
-                final boolean supportsTcpFastOpenServer,
-                final boolean supportsTcpFastOpenClient) {
+      final Supplier<IoHandlerFactory> ioHandlerFactorySupplier) {
     this.name = name;
     this.serverSocketChannelFactory = serverSocketChannelFactory;
     this.socketChannelFactory = socketChannelFactory;
     this.datagramChannelFactory = datagramChannelFactory;
-    this.eventLoopGroupFactory = eventLoopGroupFactory;
-    this.supportsTcpFastOpenServer = supportsTcpFastOpenServer;
-    this.supportsTcpFastOpenClient = supportsTcpFastOpenClient;
+    this.ioHandlerFactorySupplier = ioHandlerFactorySupplier;
   }
 
   @Override
@@ -100,16 +91,15 @@ public enum TransportType {
     return this.name;
   }
 
+  /**
+   * Creates a new event loop group for the given type.
+   *
+   * @param type the type of event loop group to create
+   * @return the event loop group
+   */
   public EventLoopGroup createEventLoopGroup(final Type type) {
-    return this.eventLoopGroupFactory.apply(this.name, type);
-  }
-
-  public boolean supportsTcpFastOpenServer() {
-    return supportsTcpFastOpenServer;
-  }
-
-  public boolean supportsTcpFastOpenClient() {
-    return supportsTcpFastOpenClient;
+    return new MultiThreadIoEventLoopGroup(
+        0, createThreadFactory(this.name, type), this.ioHandlerFactorySupplier.get());
   }
 
   private static ThreadFactory createThreadFactory(final String name, final Type type) {
@@ -126,7 +116,7 @@ public enum TransportType {
       return NIO;
     }
 
-    if(IOUring.isAvailable()) {
+    if (IoUring.isAvailable() && Boolean.getBoolean("velocity.enable-iouring-transport")) {
       return IO_URING;
     }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -47,7 +47,7 @@ import net.kyori.adventure.nbt.CompoundBinaryTag;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
 import net.kyori.adventure.text.serializer.json.JSONOptions;
 import net.kyori.adventure.text.serializer.json.legacyimpl.NBTLegacyHoverEventSerializer;
-import net.kyori.option.OptionState;
+import net.kyori.option.OptionSchema;
 
 /**
  * Utilities for writing and reading data in the Minecraft protocol.
@@ -60,14 +60,17 @@ public enum ProtocolUtils {
           .downsampleColors()
           .legacyHoverEventSerializer(NBTLegacyHoverEventSerializer.get())
           .options(
-              OptionState.optionState()
+              OptionSchema.globalSchema().stateBuilder()
               // before 1.16
               .value(JSONOptions.EMIT_RGB, Boolean.FALSE)
-              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.LEGACY_ONLY)
+              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.VALUE_FIELD)
+              .value(JSONOptions.EMIT_CLICK_EVENT_TYPE, JSONOptions.ClickEventValueMode.CAMEL_CASE)
               // before 1.20.3
               .value(JSONOptions.EMIT_COMPACT_TEXT_COMPONENT, Boolean.FALSE)
               .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_ID_AS_INT_ARRAY, Boolean.FALSE)
               .value(JSONOptions.VALIDATE_STRICT_EVENTS, Boolean.FALSE)
+              // before 1.21.5
+              .value(JSONOptions.EMIT_CHANGE_PAGE_CLICK_EVENT_PAGE_AS_STRING, Boolean.TRUE)
               .build()
           )
           .build();
@@ -75,14 +78,37 @@ public enum ProtocolUtils {
           GsonComponentSerializer.builder()
           .legacyHoverEventSerializer(NBTLegacyHoverEventSerializer.get())
           .options(
-              OptionState.optionState()
+              OptionSchema.globalSchema().stateBuilder()
               // after 1.16
               .value(JSONOptions.EMIT_RGB, Boolean.TRUE)
-              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.MODERN_ONLY)
+              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.CAMEL_CASE)
+              .value(JSONOptions.EMIT_CLICK_EVENT_TYPE, JSONOptions.ClickEventValueMode.CAMEL_CASE)
+              .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_KEY_AS_TYPE_AND_UUID_AS_ID, true)
               // before 1.20.3
               .value(JSONOptions.EMIT_COMPACT_TEXT_COMPONENT, Boolean.FALSE)
               .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_ID_AS_INT_ARRAY, Boolean.FALSE)
               .value(JSONOptions.VALIDATE_STRICT_EVENTS, Boolean.FALSE)
+              // before 1.21.5
+              .value(JSONOptions.EMIT_CHANGE_PAGE_CLICK_EVENT_PAGE_AS_STRING, Boolean.TRUE)
+              .build()
+          )
+          .build();
+  private static final GsonComponentSerializer PRE_1_21_5_SERIALIZER =
+      GsonComponentSerializer.builder()
+          .legacyHoverEventSerializer(NBTLegacyHoverEventSerializer.get())
+          .options(
+              OptionSchema.globalSchema().stateBuilder()
+              // after 1.16
+              .value(JSONOptions.EMIT_RGB, Boolean.TRUE)
+              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.CAMEL_CASE)
+              .value(JSONOptions.EMIT_CLICK_EVENT_TYPE, JSONOptions.ClickEventValueMode.CAMEL_CASE)
+              .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_KEY_AS_TYPE_AND_UUID_AS_ID, true)
+              // after 1.20.3
+              .value(JSONOptions.EMIT_COMPACT_TEXT_COMPONENT, Boolean.TRUE)
+              .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_ID_AS_INT_ARRAY, Boolean.TRUE)
+              .value(JSONOptions.VALIDATE_STRICT_EVENTS, Boolean.TRUE)
+              // before 1.21.5
+              .value(JSONOptions.EMIT_CHANGE_PAGE_CLICK_EVENT_PAGE_AS_STRING, Boolean.TRUE)
               .build()
           )
           .build();
@@ -90,14 +116,18 @@ public enum ProtocolUtils {
       GsonComponentSerializer.builder()
           .legacyHoverEventSerializer(NBTLegacyHoverEventSerializer.get())
           .options(
-              OptionState.optionState()
+              OptionSchema.globalSchema().stateBuilder()
               // after 1.16
               .value(JSONOptions.EMIT_RGB, Boolean.TRUE)
-              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.MODERN_ONLY)
+              .value(JSONOptions.EMIT_HOVER_EVENT_TYPE, JSONOptions.HoverEventValueMode.SNAKE_CASE)
+              .value(JSONOptions.EMIT_CLICK_EVENT_TYPE, JSONOptions.ClickEventValueMode.SNAKE_CASE)
               // after 1.20.3
               .value(JSONOptions.EMIT_COMPACT_TEXT_COMPONENT, Boolean.TRUE)
               .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_ID_AS_INT_ARRAY, Boolean.TRUE)
+              // after 1.21.5
+              .value(JSONOptions.EMIT_HOVER_SHOW_ENTITY_KEY_AS_TYPE_AND_UUID_AS_ID, Boolean.FALSE)
               .value(JSONOptions.VALIDATE_STRICT_EVENTS, Boolean.TRUE)
+              .value(JSONOptions.EMIT_CHANGE_PAGE_CLICK_EVENT_PAGE_AS_STRING, Boolean.FALSE)
               .build()
           )
           .build();
@@ -713,9 +743,12 @@ public enum ProtocolUtils {
    * @return the appropriate {@link GsonComponentSerializer}
    */
   public static GsonComponentSerializer getJsonChatSerializer(ProtocolVersion version) {
-    if (version.noLessThan(ProtocolVersion.MINECRAFT_1_20_3)) {
+    if (version.noLessThan(ProtocolVersion.MINECRAFT_1_21_5)) {
       return MODERN_SERIALIZER;
     }
+    if (version.noLessThan(ProtocolVersion.MINECRAFT_1_20_3)) {
+      return PRE_1_21_5_SERIALIZER;
+    }
     if (version.noLessThan(ProtocolVersion.MINECRAFT_1_16)) {
       return PRE_1_20_3_SERIALIZER;
     }

