Merge pull request #310 from Xernium/future/1.16

[Future] 1.16 Update

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

@@ -34,7 +34,8 @@ public enum ProtocolVersion {
   MINECRAFT_1_14_4(498, "1.14.4"),
   MINECRAFT_1_15(573, "1.15"),
   MINECRAFT_1_15_1(575, "1.15.1"),
-  MINECRAFT_1_15_2(578, "1.15.2");
+  MINECRAFT_1_15_2(578, "1.15.2"),
+  MINECRAFT_1_16(734, "1.16");
 
   private final int protocol;
   private final String name;

proxy/build.gradle

@@ -63,6 +63,7 @@ dependencies {
 
     compile 'it.unimi.dsi:fastutil:8.2.2'
     compile 'net.kyori:event-method-asm:3.0.0'
+    compile 'net.kyori:nbt:1.12-1.0.0-SNAPSHOT'
 
     compile 'com.mojang:brigadier:1.0.17'
 

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

@@ -12,7 +12,6 @@ import static com.velocitypowered.proxy.network.Connections.READ_TIMEOUT;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
-import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.api.proxy.ServerConnection;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.server.ServerInfo;
@@ -22,6 +21,7 @@ import com.velocitypowered.proxy.connection.ConnectionTypes;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.connection.registry.DimensionRegistry;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
@@ -40,6 +40,8 @@ import io.netty.handler.flow.FlowControlHandler;
 import io.netty.handler.timeout.ReadTimeoutHandler;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
+
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class VelocityServerConnection implements MinecraftConnectionAssociation, ServerConnection {
@@ -53,6 +55,7 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
   private BackendConnectionPhase connectionPhase = BackendConnectionPhases.UNKNOWN;
   private long lastPingId;
   private long lastPingSent;
+  private @MonotonicNonNull DimensionRegistry activeDimensionRegistry;
 
   /**
    * Initializes a new server connection.
@@ -297,4 +300,11 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
     return hasCompletedJoin;
   }
 
+  public DimensionRegistry getActiveDimensionRegistry() {
+    return activeDimensionRegistry;
+  }
+
+  public void setActiveDimensionRegistry(DimensionRegistry activeDimensionRegistry) {
+    this.activeDimensionRegistry = activeDimensionRegistry;
+  }
 }

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

@@ -32,11 +32,9 @@ import io.netty.buffer.ByteBuf;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.Queue;
-import java.util.Set;
 import java.util.UUID;
 import net.kyori.text.TextComponent;
 import net.kyori.text.format.TextColor;
@@ -313,8 +311,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     if (!spawned) {
       // Nothing special to do with regards to spawning the player
       spawned = true;
+      destination.setActiveDimensionRegistry(joinGame.getDimensionRegistry()); // 1.16
       player.getMinecraftConnection().delayedWrite(joinGame);
-
       // Required for Legacy Forge
       player.getPhase().onFirstJoin(player);
     } else {
@@ -334,13 +332,22 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       // to perform entity ID rewrites, eliminating potential issues from rewriting packets and
       // improving compatibility with mods.
       player.getMinecraftConnection().delayedWrite(joinGame);
-      int tempDim = joinGame.getDimension() == 0 ? -1 : 0;
+      // Since 1.16 this dynamic changed:
-      player.getMinecraftConnection().delayedWrite(
+      // We don't need to send two dimension swiches anymore!
-          new Respawn(tempDim, joinGame.getPartialHashedSeed(), joinGame.getDifficulty(),
+      if (player.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_16) < 0) {
-              joinGame.getGamemode(), joinGame.getLevelType()));
+        int tempDim = joinGame.getDimension() == 0 ? -1 : 0;
+        player.getMinecraftConnection().delayedWrite(
+                new Respawn(tempDim, joinGame.getPartialHashedSeed(), joinGame.getDifficulty(),
+                        joinGame.getGamemode(), joinGame.getLevelType(),
+                        false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode()));
+      }
+
       player.getMinecraftConnection().delayedWrite(
           new Respawn(joinGame.getDimension(), joinGame.getPartialHashedSeed(),
-              joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType()));
+              joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType(),
+                  false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode()));
+
+      destination.setActiveDimensionRegistry(joinGame.getDimensionRegistry()); // 1.16
     }
 
     // Remove previous boss bars. These don't get cleared when sending JoinGame, thus the need to

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

@@ -18,7 +18,10 @@ import com.velocitypowered.api.event.permission.PermissionsSetupEvent;
 import com.velocitypowered.api.event.player.GameProfileRequestEvent;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.proxy.VelocityServer;
+import com.velocitypowered.proxy.config.PlayerInfoForwarding;
+import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 
@@ -41,6 +44,7 @@ import java.security.GeneralSecurityException;
 import java.security.KeyPair;
 import java.util.Arrays;
 import java.util.Optional;
+import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ThreadLocalRandom;
 import net.kyori.text.Component;
@@ -253,10 +257,14 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
       mcConnection.write(new SetCompression(threshold));
       mcConnection.setCompressionThreshold(threshold);
     }
-
+    VelocityConfiguration configuration = server.getConfiguration();
+    UUID playerUniqueId = player.getUniqueId();
+    if (configuration.getPlayerInfoForwardingMode() == PlayerInfoForwarding.NONE) {
+      playerUniqueId = UuidUtils.generateOfflinePlayerUuid(player.getUsername());
+    }
     ServerLoginSuccess success = new ServerLoginSuccess();
     success.setUsername(player.getUsername());
-    success.setUuid(player.getUniqueId());
+    success.setUuid(playerUniqueId);
     mcConnection.write(success);
 
     mcConnection.setAssociation(player);

