Finish overhaul of packet state/registry system

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

@@ -36,7 +36,6 @@ import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.HandshakeSessionHandler;
 import com.velocitypowered.proxy.connection.client.LoginSessionHandler;
 import com.velocitypowered.proxy.connection.client.StatusSessionHandler;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundSetCompressionPacket;
 import com.velocitypowered.proxy.network.pipeline.MinecraftCipherDecoder;
@@ -45,6 +44,8 @@ import com.velocitypowered.proxy.network.pipeline.MinecraftCompressDecoder;
 import com.velocitypowered.proxy.network.pipeline.MinecraftCompressorAndLengthEncoder;
 import com.velocitypowered.proxy.network.pipeline.MinecraftDecoder;
 import com.velocitypowered.proxy.network.pipeline.MinecraftEncoder;
+import com.velocitypowered.proxy.network.registry.protocol.ProtocolRegistry;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import com.velocitypowered.proxy.util.except.QuietDecoderException;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.Channel;
@@ -75,7 +76,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
 
   private final Channel channel;
   private SocketAddress remoteAddress;
-  private StateRegistry state;
+  private ProtocolRegistry state;
   private @Nullable MinecraftSessionHandler sessionHandler;
   private ProtocolVersion protocolVersion;
   private @Nullable MinecraftConnectionAssociation association;
@@ -92,7 +93,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     this.channel = channel;
     this.remoteAddress = channel.remoteAddress();
     this.server = server;
-    this.state = StateRegistry.HANDSHAKE;
+    this.state = ProtocolStates.HANDSHAKE;
   }
 
   @Override
@@ -247,7 +248,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     if (channel.isActive()) {
       boolean is17 = this.getProtocolVersion().lt(ProtocolVersion.MINECRAFT_1_8)
           && this.getProtocolVersion().gte(ProtocolVersion.MINECRAFT_1_7_2);
-      if (is17 && this.getState() != StateRegistry.STATUS) {
+      if (is17 && this.getState() != ProtocolStates.STATUS) {
         channel.eventLoop().execute(() -> {
           // 1.7.x versions have a race condition with switching protocol states, so just explicitly
           // close the connection after a short while.
@@ -307,7 +308,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     return remoteAddress;
   }
 
-  public StateRegistry getState() {
+  public ProtocolRegistry getState() {
     return state;
   }
 
@@ -341,7 +342,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
    * Changes the state of the Minecraft connection.
    * @param state the new state
    */
-  public void setState(StateRegistry state) {
+  public void setState(ProtocolRegistry state) {
     ensureInEventLoop();
 
     this.state = state;

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

@@ -27,13 +27,13 @@ import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.network.ProtocolUtils;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundDisconnectPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundEncryptionRequestPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundLoginPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundServerLoginSuccessPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundSetCompressionPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundLoginPluginResponsePacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import com.velocitypowered.proxy.util.except.QuietRuntimeException;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -46,7 +46,6 @@ import javax.crypto.Mac;
 import javax.crypto.SecretKey;
 import javax.crypto.spec.SecretKeySpec;
 import net.kyori.adventure.text.Component;
-import net.kyori.adventure.text.TextComponent;
 
 public class LoginSessionHandler implements MinecraftSessionHandler {
 
@@ -119,7 +118,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
 
     // Move into the PLAY phase.
     MinecraftConnection smc = serverConn.ensureConnected();
-    smc.setState(StateRegistry.PLAY);
+    smc.setState(ProtocolStates.PLAY);
 
     // Switch to the transition handler.
     smc.setSessionHandler(new TransitionSessionHandler(server, serverConn, resultFuture));

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

@@ -38,11 +38,11 @@ import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.connection.registry.DimensionRegistry;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundJoinGamePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundHandshakePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundServerLoginPacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
@@ -167,11 +167,11 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
     int port = destinationAddr instanceof InetSocketAddress
         ? ((InetSocketAddress) destinationAddr).getPort() : 0;
     ServerboundHandshakePacket handshake = new ServerboundHandshakePacket(protocolVersion,
-        address, port, StateRegistry.LOGIN_ID);
+        address, port, ServerboundHandshakePacket.LOGIN_ID);
     mc.delayedWrite(handshake);
 
     mc.setProtocolVersion(protocolVersion);
-    mc.setState(StateRegistry.LOGIN);
+    mc.setState(ProtocolStates.LOGIN);
     mc.delayedWrite(new ServerboundServerLoginPacket(proxyPlayer.username()));
     mc.flush();
   }

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

@@ -41,7 +41,6 @@ import com.velocitypowered.proxy.connection.backend.BackendConnectionPhases;
 import com.velocitypowered.proxy.connection.backend.BungeeCordMessageResponder;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.network.PluginMessageUtil;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.AbstractPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundBossBarPacket;
@@ -57,6 +56,7 @@ import com.velocitypowered.proxy.network.packet.serverbound.ServerboundKeepAlive
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundResourcePackResponsePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundTabCompleteRequestPacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
@@ -69,7 +69,6 @@ import java.util.Optional;
 import java.util.Queue;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
-import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.key.Key;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
@@ -210,7 +209,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     VelocityServerConnection serverConn = player.getConnectedServer();
     MinecraftConnection backendConn = serverConn != null ? serverConn.getConnection() : null;
     if (serverConn != null && backendConn != null) {
-      if (backendConn.getState() != StateRegistry.PLAY) {
+      if (backendConn.getState() != ProtocolStates.PLAY) {
         logger.warn("A plugin message was received while the backend server was not "
             + "ready. Channel: {}. Packet discarded.", packet.getChannel());
       } else if (PluginMessageUtil.isRegister(packet)) {