proxy/src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java

@@ -40,6 +40,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_4;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_5;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_6;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_7_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_8;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9;
@@ -257,7 +258,8 @@ public enum StateRegistry {
           map(0x09, MINECRAFT_1_19_4, false),
           map(0x0A, MINECRAFT_1_20_2, false),
           map(0x0B, MINECRAFT_1_20_5, false),
-          map(0x0D, MINECRAFT_1_21_2, false));
+          map(0x0D, MINECRAFT_1_21_2, false),
+          map(0x0E, MINECRAFT_1_21_6, false));
       serverbound.register(
           LegacyChatPacket.class,
           LegacyChatPacket::new,
@@ -270,7 +272,8 @@ public enum StateRegistry {
           ChatAcknowledgementPacket.class,
           ChatAcknowledgementPacket::new,
           map(0x03, MINECRAFT_1_19_3, false),
-          map(0x04, MINECRAFT_1_21_2, false));
+          map(0x04, MINECRAFT_1_21_2, false),
+          map(0x05, MINECRAFT_1_21_6, false));
       serverbound.register(KeyedPlayerCommandPacket.class, KeyedPlayerCommandPacket::new,
           map(0x03, MINECRAFT_1_19, false),
           map(0x04, MINECRAFT_1_19_1, MINECRAFT_1_19_1, false));
@@ -280,16 +283,19 @@ public enum StateRegistry {
       serverbound.register(SessionPlayerCommandPacket.class, SessionPlayerCommandPacket::new,
           map(0x04, MINECRAFT_1_19_3, false),
           map(0x05, MINECRAFT_1_20_5, false),
-          map(0x06, MINECRAFT_1_21_2, false));
+          map(0x06, MINECRAFT_1_21_2, false),
+          map(0x07, MINECRAFT_1_21_6, false));
       serverbound.register(UnsignedPlayerCommandPacket.class, UnsignedPlayerCommandPacket::new,
           map(0x04, MINECRAFT_1_20_5, false),
-          map(0x05, MINECRAFT_1_21_2, false));
+          map(0x05, MINECRAFT_1_21_2, false),
+          map(0x06, MINECRAFT_1_21_6, false));
       serverbound.register(
           SessionPlayerChatPacket.class,
           SessionPlayerChatPacket::new,
           map(0x05, MINECRAFT_1_19_3, false),
           map(0x06, MINECRAFT_1_20_5, false),
-          map(0x07, MINECRAFT_1_21_2, false));
+          map(0x07, MINECRAFT_1_21_2, false),
+          map(0x08, MINECRAFT_1_21_6, false));
       serverbound.register(
           ClientSettingsPacket.class,
           ClientSettingsPacket::new,
@@ -304,11 +310,13 @@ public enum StateRegistry {
           map(0x08, MINECRAFT_1_19_4, false),
           map(0x09, MINECRAFT_1_20_2, false),
           map(0x0A, MINECRAFT_1_20_5, false),
-          map(0x0C, MINECRAFT_1_21_2, false));
+          map(0x0C, MINECRAFT_1_21_2, false),
+          map(0x0D, MINECRAFT_1_21_6, false));
       serverbound.register(
           ServerboundCookieResponsePacket.class, ServerboundCookieResponsePacket::new,
           map(0x11, MINECRAFT_1_20_5, false),
-          map(0x13, MINECRAFT_1_21_2, false));
+          map(0x13, MINECRAFT_1_21_2, false),
+          map(0x14, MINECRAFT_1_21_6, false));
       serverbound.register(
           PluginMessagePacket.class,
           PluginMessagePacket::new,
@@ -326,7 +334,8 @@ public enum StateRegistry {
           map(0x0F, MINECRAFT_1_20_2, false),
           map(0x10, MINECRAFT_1_20_3, false),
           map(0x12, MINECRAFT_1_20_5, false),
-          map(0x14, MINECRAFT_1_21_2, false));
+          map(0x14, MINECRAFT_1_21_2, false),
+          map(0x15, MINECRAFT_1_21_6, false));
       serverbound.register(
           KeepAlivePacket.class,
           KeepAlivePacket::new,
@@ -345,7 +354,8 @@ public enum StateRegistry {
           map(0x14, MINECRAFT_1_20_2, false),
           map(0x15, MINECRAFT_1_20_3, false),
           map(0x18, MINECRAFT_1_20_5, false),
-          map(0x1A, MINECRAFT_1_21_2, false));
+          map(0x1A, MINECRAFT_1_21_2, false),
+          map(0x1B, MINECRAFT_1_21_6, false));
       serverbound.register(
           ResourcePackResponsePacket.class,
           ResourcePackResponsePacket::new,
@@ -362,12 +372,14 @@ public enum StateRegistry {
           map(0x28, MINECRAFT_1_20_3, false),
           map(0x2B, MINECRAFT_1_20_5, false),
           map(0x2D, MINECRAFT_1_21_2, false),
-          map(0x2F, MINECRAFT_1_21_4, false));
+          map(0x2F, MINECRAFT_1_21_4, false),
+          map(0x30, MINECRAFT_1_21_6, false));
       serverbound.register(
           FinishedUpdatePacket.class, () -> FinishedUpdatePacket.INSTANCE,
           map(0x0B, MINECRAFT_1_20_2, false),
           map(0x0C, MINECRAFT_1_20_5, false),
-          map(0x0E, MINECRAFT_1_21_2, false));
+          map(0x0E, MINECRAFT_1_21_2, false),
+          map(0x0F, MINECRAFT_1_21_6, false));
 
       clientbound.register(
           BossBarPacket.class,

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressDecoder.java

@@ -39,6 +39,7 @@ public class MinecraftCompressDecoder extends MessageToMessageDecoder<ByteBuf> {
   private static final int UNCOMPRESSED_CAP =
       Boolean.getBoolean("velocity.increased-compression-cap")
           ? HARD_MAXIMUM_UNCOMPRESSED_SIZE : VANILLA_MAXIMUM_UNCOMPRESSED_SIZE;
+  private static final boolean SKIP_COMPRESSION_VALIDATION = Boolean.getBoolean("velocity.skip-uncompressed-packet-size-validation");
 
   private int threshold;
   private final VelocityCompressor compressor;
@@ -52,9 +53,11 @@ public class MinecraftCompressDecoder extends MessageToMessageDecoder<ByteBuf> {
   protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
     int claimedUncompressedSize = ProtocolUtils.readVarInt(in);
     if (claimedUncompressedSize == 0) {
-      int actualUncompressedSize = in.readableBytes();
-      checkFrame(actualUncompressedSize < threshold, "Actual uncompressed size %s is greater than"
-              + " threshold %s", actualUncompressedSize, threshold);
+      if (!SKIP_COMPRESSION_VALIDATION) {
+        int actualUncompressedSize = in.readableBytes();
+        checkFrame(actualUncompressedSize < threshold, "Actual uncompressed size %s is greater than"
+            + " threshold %s", actualUncompressedSize, threshold);
+      }
       // This message is not compressed.
       out.add(in.retain());
       return;

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftDecoder.java

@@ -135,7 +135,7 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
 
   private String getExtraConnectionDetail(int packetId) {
     return "Direction " + direction + " Protocol " + registry.version + " State " + state
-        + " ID " + Integer.toHexString(packetId);
+        + " ID 0x" + Integer.toHexString(packetId);
   }
 
   public void setProtocolVersion(ProtocolVersion protocolVersion) {

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftVarintFrameDecoder.java

@@ -19,21 +19,51 @@ package com.velocitypowered.proxy.protocol.netty;
 
 import static io.netty.util.ByteProcessor.FIND_NON_NUL;
 
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.util.except.QuietDecoderException;
+import com.velocitypowered.proxy.util.except.QuietRuntimeException;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ByteToMessageDecoder;
+import io.netty.handler.codec.CorruptedFrameException;
 import java.util.List;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 /**
  * Frames Minecraft server packets which are prefixed by a 21-bit VarInt encoding.
  */
 public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
 
+  private static final Logger LOGGER = LogManager.getLogger(MinecraftVarintFrameDecoder.class);
+  private static final QuietRuntimeException FRAME_DECODER_FAILED =
+      new QuietRuntimeException("A packet frame decoder failed. For more information, launch "
+          + "Velocity with -Dvelocity.packet-decode-logging=true to see more.");
   private static final QuietDecoderException BAD_PACKET_LENGTH =
       new QuietDecoderException("Bad packet length");
   private static final QuietDecoderException VARINT_TOO_BIG =
       new QuietDecoderException("VarInt too big");
+  private static final QuietDecoderException UNKNOWN_PACKET =
+      new QuietDecoderException("Unknown packet");
+
+  private final ProtocolUtils.Direction direction;
+  private final StateRegistry.PacketRegistry.ProtocolRegistry registry;
+  private StateRegistry state;
+
+  /**
+   * Creates a new {@code MinecraftVarintFrameDecoder} decoding packets from the specified {@code Direction}.
+   *
+   * @param direction the direction from which we decode from
+   */
+  public MinecraftVarintFrameDecoder(ProtocolUtils.Direction direction) {
+    this.direction = direction;
+    this.registry = StateRegistry.HANDSHAKE.getProtocolRegistry(
+        direction, ProtocolVersion.MINIMUM_VERSION);
+    this.state = StateRegistry.HANDSHAKE;
+  }
 
   @Override
   protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out)
@@ -62,6 +92,43 @@ public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
       throw BAD_PACKET_LENGTH;
     }
 