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionData.java

@@ -0,0 +1,193 @@
+package com.velocitypowered.proxy.connection.registry;
+
+import com.google.common.base.Preconditions;
+import net.kyori.nbt.CompoundTag;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public final class DimensionData {
+  private final String registryIdentifier;
+  private final boolean isNatural;
+  private final float ambientLight;
+  private final boolean isShrunk;
+  private final boolean isUltrawarm;
+  private final boolean hasCeiling;
+  private final boolean hasSkylight;
+  private final boolean isPiglinSafe;
+  private final boolean doBedsWork;
+  private final boolean doRespawnAnchorsWork;
+  private final boolean hasRaids;
+  private final int logicalHeight;
+  private final String burningBehaviourIdentifier;
+  private final @Nullable Long fixedTime;
+  private final @Nullable Boolean createDragonFight;
+
+  /**
+   * Initializes a new {@link DimensionData} instance.
+   * @param registryIdentifier the identifier for the dimension from the registry.
+   * @param isNatural indicates if the dimension use natural world generation (e.g. overworld)
+   * @param ambientLight the light level the client sees without external lighting
+   * @param isShrunk indicates if the world is shrunk, aka not the full 256 blocks (e.g. nether)
+   * @param isUltrawarm internal dimension warmth flag
+   * @param hasCeiling indicates if the dimension has a ceiling layer
+   * @param hasSkylight indicates if the dimension should display the sun
+   * @param isPiglinSafe indicates if piglins should naturally zombify in this dimension
+   * @param doBedsWork indicates if players should be able to sleep in beds in this dimension
+   * @param doRespawnAnchorsWork indicates if player respawn points can be used in this dimension
+   * @param hasRaids indicates if raids can be spawned in the dimension
+   * @param logicalHeight the natural max height for the given dimension
+   * @param burningBehaviourIdentifier the identifier for how burning blocks work in the dimension
+   * @param fixedTime optional. If set to any game daytime value will deactivate time cycle
+   * @param createDragonFight optional. Internal flag used in the end dimension
+   */
+  public DimensionData(String registryIdentifier, boolean isNatural,
+                       float ambientLight, boolean isShrunk, boolean isUltrawarm,
+                       boolean hasCeiling, boolean hasSkylight,
+                       boolean isPiglinSafe, boolean doBedsWork,
+                       boolean doRespawnAnchorsWork, boolean hasRaids,
+                       int logicalHeight, String burningBehaviourIdentifier,
+                       @Nullable Long fixedTime, @Nullable Boolean createDragonFight) {
+    Preconditions.checkNotNull(
+            registryIdentifier, "registryIdentifier cannot be null");
+    Preconditions.checkArgument(registryIdentifier.length() > 0 && !registryIdentifier.isBlank(),
+            "registryIdentifier cannot be empty");
+    Preconditions.checkArgument(logicalHeight >= 0, "localHeight must be >= 0");
+    Preconditions.checkNotNull(
+            burningBehaviourIdentifier, "burningBehaviourIdentifier cannot be null");
+    Preconditions.checkArgument(burningBehaviourIdentifier.length() > 0
+                    && !burningBehaviourIdentifier.isBlank(),
+            "burningBehaviourIdentifier cannot be empty");
+    this.registryIdentifier = registryIdentifier;
+    this.isNatural = isNatural;
+    this.ambientLight = ambientLight;
+    this.isShrunk = isShrunk;
+    this.isUltrawarm = isUltrawarm;
+    this.hasCeiling = hasCeiling;
+    this.hasSkylight = hasSkylight;
+    this.isPiglinSafe = isPiglinSafe;
+    this.doBedsWork = doBedsWork;
+    this.doRespawnAnchorsWork = doRespawnAnchorsWork;
+    this.hasRaids = hasRaids;
+    this.logicalHeight = logicalHeight;
+    this.burningBehaviourIdentifier = burningBehaviourIdentifier;
+    this.fixedTime = fixedTime;
+    this.createDragonFight = createDragonFight;
+  }
+
+  public String getRegistryIdentifier() {
+    return registryIdentifier;
+  }
+
+  public boolean isNatural() {
+    return isNatural;
+  }
+
+  public float getAmbientLight() {
+    return ambientLight;
+  }
+
+  public boolean isShrunk() {
+    return isShrunk;
+  }
+
+  public boolean isUltrawarm() {
+    return isUltrawarm;
+  }
+
+  public boolean hasCeiling() {
+    return hasCeiling;
+  }
+
+  public boolean hasSkylight() {
+    return hasSkylight;
+  }
+
+  public boolean isPiglinSafe() {
+    return isPiglinSafe;
+  }
+
+  public boolean doBedsWork() {
+    return doBedsWork;
+  }
+
+  public boolean doRespawnAnchorsWork() {
+    return doRespawnAnchorsWork;
+  }
+
+  public boolean hasRaids() {
+    return hasRaids;
+  }
+
+  public int getLogicalHeight() {
+    return logicalHeight;
+  }
+
+  public String getBurningBehaviourIdentifier() {
+    return burningBehaviourIdentifier;
+  }
+
+  public @Nullable Long getFixedTime() {
+    return fixedTime;
+  }
+
+  public @Nullable Boolean getCreateDragonFight() {
+    return createDragonFight;
+  }
+
+  /**
+   * Parses a given CompoundTag to a DimensionData instance.
+   * @param toRead the compound from the registry to read
+   * @return game dimension data
+   */
+  public static DimensionData decodeCompoundTag(CompoundTag toRead) {
+    Preconditions.checkNotNull(toRead, "CompoundTag cannot be null");
+    String registryIdentifier = toRead.getString("name");
+    boolean isNatural = toRead.getBoolean("natural");
+    float ambientLight = toRead.getFloat("ambient_light");
+    boolean isShrunk = toRead.getBoolean("shrunk");
+    boolean isUltrawarm = toRead.getBoolean("ultrawarm");
+    boolean hasCeiling = toRead.getBoolean("has_ceiling");
+    boolean hasSkylight = toRead.getBoolean("has_skylight");
+    boolean isPiglinSafe = toRead.getBoolean("piglin_safe");
+    boolean doBedsWork = toRead.getBoolean("bed_works");
+    boolean doRespawnAnchorsWork = toRead.getBoolean("respawn_anchor_works");
+    boolean hasRaids = toRead.getBoolean("has_raids");
+    int logicalHeight = toRead.getInt("logical_height");
+    String burningBehaviourIdentifier = toRead.getString("infiniburn");
+    Long fixedTime = toRead.contains("fixed_time")
+            ? toRead.getLong("fixed_time") : null;
+    Boolean hasEnderdragonFight = toRead.contains("has_enderdragon_fight")
+                    ? toRead.getBoolean("has_enderdragon_fight") : null;
+    return new DimensionData(
+            registryIdentifier, isNatural, ambientLight, isShrunk,
+            isUltrawarm, hasCeiling, hasSkylight, isPiglinSafe, doBedsWork, doRespawnAnchorsWork,
+            hasRaids, logicalHeight, burningBehaviourIdentifier, fixedTime, hasEnderdragonFight);
+  }
+
+  /**
+   * Encodes the Dimension data as CompoundTag.
+   * @return compound containing the dimension data
+   */
+  public CompoundTag encodeAsCompundTag() {
+    CompoundTag ret = new CompoundTag();
+    ret.putString("name", registryIdentifier);
+    ret.putBoolean("natural", isNatural);
+    ret.putFloat("ambient_light", ambientLight);
+    ret.putBoolean("shrunk", isShrunk);
+    ret.putBoolean("ultrawarm", isUltrawarm);
+    ret.putBoolean("has_ceiling", hasCeiling);
+    ret.putBoolean("has_skylight", hasSkylight);
+    ret.putBoolean("piglin_safe", isPiglinSafe);
+    ret.putBoolean("bed_works", doBedsWork);
+    ret.putBoolean("respawn_anchor_works", doRespawnAnchorsWork);
+    ret.putBoolean("has_raids", hasRaids);
+    ret.putInt("logical_height", logicalHeight);
+    ret.putString("infiniburn", burningBehaviourIdentifier);
+    if (fixedTime != null) {
+      ret.putLong("fixed_time", fixedTime);
+    }
+    if (createDragonFight != null) {
+      ret.putBoolean("has_enderdragon_fight", createDragonFight);
+    }
+    return ret;
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionInfo.java