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

@@ -58,7 +58,6 @@ import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.network.PluginMessageUtil;
 import com.velocitypowered.proxy.network.ProtocolUtils;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.AbstractPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundChatPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundDisconnectPacket;
@@ -68,6 +67,7 @@ import com.velocitypowered.proxy.network.packet.clientbound.ClientboundResourceP
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundTitlePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundChatPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundClientSettingsPacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import com.velocitypowered.proxy.tablist.VelocityTabList;
 import com.velocitypowered.proxy.tablist.VelocityTabListLegacy;
@@ -769,7 +769,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
    * ID last sent by the server.
    */
   public void sendKeepAlive() {
-    if (connection.getState() == StateRegistry.PLAY) {
+    if (connection.getState() == ProtocolStates.PLAY) {
       connection.write(new ClientboundKeepAlivePacket(ThreadLocalRandom.current().nextLong()));
     }
   }

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

@@ -29,12 +29,13 @@ import com.velocitypowered.proxy.connection.ConnectionTypes;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.forge.legacy.LegacyForgeConstants;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.legacy.LegacyDisconnectPacket;
 import com.velocitypowered.proxy.network.packet.legacy.LegacyHandshakePacket;
 import com.velocitypowered.proxy.network.packet.legacy.LegacyPingPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundHandshakePacket;
+import com.velocitypowered.proxy.network.registry.protocol.ProtocolRegistry;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import io.netty.buffer.ByteBuf;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
@@ -81,7 +82,7 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
   public boolean handle(ServerboundHandshakePacket handshake) {
     InitialInboundConnection ic = new InitialInboundConnection(connection,
         cleanVhost(handshake.getServerAddress()), handshake);
-    StateRegistry nextState = getStateForProtocol(handshake.getNextStatus());
+    ProtocolRegistry nextState = getStateForProtocol(handshake.getNextStatus());
     if (nextState == null) {
       LOGGER.error("{} provided invalid protocol {}", ic, handshake.getNextStatus());
       connection.close(true);
@@ -90,28 +91,25 @@ public class HandshakeSessionHandler implements MinecraftSessionHandler {
       connection.setProtocolVersion(handshake.getProtocolVersion());
       connection.setAssociation(ic);
 
-      switch (nextState) {
+      if (nextState == ProtocolStates.STATUS) {
-        case STATUS:
+        connection.setSessionHandler(new StatusSessionHandler(server, connection, ic));
-          connection.setSessionHandler(new StatusSessionHandler(server, connection, ic));
+      } else if (nextState == ProtocolStates.LOGIN) {
-          break;
+        this.handleLogin(handshake, ic);
-        case LOGIN:
+      } else {
-          this.handleLogin(handshake, ic);
+        // If you get this, it's a bug in Velocity.
-          break;
+        throw new AssertionError("getStateForProtocol provided invalid state!");
-        default:
-          // If you get this, it's a bug in Velocity.
-          throw new AssertionError("getStateForProtocol provided invalid state!");
       }
     }
 
     return true;
   }
 
-  private static @Nullable StateRegistry getStateForProtocol(int status) {
+  private static @Nullable ProtocolRegistry getStateForProtocol(int status) {
     switch (status) {
-      case StateRegistry.STATUS_ID:
+      case ServerboundHandshakePacket.STATUS_ID:
-        return StateRegistry.STATUS;
+        return ProtocolStates.STATUS;
-      case StateRegistry.LOGIN_ID:
+      case ServerboundHandshakePacket.LOGIN_ID:
-        return StateRegistry.LOGIN;
+        return ProtocolStates.LOGIN;
       default:
         return null;
     }

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

@@ -46,12 +46,12 @@ 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.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundEncryptionRequestPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundServerLoginSuccessPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundSetCompressionPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundEncryptionResponsePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundServerLoginPacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import io.netty.buffer.ByteBuf;
 import java.net.InetSocketAddress;
 import java.security.GeneralSecurityException;
@@ -287,7 +287,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
     mcConnection.write(new ClientboundServerLoginSuccessPacket(playerUniqueId, player.username()));
 
     mcConnection.setAssociation(player);
-    mcConnection.setState(StateRegistry.PLAY);
+    mcConnection.setState(ProtocolStates.PLAY);
 
     server.eventManager().fire(new LoginEventImpl(player))
         .thenAcceptAsync(event -> {

proxy/src/main/java/com/velocitypowered/proxy/network/packet/serverbound/ServerboundHandshakePacket.java

@@ -41,6 +41,8 @@ public class ServerboundHandshakePacket implements Packet {
     out.writeShort(packet.port);
     ProtocolUtils.writeVarInt(out, packet.nextStatus);
   };
+  public static final int STATUS_ID = 1;
+  public static final int LOGIN_ID = 2;
 
   private final ProtocolVersion protocolVersion;
   private final String serverAddress;

proxy/src/main/java/com/velocitypowered/proxy/network/pipeline/MinecraftDecoder.java

