Merge pull request #135 from Crypnotic/protocol-constants-rework

Expose ProtocolConstants to the API

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

@@ -0,0 +1,138 @@
+package com.velocitypowered.api.network;
+
+import com.google.common.collect.ImmutableMap;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Represents each Minecraft protocol version
+ */
+public enum ProtocolVersion {
+    UNKNOWN(-1, "Unknown"),
+    LEGACY(-1, "Legacy"),
+    MINECRAFT_1_8(47, "1.8"),
+    MINECRAFT_1_9(107, "1.9"),
+    MINECRAFT_1_9_1(108, "1.9.1"),
+    MINECRAFT_1_9_2(109, "1.9.2"),
+    MINECRAFT_1_9_4(110, "1.9.4"),
+    MINECRAFT_1_10(210, "1.10"),
+    MINECRAFT_1_11(315, "1.11"),
+    MINECRAFT_1_11_1(316, "1.11.1"),
+    MINECRAFT_1_12(335, "1.12"),
+    MINECRAFT_1_12_1(338, "1.12.1"),
+    MINECRAFT_1_12_2(340, "1.12.2"),
+    MINECRAFT_1_13(393, "1.13"),
+    MINECRAFT_1_13_1(401, "1.13.1"),
+    MINECRAFT_1_13_2(404, "1.13.2");
+
+    private final int protocol;
+    private final String name;
+
+    /**
+     * Represents the lowest supported version
+     */
+    public static final ProtocolVersion MINIMUM_VERSION = MINECRAFT_1_8;
+    /**
+     * Represents the highest supported version
+     */
+    public static final ProtocolVersion MAXIMUM_VERSION = MINECRAFT_1_13_2;
+
+    /**
+     * The user-friendly representation of the lowest and highest supported versions
+     */
+    public static final String SUPPORTED_VERSION_STRING = String.format("%s-%s", MINIMUM_VERSION, MAXIMUM_VERSION);
+
+    /**
+     * A map linking the protocol version number to its {@link ProtocolVersion} representation
+     */
+    public static final ImmutableMap<Integer, ProtocolVersion> ID_TO_PROTOCOL_CONSTANT;
+
+    static {
+        Map<Integer, ProtocolVersion> versions = new HashMap<>();
+        for (ProtocolVersion version : values()) {
+            versions.put(version.protocol, version);
+        }
+
+        ID_TO_PROTOCOL_CONSTANT = ImmutableMap.copyOf(versions);
+    }
+
+    ProtocolVersion(int protocol, String name) {
+        this.protocol = protocol;
+        this.name = name;
+    }
+
+    /**
+     * Returns the protocol as an int
+     *
+     * @return the protocol version
+     */
+    public int getProtocol() {
+        return protocol;
+    }
+
+    /**
+     * Returns the user-friendly name for this protocol
+     *
+     * @return the protocol name
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Gets the {@link ProtocolVersion} for the given protocol
+     *
+     * @param protocol the protocol as an int
+     * @return the protocol version
+     */
+    public static ProtocolVersion getProtocolVersion(int protocol) {
+        return ID_TO_PROTOCOL_CONSTANT.getOrDefault(protocol, UNKNOWN);
+    }
+
+    /**
+     * Returns whether the protocol is supported
+     *
+     * @param protocol the protocol as an int
+     * @return if the protocol supported
+     */
+    public static boolean isSupported(int protocol) {
+        ProtocolVersion version = ID_TO_PROTOCOL_CONSTANT.get(protocol);
+
+        return version != null && !version.isUnknown();
+    }
+
+    /**
+     * Returns whether the {@link ProtocolVersion} is supported
+     *
+     * @param version the protocol version
+     * @return if the protocol supported
+     */
+    public static boolean isSupported(ProtocolVersion version) {
+        return version != null && !version.isUnknown();
+    }
+
+    /**
+     * Returns whether this {@link ProtocolVersion} is unknown to the proxy
+     *
+     * @return if the protocol is unknown
+     */
+    public boolean isUnknown() {
+        return this == UNKNOWN;
+    }
+
+    /**
+     * Returns whether this {@link ProtocolVersion} is a legacy protocol
+     *
+     * @return if the protocol is legacy
+     */
+    public boolean isLegacy() {
+        return this == LEGACY;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+}

api/src/main/java/com/velocitypowered/api/proxy/InboundConnection.java

@@ -1,5 +1,7 @@
 package com.velocitypowered.api.proxy;
 
+import com.velocitypowered.api.network.ProtocolVersion;
+
 import java.net.InetSocketAddress;
 import java.util.Optional;
 
@@ -34,5 +36,5 @@ public interface InboundConnection {
    *
    * @return the protocol version the connection uses
    */
-  int getProtocolVersion();
+  ProtocolVersion getProtocolVersion();
 }

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

@@ -10,6 +10,8 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.UUID;
+
+import com.velocitypowered.api.network.ProtocolVersion;
 import net.kyori.text.Component;
 import org.checkerframework.checker.nullness.qual.Nullable;
 

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

@@ -10,13 +10,13 @@ import static com.velocitypowered.proxy.network.Connections.MINECRAFT_DECODER;
 import static com.velocitypowered.proxy.network.Connections.MINECRAFT_ENCODER;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.natives.compression.VelocityCompressor;
 import com.velocitypowered.natives.encryption.VelocityCipher;
 import com.velocitypowered.natives.encryption.VelocityCipherFactory;
 import com.velocitypowered.natives.util.Natives;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftCipherDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftCipherEncoder;
@@ -53,8 +53,8 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
   private SocketAddress remoteAddress;
   private StateRegistry state;
   private @Nullable MinecraftSessionHandler sessionHandler;
-  private int protocolVersion;
+  private ProtocolVersion protocolVersion;
-  private int nextProtocolVersion;
+  private ProtocolVersion nextProtocolVersion;
   private @Nullable MinecraftConnectionAssociation association;
   private boolean isLegacyForge;
   private final VelocityServer server;
@@ -204,14 +204,14 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     this.channel.pipeline().get(MinecraftDecoder.class).setState(state);
   }
 
-  public int getProtocolVersion() {
+  public ProtocolVersion getProtocolVersion() {
     return protocolVersion;
   }
 
-  public void setProtocolVersion(int protocolVersion) {
+  public void setProtocolVersion(ProtocolVersion protocolVersion) {
     this.protocolVersion = protocolVersion;
     this.nextProtocolVersion = protocolVersion;
-    if (protocolVersion != ProtocolConstants.LEGACY) {
+    if (protocolVersion != ProtocolVersion.LEGACY) {
       this.channel.pipeline().get(MinecraftEncoder.class).setProtocolVersion(protocolVersion);
       this.channel.pipeline().get(MinecraftDecoder.class).setProtocolVersion(protocolVersion);
     } else {
@@ -295,11 +295,11 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     this.canSendLegacyFmlResetPacket = isLegacyForge && canSendLegacyFMLResetPacket;
   }
 