@@ -0,0 +1,50 @@
+package com.velocitypowered.proxy.connection.registry;
+
+import com.google.common.base.Preconditions;
+
+public final class DimensionInfo {
+
+  private final String registryIdentifier;
+  private final String levelName;
+  private final boolean isFlat;
+  private final boolean isDebugType;
+
+  /**
+   * Initializes a new {@link DimensionInfo} instance.
+   * @param registryIdentifier the identifier for the dimension from the registry
+   * @param levelName the level name as displayed in the F3 menu and logs
+   * @param isFlat if true will set world lighting below surface-level to not display fog
+   * @param isDebugType if true constrains the world to the very limited debug-type world
+   */
+  public DimensionInfo(String registryIdentifier, String levelName,
+                       boolean isFlat, boolean isDebugType) {
+    this.registryIdentifier = Preconditions.checkNotNull(
+            registryIdentifier, "registryIdentifier cannot be null");
+    Preconditions.checkArgument(
+            registryIdentifier.length() > 0 && !registryIdentifier.isBlank(),
+            "registryIdentifier cannot be empty");
+    this.levelName = Preconditions.checkNotNull(
+            levelName, "levelName cannot be null");
+    Preconditions.checkArgument(
+            levelName.length() > 0 && !levelName.isBlank(),
+            "registryIdentifier cannot be empty");
+    this.isFlat = isFlat;
+    this.isDebugType = isDebugType;
+  }
+
+  public boolean isDebugType() {
+    return isDebugType;
+  }
+
+  public boolean isFlat() {
+    return isFlat;
+  }
+
+  public String getLevelName() {
+    return levelName;
+  }
+
+  public String getRegistryIdentifier() {
+    return registryIdentifier;
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/registry/DimensionRegistry.java