@@ -20,9 +20,11 @@ package com.velocitypowered.proxy.network.pipeline;
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.network.ProtocolUtils;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.PacketDirection;
+import com.velocitypowered.proxy.network.registry.packet.PacketRegistryMap;
+import com.velocitypowered.proxy.network.registry.protocol.ProtocolRegistry;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import com.velocitypowered.proxy.util.except.QuietRuntimeException;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
@@ -37,8 +39,9 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
           + "developer, launch Velocity with -Dvelocity.packet-decode-logging=true to see more.");
 
   private final PacketDirection direction;
-  private StateRegistry state;
+  private ProtocolVersion version;
-  private StateRegistry.PacketRegistry.ProtocolRegistry registry;
+  private ProtocolRegistry state;
+  private PacketRegistryMap registry;
 
   /**
    * Creates a new {@code MinecraftDecoder} decoding packets from the specified {@code direction}.
@@ -47,9 +50,9 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
    */
   public MinecraftDecoder(PacketDirection direction) {
     this.direction = Preconditions.checkNotNull(direction, "direction");
-    this.registry = StateRegistry.HANDSHAKE.getProtocolRegistry(direction,
+    this.state = ProtocolStates.HANDSHAKE;
-        ProtocolVersion.MINIMUM_VERSION);
+    this.version = ProtocolVersion.MINIMUM_VERSION;
-    this.state = StateRegistry.HANDSHAKE;
+    this.registry = this.state.lookup(direction, ProtocolVersion.MINIMUM_VERSION);
   }
 
   @Override
@@ -72,7 +75,7 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
     int packetId = ProtocolUtils.readVarInt(buf);
     Packet packet = null;
     try {
-      packet = this.registry.readPacket(packetId, buf, registry.version);
+      packet = this.registry.readPacket(packetId, buf, this.version);
     } catch (Exception e) {
       throw handleDecodeFailure(e, packet, packetId); // TODO: packet is always null
     }
@@ -92,8 +95,8 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
   }
 
   private void doLengthSanityChecks(ByteBuf buf, Packet packet) throws Exception {
-    int expectedMinLen = packet.expectedMinLength(buf, direction, registry.version);
+    int expectedMinLen = packet.expectedMinLength(buf, direction, version);
-    int expectedMaxLen = packet.expectedMaxLength(buf, direction, registry.version);
+    int expectedMaxLen = packet.expectedMaxLength(buf, direction, version);
     if (expectedMaxLen != -1 && buf.readableBytes() > expectedMaxLen) {
       throw handleOverflow(packet, expectedMaxLen, buf.readableBytes());
     }
@@ -130,16 +133,17 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
   }
 
   private String getExtraConnectionDetail(int packetId) {
-    return "Direction " + direction + " Protocol " + registry.version + " State " + state
+    return "Direction " + direction + " Protocol " + version + " State " + state
         + " ID " + Integer.toHexString(packetId);
   }
 
   public void setProtocolVersion(ProtocolVersion protocolVersion) {
-    this.registry = state.getProtocolRegistry(direction, protocolVersion);
+    this.version = protocolVersion;
+    this.registry = state.lookup(direction, protocolVersion);
   }
 
-  public void setState(StateRegistry state) {
+  public void setState(ProtocolRegistry state) {
     this.state = state;
-    this.setProtocolVersion(registry.version);
+    this.setProtocolVersion(this.version);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/network/pipeline/MinecraftEncoder.java

@@ -19,10 +19,11 @@ package com.velocitypowered.proxy.network.pipeline;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
-import com.velocitypowered.proxy.network.ProtocolUtils;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.PacketDirection;
+import com.velocitypowered.proxy.network.registry.packet.PacketRegistryMap;
+import com.velocitypowered.proxy.network.registry.protocol.ProtocolRegistry;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToByteEncoder;
@@ -30,8 +31,9 @@ import io.netty.handler.codec.MessageToByteEncoder;
 public class MinecraftEncoder extends MessageToByteEncoder<Packet> {
 
   private final PacketDirection direction;
-  private StateRegistry state;
+  private ProtocolRegistry state;
-  private StateRegistry.PacketRegistry.ProtocolRegistry registry;
+  private PacketRegistryMap registry;
+  private ProtocolVersion version;
 
   /**
    * Creates a new {@code MinecraftEncoder} encoding packets for the specified {@code direction}.
@@ -40,22 +42,23 @@ public class MinecraftEncoder extends MessageToByteEncoder<Packet> {
    */
   public MinecraftEncoder(PacketDirection direction) {
     this.direction = Preconditions.checkNotNull(direction, "direction");
-    this.registry = StateRegistry.HANDSHAKE
+    this.state = ProtocolStates.HANDSHAKE;
-        .getProtocolRegistry(direction, ProtocolVersion.MINIMUM_VERSION);
+    this.version = ProtocolVersion.MINIMUM_VERSION;
-    this.state = StateRegistry.HANDSHAKE;
+    this.registry = this.state.lookup(direction, ProtocolVersion.MINIMUM_VERSION);
   }
 
   @Override
   protected void encode(ChannelHandlerContext ctx, Packet msg, ByteBuf out) {
-    this.registry.writePacket(msg, out, registry.version);
+    this.registry.writePacket(msg, out, this.version);
   }
 
   public void setProtocolVersion(final ProtocolVersion protocolVersion) {
-    this.registry = state.getProtocolRegistry(direction, protocolVersion);
+    this.version = protocolVersion;
+    this.registry = this.state.lookup(direction, protocolVersion);
   }
 