+    if (length > 0) {
+      if (state == StateRegistry.HANDSHAKE && direction == ProtocolUtils.Direction.SERVERBOUND) {
+        StateRegistry.PacketRegistry.ProtocolRegistry registry =
+            state.getProtocolRegistry(direction, ProtocolVersion.MINIMUM_VERSION);
+
+        final int index = in.readerIndex();
+        final int packetId = readRawVarInt21(in);
+        // Index hasn't changed, we've read nothing
+        if (index == in.readerIndex()) {
+          in.resetReaderIndex();
+          return;
+        }
+        final int payloadLength = length - ProtocolUtils.varIntBytes(packetId);
+
+        MinecraftPacket packet = registry.createPacket(packetId);
+
+        // We handle every packet in this phase, if you said something we don't know, something is really wrong
+        if (packet == null) {
+          throw UNKNOWN_PACKET;
+        }
+
+        // We 'technically' have the incoming bytes of a payload here, and so, these can actually parse
+        // the packet if needed, so, we'll take advantage of the existing methods
+        int expectedMinLen = packet.expectedMinLength(in, direction, registry.version);
+        int expectedMaxLen = packet.expectedMaxLength(in, direction, registry.version);
+        if (expectedMaxLen != -1 && payloadLength > expectedMaxLen) {
+          throw handleOverflow(packet, expectedMaxLen, in.readableBytes());
+        }
+        if (payloadLength < expectedMinLen) {
+          throw handleUnderflow(packet, expectedMaxLen, in.readableBytes());
+        }
+
+
+        in.readerIndex(index);
+      }
+    }
+
     // note that zero-length packets are ignored
     if (length > 0) {
       if (in.readableBytes() < length) {
@@ -72,6 +139,16 @@ public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
     }
   }
 
+  @Override
+  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
+    if (MinecraftDecoder.DEBUG) {
+      LOGGER.atWarn()
+          .withThrowable(cause)
+          .log("Exception caught while decoding frame for {}", ctx.channel().remoteAddress());
+    }
+    super.exceptionCaught(ctx, cause);
+  }
+
   /**
    * Reads a VarInt from the buffer of up to 21 bits in size.
    *
@@ -141,4 +218,26 @@ public class MinecraftVarintFrameDecoder extends ByteToMessageDecoder {
     }
     return result | (tmp & 0x7F) << 14;
   }
+
+  private Exception handleOverflow(MinecraftPacket packet, int expected, int actual) {
+    if (MinecraftDecoder.DEBUG) {
+      return new CorruptedFrameException("Packet sent for " + packet.getClass() + " was too "
+          + "big (expected " + expected + " bytes, got " + actual + " bytes)");
+    } else {
+      return FRAME_DECODER_FAILED;
+    }
+  }
+
+  private Exception handleUnderflow(MinecraftPacket packet, int expected, int actual) {
+    if (MinecraftDecoder.DEBUG) {
+      return new CorruptedFrameException("Packet sent for " + packet.getClass() + " was too "
+          + "small (expected " + expected + " bytes, got " + actual + " bytes)");
+    } else {
+      return FRAME_DECODER_FAILED;
+    }
+  }
+
+  public void setState(StateRegistry stateRegistry) {
+    this.state = stateRegistry;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/AvailableCommandsPacket.java

@@ -50,12 +50,14 @@ import java.util.Deque;
 import java.util.Iterator;
 import java.util.Queue;
 import java.util.concurrent.CompletableFuture;
+import java.util.function.Predicate;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class AvailableCommandsPacket implements MinecraftPacket {
 
   private static final Command<CommandSource> PLACEHOLDER_COMMAND = source -> 0;
+  private static final Predicate<CommandSource> PLACEHOLDER_REQUIREMENT = source -> true;
 
   private static final byte NODE_TYPE_ROOT = 0x00;
   private static final byte NODE_TYPE_LITERAL = 0x01;
@@ -65,6 +67,7 @@ public class AvailableCommandsPacket implements MinecraftPacket {
   private static final byte FLAG_EXECUTABLE = 0x04;
   private static final byte FLAG_IS_REDIRECT = 0x08;
   private static final byte FLAG_HAS_SUGGESTIONS = 0x10;
+  private static final byte FLAG_IS_RESTRICTED = 0x20;
 
   private @MonotonicNonNull RootCommandNode<CommandSource> rootNode;
 
@@ -146,6 +149,9 @@ public class AvailableCommandsPacket implements MinecraftPacket {
     if (node.getCommand() != null) {
       flags |= FLAG_EXECUTABLE;
     }
+    if (node.getRequirement() == PLACEHOLDER_REQUIREMENT) {
+      flags |= FLAG_IS_RESTRICTED;
+    }
 
     if (node instanceof LiteralCommandNode<?>) {
       flags |= NODE_TYPE_LITERAL;
@@ -289,6 +295,11 @@ public class AvailableCommandsPacket implements MinecraftPacket {
             args.executes(PLACEHOLDER_COMMAND);
           }
 
+          // If restricted, add empty requirement
+          if ((flags & FLAG_IS_RESTRICTED) != 0) {
+            args.requires(PLACEHOLDER_REQUIREMENT);
+          }
+
           this.built = args.build();
         }
       }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/HandshakePacket.java

@@ -106,4 +106,16 @@ public class HandshakePacket implements MinecraftPacket {
   public boolean handle(MinecraftSessionHandler handler) {
     return handler.handle(this);
   }
+
+  @Override
+  public int expectedMinLength(ByteBuf buf, ProtocolUtils.Direction direction,
+                               ProtocolVersion version) {
+    return 7;
+  }
+
+  @Override
+  public int expectedMaxLength(ByteBuf buf, ProtocolUtils.Direction direction,
+                               ProtocolVersion version) {
+    return 9 + (MAXIMUM_HOSTNAME_LENGTH * 3);
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/brigadier/ArgumentPropertyRegistry.java

