Implement tab list entry uuid rewrite

unlink bungee, rewrite the current player only

README.md

@@ -7,6 +7,7 @@ A list of small tweaks I made:
   - Supported proxy types: `socks4`, `socks5`, `http`
     - Due to [an issue](https://github.com/AsyncHttpClient/async-http-client/issues/1913) in the http library velocity uses, you can only use `http` proxy for now 
   - If enabled, velocity will firstly try authenticating with the given proxy, if failed it will try again without the proxy
+- Implement UUID rewrite for TabList packets, like what bungeecord does
 
 # Velocity
 

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

@@ -56,6 +56,7 @@
 import com.velocitypowered.proxy.protocol.packet.UpsertPlayerInfo;
 import com.velocitypowered.proxy.protocol.packet.config.StartUpdate;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
+import com.velocitypowered.proxy.tablist.TabListUuidRewriter;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
@@ -263,18 +264,27 @@ public boolean handle(TabCompleteResponse packet) {
 
   @Override
   public boolean handle(LegacyPlayerListItem packet) {
+    // [fallen's fork] tab list entry uuid rewrite: impl
+    TabListUuidRewriter.rewrite(serverConn.getPlayer(), packet);
+
     serverConn.getPlayer().getTabList().processLegacy(packet);
     return false;
   }
 
   @Override
   public boolean handle(UpsertPlayerInfo packet) {
+    // [fallen's fork] tab list entry uuid rewrite: impl
+    TabListUuidRewriter.rewrite(serverConn.getPlayer(), packet);
+
     serverConn.getPlayer().getTabList().processUpdate(packet);
     return false;
   }
 
   @Override
   public boolean handle(RemovePlayerInfo packet) {
+    // [fallen's fork] tab list entry uuid rewrite: impl
+    TabListUuidRewriter.rewrite(serverConn.getPlayer(), packet);
+
     serverConn.getPlayer().getTabList().processRemove(packet);
     return false;
   }

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

@@ -49,6 +49,7 @@
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
@@ -168,6 +169,9 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
   private final ChatQueue chatQueue;
   private final ChatBuilderFactory chatBuilderFactory;
 
+  // [fallen's fork] tab list entry uuid rewrite: store offline uuid for reuse
+  private final UUID offlineUuid;
+
   ConnectedPlayer(VelocityServer server, GameProfile profile, MinecraftConnection connection,
       @Nullable InetSocketAddress virtualHost, boolean onlineMode,
       @Nullable IdentifiedKey playerKey) {
@@ -189,6 +193,9 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     this.playerKey = playerKey;
     this.chatQueue = new ChatQueue(this);
     this.chatBuilderFactory = new ChatBuilderFactory(this.getProtocolVersion());
+
+    // [fallen's fork] tab list entry uuid rewrite: store offline uuid for reuse
+    this.offlineUuid = UuidUtils.generateOfflinePlayerUuid(this.getUsername());
   }
 
   public ChatBuilderFactory getChatBuilderFactory() {
@@ -227,6 +234,11 @@ public UUID getUniqueId() {
     return profile.getId();
   }
 
+  // [fallen's fork] tab list entry uuid rewrite: store offline uuid for reuse
+  public UUID getOfflineUuid() {
+    return offlineUuid;
+  }
+
   @Override
   public Optional<ServerConnection> getCurrentServer() {
     return Optional.ofNullable(connectedServer);

proxy/src/main/java/com/velocitypowered/proxy/tablist/TabListUuidRewriter.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2018-2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.tablist;
+
+import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.protocol.packet.LegacyPlayerListItem;
+import com.velocitypowered.proxy.protocol.packet.RemovePlayerInfo;
+import com.velocitypowered.proxy.protocol.packet.UpsertPlayerInfo;
+import java.util.stream.Collectors;
+
+/**
+ * [fallen's fork] tab list entry uuid rewrite: rewrite logic.
+ */
+public class TabListUuidRewriter {
+  /**
+   * Rewrite uuid for a LegacyPlayerListItem packet.
+   */
+  public static void rewrite(ConnectedPlayer player, LegacyPlayerListItem packet) {
+    packet.getItems().replaceAll(item -> {
+      if (player.getOfflineUuid().equals(item.getUuid())) {
+        var newItem = new LegacyPlayerListItem.Item(player.getUniqueId());
+
+        newItem.setName(item.getName());
+        newItem.setProperties(item.getProperties());
+        newItem.setGameMode(item.getGameMode());
+        newItem.setLatency(item.getLatency());
+        newItem.setDisplayName(item.getDisplayName());
+        newItem.setPlayerKey(item.getPlayerKey());
+
+        item = newItem;
+      }
+
+      return item;
+    });
+  }
+
+  /**
+   * Rewrite uuid for a UpsertPlayerInfo packet.
+   */
+  public static void rewrite(ConnectedPlayer player, UpsertPlayerInfo packet) {
+    packet.getEntries().replaceAll(entry -> {
+      if (player.getOfflineUuid().equals(entry.getProfileId())) {
+        var newEntry = new UpsertPlayerInfo.Entry(player.getUniqueId());
+
+        newEntry.setProfile(player.getGameProfile());
+        newEntry.setListed(entry.isListed());
+        newEntry.setLatency(entry.getLatency());
+        newEntry.setGameMode(entry.getGameMode());
+        newEntry.setDisplayName(entry.getDisplayName());
+        newEntry.setChatSession(entry.getChatSession());
+
+        entry = newEntry;
+      }
+
+      return entry;
+    });
+  }
+
+  /**
+   * Rewrite uuid for a RemovePlayerInfo packet.
+   */
+  public static void rewrite(ConnectedPlayer player, RemovePlayerInfo packet) {
+    var newProfiles = packet.getProfilesToRemove().stream()
+        .map(uuid -> {
+          if (player.getOfflineUuid().equals(uuid)) {
+            uuid = player.getUniqueId();
+          }
+          return uuid;
+        })
+        .collect(Collectors.toList());
+    packet.setProfilesToRemove(newProfiles);
+  }
+}