-  public void setState(StateRegistry state) {
+  public void setState(ProtocolRegistry state) {
     this.state = state;
-    this.setProtocolVersion(registry.version);
+    this.setProtocolVersion(version);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/network/registry/packet/DensePacketRegistryMap.java

@@ -1,6 +1,24 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.network.ProtocolUtils;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.PacketReader;
 import com.velocitypowered.proxy.network.packet.PacketWriter;
@@ -19,6 +37,7 @@ public class DensePacketRegistryMap implements PacketRegistryMap {
   private final PacketReader<?>[] readersById;
   private final PacketWriter[] writersByClass;
   private final Class<?>[] classesById;
+  private final int[] idsByKey;
 
   public DensePacketRegistryMap(Int2ObjectMap<PacketMapping<?>> mappings) {
     int size = mappings.keySet().stream().mapToInt(x -> x).max().orElse(0) + 1;
@@ -26,17 +45,19 @@ public class DensePacketRegistryMap implements PacketRegistryMap {
     this.readersById = new PacketReader[size];
     this.writersByClass = new PacketWriter[size * 2];
     this.classesById = new Class[size * 2];
+    this.idsByKey = new int[size * 2];
 
     for (PacketMapping<?> value : mappings.values()) {
       this.readersById[value.id] = value.reader;
-      this.place(value.packetClass, value.writer);
+      this.place(value.id, value.packetClass, value.writer);
     }
   }
 
-  private void place(Class<?> key, PacketWriter<?> value) {
+  private void place(int packetId, Class<?> key, PacketWriter<?> value) {
     int bucket = findEmpty(key);
     this.writersByClass[bucket] = value;
     this.classesById[bucket] = key;
+    this.idsByKey[bucket] = packetId;
   }
 
   private int findEmpty(Class<?> key) {
@@ -86,9 +107,10 @@ public class DensePacketRegistryMap implements PacketRegistryMap {
 
   @Override
   public <P extends Packet> void writePacket(P packet, ByteBuf buf, ProtocolVersion version) {
-    int id = this.index(packet.getClass());
+    int bucket = this.index(packet.getClass());
-    if (id != -1) {
+    if (bucket != -1) {
-      this.writersByClass[id].write(buf, packet, version);
+      ProtocolUtils.writeVarInt(buf, this.idsByKey[bucket]);
+      this.writersByClass[bucket].write(buf, packet, version);
     } else {
       throw new IllegalArgumentException(String.format(
           "Unable to find id for packet of type %s in protocol %s",

proxy/src/main/java/com/velocitypowered/proxy/network/registry/packet/EmptyPacketRegistryMap.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;
@@ -21,7 +38,7 @@ public class EmptyPacketRegistryMap implements PacketRegistryMap {
   @Override
   public <P extends Packet> void writePacket(P packet, ByteBuf buf, ProtocolVersion version) {
     throw new IllegalArgumentException(String.format(
-        "Unable to find id for packet of type %s in protocol %s",
+        "Unable to find id for packet of type %s for version %s",
         packet.getClass().getName(), version
     ));
   }

proxy/src/main/java/com/velocitypowered/proxy/network/registry/packet/PacketRegistryBuilder.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.packet;
 
 import com.velocitypowered.proxy.network.packet.Packet;
@@ -16,8 +33,7 @@ public class PacketRegistryBuilder {
     this.mappings = new Int2ObjectOpenHashMap<>();
   }
 
-  public PacketRegistryBuilder(
+  public PacketRegistryBuilder(Int2ObjectMap<PacketMapping<?>> mappings, boolean dense) {
-      Int2ObjectMap<PacketMapping<?>> mappings, boolean dense) {
     this.mappings = new Int2ObjectOpenHashMap<>(mappings);
     this.dense = dense;
   }
@@ -29,7 +45,7 @@ public class PacketRegistryBuilder {
   }
 
   public <P extends Packet> PacketRegistryBuilder register(int id, Class<P> packetClass,
-      PacketWriter<P> writer, PacketReader<P> reader) {
+      PacketReader<P> reader, PacketWriter<P> writer) {
     mappings.put(id, new PacketMapping(id, packetClass, writer, reader));
     return this;
   }

proxy/src/main/java/com/velocitypowered/proxy/network/registry/packet/PacketRegistryMap.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;

proxy/src/main/java/com/velocitypowered/proxy/network/registry/packet/RegularPacketRegistryMap.java

@@ -1,6 +1,24 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.packet;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.network.ProtocolUtils;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.PacketReader;
 import com.velocitypowered.proxy.network.packet.PacketWriter;
@@ -60,7 +78,7 @@ public class RegularPacketRegistryMap implements PacketRegistryMap {
 