@@ -23,6 +23,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_19_4;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_20_3;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_20_5;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_5;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_21_6;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.ArgumentIdentifier.id;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.ArgumentIdentifier.mapSet;
 import static com.velocitypowered.proxy.protocol.packet.brigadier.DoubleArgumentPropertySerializer.DOUBLE;
@@ -164,6 +165,7 @@ public class ArgumentPropertyRegistry {
           return i;
         }
       }
+      throw new IllegalArgumentException("Argument type identifier " + id + " unknown.");
     } else {
       String identifier = ProtocolUtils.readString(buf);
       for (ArgumentIdentifier i : byIdentifier.keySet()) {
@@ -207,68 +209,79 @@ public class ArgumentPropertyRegistry {
     empty(id("minecraft:item_stack", mapSet(MINECRAFT_1_19, 14)));
     empty(id("minecraft:item_predicate", mapSet(MINECRAFT_1_19, 15)));
     empty(id("minecraft:color", mapSet(MINECRAFT_1_19, 16)));
-    empty(id("minecraft:component", mapSet(MINECRAFT_1_19, 17)));
-    empty(id("minecraft:style", mapSet(MINECRAFT_1_20_3, 18))); // added 1.20.3
-    empty(id("minecraft:message", mapSet(MINECRAFT_1_20_3, 19), mapSet(MINECRAFT_1_19, 18)));
-    empty(id("minecraft:nbt_compound_tag", mapSet(MINECRAFT_1_20_3, 20), mapSet(MINECRAFT_1_19, 19))); // added in 1.14
-    empty(id("minecraft:nbt_tag", mapSet(MINECRAFT_1_20_3, 21), mapSet(MINECRAFT_1_19, 20))); // added in 1.14
-    empty(id("minecraft:nbt_path", mapSet(MINECRAFT_1_20_3, 22), mapSet(MINECRAFT_1_19, 21)));
-    empty(id("minecraft:objective", mapSet(MINECRAFT_1_20_3, 23), mapSet(MINECRAFT_1_19, 22)));
-    empty(id("minecraft:objective_criteria", mapSet(MINECRAFT_1_20_3, 24), mapSet(MINECRAFT_1_19, 23)));
-    empty(id("minecraft:operation", mapSet(MINECRAFT_1_20_3, 25), mapSet(MINECRAFT_1_19, 24)));
-    empty(id("minecraft:particle", mapSet(MINECRAFT_1_20_3, 26), mapSet(MINECRAFT_1_19, 25)));
-    empty(id("minecraft:angle", mapSet(MINECRAFT_1_20_3, 27), mapSet(MINECRAFT_1_19, 26))); // added in 1.16.2
-    empty(id("minecraft:rotation", mapSet(MINECRAFT_1_20_3, 28), mapSet(MINECRAFT_1_19, 27)));
-    empty(id("minecraft:scoreboard_slot", mapSet(MINECRAFT_1_20_3, 29), mapSet(MINECRAFT_1_19, 28)));
-    empty(id("minecraft:score_holder", mapSet(MINECRAFT_1_20_3, 30), mapSet(MINECRAFT_1_19, 29)), ByteArgumentPropertySerializer.BYTE);
-    empty(id("minecraft:swizzle", mapSet(MINECRAFT_1_20_3, 31), mapSet(MINECRAFT_1_19, 30)));
-    empty(id("minecraft:team", mapSet(MINECRAFT_1_20_3, 32), mapSet(MINECRAFT_1_19, 31)));
-    empty(id("minecraft:item_slot", mapSet(MINECRAFT_1_20_3, 33), mapSet(MINECRAFT_1_19, 32)));
-    empty(id("minecraft:item_slots", mapSet(MINECRAFT_1_20_5, 34))); // added 1.20.5
-    empty(id("minecraft:resource_location", mapSet(MINECRAFT_1_20_5, 35), mapSet(MINECRAFT_1_20_3, 34), mapSet(MINECRAFT_1_19, 33)));
+    empty(id("minecraft:component", mapSet(MINECRAFT_1_21_6, 18), mapSet(MINECRAFT_1_19, 17)));
+    empty(id("minecraft:style", mapSet(MINECRAFT_1_21_6, 19), mapSet(MINECRAFT_1_20_3, 18))); // added 1.20.3
+    empty(id("minecraft:message", mapSet(MINECRAFT_1_21_6, 20), mapSet(MINECRAFT_1_20_3, 19), mapSet(MINECRAFT_1_19, 18)));
+    empty(id("minecraft:nbt_compound_tag", mapSet(MINECRAFT_1_21_6, 21), mapSet(MINECRAFT_1_20_3, 20), mapSet(MINECRAFT_1_19, 19))); // added in 1.14
+    empty(id("minecraft:nbt_tag", mapSet(MINECRAFT_1_21_6, 22), mapSet(MINECRAFT_1_20_3, 21), mapSet(MINECRAFT_1_19, 20))); // added in 1.14
+    empty(id("minecraft:nbt_path", mapSet(MINECRAFT_1_21_6, 23), mapSet(MINECRAFT_1_20_3, 22), mapSet(MINECRAFT_1_19, 21)));
+    empty(id("minecraft:objective", mapSet(MINECRAFT_1_21_6, 24), mapSet(MINECRAFT_1_20_3, 23), mapSet(MINECRAFT_1_19, 22)));
+    empty(id("minecraft:objective_criteria", mapSet(MINECRAFT_1_21_6, 25), mapSet(MINECRAFT_1_20_3, 24), mapSet(MINECRAFT_1_19, 23)));
+    empty(id("minecraft:operation", mapSet(MINECRAFT_1_21_6, 26), mapSet(MINECRAFT_1_20_3, 25), mapSet(MINECRAFT_1_19, 24)));
+    empty(id("minecraft:particle", mapSet(MINECRAFT_1_21_6, 27), mapSet(MINECRAFT_1_20_3, 26), mapSet(MINECRAFT_1_19, 25)));
+    empty(id("minecraft:angle", mapSet(MINECRAFT_1_21_6, 28), mapSet(MINECRAFT_1_20_3, 27), mapSet(MINECRAFT_1_19, 26))); // added in 1.16.2
+    empty(id("minecraft:rotation", mapSet(MINECRAFT_1_21_6, 29), mapSet(MINECRAFT_1_20_3, 28), mapSet(MINECRAFT_1_19, 27)));
+    empty(id("minecraft:scoreboard_slot", mapSet(MINECRAFT_1_21_6, 30), mapSet(MINECRAFT_1_20_3, 29), mapSet(MINECRAFT_1_19, 28)));
+    empty(id("minecraft:score_holder", mapSet(MINECRAFT_1_21_6, 31), mapSet(MINECRAFT_1_20_3, 30), mapSet(MINECRAFT_1_19, 29)),
+        ByteArgumentPropertySerializer.BYTE);
+    empty(id("minecraft:swizzle", mapSet(MINECRAFT_1_21_6, 32), mapSet(MINECRAFT_1_20_3, 31), mapSet(MINECRAFT_1_19, 30)));
+    empty(id("minecraft:team", mapSet(MINECRAFT_1_21_6, 33), mapSet(MINECRAFT_1_20_3, 32), mapSet(MINECRAFT_1_19, 31)));
+    empty(id("minecraft:item_slot", mapSet(MINECRAFT_1_21_6, 34), mapSet(MINECRAFT_1_20_3, 33), mapSet(MINECRAFT_1_19, 32)));
+    empty(id("minecraft:item_slots", mapSet(MINECRAFT_1_21_6, 35), mapSet(MINECRAFT_1_20_5, 34))); // added 1.20.5
+    empty(id("minecraft:resource_location", mapSet(MINECRAFT_1_21_6, 36), mapSet(MINECRAFT_1_20_5, 35), mapSet(MINECRAFT_1_20_3, 34),
+        mapSet(MINECRAFT_1_19, 33)));
     empty(id("minecraft:mob_effect", mapSet(MINECRAFT_1_19_3, -1), mapSet(MINECRAFT_1_19, 34)));
-    empty(id("minecraft:function", mapSet(MINECRAFT_1_20_5, 36), mapSet(MINECRAFT_1_20_3, 35), mapSet(MINECRAFT_1_19_3, 34),
-        mapSet(MINECRAFT_1_19, 35)));
-    empty(id("minecraft:entity_anchor", mapSet(MINECRAFT_1_20_5, 37), mapSet(MINECRAFT_1_20_3, 36), mapSet(MINECRAFT_1_19_3, 35),
-        mapSet(MINECRAFT_1_19, 36)));
-    empty(id("minecraft:int_range", mapSet(MINECRAFT_1_20_5, 38), mapSet(MINECRAFT_1_20_3, 37), mapSet(MINECRAFT_1_19_3, 36),
-        mapSet(MINECRAFT_1_19, 37)));
-    empty(id("minecraft:float_range", mapSet(MINECRAFT_1_20_5, 39), mapSet(MINECRAFT_1_20_3, 38), mapSet(MINECRAFT_1_19_3, 37),
-        mapSet(MINECRAFT_1_19, 38)));
+    empty(id("minecraft:function", mapSet(MINECRAFT_1_21_6, 37), mapSet(MINECRAFT_1_20_5, 36), mapSet(MINECRAFT_1_20_3, 35),
+        mapSet(MINECRAFT_1_19_3, 34), mapSet(MINECRAFT_1_19, 35)));
+    empty(id("minecraft:entity_anchor", mapSet(MINECRAFT_1_21_6, 38), mapSet(MINECRAFT_1_20_5, 37), mapSet(MINECRAFT_1_20_3, 36),
+        mapSet(MINECRAFT_1_19_3, 35), mapSet(MINECRAFT_1_19, 36)));
+    empty(id("minecraft:int_range", mapSet(MINECRAFT_1_21_6, 39), mapSet(MINECRAFT_1_20_5, 38), mapSet(MINECRAFT_1_20_3, 37),
+        mapSet(MINECRAFT_1_19_3, 36), mapSet(MINECRAFT_1_19, 37)));
+    empty(id("minecraft:float_range", mapSet(MINECRAFT_1_21_6, 40), mapSet(MINECRAFT_1_20_5, 39), mapSet(MINECRAFT_1_20_3, 38),
+        mapSet(MINECRAFT_1_19_3, 37), mapSet(MINECRAFT_1_19, 38)));
     empty(id("minecraft:item_enchantment", mapSet(MINECRAFT_1_19_3, -1), mapSet(MINECRAFT_1_19, 39)));
     empty(id("minecraft:entity_summon", mapSet(MINECRAFT_1_19_3, -1), mapSet(MINECRAFT_1_19, 40)));
-    empty(id("minecraft:dimension", mapSet(MINECRAFT_1_20_5, 40), mapSet(MINECRAFT_1_20_3, 39), mapSet(MINECRAFT_1_19_3, 38),
-        mapSet(MINECRAFT_1_19, 41)));
-    empty(id("minecraft:gamemode", mapSet(MINECRAFT_1_20_5, 41), mapSet(MINECRAFT_1_20_3, 40), mapSet(MINECRAFT_1_19_3, 39))); // 1.19.3
+    empty(id("minecraft:dimension", mapSet(MINECRAFT_1_21_6, 41), mapSet(MINECRAFT_1_20_5, 40), mapSet(MINECRAFT_1_20_3, 39),
+        mapSet(MINECRAFT_1_19_3, 38), mapSet(MINECRAFT_1_19, 41)));
+    empty(id("minecraft:gamemode", mapSet(MINECRAFT_1_21_6, 42), mapSet(MINECRAFT_1_20_5, 41), mapSet(MINECRAFT_1_20_3, 40),
+        mapSet(MINECRAFT_1_19_3, 39))); // 1.19.3
 