-  public int getNextProtocolVersion() {
+  public ProtocolVersion getNextProtocolVersion() {
     return this.nextProtocolVersion;
   }
 
-  public void setNextProtocolVersion(int nextProtocolVersion) {
+  public void setNextProtocolVersion(ProtocolVersion nextProtocolVersion) {
     this.nextProtocolVersion = nextProtocolVersion;
   }
 }

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

@@ -2,6 +2,7 @@ package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
@@ -9,7 +10,6 @@ import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
 import com.velocitypowered.proxy.connection.forge.ForgeConstants;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.JoinGame;
@@ -170,7 +170,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
       return false;
     }
     boolean minecraftOrFmlMessage;
-    if (mc.getProtocolVersion() <= ProtocolConstants.MINECRAFT_1_12_2) {
+    if (mc.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_12_2) <= 0) {
       String channel = message.getChannel();
       minecraftOrFmlMessage = channel.startsWith("MC|") || channel
           .startsWith(ForgeConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL);

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

@@ -14,12 +14,13 @@ 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;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.PlayerInfoForwarding;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
@@ -69,9 +70,9 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
                 .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
                 .addLast(FRAME_ENCODER, MinecraftVarintLengthEncoder.INSTANCE)
                 .addLast(MINECRAFT_DECODER,
-                    new MinecraftDecoder(ProtocolConstants.Direction.CLIENTBOUND))
+                    new MinecraftDecoder(ProtocolUtils.Direction.CLIENTBOUND))
                 .addLast(MINECRAFT_ENCODER,
-                    new MinecraftEncoder(ProtocolConstants.Direction.SERVERBOUND));
+                    new MinecraftEncoder(ProtocolUtils.Direction.SERVERBOUND));
 
             MinecraftConnection mc = new MinecraftConnection(ch, server);
             mc.setState(StateRegistry.HANDSHAKE);
@@ -140,7 +141,7 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
     handshake.setPort(registeredServer.getServerInfo().getAddress().getPort());
     mc.write(handshake);
 
-    int protocolVersion = proxyPlayer.getConnection().getNextProtocolVersion();
+    ProtocolVersion protocolVersion = proxyPlayer.getConnection().getNextProtocolVersion();
     mc.setProtocolVersion(protocolVersion);
     mc.setState(StateRegistry.LOGIN);
     mc.write(new ServerLogin(proxyPlayer.getUsername()));

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

@@ -4,6 +4,7 @@ import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.event.player.PlayerChatEvent;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
@@ -11,7 +12,6 @@ import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.connection.forge.ForgeConstants;
 import com.velocitypowered.proxy.connection.forge.ForgeUtil;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
 import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
@@ -335,9 +335,9 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     serverBossBars.clear();
 
     // Tell the server about this client's plugin message channels.
-    int serverVersion = serverMc.getProtocolVersion();
+    ProtocolVersion serverVersion = serverMc.getProtocolVersion();
     Collection<String> toRegister = new HashSet<>(knownChannels);
-    if (serverVersion >= ProtocolConstants.MINECRAFT_1_13) {
+    if (serverVersion.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0) {
       toRegister.addAll(server.getChannelRegistrar().getModernChannelIds());
     } else {
       toRegister.addAll(server.getChannelRegistrar().getIdsForLegacyConnections());

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

@@ -22,6 +22,7 @@ import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.MessagePosition;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.util.title.TextTitle;
 import com.velocitypowered.api.util.title.Title;
 import com.velocitypowered.api.util.title.Titles;
@@ -32,7 +33,6 @@ import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.connection.forge.ForgeConstants;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
@@ -164,7 +164,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   }
 
   @Override
-  public int getProtocolVersion() {
+  public ProtocolVersion getProtocolVersion() {
     return connection.getProtocolVersion();
   }
 
@@ -176,7 +176,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     byte pos = (byte) position.ordinal();
     String json;
     if (position == MessagePosition.ACTION_BAR) {
-      if (getProtocolVersion() >= ProtocolConstants.MINECRAFT_1_11) {
+      if (getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_11) >= 0) {
         // We can use the title packet instead.
         TitlePacket pkt = new TitlePacket();
         pkt.setAction(TitlePacket.SET_ACTION_BAR);

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

@@ -6,13 +6,13 @@ import com.velocitypowered.api.event.connection.ConnectionHandshakeEvent;
 import com.velocitypowered.api.event.proxy.ProxyPingEvent;
 import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.api.proxy.server.ServerPing;
+import com.velocitypowered.api.network.ProtocolVersion;
 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;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
@@ -40,11 +40,11 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(LegacyPing packet) {
-    connection.setProtocolVersion(ProtocolConstants.LEGACY);
+    connection.setProtocolVersion(ProtocolVersion.LEGACY);
     VelocityConfiguration configuration = server.getConfiguration();
     ServerPing ping = new ServerPing(
-        new ServerPing.Version(ProtocolConstants.MAXIMUM_GENERIC_VERSION,
+        new ServerPing.Version(ProtocolVersion.MAXIMUM_VERSION.getProtocol(),
-            "Velocity " + ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING),
+            "Velocity " + ProtocolVersion.SUPPORTED_VERSION_STRING),
         new ServerPing.Players(server.getPlayerCount(), configuration.getShowMaxPlayers(),
             ImmutableList.of()),
         configuration.getMotdComponent(),
@@ -82,7 +82,7 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
         connection.setState(StateRegistry.LOGIN);
         connection.setProtocolVersion(handshake.getProtocolVersion());
 
-        if (!ProtocolConstants.isSupported(handshake.getProtocolVersion())) {
+        if (!ProtocolVersion.isSupported(handshake.getProtocolVersion())) {
           connection.closeWith(Disconnect
               .create(TranslatableComponent.of("multiplayer.disconnect.outdated_client")));
           return true;
@@ -110,7 +110,7 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
         // If the proxy is configured for modern forwarding, we must deny connections from 1.12.2
         // and lower, otherwise IP information will never get forwarded.
         if (server.getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN
-            && handshake.getProtocolVersion() < ProtocolConstants.MINECRAFT_1_13) {
+            && handshake.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_13) < 0) {
           connection.closeWith(Disconnect
               .create(TextComponent.of("This server is only compatible with 1.13 and above.")));
           return true;
@@ -165,8 +165,8 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
     }
 
     @Override
-    public int getProtocolVersion() {
+    public ProtocolVersion getProtocolVersion() {
-      return 0;
+      return ProtocolVersion.UNKNOWN;
     }
   }
 }

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

@@ -1,6 +1,7 @@
 package com.velocitypowered.proxy.connection.client;
 
 import com.velocitypowered.api.proxy.InboundConnection;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
 import java.net.InetSocketAddress;
@@ -35,7 +36,7 @@ class InitialInboundConnection implements InboundConnection {
   }
 