@@ -0,0 +1,109 @@
+package com.velocitypowered.proxy.connection.registry;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
+
+import java.util.Map;
+import java.util.Set;
+
+import net.kyori.nbt.CompoundTag;
+import net.kyori.nbt.ListTag;
+import net.kyori.nbt.Tag;
+import net.kyori.nbt.TagType;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+
+public final class DimensionRegistry {
+
+  private final Map<String, DimensionData> registeredDimensions;
+  private final ImmutableSet<String> levelNames;
+
+  /**
+   * Initializes a new {@link DimensionRegistry} instance.
+   * This registry is required for 1.16+ clients/servers to communicate,
+   * it constrains the dimension types and names the client can be sent
+   * in a Respawn action (dimension change).
+   * This WILL raise an IllegalArgumentException if the following is not met:
+   * - At least one valid DimensionData instance is provided
+   * - At least one valid world name is provided
+   * @param registeredDimensions a populated {@link ImmutableSet} containing dimension data types
+   * @param levelNames a populated {@link ImmutableSet} of the level (world) names the server offers
+   */
+  public DimensionRegistry(ImmutableSet<DimensionData> registeredDimensions,
+                            ImmutableSet<String> levelNames) {
+    Preconditions.checkNotNull(registeredDimensions,
+            "registeredDimensions cannot be null");
+    Preconditions.checkNotNull(levelNames,
+            "levelNames cannot be null");
+    Preconditions.checkArgument(registeredDimensions.size() > 0,
+            "registeredDimensions needs to be populated");
+    Preconditions.checkArgument(levelNames.size() > 0,
+            "levelNames needs to populated");
+    this.registeredDimensions = Maps.uniqueIndex(
+            registeredDimensions, DimensionData::getRegistryIdentifier);
+    this.levelNames = levelNames;
+  }
+
+  public Map<String, DimensionData> getRegisteredDimensions() {
+    return registeredDimensions;
+  }
+
+  public Set<String> getLevelNames() {
+    return levelNames;
+  }
+
+  /**
+   * Returns the internal dimension data type as used by the game.
+   * @param dimensionIdentifier how the dimension is identified by the connection
+   * @return game dimension data or null if not registered
+   */
+  public @Nullable DimensionData getDimensionData(String dimensionIdentifier) {
+    return registeredDimensions.get(dimensionIdentifier);
+  }
+
+  /**
+   * Checks a {@link DimensionInfo} against this registry.
+   * @param toValidate the {@link DimensionInfo} to validate
+   * @return true: the dimension information is valid for this registry
+   */
+  public boolean isValidFor(DimensionInfo toValidate) {
+    if (toValidate == null) {
+      return false;
+    }
+    return registeredDimensions.containsKey(toValidate.getRegistryIdentifier())
+            && levelNames.contains(toValidate.getLevelName());
+  }
+
+  /**
+   * Encodes the stored Dimension registry as CompoundTag.
+   * @return the CompoundTag containing identifier:type mappings
+   */
+  public CompoundTag encodeRegistry() {
+    CompoundTag ret = new CompoundTag();
+    ListTag list = new ListTag(TagType.COMPOUND);
+    for (DimensionData iter : registeredDimensions.values()) {
+      list.add(iter.encodeAsCompundTag());
+    }
+    ret.put("dimension", list);
+    return ret;
+  }
+
+  /**
+   * Decodes a CompoundTag storing a dimension registry.
+   * @param toParse CompoundTag containing a dimension registry
+   */
+  public static ImmutableSet<DimensionData> fromGameData(CompoundTag toParse) {
+    Preconditions.checkNotNull(toParse, "CompoundTag cannot be null");
+    Preconditions.checkArgument(toParse.contains("dimension", TagType.LIST),
+            "CompoundTag does not contain a dimension list");
+    ListTag dimensions = toParse.getList("dimension");
+    ImmutableSet.Builder<DimensionData> mappings = ImmutableSet.builder();
+    for (Tag iter : dimensions) {
+      if (iter instanceof CompoundTag) {
+        mappings.add(DimensionData.decodeCompoundTag((CompoundTag) iter));
+      }
+    }
+    return mappings.build();
+  }
+}

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

@@ -6,13 +6,24 @@ import static com.google.common.base.Preconditions.checkState;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.util.GameProfile;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufInputStream;
+import io.netty.buffer.ByteBufOutputStream;
 import io.netty.buffer.ByteBufUtil;
+import io.netty.handler.codec.DecoderException;
+import io.netty.handler.codec.EncoderException;
 
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 
+import net.kyori.nbt.CompoundTag;
+import net.kyori.nbt.TagIO;
+import net.kyori.nbt.TagType;
+
 public enum ProtocolUtils {
   ;
   private static final int DEFAULT_MAX_STRING_SIZE = 65536; // 64KiB
@@ -153,6 +164,100 @@ public enum ProtocolUtils {
     buf.writeLong(uuid.getLeastSignificantBits());
   }
 
+  /**
+   * Reads an UUID stored as an Integer Array from the {@code buf}.
+   * @param buf the buffer to read from
+   * @return the UUID from the buffer
+   */
+  public static UUID readUuidIntArray(ByteBuf buf) {
+    long msbHigh = (long) buf.readInt() << 32;
+    long msbLow = (long) buf.readInt() & 0xFFFFFFFFL;
+    long msb = msbHigh | msbLow;
+    long lsbHigh = (long) buf.readInt() << 32;
+    long lsbLow = (long) buf.readInt() & 0xFFFFFFFFL;
+    long lsb = lsbHigh | lsbLow;
+    return new UUID(msb, lsb);
+  }
+
+  /**
+   * Writes an UUID as an Integer Array to the {@code buf}.
+   * @param buf the buffer to write to
+   * @param uuid the UUID to write
+   */
+  public static void writeUuidIntArray(ByteBuf buf, UUID uuid) {
+    buf.writeInt((int) (uuid.getMostSignificantBits() >> 32));
+    buf.writeInt((int) uuid.getMostSignificantBits());
+    buf.writeInt((int) (uuid.getLeastSignificantBits() >> 32));
+    buf.writeInt((int) uuid.getLeastSignificantBits());
+  }
+
+  /**
+   * Reads a {@link net.kyori.nbt.CompoundTag} from the {@code buf}.
+   * @param buf the buffer to read from
+   * @return {@link net.kyori.nbt.CompoundTag} the CompoundTag from the buffer
+   */
+  public static CompoundTag readCompoundTag(ByteBuf buf) {
+    int indexBefore = buf.readerIndex();
+    byte startType = buf.readByte();
+    if (startType == 0) {
+      throw new DecoderException("Invalid NBT start-type (end/empty)");
+    }
+    buf.readerIndex(indexBefore);
+    try {
+      return TagIO.readDataInput(new ByteBufInputStream(buf));
+    } catch (IOException thrown) {
+      throw new DecoderException(
+              "Unable to parse NBT CompoundTag, full error: " + thrown.getMessage());
+    }
+  }
+
+  /**
+   * Writes a CompoundTag to the {@code buf}.
+   * @param buf the buffer to write to
+   * @param compoundTag the CompoundTag to write
+   */
+  public static void writeCompoundTag(ByteBuf buf, CompoundTag compoundTag) {
+    if (compoundTag == null) {
+      buf.writeByte(0);
+      return;
+    }
+    try {
+      TagIO.writeDataOutput(compoundTag, new ByteBufOutputStream(buf));
+    } catch (IOException e) {
+      throw new EncoderException("Unable to encode NBT CompoundTag");
+    }
+  }
+
+  /**
+   * Reads a String array from the {@code buf}.
+   * @param buf the buffer to read from
+   * @return the String array from the buffer
+   */
+  public static String[] readStringArray(ByteBuf buf) {
+    int length = readVarInt(buf);
+    String[] ret = new String[length];
+    for (int i = 0; i < length; i++) {
+      ret[i] = readString(buf);
+    }
+    return ret;
+  }
+
+  /**
+   * Writes a String Array to the {@code buf}.
+   * @param buf the buffer to write to
+   * @param stringArray the array to write
+   */
+  public static void writeStringArray(ByteBuf buf, String[] stringArray) {
+    if (stringArray == null) {
+      writeVarInt(buf, 0);
+      return;
+    }
+    writeVarInt(buf, stringArray.length);
+    for (int i = 0; i < stringArray.length; i++) {
+      writeString(buf, stringArray[i]);
+    }
+  }
+
   /**
    * Writes a list of {@link com.velocitypowered.api.util.GameProfile.Property} to the buffer.
    * @param buf the buffer to write to