     PacketWriter writer = this.writersById.get(packetId);
     assert writer != null;
+    ProtocolUtils.writeVarInt(buf, packetId);
     writer.write(buf, packet, version);
-
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/network/registry/protocol/ProtocolRegistry.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.protocol;
 
 import com.velocitypowered.api.network.ProtocolVersion;

proxy/src/main/java/com/velocitypowered/proxy/network/registry/protocol/SimpleProtocolRegistry.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.protocol;
 
 import com.velocitypowered.api.network.ProtocolVersion;

proxy/src/main/java/com/velocitypowered/proxy/network/registry/protocol/VersionSpecificProtocolRegistry.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.protocol;
 
 import com.velocitypowered.api.network.ProtocolVersion;

proxy/src/main/java/com/velocitypowered/proxy/network/registry/state/LoginPacketRegistry.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.network.registry.state;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.network.packet.clientbound.ClientboundDisconnectPacket;
+import com.velocitypowered.proxy.network.packet.clientbound.ClientboundEncryptionRequestPacket;
+import com.velocitypowered.proxy.network.packet.clientbound.ClientboundLoginPluginMessagePacket;
+import com.velocitypowered.proxy.network.packet.clientbound.ClientboundServerLoginSuccessPacket;
+import com.velocitypowered.proxy.network.packet.clientbound.ClientboundSetCompressionPacket;
+import com.velocitypowered.proxy.network.packet.serverbound.ServerboundEncryptionResponsePacket;
+import com.velocitypowered.proxy.network.packet.serverbound.ServerboundLoginPluginResponsePacket;
+import com.velocitypowered.proxy.network.packet.serverbound.ServerboundServerLoginPacket;
+import com.velocitypowered.proxy.network.registry.packet.PacketRegistryBuilder;
+import com.velocitypowered.proxy.network.registry.packet.PacketRegistryMap;
+
+public class LoginPacketRegistry {
+  private LoginPacketRegistry() {
+    throw new AssertionError();
+  }
+
+  public static final PacketRegistryMap SERVERBOUND_LOGIN_1_7 = baseProtocolServerbound().build();
+
+  public static final PacketRegistryMap CLIENTBOUND_LOGIN_1_7 = baseProtocolClientbound().build();
+
+  public static final PacketRegistryMap CLIENTBOUND_LOGIN_1_8 = baseProtocolClientbound()
+      .register(0x03, ClientboundSetCompressionPacket.class,
+          ClientboundSetCompressionPacket.DECODER,
+          ClientboundSetCompressionPacket.ENCODER)
+      .build();
+
+  public static final PacketRegistryMap CLIENTBOUND_LOGIN_1_13 = baseProtocolClientbound()
+      .register(0x03, ClientboundSetCompressionPacket.class,
+          ClientboundSetCompressionPacket.DECODER,
+          ClientboundSetCompressionPacket.ENCODER)
+      .register(0x04, ClientboundLoginPluginMessagePacket.class,
+          ClientboundLoginPluginMessagePacket.DECODER,
+          ClientboundLoginPluginMessagePacket.ENCODER)
+      .build();
+
+  public static final PacketRegistryMap SERVERBOUND_LOGIN_1_13 = baseProtocolServerbound()
+      .register(0x02, ServerboundLoginPluginResponsePacket.class,
+          ServerboundLoginPluginResponsePacket.DECODER,
+          ServerboundLoginPluginResponsePacket.ENCODER)
+      .build();
+
+  private static PacketRegistryBuilder baseProtocolServerbound() {
+    return new PacketRegistryBuilder()
+        .dense()
+        .register(0x00, ServerboundServerLoginPacket.class, ServerboundServerLoginPacket.DECODER,
+            ServerboundServerLoginPacket.ENCODER
+        )
+        .register(0x01, ServerboundEncryptionResponsePacket.class,
+            ServerboundEncryptionResponsePacket.DECODER,
+            ServerboundEncryptionResponsePacket.ENCODER);
+  }
+
+  private static PacketRegistryBuilder baseProtocolClientbound() {
+    return new PacketRegistryBuilder()
+        .dense()
+        .register(0x00, ClientboundDisconnectPacket.class, ClientboundDisconnectPacket.DECODER,
+            ClientboundDisconnectPacket.ENCODER)
+        .register(0x01, ClientboundEncryptionRequestPacket.class,
+            ClientboundEncryptionRequestPacket.DECODER, ClientboundEncryptionRequestPacket.ENCODER)
+        .register(0x02, ClientboundServerLoginSuccessPacket.class,
+            ClientboundServerLoginSuccessPacket.DECODER,
+            ClientboundServerLoginSuccessPacket.ENCODER);
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/network/registry/state/PlayPacketRegistry.java

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.network;
+package com.velocitypowered.proxy.network.registry.state;
 
 import static com.google.common.collect.Iterables.getLast;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_12;
@@ -33,6 +33,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION;
 import static com.velocitypowered.api.network.ProtocolVersion.SUPPORTED_VERSIONS;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.network.ProtocolUtils;
 import com.velocitypowered.proxy.network.packet.Packet;
 import com.velocitypowered.proxy.network.packet.PacketDirection;
 import com.velocitypowered.proxy.network.packet.PacketReader;
@@ -41,88 +42,44 @@ import com.velocitypowered.proxy.network.packet.clientbound.ClientboundAvailable
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundBossBarPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundChatPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundDisconnectPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundEncryptionRequestPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundHeaderAndFooterPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundJoinGamePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundKeepAlivePacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundLoginPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundPlayerListItemPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundResourcePackRequestPacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundRespawnPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundServerLoginSuccessPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundSetCompressionPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundStatusPingPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundStatusResponsePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundTabCompleteResponsePacket;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundTitlePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundChatPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundClientSettingsPacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundEncryptionResponsePacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundHandshakePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundKeepAlivePacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundLoginPluginResponsePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundPluginMessagePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundResourcePackResponsePacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundServerLoginPacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundStatusPingPacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundStatusRequestPacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundTabCompleteRequestPacket;
+import com.velocitypowered.proxy.network.registry.packet.PacketRegistryMap;
+import com.velocitypowered.proxy.network.registry.protocol.ProtocolRegistry;
 import io.netty.buffer.ByteBuf;
 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.Collections;
 import java.util.EnumMap;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.Objects;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public enum StateRegistry {
+class PlayPacketRegistry implements ProtocolRegistry {
 