-    empty(id("minecraft:time", mapSet(MINECRAFT_1_20_5, 42), mapSet(MINECRAFT_1_20_3, 41), mapSet(MINECRAFT_1_19_3, 40),
-        mapSet(MINECRAFT_1_19, 42)), TimeArgumentSerializer.TIME); // added in 1.14
+    empty(id("minecraft:time", mapSet(MINECRAFT_1_21_6, 43), mapSet(MINECRAFT_1_20_5, 42), mapSet(MINECRAFT_1_20_3, 41),
+        mapSet(MINECRAFT_1_19_3, 40), mapSet(MINECRAFT_1_19, 42)), TimeArgumentSerializer.TIME); // added in 1.14
 
-    register(id("minecraft:resource_or_tag", mapSet(MINECRAFT_1_20_5, 43), mapSet(MINECRAFT_1_20_3, 42), mapSet(MINECRAFT_1_19_3, 41),
-        mapSet(MINECRAFT_1_19, 43)), RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
-    register(id("minecraft:resource_or_tag_key", mapSet(MINECRAFT_1_20_5, 44), mapSet(MINECRAFT_1_20_3, 43), mapSet(MINECRAFT_1_19_3, 42)),
+    register(id("minecraft:resource_or_tag", mapSet(MINECRAFT_1_21_6, 44), mapSet(MINECRAFT_1_20_5, 43), mapSet(MINECRAFT_1_20_3, 42),
+        mapSet(MINECRAFT_1_19_3, 41), mapSet(MINECRAFT_1_19, 43)), RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
+    register(id("minecraft:resource_or_tag_key", mapSet(MINECRAFT_1_21_6, 45), mapSet(MINECRAFT_1_20_5, 44), mapSet(MINECRAFT_1_20_3, 43),
+        mapSet(MINECRAFT_1_19_3, 42)),
         RegistryKeyArgumentList.ResourceOrTagKey.class,
         RegistryKeyArgumentList.ResourceOrTagKey.Serializer.REGISTRY);
-    register(id("minecraft:resource", mapSet(MINECRAFT_1_20_5, 45), mapSet(MINECRAFT_1_20_3, 44), mapSet(MINECRAFT_1_19_3, 43),
-        mapSet(MINECRAFT_1_19, 44)),
+    register(id("minecraft:resource", mapSet(MINECRAFT_1_21_6, 46), mapSet(MINECRAFT_1_20_5, 45), mapSet(MINECRAFT_1_20_3, 44),
+        mapSet(MINECRAFT_1_19_3, 43), mapSet(MINECRAFT_1_19, 44)),
         RegistryKeyArgument.class, RegistryKeyArgumentSerializer.REGISTRY);
-    register(id("minecraft:resource_key", mapSet(MINECRAFT_1_20_5, 46), mapSet(MINECRAFT_1_20_3, 45), mapSet(MINECRAFT_1_19_3, 44)),
+    register(id("minecraft:resource_key", mapSet(MINECRAFT_1_21_6, 47), mapSet(MINECRAFT_1_20_5, 46), mapSet(MINECRAFT_1_20_3, 45),
+        mapSet(MINECRAFT_1_19_3, 44)),
         RegistryKeyArgumentList.ResourceKey.class,
         RegistryKeyArgumentList.ResourceKey.Serializer.REGISTRY);
-    register(id("minecraft:resource_selector", mapSet(MINECRAFT_1_21_5, 47)),
+    register(id("minecraft:resource_selector", mapSet(MINECRAFT_1_21_6, 48), mapSet(MINECRAFT_1_21_5, 47)),
         RegistryKeyArgumentList.ResourceSelector.class,
         RegistryKeyArgumentList.ResourceSelector.Serializer.REGISTRY);
 
-    empty(id("minecraft:template_mirror", mapSet(MINECRAFT_1_21_5, 48), mapSet(MINECRAFT_1_20_5, 47), mapSet(MINECRAFT_1_20_3, 46), mapSet(MINECRAFT_1_19, 45))); // 1.19
-    empty(id("minecraft:template_rotation", mapSet(MINECRAFT_1_21_5, 49), mapSet(MINECRAFT_1_20_5, 48), mapSet(MINECRAFT_1_20_3, 47), mapSet(MINECRAFT_1_19, 46))); // 1.19
-    empty(id("minecraft:heightmap", mapSet(MINECRAFT_1_21_5, 50), mapSet(MINECRAFT_1_20_3, 49), mapSet(MINECRAFT_1_19_4, 47))); // 1.19.4
+    empty(id("minecraft:template_mirror", mapSet(MINECRAFT_1_21_6, 49), mapSet(MINECRAFT_1_21_5, 48), mapSet(MINECRAFT_1_20_5, 47),
+        mapSet(MINECRAFT_1_20_3, 46), mapSet(MINECRAFT_1_19, 45))); // 1.19
+    empty(id("minecraft:template_rotation", mapSet(MINECRAFT_1_21_6, 50), mapSet(MINECRAFT_1_21_5, 49), mapSet(MINECRAFT_1_20_5, 48),
+        mapSet(MINECRAFT_1_20_3, 47), mapSet(MINECRAFT_1_19, 46))); // 1.19
+    empty(id("minecraft:heightmap", mapSet(MINECRAFT_1_21_6, 51), mapSet(MINECRAFT_1_21_5, 50), mapSet(MINECRAFT_1_20_3, 49),
+        mapSet(MINECRAFT_1_19_4, 47))); // 1.19.4
 
-    empty(id("minecraft:uuid", mapSet(MINECRAFT_1_21_5, 54),mapSet(MINECRAFT_1_20_5, 53), mapSet(MINECRAFT_1_20_3, 48), mapSet(MINECRAFT_1_19_4, 48),
-        mapSet(MINECRAFT_1_19, 47))); // added in 1.16
+    empty(id("minecraft:uuid", mapSet(MINECRAFT_1_21_6, 56), mapSet(MINECRAFT_1_21_5, 54),mapSet(MINECRAFT_1_20_5, 53), mapSet(MINECRAFT_1_20_3, 48),
+        mapSet(MINECRAFT_1_19_4, 48), mapSet(MINECRAFT_1_19, 47))); // added in 1.16
 
-    empty(id("minecraft:loot_table", mapSet(MINECRAFT_1_21_5, 51), mapSet(MINECRAFT_1_20_5, 50)));
-    empty(id("minecraft:loot_predicate", mapSet(MINECRAFT_1_21_5, 52), mapSet(MINECRAFT_1_20_5, 51)));
-    empty(id("minecraft:loot_modifier", mapSet(MINECRAFT_1_21_5, 53), mapSet(MINECRAFT_1_20_5, 52)));
+    empty(id("minecraft:loot_table", mapSet(MINECRAFT_1_21_6, 52), mapSet(MINECRAFT_1_21_5, 51), mapSet(MINECRAFT_1_20_5, 50)));
+    empty(id("minecraft:loot_predicate", mapSet(MINECRAFT_1_21_6, 53), mapSet(MINECRAFT_1_21_5, 52), mapSet(MINECRAFT_1_20_5, 51)));
+    empty(id("minecraft:loot_modifier", mapSet(MINECRAFT_1_21_6, 54), mapSet(MINECRAFT_1_21_5, 53), mapSet(MINECRAFT_1_20_5, 52)));
+
+    empty(id("minecraft:hex_color", mapSet(MINECRAFT_1_21_6, 17))); // added in 1.21.6
+    empty(id("minecraft:dialog", mapSet(MINECRAFT_1_21_6, 55))); // added in 1.21.6
 
     // Crossstitch support
     register(id("crossstitch:mod_argument", mapSet(MINECRAFT_1_19, -256)), ModArgumentProperty.class, MOD);

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/RateLimitedCommandHandler.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2025 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.packet.chat;
+
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.proxy.VelocityServer;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import net.kyori.adventure.text.Component;
+
+public abstract class RateLimitedCommandHandler<T extends MinecraftPacket> implements CommandHandler<T> {
+
+    private final Player player;
+    private final VelocityServer velocityServer;
+
+    private int failedAttempts;
+
+    protected RateLimitedCommandHandler(Player player, VelocityServer velocityServer) {
+        this.player = player;
+        this.velocityServer = velocityServer;
+    }
+
+    @Override
+    public boolean handlePlayerCommand(MinecraftPacket packet) {
+        if (packetClass().isInstance(packet)) {
+            if (!velocityServer.getCommandRateLimiter().attempt(player.getUniqueId())) {
+                if (velocityServer.getConfiguration().isKickOnCommandRateLimit() && failedAttempts++ >= velocityServer.getConfiguration().getKickAfterRateLimitedCommands()) {
+                    player.disconnect(Component.translatable("velocity.kick.command-rate-limit"));
+                }
+
+                if (velocityServer.getConfiguration().isForwardCommandsIfRateLimited()) {
+                    return false; // Send the packet to the server
+                }
+            } else {
+                failedAttempts = 0;
+            }
+
+            handlePlayerCommandInternal(packetClass().cast(packet));
+            return true;
+        }
+
+        return false;
+    }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/keyed/KeyedCommandHandler.java