   @Override
-  public int getProtocolVersion() {
+  public ProtocolVersion getProtocolVersion() {
     return connection.getProtocolVersion();
   }
 }

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

@@ -3,7 +3,7 @@ package com.velocitypowered.proxy.connection.client;
 import static com.velocitypowered.proxy.VelocityServer.GSON;
 import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
 import static com.velocitypowered.proxy.connection.VelocityConstants.VELOCITY_IP_FORWARDING_CHANNEL;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.*;
+import static com.velocitypowered.api.network.ProtocolVersion.*;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.event.connection.LoginEvent;
@@ -15,10 +15,12 @@ import com.velocitypowered.api.event.player.GameProfileRequestEvent;
 import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.PlayerInfoForwarding;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.EncryptionRequest;
@@ -73,7 +75,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
   @Override
   public boolean handle(ServerLogin packet) {
     this.login = packet;
-    if (inbound.getProtocolVersion() >= MINECRAFT_1_13) {
+    if (inbound.getProtocolVersion().compareTo(MINECRAFT_1_13) >= 0) {
       playerInfoId = ThreadLocalRandom.current().nextInt();
       inbound.write(new LoginPluginMessage(playerInfoId, VELOCITY_IP_FORWARDING_CHANNEL,
           Unpooled.EMPTY_BUFFER));

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

@@ -5,11 +5,11 @@ import com.velocitypowered.api.event.proxy.ProxyPingEvent;
 import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.api.proxy.server.ServerPing;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.StatusPing;
 import com.velocitypowered.proxy.protocol.packet.StatusRequest;
 import com.velocitypowered.proxy.protocol.packet.StatusResponse;
@@ -38,11 +38,12 @@ public class StatusSessionHandler implements MinecraftSessionHandler {
   public boolean handle(StatusRequest packet) {
     VelocityConfiguration configuration = server.getConfiguration();
 
-    int shownVersion = ProtocolConstants.isSupported(connection.getProtocolVersion())
+    ProtocolVersion shownVersion = ProtocolVersion.isSupported(connection.getProtocolVersion()) ? connection
-        ? connection.getProtocolVersion() : ProtocolConstants.MAXIMUM_GENERIC_VERSION;
+        .getProtocolVersion() :
+        ProtocolVersion.MAXIMUM_VERSION;
     ServerPing initialPing = new ServerPing(
-        new ServerPing.Version(shownVersion,
+        new ServerPing.Version(shownVersion.getProtocol(),
-            "Velocity " + ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING),
+            "Velocity " + ProtocolVersion.SUPPORTED_VERSION_STRING),
         new ServerPing.Players(server.getPlayerCount(), configuration.getShowMaxPlayers(),
             ImmutableList.of()),
         configuration.getMotdComponent(),

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

@@ -11,7 +11,7 @@ import static com.velocitypowered.proxy.network.Connections.READ_TIMEOUT;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.client.HandshakeSessionHandler;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.LegacyPingDecoder;
 import com.velocitypowered.proxy.protocol.netty.LegacyPingEncoder;
@@ -44,8 +44,8 @@ public class ServerChannelInitializer extends ChannelInitializer<Channel> {
         .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
         .addLast(LEGACY_PING_ENCODER, LegacyPingEncoder.INSTANCE)
         .addLast(FRAME_ENCODER, MinecraftVarintLengthEncoder.INSTANCE)
-        .addLast(MINECRAFT_DECODER, new MinecraftDecoder(ProtocolConstants.Direction.SERVERBOUND))
+        .addLast(MINECRAFT_DECODER, new MinecraftDecoder(ProtocolUtils.Direction.SERVERBOUND))
-        .addLast(MINECRAFT_ENCODER, new MinecraftEncoder(ProtocolConstants.Direction.CLIENTBOUND));
+        .addLast(MINECRAFT_ENCODER, new MinecraftEncoder(ProtocolUtils.Direction.CLIENTBOUND));
 
     final MinecraftConnection connection = new MinecraftConnection(ch, this.server);
     connection.setState(StateRegistry.HANDSHAKE);

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

@@ -1,13 +1,14 @@
 package com.velocitypowered.proxy.protocol;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import io.netty.buffer.ByteBuf;
 
 public interface MinecraftPacket {
 
-  void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion);
+  void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion);
 
-  void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion);
+  void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion);
 
   boolean handle(MinecraftSessionHandler handler);
 }

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

@@ -1,60 +0,0 @@
-package com.velocitypowered.proxy.protocol;
-
-import com.google.common.primitives.ImmutableIntArray;
-
-public enum ProtocolConstants {
-  ;
-  public static final int LEGACY = -1;
-
-  public static final int MINECRAFT_1_8 = 47;
-  public static final int MINECRAFT_1_9 = 107;
-  public static final int MINECRAFT_1_9_1 = 108;
-  public static final int MINECRAFT_1_9_2 = 109;
-  public static final int MINECRAFT_1_9_4 = 110;
-  public static final int MINECRAFT_1_10 = 210;
-  public static final int MINECRAFT_1_11 = 315;
-  public static final int MINECRAFT_1_11_1 = 316;
-  public static final int MINECRAFT_1_12 = 335;
-  public static final int MINECRAFT_1_12_1 = 338;
-  public static final int MINECRAFT_1_12_2 = 340;
-  public static final int MINECRAFT_1_13 = 393;
-  public static final int MINECRAFT_1_13_1 = 401;
-  public static final int MINECRAFT_1_13_2 = 404;
-
-  public static final int MINIMUM_GENERIC_VERSION = MINECRAFT_1_8;
-  public static final int MAXIMUM_GENERIC_VERSION = MINECRAFT_1_13_2;
-
-  public static final String SUPPORTED_GENERIC_VERSION_STRING = "1.8-1.13.2";
-
-  public static final ImmutableIntArray SUPPORTED_VERSIONS = ImmutableIntArray.of(
-      MINECRAFT_1_8,
-      MINECRAFT_1_9,
-      MINECRAFT_1_9_1,
-      MINECRAFT_1_9_2,
-      MINECRAFT_1_9_4,
-      MINECRAFT_1_10,
-      MINECRAFT_1_11,
-      MINECRAFT_1_11_1,
-      MINECRAFT_1_12,
-      MINECRAFT_1_12_1,
-      MINECRAFT_1_12_2,
-      MINECRAFT_1_13,
-      MINECRAFT_1_13_1,
-      MINECRAFT_1_13_2
-  );
-
-  public static boolean isSupported(int version) {
-    return SUPPORTED_VERSIONS.contains(version);
-  }
-
-  public enum Direction {
-    SERVERBOUND,
-    CLIENTBOUND;
-
-    public StateRegistry.PacketRegistry.ProtocolVersion getProtocol(StateRegistry state,
-        int protocolVersion) {
-      return (this == SERVERBOUND ? state.SERVERBOUND : state.CLIENTBOUND)
-          .getVersion(protocolVersion);
-    }
-  }
-}