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

@@ -6,6 +6,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12_1;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_14;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_15;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_16;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_8;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_4;
@@ -113,54 +114,64 @@ public enum StateRegistry {
           map(0x0C, MINECRAFT_1_12, false),
           map(0x0B, MINECRAFT_1_12_1, false),
           map(0x0E, MINECRAFT_1_13, false),
-          map(0x0F, MINECRAFT_1_14, false));
+          map(0x0F, MINECRAFT_1_14, false),
+          map(0x10, MINECRAFT_1_16, false));
       serverbound.register(ResourcePackResponse.class, ResourcePackResponse::new,
           map(0x19, MINECRAFT_1_8, false),
           map(0x16, MINECRAFT_1_9, false),
           map(0x18, MINECRAFT_1_12, false),
           map(0x1D, MINECRAFT_1_13, false),
-          map(0x1F, MINECRAFT_1_14, false));
+          map(0x1F, MINECRAFT_1_14, false),
+          map(0x20, MINECRAFT_1_16, false));
 
       clientbound.register(BossBar.class, BossBar::new,
           map(0x0C, MINECRAFT_1_9, false),
-          map(0x0D, MINECRAFT_1_15, false));
+          map(0x0D, MINECRAFT_1_15, false),
+          map(0x0C, MINECRAFT_1_16, false));
       clientbound.register(Chat.class, Chat::new,
           map(0x02, MINECRAFT_1_8, true),
           map(0x0F, MINECRAFT_1_9, true),
           map(0x0E, MINECRAFT_1_13, true),
-          map(0x0F, MINECRAFT_1_15, true));
+          map(0x0F, MINECRAFT_1_15, true),
+          map(0x0E, MINECRAFT_1_16, true));
       clientbound.register(TabCompleteResponse.class, TabCompleteResponse::new,
           map(0x3A, MINECRAFT_1_8, false),
           map(0x0E, MINECRAFT_1_9, false),
           map(0x10, MINECRAFT_1_13, false),
-          map(0x11, MINECRAFT_1_15, false));
+          map(0x11, MINECRAFT_1_15, false),
+          map(0x10, MINECRAFT_1_16, false));
       clientbound.register(AvailableCommands.class, AvailableCommands::new,
           map(0x11, MINECRAFT_1_13, false),
-          map(0x12, MINECRAFT_1_15, false));
+          map(0x12, MINECRAFT_1_15, false),
+          map(0x11, MINECRAFT_1_16, false));
       clientbound.register(PluginMessage.class, PluginMessage::new,
           map(0x3F, MINECRAFT_1_8, false),
           map(0x18, MINECRAFT_1_9, false),
           map(0x19, MINECRAFT_1_13, false),
           map(0x18, MINECRAFT_1_14, false),
-          map(0x19, MINECRAFT_1_15, false));
+          map(0x19, MINECRAFT_1_15, false),
+          map(0x18, MINECRAFT_1_16, false));
       clientbound.register(Disconnect.class, Disconnect::new,
           map(0x40, MINECRAFT_1_8, false),
           map(0x1A, MINECRAFT_1_9, false),
           map(0x1B, MINECRAFT_1_13, false),
           map(0x1A, MINECRAFT_1_14, false),
-          map(0x1B, MINECRAFT_1_15, false));
+          map(0x1B, MINECRAFT_1_15, false),
+          map(0x1A, MINECRAFT_1_16, false));
       clientbound.register(KeepAlive.class, KeepAlive::new,
           map(0x00, MINECRAFT_1_8, false),
           map(0x1F, MINECRAFT_1_9, false),
           map(0x21, MINECRAFT_1_13, false),
           map(0x20, MINECRAFT_1_14, false),
-          map(0x21, MINECRAFT_1_15, false));
+          map(0x21, MINECRAFT_1_15, false),
+          map(0x20, MINECRAFT_1_16, false));
       clientbound.register(JoinGame.class, JoinGame::new,
           map(0x01, MINECRAFT_1_8, false),
           map(0x23, MINECRAFT_1_9, false),
           map(0x25, MINECRAFT_1_13, false),
           map(0x25, MINECRAFT_1_14, false),
-          map(0x26, MINECRAFT_1_15, false));
+          map(0x26, MINECRAFT_1_15, false),
+          map(0x25, MINECRAFT_1_16, false));
       clientbound.register(Respawn.class, Respawn::new,
           map(0x07, MINECRAFT_1_8, true),
           map(0x33, MINECRAFT_1_9, true),
@@ -168,7 +179,8 @@ public enum StateRegistry {
           map(0x35, MINECRAFT_1_12_1, true),
           map(0x38, MINECRAFT_1_13, true),
           map(0x3A, MINECRAFT_1_14, true),
-          map(0x3B, MINECRAFT_1_15, true));
+          map(0x3B, MINECRAFT_1_15, true),
+          map(0x3A, MINECRAFT_1_16, true));
       clientbound.register(ResourcePackRequest.class, ResourcePackRequest::new,
           map(0x48, MINECRAFT_1_8, true),
           map(0x32, MINECRAFT_1_9, true),
@@ -176,7 +188,8 @@ public enum StateRegistry {
           map(0x34, MINECRAFT_1_12_1, true),
           map(0x37, MINECRAFT_1_13, true),
           map(0x39, MINECRAFT_1_14, true),
-          map(0x3A, MINECRAFT_1_15, true));
+          map(0x3A, MINECRAFT_1_15, true),
+          map(0x39, MINECRAFT_1_16, true));
       clientbound.register(HeaderAndFooter.class, HeaderAndFooter::new,
           map(0x47, MINECRAFT_1_8, true),
           map(0x48, MINECRAFT_1_9, true),
@@ -185,7 +198,8 @@ public enum StateRegistry {
           map(0x4A, MINECRAFT_1_12_1, true),
           map(0x4E, MINECRAFT_1_13, true),
           map(0x53, MINECRAFT_1_14, true),
-          map(0x54, MINECRAFT_1_15, true));
+          map(0x54, MINECRAFT_1_15, true),
+          map(0x53, MINECRAFT_1_16, true));
       clientbound.register(TitlePacket.class, TitlePacket::new,
           map(0x45, MINECRAFT_1_8, true),
           map(0x45, MINECRAFT_1_9, true),
@@ -193,14 +207,16 @@ public enum StateRegistry {
           map(0x48, MINECRAFT_1_12_1, true),
           map(0x4B, MINECRAFT_1_13, true),
           map(0x4F, MINECRAFT_1_14, true),
-          map(0x50, MINECRAFT_1_15, true));
+          map(0x50, MINECRAFT_1_15, true),
+          map(0x4F, MINECRAFT_1_16, true));
       clientbound.register(PlayerListItem.class, PlayerListItem::new,
           map(0x38, MINECRAFT_1_8, false),
           map(0x2D, MINECRAFT_1_9, false),
           map(0x2E, MINECRAFT_1_12_1, false),
           map(0x30, MINECRAFT_1_13, false),
           map(0x33, MINECRAFT_1_14, false),
-          map(0x34, MINECRAFT_1_15, false));
+          map(0x34, MINECRAFT_1_15, false),
+          map(0x33, MINECRAFT_1_16, false));
     }
   },
   LOGIN {