@@ -21,17 +21,18 @@ import com.velocitypowered.api.event.command.CommandExecuteEvent;
 import com.velocitypowered.api.proxy.crypto.IdentifiedKey;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.protocol.packet.chat.CommandHandler;
+import com.velocitypowered.proxy.protocol.packet.chat.RateLimitedCommandHandler;
 import com.velocitypowered.proxy.protocol.packet.chat.builder.ChatBuilderV2;
 import java.util.concurrent.CompletableFuture;
 import net.kyori.adventure.text.Component;
 
-public class KeyedCommandHandler implements CommandHandler<KeyedPlayerCommandPacket> {
+public class KeyedCommandHandler extends RateLimitedCommandHandler<KeyedPlayerCommandPacket> {
 
   private final ConnectedPlayer player;
   private final VelocityServer server;
 
   public KeyedCommandHandler(ConnectedPlayer player, VelocityServer server) {
+    super(player, server);
     this.player = player;
     this.server = server;
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/legacy/LegacyCommandHandler.java

@@ -20,16 +20,18 @@ package com.velocitypowered.proxy.protocol.packet.chat.legacy;
 import com.velocitypowered.api.event.command.CommandExecuteEvent;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.protocol.packet.chat.CommandHandler;
+import com.velocitypowered.proxy.protocol.packet.chat.RateLimitedCommandHandler;
+
 import java.time.Instant;
 import java.util.concurrent.CompletableFuture;
 
-public class LegacyCommandHandler implements CommandHandler<LegacyChatPacket> {
+public class LegacyCommandHandler extends RateLimitedCommandHandler<LegacyChatPacket> {
 
   private final ConnectedPlayer player;
   private final VelocityServer server;
 
   public LegacyCommandHandler(ConnectedPlayer player, VelocityServer server) {
+    super(player, server);
     this.player = player;
     this.server = server;
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionCommandHandler.java

@@ -22,17 +22,19 @@ import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.ChatAcknowledgementPacket;
-import com.velocitypowered.proxy.protocol.packet.chat.CommandHandler;
 import java.util.concurrent.CompletableFuture;
+
+import com.velocitypowered.proxy.protocol.packet.chat.RateLimitedCommandHandler;
 import net.kyori.adventure.text.Component;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public class SessionCommandHandler implements CommandHandler<SessionPlayerCommandPacket> {
+public class SessionCommandHandler extends RateLimitedCommandHandler<SessionPlayerCommandPacket> {
 
   private final ConnectedPlayer player;
   private final VelocityServer server;
 
   public SessionCommandHandler(ConnectedPlayer player, VelocityServer server) {
+    super(player, server);
     this.player = player;
     this.server = server;
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/config/KnownPacksPacket.java

@@ -36,7 +36,7 @@ public class KnownPacksPacket implements MinecraftPacket {
     public void decode(ByteBuf buf, ProtocolUtils.Direction direction,
                        ProtocolVersion protocolVersion) {
         final int packCount = ProtocolUtils.readVarInt(buf);
-        if (packCount > MAX_LENGTH_PACKS) {
+        if (direction == ProtocolUtils.Direction.SERVERBOUND && packCount > MAX_LENGTH_PACKS) {
           throw TOO_MANY_PACKS;
         }
 

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

@@ -22,13 +22,20 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
+import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
+import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 import com.velocitypowered.api.util.ProxyVersion;
+import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.packet.PluginMessagePacket;
+import com.velocitypowered.proxy.util.except.QuietDecoderException;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import java.nio.charset.StandardCharsets;
 import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
 import java.util.regex.Pattern;
@@ -85,13 +92,18 @@ public final class PluginMessageUtil {
         .equals(UNREGISTER_CHANNEL);
   }
 
+  private static final QuietDecoderException ILLEGAL_CHANNEL = new QuietDecoderException("Illegal channel");
+
   /**
    * Fetches all the channels in a register or unregister plugin message.
    *
+   * @param existingChannels the number of channels already registered
    * @param message the message to get the channels from
    * @return the channels, as an immutable list
    */
-  public static List<String> getChannels(PluginMessagePacket message) {
+  public static List<ChannelIdentifier> getChannels(int existingChannels,
+                                                    PluginMessagePacket message,
+                                                    ProtocolVersion protocolVersion) {
     checkNotNull(message, "message");
     checkArgument(isRegister(message) || isUnregister(message), "Unknown channel type %s",
         message.getChannel());
@@ -100,8 +112,28 @@ public final class PluginMessageUtil {
       // has caused issues with 1.13+ compatibility. Just return an empty list.
       return ImmutableList.of();
     }
-    String channels = message.content().toString(StandardCharsets.UTF_8);
-    return ImmutableList.copyOf(channels.split("\0"));
+    String payload = message.content().toString(StandardCharsets.UTF_8);
+    checkArgument(payload.length() <= Short.MAX_VALUE, "payload too long: %s", payload.length());
+    String[] channels = payload.split("\0");
+    checkArgument(existingChannels + channels.length <= ConnectedPlayer.MAX_CLIENTSIDE_PLUGIN_CHANNELS,
+        "too many channels: %s + %s > %s", existingChannels, channels.length, ConnectedPlayer.MAX_CLIENTSIDE_PLUGIN_CHANNELS);
+    ImmutableList.Builder<ChannelIdentifier> channelIdentifiers = ImmutableList.builderWithExpectedSize(channels.length);
+    try {
+      for (String channel : channels) {
+        if (protocolVersion.noLessThan(ProtocolVersion.MINECRAFT_1_13)) {
+          channelIdentifiers.add(MinecraftChannelIdentifier.from(channel));
+        } else {
+          channelIdentifiers.add(new LegacyChannelIdentifier(channel));
+        }
+      }
+    } catch (IllegalArgumentException e) {
+      if (MinecraftDecoder.DEBUG) {
+        throw e;
+      } else {
+        throw ILLEGAL_CHANNEL;
+      }
+    }
+    return channelIdentifiers.build();
   }
 
   /**
@@ -112,16 +144,31 @@ public final class PluginMessageUtil {
    * @return the plugin message to send
    */
   public static PluginMessagePacket constructChannelsPacket(ProtocolVersion protocolVersion,
-                                                            Collection<String> channels) {
+                                                            Collection<ChannelIdentifier> channels) {
     checkNotNull(channels, "channels");
     checkArgument(!channels.isEmpty(), "no channels specified");
     String channelName = protocolVersion.noLessThan(ProtocolVersion.MINECRAFT_1_13)
         ? REGISTER_CHANNEL : REGISTER_CHANNEL_LEGACY;
     ByteBuf contents = Unpooled.buffer();
-    contents.writeCharSequence(String.join("\0", channels), StandardCharsets.UTF_8);
+    contents.writeCharSequence(joinChannels(channels), StandardCharsets.UTF_8);
     return new PluginMessagePacket(channelName, contents);
   }
 
+  private static String joinChannels(Collection<ChannelIdentifier> channels) {
+    checkNotNull(channels, "channels");
+    checkArgument(!channels.isEmpty(), "no channels specified");
+    StringBuilder sb = new StringBuilder();
+    Iterator<ChannelIdentifier> iterator = channels.iterator();
+    while (iterator.hasNext()) {
+      ChannelIdentifier channel = iterator.next();
+      sb.append(channel.getId());
+      if (iterator.hasNext()) {
+        sb.append('\0');
+      }
+    }
+    return sb.toString();
+  }
+
   /**
    * Rewrites the brand message to indicate the presence of Velocity.
    *

proxy/src/main/java/com/velocitypowered/proxy/server/VelocityRegisteredServer.java

@@ -114,7 +114,7 @@ public class VelocityRegisteredServer implements RegisteredServer, ForwardingAud
     server.createBootstrap(loop).handler(new ChannelInitializer<>() {
       @Override
       protected void initChannel(Channel ch) {
-        ch.pipeline().addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
+        ch.pipeline().addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder(ProtocolUtils.Direction.CLIENTBOUND))
             .addLast(READ_TIMEOUT, new ReadTimeoutHandler(
                 pingOptions.getTimeout() == 0
                     ? server.getConfiguration().getReadTimeout()

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

@@ -24,9 +24,6 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.TranslatableComponent;
 import net.kyori.adventure.text.flattener.ComponentFlattener;
 import net.kyori.adventure.translation.GlobalTranslator;
-import net.kyori.adventure.translation.TranslationRegistry;
-import net.kyori.adventure.translation.Translator;
-import org.jetbrains.annotations.Nullable;
 