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

@@ -2,8 +2,10 @@ package com.velocitypowered.proxy.protocol;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.api.network.ProtocolVersion;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
+
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
@@ -119,4 +121,15 @@ public enum ProtocolUtils {
     }
     return properties;
   }
+
+  public enum Direction {
+    SERVERBOUND,
+    CLIENTBOUND;
+
+    public StateRegistry.PacketRegistry.ProtocolRegistry getProtocolRegistry(StateRegistry state,
+                                                                    ProtocolVersion protocolVersion) {
+      return (this == SERVERBOUND ? state.SERVERBOUND : state.CLIENTBOUND)
+              .getProtocolRegistry(protocolVersion);
+    }
+  }
 }

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

@@ -1,23 +1,26 @@
 package com.velocitypowered.proxy.protocol;
 
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.Direction;
+import static com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_10;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_10;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_11;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_11;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_11_1;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_11_1;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12_1;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12_1;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12_2;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12_2;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_13;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_13_1;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13_1;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_13_2;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13_2;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_8;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_8;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_9;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_9_1;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_1;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_9_2;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_2;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_9_4;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_4;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINIMUM_GENERIC_VERSION;
+import static com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION;
 
-import com.google.common.primitives.ImmutableIntArray;
+import com.google.common.collect.ImmutableBiMap;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
 import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.protocol.packet.ClientSettings;
@@ -46,8 +49,10 @@ import io.netty.util.collection.IntObjectHashMap;
 import io.netty.util.collection.IntObjectMap;
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
-import java.util.Objects;
+
+import java.util.*;
 import java.util.function.Supplier;
+
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public enum StateRegistry {
@@ -195,38 +200,40 @@ public enum StateRegistry {
 
   public static class PacketRegistry {
 
-    private static final IntObjectMap<ImmutableIntArray> LINKED_PROTOCOL_VERSIONS = new IntObjectHashMap<>();
+    private static final EnumMap<ProtocolVersion, ImmutableList<ProtocolVersion>> LINKED_PROTOCOL_VERSIONS = new EnumMap(ProtocolVersion.class);
 
     static {
-      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_9,
+      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_9, ImmutableList.of(MINECRAFT_1_9_1, MINECRAFT_1_9_2, MINECRAFT_1_9_4));
-          ImmutableIntArray.of(MINECRAFT_1_9_1, MINECRAFT_1_9_2, MINECRAFT_1_9_4));
+      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_9_4, ImmutableList.of(MINECRAFT_1_10, MINECRAFT_1_11, MINECRAFT_1_11_1));
-      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_9_4,
+      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_12, ImmutableList.of(MINECRAFT_1_12_1));
-          ImmutableIntArray.of(MINECRAFT_1_10, MINECRAFT_1_11, MINECRAFT_1_11_1));
+      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_12_1, ImmutableList.of(MINECRAFT_1_12_2));
-      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_12, ImmutableIntArray.of(MINECRAFT_1_12_1));
+      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_13, ImmutableList.of(MINECRAFT_1_13_1, MINECRAFT_1_13_2));
-      LINKED_PROTOCOL_VERSIONS.put(MINECRAFT_1_12_1, ImmutableIntArray.of(MINECRAFT_1_12_2));
-      LINKED_PROTOCOL_VERSIONS
-          .put(MINECRAFT_1_13, ImmutableIntArray.of(MINECRAFT_1_13_1, MINECRAFT_1_13_2));
     }
 
     private final Direction direction;
-    private final IntObjectMap<ProtocolVersion> versions = new IntObjectHashMap<>(16);
+    private final Map<ProtocolVersion, ProtocolRegistry> versions;
     private boolean fallback = true;
 
     PacketRegistry(Direction direction) {
       this.direction = direction;
-      ProtocolConstants.SUPPORTED_VERSIONS
+
-          .forEach(version -> versions.put(version, new ProtocolVersion(version)));
+      EnumMap<ProtocolVersion, ProtocolRegistry> mutableVersions = new EnumMap(ProtocolVersion.class);
+      for (ProtocolVersion version : ProtocolVersion.values()) {
+        mutableVersions.put(version, new ProtocolRegistry(version));
       }
 
-    public ProtocolVersion getVersion(final int version) {
+      this.versions = Collections.unmodifiableMap(mutableVersions);
-      ProtocolVersion result = versions.get(version);
+    }
-      if (result == null) {
+
+    public ProtocolRegistry getProtocolRegistry(final ProtocolVersion version) {
+      ProtocolRegistry registry = versions.get(version);
+      if (registry == null) {
         if (fallback) {
-          return getVersion(MINIMUM_GENERIC_VERSION);
+          return getProtocolRegistry(MINIMUM_VERSION);
         }
         throw new IllegalArgumentException("Could not find data for protocol version " + version);
       }
-      return result;
+      return registry;
     }
 
     public <P extends MinecraftPacket> void register(Class<P> clazz, Supplier<P> packetSupplier,
@@ -236,20 +243,20 @@ public enum StateRegistry {
       }
 
       for (final PacketMapping mapping : mappings) {
-        ProtocolVersion version = this.versions.get(mapping.protocolVersion);
+        ProtocolRegistry registry = this.versions.get(mapping.protocolVersion);
-        if (version == null) {
+        if (registry == null) {
           throw new IllegalArgumentException("Unknown protocol version " + mapping.protocolVersion);
         }
         if (!mapping.encodeOnly) {
-          version.packetIdToSupplier.put(mapping.id, packetSupplier);
+          registry.packetIdToSupplier.put(mapping.id, packetSupplier);
         }
-        version.packetClassToId.put(clazz, mapping.id);
+        registry.packetClassToId.put(clazz, mapping.id);
 
-        ImmutableIntArray linked = LINKED_PROTOCOL_VERSIONS.get(mapping.protocolVersion);
+        ImmutableList<ProtocolVersion> linked = LINKED_PROTOCOL_VERSIONS.get(mapping.protocolVersion);
         if (linked != null) {
           links:
-          for (int i = 0; i < linked.length(); i++) {
+          for (int i = 0; i < linked.size(); i++) {
-            int linkedVersion = linked.get(i);
+            ProtocolVersion linkedVersion = linked.get(i);
             // Make sure that later mappings override this one.
             for (PacketMapping m : mappings) {
               if (linkedVersion == m.protocolVersion) {
@@ -262,15 +269,15 @@ public enum StateRegistry {
       }
     }
 
-    public class ProtocolVersion {
+    public class ProtocolRegistry {
 
-      public final int version;
+      public final ProtocolVersion version;
       final IntObjectMap<Supplier<? extends MinecraftPacket>> packetIdToSupplier =
           new IntObjectHashMap<>(16, 0.5f);
       final Object2IntMap<Class<? extends MinecraftPacket>> packetClassToId =
           new Object2IntOpenHashMap<>(16, 0.5f);
 