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

@@ -10,20 +10,25 @@ import net.kyori.text.Component;
 import net.kyori.text.serializer.gson.GsonComponentSerializer;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
+import java.util.UUID;
+
 public class Chat implements MinecraftPacket {
 
   public static final byte CHAT_TYPE = (byte) 0;
   public static final int MAX_SERVERBOUND_MESSAGE_LENGTH = 256;
+  public static final UUID EMPTY_SENDER = new UUID(0, 0);
 
   private @Nullable String message;
   private byte type;
+  private @Nullable UUID sender;
 
   public Chat() {
   }
 
-  public Chat(String message, byte type) {
+  public Chat(String message, byte type, UUID sender) {
     this.message = message;
     this.type = type;
+    this.sender = sender;
   }
 
   public String getMessage() {
@@ -45,11 +50,20 @@ public class Chat implements MinecraftPacket {
     this.type = type;
   }
 
+  public UUID getSenderUuid() {
+    return sender;
+  }
+
+  public void setSenderUuid(UUID sender) {
+    this.sender = sender;
+  }
+
   @Override
   public String toString() {
     return "Chat{"
         + "message='" + message + '\''
         + ", type=" + type
+        + ", sender=" + sender
         + '}';
   }
 
@@ -58,6 +72,9 @@ public class Chat implements MinecraftPacket {
     message = ProtocolUtils.readString(buf);
     if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       type = buf.readByte();
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+        sender = ProtocolUtils.readUuid(buf);
+      }
     }
   }
 
@@ -69,6 +86,9 @@ public class Chat implements MinecraftPacket {
     ProtocolUtils.writeString(buf, message);
     if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       buf.writeByte(type);
+      if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+        ProtocolUtils.writeUuid(buf, sender == null ? EMPTY_SENDER : sender);
+      }
     }
   }
 
@@ -78,15 +98,15 @@ public class Chat implements MinecraftPacket {
   }
 
   public static Chat createClientbound(Component component) {
-    return createClientbound(component, CHAT_TYPE);
+    return createClientbound(component, CHAT_TYPE, EMPTY_SENDER);
   }
 
-  public static Chat createClientbound(Component component, byte type) {
+  public static Chat createClientbound(Component component, byte type, UUID sender) {
     Preconditions.checkNotNull(component, "component");
-    return new Chat(GsonComponentSerializer.INSTANCE.serialize(component), type);
+    return new Chat(GsonComponentSerializer.INSTANCE.serialize(component), type, sender);
   }
 
   public static Chat createServerbound(String message) {
-    return new Chat(message, CHAT_TYPE);
+    return new Chat(message, CHAT_TYPE, EMPTY_SENDER);
   }
 }