-  HANDSHAKE(true) {
+  static final ProtocolRegistry PLAY = new PlayPacketRegistry();
-    {
+
-      serverbound.register(
+  private PlayPacketRegistry() {
-          ServerboundHandshakePacket.class,
+    this.clientbound = new PacketRegistry(PacketDirection.CLIENTBOUND);
-          ServerboundHandshakePacket.DECODER,
+    this.serverbound = new PacketRegistry(PacketDirection.SERVERBOUND);
-          ServerboundHandshakePacket.ENCODER,
-          map(0x00, MINECRAFT_1_7_2, false)
-      );
-    }
-  },
-  STATUS(true) {
-    {
-      serverbound.register(
-          ServerboundStatusRequestPacket.class,
-          ServerboundStatusRequestPacket.DECODER,
-          ServerboundStatusRequestPacket.ENCODER,
-          map(0x00, MINECRAFT_1_7_2, false)
-      );
-      serverbound.register(
-          ServerboundStatusPingPacket.class,
-          ServerboundStatusPingPacket.DECODER,
-          ServerboundStatusPingPacket.ENCODER,
-          map(0x01, MINECRAFT_1_7_2, false)
-      );
 
-      clientbound.register(
-          ClientboundStatusResponsePacket.class,
-          ClientboundStatusResponsePacket.DECODER,
-          ClientboundStatusResponsePacket.ENCODER,
-          map(0x00, MINECRAFT_1_7_2, false)
-      );
-      clientbound.register(
-          ClientboundStatusPingPacket.class,
-          ClientboundStatusPingPacket.DECODER,
-          ClientboundStatusPingPacket.ENCODER,
-          map(0x01, MINECRAFT_1_7_2, false)
-      );
-    }
-  },
-  PLAY(false) {
     {
       serverbound.register(
           ServerboundTabCompleteRequestPacket.class,
@@ -346,73 +303,16 @@ public enum StateRegistry {
           map(0x32, MINECRAFT_1_16_2, false)
       );
     }
-  },
-  LOGIN(true) {
-    {
-      serverbound.register(
-          ServerboundServerLoginPacket.class,
-          ServerboundServerLoginPacket.DECODER,
-          ServerboundServerLoginPacket.ENCODER,
-          map(0x00, MINECRAFT_1_7_2, false)
-      );
-      serverbound.register(
-          ServerboundEncryptionResponsePacket.class,
-          ServerboundEncryptionResponsePacket.DECODER,
-          ServerboundEncryptionResponsePacket.ENCODER,
-          map(0x01, MINECRAFT_1_7_2, false)
-      );
-      serverbound.register(
-          ServerboundLoginPluginResponsePacket.class,
-          ServerboundLoginPluginResponsePacket.DECODER,
-          ServerboundLoginPluginResponsePacket.ENCODER,
-          map(0x02, MINECRAFT_1_13, false)
-      );
 
-      clientbound.register(
+    serverbound.compact();
-          ClientboundDisconnectPacket.class,
+    clientbound.compact();
-          ClientboundDisconnectPacket.DECODER,
+  }
-          ClientboundDisconnectPacket.ENCODER,
-          map(0x00, MINECRAFT_1_7_2, false)
-      );
-      clientbound.register(
-          ClientboundEncryptionRequestPacket.class,
-          ClientboundEncryptionRequestPacket.DECODER,
-          ClientboundEncryptionRequestPacket.ENCODER,
-          map(0x01, MINECRAFT_1_7_2, false)
-      );
-      clientbound.register(
-          ClientboundServerLoginSuccessPacket.class,
-          ClientboundServerLoginSuccessPacket.DECODER,
-          ClientboundServerLoginSuccessPacket.ENCODER,
-          map(0x02, MINECRAFT_1_7_2, false)
-      );
-      clientbound.register(
-          ClientboundSetCompressionPacket.class,
-          ClientboundSetCompressionPacket.DECODER,
-          ClientboundSetCompressionPacket.ENCODER,
-          map(0x03, MINECRAFT_1_8, false)
-      );
-      clientbound.register(
-          ClientboundLoginPluginMessagePacket.class,
-          ClientboundLoginPluginMessagePacket.DECODER,
-          ClientboundLoginPluginMessagePacket.ENCODER,
-          map(0x04, MINECRAFT_1_13, false)
-      );
-    }
-  };
 
-  public static final int STATUS_ID = 1;
-  public static final int LOGIN_ID = 2;
   public final PacketRegistry clientbound;
   public final PacketRegistry serverbound;
 