-      ProtocolVersion(final int version) {
+      ProtocolRegistry(final ProtocolVersion version) {
         this.version = version;
         this.packetClassToId.defaultReturnValue(Integer.MIN_VALUE);
       }
@@ -299,10 +306,10 @@ public enum StateRegistry {
   public static class PacketMapping {
 
     private final int id;
-    private final int protocolVersion;
+    private final ProtocolVersion protocolVersion;
     private final boolean encodeOnly;
 
-    public PacketMapping(int id, int protocolVersion, boolean packetDecoding) {
+    public PacketMapping(int id, ProtocolVersion protocolVersion, boolean packetDecoding) {
       this.id = id;
       this.protocolVersion = protocolVersion;
       this.encodeOnly = packetDecoding;
@@ -345,7 +352,7 @@ public enum StateRegistry {
    * @param encodeOnly When true packet decoding will be disabled
    * @return PacketMapping with the provided arguments
    */
-  private static PacketMapping map(int id, int version, boolean encodeOnly) {
+  private static PacketMapping map(int id, ProtocolVersion version, boolean encodeOnly) {
     return new PacketMapping(id, version, encodeOnly);
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/GS4QueryHandler.java

@@ -10,8 +10,8 @@ import com.velocitypowered.api.event.query.ProxyQueryEvent;
 import com.velocitypowered.api.plugin.PluginContainer;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.server.QueryResponse;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.SimpleChannelInboundHandler;
@@ -73,7 +73,7 @@ public class GS4QueryHandler extends SimpleChannelInboundHandler<DatagramPacket>
     return QueryResponse.builder()
         .hostname(ComponentSerializers.PLAIN
             .serialize(server.getConfiguration().getMotdComponent()))
-        .gameVersion(ProtocolConstants.SUPPORTED_GENERIC_VERSION_STRING)
+        .gameVersion(ProtocolVersion.SUPPORTED_VERSION_STRING)
         .map(server.getConfiguration().getQueryMap())
         .currentPlayers(server.getPlayerCount())
         .maxPlayers(server.getConfiguration().getShowMaxPlayers())

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.netty;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import io.netty.buffer.ByteBuf;
@@ -13,14 +13,14 @@ import java.util.List;
 
 public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf> {
 
-  private final ProtocolConstants.Direction direction;
+  private final ProtocolUtils.Direction direction;
   private StateRegistry state;
-  private StateRegistry.PacketRegistry.ProtocolVersion protocolVersion;
+  private StateRegistry.PacketRegistry.ProtocolRegistry registry;
 
-  public MinecraftDecoder(ProtocolConstants.Direction direction) {
+  public MinecraftDecoder(ProtocolUtils.Direction direction) {
     this.direction = Preconditions.checkNotNull(direction, "direction");
-    this.protocolVersion = direction
+    this.registry = direction
-        .getProtocol(StateRegistry.HANDSHAKE, ProtocolConstants.MINIMUM_GENERIC_VERSION);
+        .getProtocolRegistry(StateRegistry.HANDSHAKE, ProtocolVersion.MINIMUM_VERSION);
     this.state = StateRegistry.HANDSHAKE;
   }
 
@@ -33,35 +33,35 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf> {
     ByteBuf slice = msg.slice();
 
     int packetId = ProtocolUtils.readVarInt(msg);
-    MinecraftPacket packet = this.protocolVersion.createPacket(packetId);
+    MinecraftPacket packet = this.registry.createPacket(packetId);
     if (packet == null) {
       msg.skipBytes(msg.readableBytes());
       out.add(slice.retain());
     } else {
       try {
-        packet.decode(msg, direction, protocolVersion.version);
+        packet.decode(msg, direction, registry.version);
       } catch (Exception e) {
         throw new CorruptedFrameException(
             "Error decoding " + packet.getClass() + " Direction " + direction
-                + " Protocol " + protocolVersion.version + " State " + state + " ID " + Integer
+                + " Protocol " + registry.version + " State " + state + " ID " + Integer
                 .toHexString(packetId), e);
       }
       if (msg.isReadable()) {
         throw new CorruptedFrameException(
             "Did not read full packet for " + packet.getClass() + " Direction " + direction
-                + " Protocol " + protocolVersion.version + " State " + state + " ID " + Integer
+                + " Protocol " + registry.version + " State " + state + " ID " + Integer
                 .toHexString(packetId));
       }
       out.add(packet);
     }
   }
 
-  public void setProtocolVersion(int protocolVersion) {
+  public void setProtocolVersion(ProtocolVersion protocolVersion) {
-    this.protocolVersion = direction.getProtocol(state, protocolVersion);
+    this.registry = direction.getProtocolRegistry(state, protocolVersion);
   }
 
   public void setState(StateRegistry state) {
     this.state = state;
-    this.setProtocolVersion(protocolVersion.version);
+    this.setProtocolVersion(registry.version);
   }
 }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.netty;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import io.netty.buffer.ByteBuf;
@@ -11,30 +11,30 @@ import io.netty.handler.codec.MessageToByteEncoder;
 
 public class MinecraftEncoder extends MessageToByteEncoder<MinecraftPacket> {
 
-  private final ProtocolConstants.Direction direction;
+  private final ProtocolUtils.Direction direction;
   private StateRegistry state;
-  private StateRegistry.PacketRegistry.ProtocolVersion protocolVersion;
+  private StateRegistry.PacketRegistry.ProtocolRegistry registry;
 
-  public MinecraftEncoder(ProtocolConstants.Direction direction) {
+  public MinecraftEncoder(ProtocolUtils.Direction direction) {
     this.direction = Preconditions.checkNotNull(direction, "direction");
-    this.protocolVersion = direction
+    this.registry = direction
-        .getProtocol(StateRegistry.HANDSHAKE, ProtocolConstants.MINIMUM_GENERIC_VERSION);
+        .getProtocolRegistry(StateRegistry.HANDSHAKE, ProtocolVersion.MINIMUM_VERSION);
     this.state = StateRegistry.HANDSHAKE;
   }
 
   @Override
   protected void encode(ChannelHandlerContext ctx, MinecraftPacket msg, ByteBuf out) {
-    int packetId = this.protocolVersion.getPacketId(msg);
+    int packetId = this.registry.getPacketId(msg);
     ProtocolUtils.writeVarInt(out, packetId);
-    msg.encode(out, direction, protocolVersion.version);
+    msg.encode(out, direction, registry.version);
   }
 