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

@@ -1,9 +1,12 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.google.common.collect.ImmutableSet;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.connection.registry.DimensionData;
-import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.connection.registry.DimensionInfo;
+import com.velocitypowered.proxy.connection.registry.DimensionRegistry;
+import com.velocitypowered.proxy.protocol.*;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -16,9 +19,12 @@ public class JoinGame implements MinecraftPacket {
   private short difficulty;
   private short maxPlayers;
   private @Nullable String levelType;
-  private int viewDistance; //1.14+
+  private int viewDistance; // 1.14+
   private boolean reducedDebugInfo;
   private boolean showRespawnScreen;
+  private DimensionRegistry dimensionRegistry; // 1.16+
+  private DimensionInfo dimensionInfo; // 1.16+
+  private short previousGamemode; // 1.16+
 
   public int getEntityId() {
     return entityId;
@@ -64,10 +70,7 @@ public class JoinGame implements MinecraftPacket {
     this.maxPlayers = maxPlayers;
   }
 
-  public String getLevelType() {
+  public @Nullable String getLevelType() {
-    if (levelType == null) {
-      throw new IllegalStateException("No level type specified.");
-    }
     return levelType;
   }
 
@@ -91,6 +94,30 @@ public class JoinGame implements MinecraftPacket {
     this.reducedDebugInfo = reducedDebugInfo;
   }
 
+  public DimensionInfo getDimensionInfo() {
+    return dimensionInfo;
+  }
+
+  public void setDimensionInfo(DimensionInfo dimensionInfo) {
+    this.dimensionInfo = dimensionInfo;
+  }
+
+  public DimensionRegistry getDimensionRegistry() {
+    return dimensionRegistry;
+  }
+
+  public void setDimensionRegistry(DimensionRegistry dimensionRegistry) {
+    this.dimensionRegistry = dimensionRegistry;
+  }
+
+  public short getPreviousGamemode() {
+    return previousGamemode;
+  }
+
+  public void setPreviousGamemode(short previousGamemode) {
+    this.previousGamemode = previousGamemode;
+  }
+
   @Override
   public String toString() {
     return "JoinGame{"
@@ -103,14 +130,26 @@ public class JoinGame implements MinecraftPacket {
         + ", levelType='" + levelType + '\''
         + ", viewDistance=" + viewDistance
         + ", reducedDebugInfo=" + reducedDebugInfo
+        + ", dimensionRegistry='" + dimensionRegistry.toString() + '\''
+        + ", dimensionInfo='" + dimensionInfo.toString() + '\''
+        + ", previousGamemode=" + previousGamemode
         + '}';
   }
 
   @Override
   public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     this.entityId = buf.readInt();
-    this.gamemode = buf.readUnsignedByte();
+    this.gamemode = buf.readByte();
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
+    String dimensionIdentifier = null;
+    String levelName = null;
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      this.previousGamemode = buf.readByte();
+      ImmutableSet<String> levelNames = ImmutableSet.copyOf(ProtocolUtils.readStringArray(buf));
+      ImmutableSet<DimensionData> readData = DimensionRegistry.fromGameData(ProtocolUtils.readCompoundTag(buf));
+      this.dimensionRegistry = new DimensionRegistry(readData, levelNames);
+      dimensionIdentifier = ProtocolUtils.readString(buf);
+      levelName = ProtocolUtils.readString(buf);
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
       this.dimension = buf.readInt();
     } else {
       this.dimension = buf.readByte();
@@ -122,7 +161,9 @@ public class JoinGame implements MinecraftPacket {
       this.partialHashedSeed = buf.readLong();
     }
     this.maxPlayers = buf.readUnsignedByte();
-    this.levelType = ProtocolUtils.readString(buf, 16);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) < 0) {
+      this.levelType = ProtocolUtils.readString(buf, 16);
+    }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_14) >= 0) {
       this.viewDistance = ProtocolUtils.readVarInt(buf);
     }
@@ -130,13 +171,25 @@ public class JoinGame implements MinecraftPacket {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_15) >= 0) {
       this.showRespawnScreen = buf.readBoolean();
     }
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      boolean isDebug = buf.readBoolean();
+      boolean isFlat = buf.readBoolean();
+      this.dimensionInfo = new DimensionInfo(dimensionIdentifier, levelName, isFlat, isDebug);
+    }
   }
 
   @Override
   public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     buf.writeInt(entityId);
     buf.writeByte(gamemode);
-    if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      buf.writeByte(previousGamemode);
+      ProtocolUtils.writeStringArray(buf, dimensionRegistry.getLevelNames().toArray(
+              new String[dimensionRegistry.getLevelNames().size()]));
+      ProtocolUtils.writeCompoundTag(buf, dimensionRegistry.encodeRegistry());
+      ProtocolUtils.writeString(buf, dimensionInfo.getRegistryIdentifier());
+      ProtocolUtils.writeString(buf, dimensionInfo.getLevelName());
+    } else if (version.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
       buf.writeInt(dimension);
     } else {
       buf.writeByte(dimension);
@@ -148,10 +201,12 @@ public class JoinGame implements MinecraftPacket {
       buf.writeLong(partialHashedSeed);
     }
     buf.writeByte(maxPlayers);
-    if (levelType == null) {
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) < 0) {
-      throw new IllegalStateException("No level type specified.");
+      if (levelType == null) {
+        throw new IllegalStateException("No level type specified.");
+      }
+      ProtocolUtils.writeString(buf, levelType);
     }
-    ProtocolUtils.writeString(buf, levelType);
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_14) >= 0) {
       ProtocolUtils.writeVarInt(buf,viewDistance);
     }
@@ -159,6 +214,10 @@ public class JoinGame implements MinecraftPacket {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_15) >= 0) {
       buf.writeBoolean(showRespawnScreen);
     }
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      buf.writeBoolean(dimensionInfo.isDebugType());
+      buf.writeBoolean(dimensionInfo.isFlat());
+    }
   }
 