-  StateRegistry(boolean useMinimumIfVersionNotFound) {
+  public PacketRegistryMap lookup(PacketDirection direction,
-    this.clientbound = new PacketRegistry(PacketDirection.CLIENTBOUND, useMinimumIfVersionNotFound);
+      ProtocolVersion version) {
-    this.serverbound = new PacketRegistry(PacketDirection.SERVERBOUND, useMinimumIfVersionNotFound);
-  }
-
-  public PacketRegistry.ProtocolRegistry getProtocolRegistry(PacketDirection direction,
-                                                             ProtocolVersion version) {
     return (direction == PacketDirection.SERVERBOUND ? this.serverbound : this.clientbound)
       .getProtocolRegistry(version);
   }
@@ -421,15 +321,9 @@ public enum StateRegistry {
 
     private final PacketDirection direction;
     private final Map<ProtocolVersion, ProtocolRegistry> versions;
-    private final boolean useMinimumIfVersionNotFound;
 
     PacketRegistry(PacketDirection direction) {
-      this(direction, true);
-    }
-
-    PacketRegistry(PacketDirection direction, boolean useMinimumIfVersionNotFound) {
       this.direction = direction;
-      this.useMinimumIfVersionNotFound = useMinimumIfVersionNotFound;
 
       Map<ProtocolVersion, ProtocolRegistry> mutableVersions = new EnumMap<>(ProtocolVersion.class);
       for (ProtocolVersion version : ProtocolVersion.values()) {
@@ -438,15 +332,12 @@ public enum StateRegistry {
         }
       }
 
-      this.versions = Collections.unmodifiableMap(mutableVersions);
+      this.versions = mutableVersions;
     }
 
     ProtocolRegistry getProtocolRegistry(final ProtocolVersion version) {
       ProtocolRegistry registry = versions.get(version);
       if (registry == null) {
-        if (useMinimumIfVersionNotFound) {
-          return getProtocolRegistry(MINIMUM_VERSION);
-        }
         throw new IllegalArgumentException("Could not find data for protocol version " + version);
       }
       return registry;
@@ -499,9 +390,26 @@ public enum StateRegistry {
       }
     }
 
-    public class ProtocolRegistry {
+    public void compact() {
+      ProtocolRegistry last = this.versions.get(MINIMUM_VERSION);
+      for (Entry<ProtocolVersion, ProtocolRegistry> entry : this.versions
+          .entrySet()) {
+        if (entry.getValue() == last) {
+          continue;
+        }
 
-      public final ProtocolVersion version;
+        if (entry.getValue().packetClassToId.equals(last.packetClassToId)
+            && entry.getValue().packetClassToWriter.equals(last.packetClassToWriter)) {
+          entry.setValue(last);
+        } else {
+          last = entry.getValue();
+        }
+      }
+    }
+
+    public class ProtocolRegistry implements PacketRegistryMap {
+
+      private final ProtocolVersion version;
       final IntObjectMap<PacketReader<? extends Packet>> packetIdToReader =
           new IntObjectHashMap<>(16, 0.5f);
       final Object2IntMap<Class<? extends Packet>> packetClassToId =
@@ -519,7 +427,6 @@ public enum StateRegistry {
        *
        * @param id the packet ID
        * @param buf the bytebuf
-       * @param version the protocol version
        * @return the packet instance, or {@code null} if the ID is not registered
        */
       public @Nullable Packet readPacket(final int id, ByteBuf buf, ProtocolVersion version) {
@@ -535,7 +442,6 @@ public enum StateRegistry {
        *
        * @param packet the packet
        * @param buf the bytebuf
-       * @param version the protocol version
        */
       public <P extends Packet> void writePacket(P packet, ByteBuf buf, ProtocolVersion version) {
         final int id = this.packetClassToId.getInt(packet.getClass());

proxy/src/main/java/com/velocitypowered/proxy/network/registry/state/ProtocolStates.java

@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 package com.velocitypowered.proxy.network.registry.state;
 
 import com.velocitypowered.api.network.ProtocolVersion;
@@ -16,39 +33,43 @@ public class ProtocolStates {
   public static final ProtocolRegistry HANDSHAKE;
   public static final ProtocolRegistry STATUS;
   public static final ProtocolRegistry LOGIN;
+  public static final ProtocolRegistry PLAY;
 
   static {
     HANDSHAKE = new SimpleProtocolRegistry(
         new PacketRegistryBuilder()
-            .dense()
+            .register(0x00, ServerboundHandshakePacket.class, ServerboundHandshakePacket.DECODER,
-            .register(0x00, ServerboundHandshakePacket.class, ServerboundHandshakePacket.ENCODER,
+                ServerboundHandshakePacket.ENCODER)
-              ServerboundHandshakePacket.DECODER)
             .build(),
         EmptyPacketRegistryMap.INSTANCE);
 
     STATUS = new SimpleProtocolRegistry(
         new PacketRegistryBuilder()
-            .dense()
             .register(0x00, ServerboundStatusRequestPacket.class,
-                ServerboundStatusRequestPacket.ENCODER,
+                ServerboundStatusRequestPacket.DECODER, ServerboundStatusRequestPacket.ENCODER
-                ServerboundStatusRequestPacket.DECODER)
+            )
             .register(0x01, ServerboundStatusPingPacket.class,
-                ServerboundStatusPingPacket.ENCODER,
+                ServerboundStatusPingPacket.DECODER, ServerboundStatusPingPacket.ENCODER
-                ServerboundStatusPingPacket.DECODER)
+            )
             .build(),
         new PacketRegistryBuilder()
-            .dense()
             .register(0x00, ClientboundStatusResponsePacket.class,
-                ClientboundStatusResponsePacket.ENCODER,
+                ClientboundStatusResponsePacket.DECODER, ClientboundStatusResponsePacket.ENCODER
-                ClientboundStatusResponsePacket.DECODER)
+            )
             .register(0x01, ClientboundStatusPingPacket.class,
-                ClientboundStatusPingPacket.ENCODER,
+                ClientboundStatusPingPacket.DECODER, ClientboundStatusPingPacket.ENCODER
-                ClientboundStatusPingPacket.DECODER)
+            )
             .build());
 