 /**
  * Velocity Translation Mapper.
@@ -43,25 +40,9 @@ public enum TranslatableMapper implements BiConsumer<TranslatableComponent, Cons
           final TranslatableComponent translatableComponent,
           final Consumer<Component> componentConsumer
   ) {
-    for (final Translator source : GlobalTranslator.translator().sources()) {
-      if (source instanceof TranslationRegistry registry
-              && registry.contains(translatableComponent.key())) {
-        componentConsumer.accept(GlobalTranslator.render(translatableComponent,
-                ClosestLocaleMatcher.INSTANCE.lookupClosest(Locale.getDefault())));
-        return;
-      }
-    }
-    final @Nullable String fallback = translatableComponent.fallback();
-    if (fallback == null) {
-      return;
-    }
-    for (final Translator source : GlobalTranslator.translator().sources()) {
-      if (source instanceof TranslationRegistry registry && registry.contains(fallback)) {
-        componentConsumer.accept(
-                GlobalTranslator.render(Component.translatable(fallback),
-                        ClosestLocaleMatcher.INSTANCE.lookupClosest(Locale.getDefault())));
-        return;
-      }
+    final Locale locale = ClosestLocaleMatcher.INSTANCE.lookupClosest(Locale.getDefault());
+    if (GlobalTranslator.translator().canTranslate(translatableComponent.key(), locale)) {
+      componentConsumer.accept(GlobalTranslator.render(translatableComponent, locale));
     }
   }
 }

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

@@ -79,10 +79,10 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
    *
    * @return all legacy channel IDs
    */
-  public Collection<String> getLegacyChannelIds() {
-    Collection<String> ids = new HashSet<>();
+  public Collection<ChannelIdentifier> getLegacyChannelIds() {
+    Collection<ChannelIdentifier> ids = new HashSet<>();
     for (ChannelIdentifier value : identifierMap.values()) {
-      ids.add(value.getId());
+      ids.add(new LegacyChannelIdentifier(value.getId()));
     }
     return ids;
   }
@@ -92,13 +92,13 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
    *
    * @return the channel IDs for Minecraft 1.13 and above
    */
-  public Collection<String> getModernChannelIds() {
-    Collection<String> ids = new HashSet<>();
+  public Collection<ChannelIdentifier> getModernChannelIds() {
+    Collection<ChannelIdentifier> ids = new HashSet<>();
     for (ChannelIdentifier value : identifierMap.values()) {
       if (value instanceof MinecraftChannelIdentifier) {
-        ids.add(value.getId());
+        ids.add(value);
       } else {
-        ids.add(PluginMessageUtil.transformLegacyToModernChannel(value.getId()));
+        ids.add(MinecraftChannelIdentifier.from(PluginMessageUtil.transformLegacyToModernChannel(value.getId())));
       }
     }
     return ids;
@@ -114,7 +114,7 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
    * @param protocolVersion the protocol version in use
    * @return the list of channels to register
    */
-  public Collection<String> getChannelsForProtocol(ProtocolVersion protocolVersion) {
+  public Collection<ChannelIdentifier> getChannelsForProtocol(ProtocolVersion protocolVersion) {
     if (protocolVersion.noLessThan(ProtocolVersion.MINECRAFT_1_13)) {
       return getModernChannelIds();
     }

proxy/src/main/java/com/velocitypowered/proxy/util/collect/CappedSet.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2019-2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.util.collect;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ForwardingSet;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * An unsynchronized collection that puts an upper bound on the size of the collection.
+ */
+public final class CappedSet<T> extends ForwardingSet<T> {
+
+  private final Set<T> delegate;
+  private final int upperSize;
+
+  private CappedSet(Set<T> delegate, int upperSize) {
+    this.delegate = delegate;
+    this.upperSize = upperSize;
+  }
+
+  /**
+   * Creates a capped collection backed by a {@link HashSet}.
+   *
+   * @param maxSize the maximum size of the collection
+   * @param <T>     the type of elements in the collection
+   * @return the new collection
+   */
+  public static <T> Set<T> create(int maxSize) {
+    return new CappedSet<>(new HashSet<>(), maxSize);
+  }
+
+  @Override
+  protected Set<T> delegate() {
+    return delegate;
+  }
+
+  @Override
+  public boolean add(T element) {
+    if (this.delegate.size() >= upperSize) {
+      Preconditions.checkState(this.delegate.contains(element),
+          "collection is too large (%s >= %s)",
+          this.delegate.size(), this.upperSize);
+      return false;
+    }
+    return this.delegate.add(element);
+  }
+
+  @Override
+  public boolean addAll(Collection<? extends T> collection) {
+    return this.standardAddAll(collection);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/util/ratelimit/CaffeineCacheRatelimiter.java

@@ -22,15 +22,15 @@ import com.github.benmanes.caffeine.cache.Caffeine;
 import com.github.benmanes.caffeine.cache.Ticker;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
-import java.net.InetAddress;
 import java.util.concurrent.TimeUnit;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * A simple rate-limiter based on a Caffeine {@link Cache}.
  */
-public class CaffeineCacheRatelimiter implements Ratelimiter {
+public class CaffeineCacheRatelimiter<T> implements Ratelimiter<T> {
 
-  private final Cache<InetAddress, Long> expiringCache;
+  private final Cache<T, Long> expiringCache;
   private final long timeoutNanos;
 
   CaffeineCacheRatelimiter(long time, TimeUnit unit) {
@@ -49,16 +49,15 @@ public class CaffeineCacheRatelimiter implements Ratelimiter {
   }
 
   /**
-   * Attempts to rate-limit the client.
+   * Attempts to rate-limit the object.
    *
-   * @param address the address to rate limit
-   * @return true if we should allow the client, false if we should rate-limit
+   * @param key the object to rate limit
+   * @return true if we should allow the object, false if we should rate-limit
    */
   @Override
-  public boolean attempt(InetAddress address) {
-    Preconditions.checkNotNull(address, "address");
+  public boolean attempt(@NotNull  T key) {
     long expectedNewValue = System.nanoTime() + timeoutNanos;
-    long last = expiringCache.get(address, (address1) -> expectedNewValue);
+    long last = expiringCache.get(key, (key1) -> expectedNewValue);
     return expectedNewValue == last;
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/util/ratelimit/NoopCacheRatelimiter.java

@@ -17,16 +17,16 @@
 
 package com.velocitypowered.proxy.util.ratelimit;
 
-import java.net.InetAddress;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * A {@link Ratelimiter} that does no rate-limiting.
  */
-enum NoopCacheRatelimiter implements Ratelimiter {
+enum NoopCacheRatelimiter implements Ratelimiter<Object> {
   INSTANCE;
 
   @Override
-  public boolean attempt(InetAddress address) {
+  public boolean attempt(@NotNull Object key) {
     return true;
   }
 }

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

@@ -17,18 +17,18 @@
 
 package com.velocitypowered.proxy.util.ratelimit;
 
-import java.net.InetAddress;
+import org.jetbrains.annotations.NotNull;
 
 /**
- * Allows rate limiting of clients.
+ * Allows rate limiting of objects.
  */
-public interface Ratelimiter {
+public interface Ratelimiter<T> {
 
   /**
-   * Determines whether or not to allow the connection.
-   *
-   * @param address the address to rate limit
-   * @return true if allowed, false if not
-   */
-  boolean attempt(InetAddress address);
+  * Attempts to rate-limit the object.
+  *
+  * @param key the object to rate limit
+  * @return true if we should allow the object, false if we should rate-limit
+  */
+  boolean attempt(@NotNull T key);
 }

proxy/src/main/java/com/velocitypowered/proxy/util/ratelimit/Ratelimiters.java

@@ -28,8 +28,9 @@ public final class Ratelimiters {
     throw new AssertionError();
   }
 
-  public static Ratelimiter createWithMilliseconds(long ms) {
-    return ms <= 0 ? NoopCacheRatelimiter.INSTANCE : new CaffeineCacheRatelimiter(ms,
+  @SuppressWarnings("unchecked")
+  public static <T> Ratelimiter<T> createWithMilliseconds(long ms) {
+    return ms <= 0 ? (Ratelimiter<T>) NoopCacheRatelimiter.INSTANCE : new CaffeineCacheRatelimiter(ms,
         TimeUnit.MILLISECONDS);
   }
 }

proxy/src/main/resources/com/velocitypowered/proxy/l10n/messages.properties

@@ -63,3 +63,5 @@ velocity.command.dump-offline=Likely cause: Invalid system DNS settings or no in
 velocity.command.send-usage=/send <player> <server>
 # Kick
 velocity.kick.shutdown=Proxy shutting down.
+velocity.kick.command-rate-limit=You are sending too many commands too quickly.
+velocity.kick.tab-complete-rate-limit=You are sending too many tab complete requests too quickly.