   @Override

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

@@ -2,6 +2,7 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+import com.velocitypowered.proxy.connection.registry.DimensionInfo;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
@@ -13,17 +14,24 @@ public class Respawn implements MinecraftPacket {
   private short difficulty;
   private short gamemode;
   private String levelType = "";
+  private boolean shouldKeepPlayerData; // 1.16+
+  private DimensionInfo dimensionInfo; // 1.16+
+  private short previousGamemode; // 1.16+
 
   public Respawn() {
   }
 
   public Respawn(int dimension, long partialHashedSeed, short difficulty, short gamemode,
-      String levelType) {
+      String levelType, boolean shouldKeepPlayerData, DimensionInfo dimensionInfo,
+                 short previousGamemode) {
     this.dimension = dimension;
     this.partialHashedSeed = partialHashedSeed;
     this.difficulty = difficulty;
     this.gamemode = gamemode;
     this.levelType = levelType;
+    this.shouldKeepPlayerData = shouldKeepPlayerData;
+    this.dimensionInfo = dimensionInfo;
+    this.previousGamemode = previousGamemode;
   }
 
   public int getDimension() {
@@ -66,6 +74,22 @@ public class Respawn implements MinecraftPacket {
     this.levelType = levelType;
   }
 
+  public boolean getShouldKeepPlayerData() {
+    return shouldKeepPlayerData;
+  }
+
+  public void setShouldKeepPlayerData(boolean shouldKeepPlayerData) {
+    this.shouldKeepPlayerData = shouldKeepPlayerData;
+  }
+
+  public short getPreviousGamemode() {
+    return previousGamemode;
+  }
+
+  public void setPreviousGamemode(short previousGamemode) {
+    this.previousGamemode = previousGamemode;
+  }
+
   @Override
   public String toString() {
     return "Respawn{"
@@ -74,25 +98,48 @@ public class Respawn implements MinecraftPacket {
         + ", difficulty=" + difficulty
         + ", gamemode=" + gamemode
         + ", levelType='" + levelType + '\''
+        + ", shouldKeepPlayerData=" + shouldKeepPlayerData
+        + ", dimensionRegistryName='" + dimensionInfo.toString() + '\''
+        + ", previousGamemode=" + previousGamemode
         + '}';
   }
 
   @Override
   public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
-    this.dimension = buf.readInt();
+    String dimensionIdentifier = null;
+    String levelName = null;
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      dimensionIdentifier = ProtocolUtils.readString(buf);
+      levelName = ProtocolUtils.readString(buf);
+    } else {
+      this.dimension = buf.readInt();
+    }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_13_2) <= 0) {
       this.difficulty = buf.readUnsignedByte();
     }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_15) >= 0) {
       this.partialHashedSeed = buf.readLong();
     }
-    this.gamemode = buf.readUnsignedByte();
+    this.gamemode = buf.readByte();
-    this.levelType = ProtocolUtils.readString(buf, 16);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      this.previousGamemode = buf.readByte();
+      boolean isDebug = buf.readBoolean();
+      boolean isFlat = buf.readBoolean();
+      this.dimensionInfo = new DimensionInfo(dimensionIdentifier, levelName, isFlat, isDebug);
+      this.shouldKeepPlayerData = buf.readBoolean();
+    } else {
+      this.levelType = ProtocolUtils.readString(buf, 16);
+    }
   }
 
   @Override
   public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
-    buf.writeInt(dimension);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      ProtocolUtils.writeString(buf, dimensionInfo.getRegistryIdentifier());
+      ProtocolUtils.writeString(buf, dimensionInfo.getLevelName());
+    } else {
+      buf.writeInt(dimension);
+    }
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_13_2) <= 0) {
       buf.writeByte(difficulty);
     }
@@ -100,7 +147,14 @@ public class Respawn implements MinecraftPacket {
       buf.writeLong(partialHashedSeed);
     }
     buf.writeByte(gamemode);
-    ProtocolUtils.writeString(buf, levelType);
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      buf.writeByte(previousGamemode);
+      buf.writeBoolean(dimensionInfo.isDebugType());
+      buf.writeBoolean(dimensionInfo.isFlat());
+      buf.writeBoolean(shouldKeepPlayerData);
+    } else {
+      ProtocolUtils.writeString(buf, levelType);
+    }
   }
 
   @Override

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

@@ -45,7 +45,11 @@ public class ServerLoginSuccess implements MinecraftPacket {
 
   @Override
   public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
-    uuid = UUID.fromString(ProtocolUtils.readString(buf, 36));
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      uuid = ProtocolUtils.readUuidIntArray(buf);
+    } else {
+      uuid = UUID.fromString(ProtocolUtils.readString(buf, 36));
+    }
     username = ProtocolUtils.readString(buf, 16);
   }
 
@@ -54,7 +58,11 @@ public class ServerLoginSuccess implements MinecraftPacket {
     if (uuid == null) {
       throw new IllegalStateException("No UUID specified!");
     }
-    ProtocolUtils.writeString(buf, uuid.toString());
+    if (version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0) {
+      ProtocolUtils.writeUuidIntArray(buf, uuid);
+    } else {
+      ProtocolUtils.writeString(buf, uuid.toString());
+    }
     if (username == null) {
       throw new IllegalStateException("No username specified!");
     }

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

@@ -134,5 +134,6 @@ public class ArgumentPropertyRegistry {
     dummy("minecraft:int_range", DUMMY);
     dummy("minecraft:float_range", DUMMY);
     dummy("minecraft:time", DUMMY); // added in 1.14
+    dummy("minecraft:uuid", DUMMY); // added in 1.16
   }
 }