     LOGIN = new VersionSpecificProtocolRegistry()
-        .register(ProtocolVersion.MINECRAFT_1_7_2, ProtocolVersion.MINECRAFT_1_8,
+        .register(ProtocolVersion.MINECRAFT_1_7_2, ProtocolVersion.MINECRAFT_1_7_6,
-            Version172To176.SERVERBOUND_LOGIN, Version172To176.CLIENTBOUND_LOGIN);
+            LoginPacketRegistry.SERVERBOUND_LOGIN_1_7, LoginPacketRegistry.CLIENTBOUND_LOGIN_1_7)
+        .register(ProtocolVersion.MINECRAFT_1_8, ProtocolVersion.MINECRAFT_1_12_2,
+            LoginPacketRegistry.SERVERBOUND_LOGIN_1_7, LoginPacketRegistry.CLIENTBOUND_LOGIN_1_8)
+        .register(ProtocolVersion.MINECRAFT_1_13, ProtocolVersion.MAXIMUM_VERSION,
+            LoginPacketRegistry.SERVERBOUND_LOGIN_1_13, LoginPacketRegistry.CLIENTBOUND_LOGIN_1_13);
+
+    PLAY = PlayPacketRegistry.PLAY;
   }
 
   private ProtocolStates() {

proxy/src/main/java/com/velocitypowered/proxy/network/registry/state/Version172To176.java

@@ -1,39 +0,0 @@
-package com.velocitypowered.proxy.network.registry.state;
-
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundDisconnectPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundEncryptionRequestPacket;
-import com.velocitypowered.proxy.network.packet.clientbound.ClientboundServerLoginSuccessPacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundEncryptionResponsePacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundServerLoginPacket;
-import com.velocitypowered.proxy.network.packet.serverbound.ServerboundTabCompleteRequestPacket;
-import com.velocitypowered.proxy.network.registry.packet.PacketRegistryBuilder;
-import com.velocitypowered.proxy.network.registry.packet.PacketRegistryMap;
-
-public class Version172To176 {
-  private Version172To176() {
-    throw new AssertionError();
-  }
-
-  public static final PacketRegistryMap SERVERBOUND_LOGIN = new PacketRegistryBuilder()
-      .dense()
-      .register(0x00, ServerboundServerLoginPacket.class, ServerboundServerLoginPacket.ENCODER,
-          ServerboundServerLoginPacket.DECODER)
-      .register(0x01, ServerboundEncryptionResponsePacket.class,
-          ServerboundEncryptionResponsePacket.ENCODER, ServerboundEncryptionResponsePacket.DECODER)
-      .build();
-
-  public static final PacketRegistryMap CLIENTBOUND_LOGIN = new PacketRegistryBuilder()
-      .dense()
-      .register(0x00, ClientboundDisconnectPacket.class, ClientboundDisconnectPacket.ENCODER,
-          ClientboundDisconnectPacket.DECODER)
-      .register(0x01, ClientboundEncryptionRequestPacket.class,
-          ClientboundEncryptionRequestPacket.ENCODER, ClientboundEncryptionRequestPacket.DECODER)
-      .register(0x02, ClientboundServerLoginSuccessPacket.class,
-          ClientboundServerLoginSuccessPacket.ENCODER, ClientboundServerLoginSuccessPacket.DECODER)
-      .build();
-
-  public static final PacketRegistryMap SERVERBOUND_PLAY = new PacketRegistryBuilder()
-      .register(0x14, ServerboundTabCompleteRequestPacket.class,
-          ServerboundTabCompleteRequestPacket.ENCODER, ServerboundTabCompleteRequestPacket.DECODER)
-      .build();
-}

proxy/src/main/java/com/velocitypowered/proxy/network/registry/version/GenericVersions.java

@@ -1,5 +0,0 @@
-package com.velocitypowered.proxy.network.registry.version;
-
-public class GenericVersions {
-
-}

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

@@ -23,10 +23,10 @@ import com.velocitypowered.api.proxy.server.ServerPing;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.network.StateRegistry;
 import com.velocitypowered.proxy.network.packet.clientbound.ClientboundStatusResponsePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundHandshakePacket;
 import com.velocitypowered.proxy.network.packet.serverbound.ServerboundStatusRequestPacket;
+import com.velocitypowered.proxy.network.registry.state.ProtocolStates;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
@@ -67,10 +67,10 @@ public class PingSessionHandler implements MinecraftSessionHandler {
         version,
         hostname,
         port,
-        StateRegistry.STATUS_ID
+        ServerboundHandshakePacket.STATUS_ID
     ));
 
-    connection.setState(StateRegistry.STATUS);
+    connection.setState(ProtocolStates.STATUS);
     connection.delayedWrite(ServerboundStatusRequestPacket.INSTANCE);
 
     connection.flush();