proxy/src/main/resources/com/velocitypowered/proxy/l10n/messages_bg_BG.properties

@@ -35,7 +35,7 @@ velocity.command.generic-error=Възникна грешка при изпълн
 velocity.command.command-does-not-exist=Тази команда не съществува.
 velocity.command.players-only=Само играчи могат да изпълняват тази команда.
 velocity.command.server-does-not-exist=Сървър с името {0} не съществува.
-velocity.command.player-not-found=Този играч {0} не съществува.
+velocity.command.player-not-found=Играч с името {0} не съществува.
 velocity.command.server-current-server=В момента сте свързан към {0}.
 velocity.command.server-too-many=Има прекалено много регистрирани сървъри. Използвайте TAB, за да видите всички налични сървъри.
 velocity.command.server-available=Налични сървъри\:

proxy/src/main/resources/com/velocitypowered/proxy/l10n/messages_es_ES.properties

@@ -29,7 +29,7 @@ velocity.error.modern-forwarding-needs-new-client=Este servidor solo es compatib
 velocity.error.modern-forwarding-failed=El servidor no ha enviado una solicitud de reenvío al proxy. Asegúrate de que tu servidor está configurado para usar el método de reenvío de Velocity.
 velocity.error.moved-to-new-server=Has sido echado de {0}\: {1}
 velocity.error.no-available-servers=No hay servidores disponibles a los que conectarte. Inténtalo de nuevo más tarde o contacta con un administrador.
-velocity.error.illegal-chat-characters=Illegal characters in chat
+velocity.error.illegal-chat-characters=Caracteres no válidos en el chat
 # Commands
 velocity.command.generic-error=Se ha producido un error al ejecutar este comando.
 velocity.command.command-does-not-exist=Este comando no existe.
@@ -60,6 +60,6 @@ velocity.command.dump-success=Se ha creado un informe anónimo que contiene info
 velocity.command.dump-will-expire=Este enlace caducará en unos días.
 velocity.command.dump-server-error=Se ha producido un error en los servidores de Velocity y la subida no se ha podido completar. Notifica al equipo de Velocity sobre este problema y proporciona los detalles sobre este error disponibles en el archivo de registro o la consola de tu servidor Velocity.
 velocity.command.dump-offline=Causa probable\: la configuración DNS del sistema no es válida o no hay conexión a internet
-velocity.command.send-usage=/send <player> <server>
+velocity.command.send-usage=/send <jugador> <servidor>
 # Kick
-velocity.kick.shutdown=Proxy shutting down.
+velocity.kick.shutdown=El proxy se ha apagado.

proxy/src/main/resources/default-velocity.toml

@@ -66,6 +66,11 @@ kick-existing-players = false
 #                  configuration is used if no servers could be contacted.
 ping-passthrough = "DISABLED"
 
+# If enabled (default is false), then a sample of the online players on the proxy will be visible
+# when hovering over the player count in the server list.
+# This doesn't have any effect when ping passthrough is set to either "description" or "all".
+sample-players-in-ping = false
+
 # If not enabled (default is true) player IP addresses will be replaced by <ip address withheld> in logs
 enable-player-address-logging = true
 
@@ -151,6 +156,27 @@ accepts-transfers = false
 # threads. Disabled by default. Requires Linux or macOS.
 enable-reuse-port = false
 
+# How fast (in milliseconds) are clients allowed to send commands after the last command
+# By default this is 50ms (20 commands per second)
+command-rate-limit = 50
+
+# Should we forward commands to the backend upon being rate limited?
+# This will forward the command to the server instead of processing it on the proxy.
+# Since most server implementations have a rate limit, this will prevent the player
+# from being able to send excessive commands to the server.
+forward-commands-if-rate-limited = true
+
+# How many commands are allowed to be sent after the rate limit is hit before the player is kicked?
+# Setting this to 0 or lower will disable this feature.
+kick-after-rate-limited-commands = 0
+
+# How fast (in milliseconds) are clients allowed to send tab completions after the last tab completion
+tab-complete-rate-limit = 10
+
+# How many tab completions are allowed to be sent after the rate limit is hit before the player is kicked?
+# Setting this to 0 or lower will disable this feature.
+kick-after-rate-limited-tab-completes = 0
+
 [query]
 # Whether to enable responding to GameSpy 4 query responses or not.
 enabled = false

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

@@ -20,8 +20,10 @@ package com.velocitypowered.proxy.util;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import com.google.common.collect.ImmutableSet;
+import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
+import java.util.stream.Collectors;
 import org.junit.jupiter.api.Test;
 
 class VelocityChannelRegistrarTest {
@@ -46,9 +48,9 @@ class VelocityChannelRegistrarTest {
     // Two channels cover the modern channel (velocity:test) and the legacy-mapped channel
     // (legacy:velocitytest). Make sure they're what we expect.
     assertEquals(ImmutableSet.of(MODERN.getId(), SIMPLE_LEGACY_REMAPPED), registrar
-        .getModernChannelIds());
+        .getModernChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));
     assertEquals(ImmutableSet.of(SIMPLE_LEGACY.getId(), MODERN.getId()), registrar
-        .getLegacyChannelIds());
+        .getLegacyChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));
   }
 
   @Test
@@ -57,9 +59,10 @@ class VelocityChannelRegistrarTest {
     registrar.register(SPECIAL_REMAP_LEGACY, MODERN_SPECIAL_REMAP);
 
     // This one, just one channel for the modern case.
-    assertEquals(ImmutableSet.of(MODERN_SPECIAL_REMAP.getId()), registrar.getModernChannelIds());
+    assertEquals(ImmutableSet.of(MODERN_SPECIAL_REMAP.getId()),
+        registrar.getModernChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));
     assertEquals(ImmutableSet.of(MODERN_SPECIAL_REMAP.getId(), SPECIAL_REMAP_LEGACY.getId()),
-        registrar.getLegacyChannelIds());
+        registrar.getLegacyChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));
   }
 
   @Test
@@ -68,7 +71,9 @@ class VelocityChannelRegistrarTest {
     registrar.register(MODERN, SIMPLE_LEGACY);
     registrar.unregister(SIMPLE_LEGACY);
 
-    assertEquals(ImmutableSet.of(MODERN.getId()), registrar.getModernChannelIds());
-    assertEquals(ImmutableSet.of(MODERN.getId()), registrar.getLegacyChannelIds());
+    assertEquals(ImmutableSet.of(MODERN.getId()),
+        registrar.getModernChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));;
+    assertEquals(ImmutableSet.of(MODERN.getId()),
+        registrar.getLegacyChannelIds().stream().map(ChannelIdentifier::getId).collect(Collectors.toSet()));
   }
 }

proxy/src/test/java/com/velocitypowered/proxy/util/collect/CappedSetTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2019-2021 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.util.collect;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.Collection;
+import java.util.Set;
+import org.junit.jupiter.api.Test;
+
+class CappedSetTest {
+
+  @Test
+  void basicVerification() {
+    Collection<String> coll = CappedSet.create(1);
+    assertTrue(coll.add("coffee"), "did not add single item");
+    assertThrows(IllegalStateException.class, () -> coll.add("tea"),
+        "item was added to collection although it is too full");
+    assertEquals(1, coll.size(), "collection grew in size unexpectedly");
+  }
+
+  @Test
+  void testAddAll() {
+    Set<String> doesFill1 = ImmutableSet.of("coffee", "tea");
+    Set<String> doesFill2 = ImmutableSet.of("chocolate");
+    Set<String> overfill = ImmutableSet.of("Coke", "Pepsi");
+
+    Collection<String> coll = CappedSet.create(3);
+    assertTrue(coll.addAll(doesFill1), "did not add items");
+    assertTrue(coll.addAll(doesFill2), "did not add items");
+    assertThrows(IllegalStateException.class, () -> coll.addAll(overfill),
+        "items added to collection although it is too full");
+    assertEquals(3, coll.size(), "collection grew in size unexpectedly");
+  }
+
+  @Test
+  void handlesSetBehaviorCorrectly() {
+    Set<String> doesFill1 = ImmutableSet.of("coffee", "tea");
+    Set<String> doesFill2 = ImmutableSet.of("coffee", "chocolate");
+    Set<String> overfill = ImmutableSet.of("coffee", "Coke", "Pepsi");
+
+    Collection<String> coll = CappedSet.create(3);
+    assertTrue(coll.addAll(doesFill1), "did not add items");
+    assertTrue(coll.addAll(doesFill2), "did not add items");
+    assertThrows(IllegalStateException.class, () -> coll.addAll(overfill),
+        "items added to collection although it is too full");
+
+    assertFalse(coll.addAll(doesFill1), "added items?!?");
+
+    assertEquals(3, coll.size(), "collection grew in size unexpectedly");
+  }
+}