-  public void setProtocolVersion(final int protocolVersion) {
+  public void setProtocolVersion(final ProtocolVersion protocolVersion) {
-    this.protocolVersion = direction.getProtocol(state, protocolVersion);
+    this.registry = direction.getProtocolRegistry(state, protocolVersion);
   }
 
   public void setState(StateRegistry state) {
     this.state = state;
-    this.setProtocolVersion(protocolVersion.version);
+    this.setProtocolVersion(registry.version);
   }
 }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.UUID;
@@ -97,7 +97,7 @@ public class BossBar implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.uuid = ProtocolUtils.readUuid(buf);
     this.action = ProtocolUtils.readVarInt(buf);
     switch (action) {
@@ -129,7 +129,7 @@ public class BossBar implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (uuid == null) {
       throw new IllegalStateException("No boss bar UUID specified");
     }

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

@@ -1,9 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import net.kyori.text.Component;
@@ -54,20 +54,20 @@ public class Chat implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     message = ProtocolUtils.readString(buf);
-    if (direction == ProtocolConstants.Direction.CLIENTBOUND) {
+    if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       type = buf.readByte();
     }
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (message == null) {
       throw new IllegalStateException("Message is not specified");
     }
     ProtocolUtils.writeString(buf, message);
-    if (direction == ProtocolConstants.Direction.CLIENTBOUND) {
+    if (direction == ProtocolUtils.Direction.CLIENTBOUND) {
       buf.writeByte(type);
     }
   }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -93,20 +93,20 @@ public class ClientSettings implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.locale = ProtocolUtils.readString(buf, 16);
     this.viewDistance = buf.readByte();
     this.chatVisibility = ProtocolUtils.readVarInt(buf);
     this.chatColors = buf.readBoolean();
     this.skinParts = buf.readUnsignedByte();
 
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_9) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       this.mainHand = ProtocolUtils.readVarInt(buf);
     }
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (locale == null) {
       throw new IllegalStateException("No locale specified");
     }
@@ -116,7 +116,7 @@ public class ClientSettings implements MinecraftPacket {
     buf.writeBoolean(chatColors);
     buf.writeByte(skinParts);
 
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_9) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       ProtocolUtils.writeVarInt(buf, mainHand);
     }
   }

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

@@ -1,9 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import net.kyori.text.Component;
@@ -40,12 +40,12 @@ public class Disconnect implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     reason = ProtocolUtils.readString(buf);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (reason == null) {
       throw new IllegalStateException("No reason specified.");
     }

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

@@ -2,9 +2,9 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.Arrays;
@@ -40,14 +40,14 @@ public class EncryptionRequest implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.serverId = ProtocolUtils.readString(buf, 20);
     publicKey = ProtocolUtils.readByteArray(buf, 256);
     verifyToken = ProtocolUtils.readByteArray(buf, 16);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeString(buf, this.serverId);
     ProtocolUtils.writeByteArray(buf, publicKey);
     ProtocolUtils.writeByteArray(buf, verifyToken);

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

@@ -2,9 +2,9 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.Arrays;
@@ -39,13 +39,13 @@ public class EncryptionResponse implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.sharedSecret = ProtocolUtils.readByteArray(buf, 256);
     this.verifyToken = ProtocolUtils.readByteArray(buf, 128);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeByteArray(buf, sharedSecret);
     ProtocolUtils.writeByteArray(buf, verifyToken);
   }

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

@@ -1,23 +1,23 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
 public class Handshake implements MinecraftPacket {
 
-  private int protocolVersion;
+  private ProtocolVersion protocolVersion;
   private String serverAddress = "";
   private int port;
   private int nextStatus;
 
-  public int getProtocolVersion() {
+  public ProtocolVersion getProtocolVersion() {
     return protocolVersion;
   }
 
-  public void setProtocolVersion(int protocolVersion) {
+  public void setProtocolVersion(ProtocolVersion protocolVersion) {
     this.protocolVersion = protocolVersion;
   }
 
@@ -56,16 +56,16 @@ public class Handshake implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
-    this.protocolVersion = ProtocolUtils.readVarInt(buf);
+    this.protocolVersion = ProtocolVersion.getProtocolVersion(ProtocolUtils.readVarInt(buf));
     this.serverAddress = ProtocolUtils.readString(buf);
     this.port = buf.readUnsignedShort();
     this.nextStatus = ProtocolUtils.readVarInt(buf);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
-    ProtocolUtils.writeVarInt(buf, this.protocolVersion);
+    ProtocolUtils.writeVarInt(buf, this.protocolVersion.getProtocol());
     ProtocolUtils.writeString(buf, this.serverAddress);
     buf.writeShort(this.port);
     ProtocolUtils.writeVarInt(buf, this.nextStatus);

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

@@ -3,9 +3,10 @@ package com.velocitypowered.proxy.protocol.packet;
 import static com.velocitypowered.proxy.protocol.ProtocolUtils.writeString;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants.Direction;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import net.kyori.text.Component;
 import net.kyori.text.serializer.ComponentSerializer;
@@ -37,12 +38,12 @@ public class HeaderAndFooter implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException("Decode is not implemented");
   }
 
   @Override
-  public void encode(ByteBuf buf, Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     writeString(buf, header);
     writeString(buf, footer);
   }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -90,10 +90,10 @@ public class JoinGame implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.entityId = buf.readInt();
     this.gamemode = buf.readUnsignedByte();
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_9_1) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
       this.dimension = buf.readInt();
     } else {
       this.dimension = buf.readByte();
@@ -105,10 +105,10 @@ public class JoinGame implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     buf.writeInt(entityId);
     buf.writeByte(gamemode);
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_9_1) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9_1) >= 0) {
       buf.writeInt(dimension);
     } else {
       buf.writeByte(dimension);

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

@@ -1,10 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12_2;
+import com.velocitypowered.api.network.ProtocolVersion;
-
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
@@ -28,17 +26,17 @@ public class KeepAlive implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
-    if (protocolVersion >= MINECRAFT_1_12_2) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_12_2) >= 0) {
       randomId = buf.readLong();
     } else {
       randomId = ProtocolUtils.readVarInt(buf);
     }
-  }
+}
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
-    if (protocolVersion >= MINECRAFT_1_12_2) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_12_2) >= 0) {
       buf.writeLong(randomId);
     } else {
       ProtocolUtils.writeVarInt(buf, (int) randomId);

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

@@ -1,19 +1,20 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
 public class LegacyHandshake implements MinecraftPacket {
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException();
   }
 

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

@@ -1,19 +1,20 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
 public class LegacyPing implements MinecraftPacket {
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException();
   }
 

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

@@ -2,6 +2,7 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.proxy.server.ServerPing;
+import com.velocitypowered.api.network.ProtocolVersion;
 import net.kyori.text.serializer.ComponentSerializers;
 
 public class LegacyPingResponse {

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -49,7 +49,7 @@ public class LoginPluginMessage implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.id = ProtocolUtils.readVarInt(buf);
     this.channel = ProtocolUtils.readString(buf);
     if (buf.isReadable()) {
@@ -60,7 +60,7 @@ public class LoginPluginMessage implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, id);
     if (channel == null) {
       throw new IllegalStateException("Channel is not specified!");

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -47,7 +47,7 @@ public class LoginPluginResponse implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.id = ProtocolUtils.readVarInt(buf);
     this.success = buf.readBoolean();
     if (buf.isReadable()) {
@@ -58,7 +58,7 @@ public class LoginPluginResponse implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, id);
     buf.writeBoolean(success);
     buf.writeBytes(data);

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

@@ -3,9 +3,9 @@ package com.velocitypowered.proxy.protocol.packet;
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.ArrayList;
@@ -42,7 +42,7 @@ public class PlayerListItem implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     action = ProtocolUtils.readVarInt(buf);
     int length = ProtocolUtils.readVarInt(buf);
 
@@ -84,7 +84,7 @@ public class PlayerListItem implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, action);
     ProtocolUtils.writeVarInt(buf, items.size());
     for (Item item : items) {

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

@@ -2,9 +2,9 @@ package com.velocitypowered.proxy.protocol.packet;
 
 import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
@@ -43,14 +43,14 @@ public class PluginMessage implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.channel = ProtocolUtils.readString(buf);
     this.data = new byte[buf.readableBytes()];
     buf.readBytes(data);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (channel == null) {
       throw new IllegalStateException("Channel is not specified.");
     }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
@@ -66,7 +66,7 @@ public class Respawn implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.dimension = buf.readInt();
     this.difficulty = buf.readUnsignedByte();
     this.gamemode = buf.readUnsignedByte();
@@ -74,7 +74,7 @@ public class Respawn implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     buf.writeInt(dimension);
     buf.writeByte(difficulty);
     buf.writeByte(gamemode);

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

@@ -1,9 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -34,12 +34,12 @@ public class ServerLogin implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     username = ProtocolUtils.readString(buf, 16);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (username == null) {
       throw new IllegalStateException("No username found!");
     }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.UUID;
@@ -44,13 +44,13 @@ public class ServerLoginSuccess implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     uuid = UUID.fromString(ProtocolUtils.readString(buf, 36));
     username = ProtocolUtils.readString(buf, 16);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (uuid == null) {
       throw new IllegalStateException("No UUID specified!");
     }

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
@@ -33,12 +33,12 @@ public class SetCompression implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.threshold = ProtocolUtils.readVarInt(buf);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, threshold);
   }
 

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

@@ -1,8 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
 public class StatusPing implements MinecraftPacket {
@@ -10,12 +11,12 @@ public class StatusPing implements MinecraftPacket {
   private long randomId;
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     randomId = buf.readLong();
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     buf.writeLong(randomId);
   }
 

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

@@ -1,8 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 
 public class StatusRequest implements MinecraftPacket {
@@ -14,12 +15,12 @@ public class StatusRequest implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     // There is no additional data to decode.
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     // There is no data to decode.
   }
 

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -33,12 +33,12 @@ public class StatusResponse implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     status = ProtocolUtils.readString(buf, Short.MAX_VALUE);
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (status == null) {
       throw new IllegalStateException("Status is not specified");
     }

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

@@ -1,10 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_9;
+import com.velocitypowered.api.network.ProtocolVersion;
-
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -62,9 +60,9 @@ public class TabCompleteRequest implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     this.command = ProtocolUtils.readString(buf);
-    if (protocolVersion >= MINECRAFT_1_9) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       this.assumeCommand = buf.readBoolean();
     }
     this.hasPosition = buf.readBoolean();
@@ -74,12 +72,12 @@ public class TabCompleteRequest implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     if (command == null) {
       throw new IllegalStateException("Command is not specified");
     }
     ProtocolUtils.writeString(buf, command);
-    if (protocolVersion >= MINECRAFT_1_9) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       buf.writeBoolean(assumeCommand);
     }
     buf.writeBoolean(hasPosition);

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import java.util.ArrayList;
@@ -24,7 +24,7 @@ public class TabCompleteResponse implements MinecraftPacket {
   }
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     int offersAvailable = ProtocolUtils.readVarInt(buf);
     for (int i = 0; i < offersAvailable; i++) {
       offers.add(ProtocolUtils.readString(buf));
@@ -32,7 +32,7 @@ public class TabCompleteResponse implements MinecraftPacket {
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, offers.size());
     for (String offer : offers) {
       ProtocolUtils.writeString(buf, offer);

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

@@ -1,8 +1,8 @@
 package com.velocitypowered.proxy.protocol.packet;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -26,14 +26,14 @@ public class TitlePacket implements MinecraftPacket {
   private int fadeOut;
 
   @Override
-  public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     throw new UnsupportedOperationException(); // encode only
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
     ProtocolUtils.writeVarInt(buf, action);
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_11) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_11) >= 0) {
       // 1.11+ shifted the action enum by 1 to handle the action bar
       switch (action) {
         case SET_TITLE:
@@ -118,23 +118,23 @@ public class TitlePacket implements MinecraftPacket {
     this.fadeOut = fadeOut;
   }
 
-  public static TitlePacket hideForProtocolVersion(int protocolVersion) {
+  public static TitlePacket hideForProtocolVersion(ProtocolVersion protocolVersion) {
     TitlePacket packet = new TitlePacket();
-    packet.setAction(protocolVersion >= ProtocolConstants.MINECRAFT_1_11 ? TitlePacket.HIDE
+    packet.setAction(protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_11) >= 0 ? TitlePacket.HIDE
         : TitlePacket.HIDE_OLD);
     return packet;
   }
 
-  public static TitlePacket resetForProtocolVersion(int protocolVersion) {
+  public static TitlePacket resetForProtocolVersion(ProtocolVersion protocolVersion) {
     TitlePacket packet = new TitlePacket();
-    packet.setAction(protocolVersion >= ProtocolConstants.MINECRAFT_1_11 ? TitlePacket.RESET
+    packet.setAction(protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_11) >= 0 ? TitlePacket.RESET
         : TitlePacket.RESET_OLD);
     return packet;
   }
 
-  public static TitlePacket timesForProtocolVersion(int protocolVersion) {
+  public static TitlePacket timesForProtocolVersion(ProtocolVersion protocolVersion) {
     TitlePacket packet = new TitlePacket();
-    packet.setAction(protocolVersion >= ProtocolConstants.MINECRAFT_1_11 ? TitlePacket.SET_TIMES
+    packet.setAction(protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_11) >= 0 ? TitlePacket.SET_TIMES
         : TitlePacket.SET_TIMES_OLD);
     return packet;
   }

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

@@ -6,7 +6,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.util.ProxyVersion;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import io.netty.buffer.ByteBuf;
@@ -80,10 +80,11 @@ public class PluginMessageUtil {
    * @param channels the channels to register
    * @return the plugin message to send
    */
-  public static PluginMessage constructChannelsPacket(int protocolVersion,
+
+  public static PluginMessage constructChannelsPacket(ProtocolVersion protocolVersion,
                                                       Collection<String> channels) {
-    checkNotNull(channels, "channels");
+    Preconditions.checkNotNull(channels, "channels");
-    String channelName = protocolVersion >= ProtocolConstants.MINECRAFT_1_13 ? REGISTER_CHANNEL
+    String channelName = protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0 ? REGISTER_CHANNEL
         : REGISTER_CHANNEL_LEGACY;
     PluginMessage message = new PluginMessage();
     message.setChannel(channelName);

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

@@ -2,10 +2,10 @@ package com.velocitypowered.proxy.server;
 
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerPing;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
 import com.velocitypowered.proxy.protocol.packet.StatusRequest;
@@ -33,7 +33,7 @@ public class PingSessionHandler implements MinecraftSessionHandler {
     handshake.setNextStatus(StateRegistry.STATUS_ID);
     handshake.setServerAddress(server.getServerInfo().getAddress().getHostString());
     handshake.setPort(server.getServerInfo().getAddress().getPort());
-    handshake.setProtocolVersion(ProtocolConstants.MINIMUM_GENERIC_VERSION);
+    handshake.setProtocolVersion(ProtocolVersion.MINIMUM_VERSION);
     connection.write(handshake);
 
     connection.setState(StateRegistry.STATUS);

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

@@ -18,7 +18,7 @@ import com.velocitypowered.api.proxy.server.ServerPing;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
@@ -74,9 +74,9 @@ public class VelocityRegisteredServer implements RegisteredServer {
                 .addLast(FRAME_DECODER, new MinecraftVarintFrameDecoder())
                 .addLast(FRAME_ENCODER, MinecraftVarintLengthEncoder.INSTANCE)
                 .addLast(MINECRAFT_DECODER,
-                    new MinecraftDecoder(ProtocolConstants.Direction.CLIENTBOUND))
+                    new MinecraftDecoder(ProtocolUtils.Direction.CLIENTBOUND))
                 .addLast(MINECRAFT_ENCODER,
-                    new MinecraftEncoder(ProtocolConstants.Direction.SERVERBOUND));
+                    new MinecraftEncoder(ProtocolUtils.Direction.SERVERBOUND));
 
             MinecraftConnection connection = new MinecraftConnection(ch, server);
             connection.setState(StateRegistry.HANDSHAKE);

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

@@ -6,11 +6,13 @@ import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.ChannelRegistrar;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
-import com.velocitypowered.proxy.protocol.ProtocolConstants;
+
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+
+import com.velocitypowered.api.network.ProtocolVersion;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class VelocityChannelRegistrar implements ChannelRegistrar {
@@ -70,8 +72,8 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
     return identifierMap.get(id);
   }
 
-  public Collection<String> getChannelsForProtocol(int protocolVersion) {
+  public Collection<String> getChannelsForProtocol(ProtocolVersion protocolVersion) {
-    if (protocolVersion >= ProtocolConstants.MINECRAFT_1_13) {
+    if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0) {
       return getModernChannelIds();
     }
     return getIdsForLegacyConnections();

proxy/src/test/java/com/velocitypowered/proxy/protocol/PacketRegistryTest.java

@@ -1,12 +1,13 @@
 package com.velocitypowered.proxy.protocol;
 
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12_1;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12_1;
-import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12_2;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12_2;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
 import org.junit.jupiter.api.Test;
 
@@ -14,7 +15,7 @@ class PacketRegistryTest {
 
   private StateRegistry.PacketRegistry setupRegistry() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
-        ProtocolConstants.Direction.CLIENTBOUND);
+        ProtocolUtils.Direction.CLIENTBOUND);
     registry.register(Handshake.class, Handshake::new,
         new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12, false));
     return registry;
@@ -23,46 +24,46 @@ class PacketRegistryTest {
   @Test
   void packetRegistryWorks() {
     StateRegistry.PacketRegistry registry = setupRegistry();
-    MinecraftPacket packet = registry.getVersion(MINECRAFT_1_12).createPacket(0);
+    MinecraftPacket packet = registry.getProtocolRegistry(MINECRAFT_1_12).createPacket(0);
     assertNotNull(packet, "Packet was not found in registry");
     assertEquals(Handshake.class, packet.getClass(), "Registry returned wrong class");
 
-    assertEquals(0, registry.getVersion(MINECRAFT_1_12).getPacketId(packet),
+    assertEquals(0, registry.getProtocolRegistry(MINECRAFT_1_12).getPacketId(packet),
         "Registry did not return the correct packet ID");
   }
 
   @Test
   void packetRegistryLinkingWorks() {
     StateRegistry.PacketRegistry registry = setupRegistry();
-    MinecraftPacket packet = registry.getVersion(MINECRAFT_1_12_1).createPacket(0);
+    MinecraftPacket packet = registry.getProtocolRegistry(MINECRAFT_1_12_1).createPacket(0);
     assertNotNull(packet, "Packet was not found in registry");
     assertEquals(Handshake.class, packet.getClass(), "Registry returned wrong class");
-    assertEquals(0, registry.getVersion(MINECRAFT_1_12_1).getPacketId(packet),
+    assertEquals(0, registry.getProtocolRegistry(MINECRAFT_1_12_1).getPacketId(packet),
         "Registry did not return the correct packet ID");
   }
 
   @Test
   void failOnNoMappings() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
-        ProtocolConstants.Direction.CLIENTBOUND);
+        ProtocolUtils.Direction.CLIENTBOUND);
     assertThrows(IllegalArgumentException.class,
         () -> registry.register(Handshake.class, Handshake::new));
     assertThrows(IllegalArgumentException.class,
-        () -> registry.getVersion(0).getPacketId(new Handshake()));
+        () -> registry.getProtocolRegistry(ProtocolVersion.UNKNOWN).getPacketId(new Handshake()));
   }
 
   @Test
   void registrySuppliesCorrectPacketsByProtocol() {
     StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(
-        ProtocolConstants.Direction.CLIENTBOUND);
+        ProtocolUtils.Direction.CLIENTBOUND);
     registry.register(Handshake.class, Handshake::new,
         new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12, false),
         new StateRegistry.PacketMapping(0x01, MINECRAFT_1_12_1, false));
     assertEquals(Handshake.class,
-        registry.getVersion(MINECRAFT_1_12).createPacket(0x00).getClass());
+        registry.getProtocolRegistry(MINECRAFT_1_12).createPacket(0x00).getClass());
     assertEquals(Handshake.class,
-        registry.getVersion(MINECRAFT_1_12_1).createPacket(0x01).getClass());
+        registry.getProtocolRegistry(MINECRAFT_1_12_1).createPacket(0x01).getClass());
     assertEquals(Handshake.class,
-        registry.getVersion(MINECRAFT_1_12_2).createPacket(0x01).getClass());
+        registry.getProtocolRegistry(MINECRAFT_1_12_2).createPacket(0x01).getClass());
   }
 }