Several improvements and fixes for 1.20.2 (#1097)

* Send LoginAcknowledged immediately

* Resend player list header/footer after backend server switched to config state

* Fix clearHeaderAndFooter not clearing fields in ConnectedPlayer

* Clear boss bars, header/footer, tab list when switching client to config state

* Send client settings in config state

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

@@ -31,7 +31,6 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.event.HoverEvent;
 import net.kyori.adventure.text.event.HoverEventSource;
 import org.checkerframework.checker.nullness.qual.Nullable;
-import org.checkerframework.checker.nullness.qual.Nullable;
 import org.jetbrains.annotations.NotNull;
 
 /**
@@ -148,10 +147,17 @@ public interface Player extends
   /**
    * Clears the tab list header and footer for the player.
    *
-   * @deprecated Use {@link TabList#clearHeaderAndFooter()}.
+   * @deprecated Use {@link Player#clearPlayerListHeaderAndFooter()}.
    */
   @Deprecated
-  void clearHeaderAndFooter();
+  default void clearHeaderAndFooter() {
+    clearPlayerListHeaderAndFooter();
+  }
+
+  /**
+   * Clears the player list header and footer.
+   */
+  void clearPlayerListHeaderAndFooter();
 
   /**
    * Returns the player's player list header.

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

@@ -24,6 +24,7 @@ import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.client.ClientConfigSessionHandler;
+import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
@@ -152,22 +153,26 @@ public class ConfigSessionHandler implements MinecraftSessionHandler {
   @Override
   public boolean handle(FinishedUpdate packet) {
     MinecraftConnection smc = serverConn.ensureConnected();
+    ConnectedPlayer player = serverConn.getPlayer();
     ClientConfigSessionHandler configHandler =
-        (ClientConfigSessionHandler) serverConn.getPlayer().getConnection()
+        (ClientConfigSessionHandler) player.getConnection().getActiveSessionHandler();
-            .getActiveSessionHandler();
 
     smc.setAutoReading(false);
     // Even when not auto reading messages are still decoded. Decode them with the correct state
     smc.getChannel().pipeline().get(MinecraftDecoder.class).setState(StateRegistry.PLAY);
     configHandler.handleBackendFinishUpdate(serverConn).thenAcceptAsync((unused) -> {
-      if (serverConn == serverConn.getPlayer().getConnectedServer()) {
+      if (serverConn == player.getConnectedServer()) {
         smc.setActiveSessionHandler(StateRegistry.PLAY);
+        player.sendPlayerListHeaderAndFooter(
+            player.getPlayerListHeader(), player.getPlayerListFooter());
+        // The client cleared the tab list. TODO: Restore changes done via TabList API
+        player.getTabList().clearAllSilent();
       } else {
         smc.setActiveSessionHandler(StateRegistry.PLAY,
             new TransitionSessionHandler(server, serverConn, resultFuture));
       }
-      if (serverConn.getPlayer().getAppliedResourcePack() == null && resourcePackToApply != null) {
+      if (player.getAppliedResourcePack() == null && resourcePackToApply != null) {
-        serverConn.getPlayer().queueResourcePack(resourcePackToApply);
+        player.queueResourcePack(resourcePackToApply);
       }
       smc.setAutoReading(true);
     }, smc.eventLoop());

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

@@ -156,22 +156,20 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
       smc.setActiveSessionHandler(StateRegistry.PLAY,
           new TransitionSessionHandler(server, serverConn, resultFuture));
     } else {
-      smc.setAutoReading(false);
+      smc.write(new LoginAcknowledged());
-      CompletableFuture<Void> switchFuture;
+      smc.setActiveSessionHandler(StateRegistry.CONFIG,
-      if (serverConn.getPlayer().getConnection()
+          new ConfigSessionHandler(server, serverConn, resultFuture));
-          .getActiveSessionHandler() instanceof ClientPlaySessionHandler) {
+      ConnectedPlayer player = serverConn.getPlayer();
-        switchFuture = ((ClientPlaySessionHandler) serverConn.getPlayer().getConnection()
+      if (player.getClientSettingsPacket() != null) {
-            .getActiveSessionHandler()).doSwitch();
+        smc.write(player.getClientSettingsPacket());
-      } else {
+      }
-        switchFuture = CompletableFuture.completedFuture(null);
+      if (player.getConnection().getActiveSessionHandler() instanceof ClientPlaySessionHandler) {
+        smc.setAutoReading(false);
+        ((ClientPlaySessionHandler) player.getConnection()
+            .getActiveSessionHandler()).doSwitch().thenAcceptAsync((unused) -> {
+              smc.setAutoReading(true);
+            }, smc.eventLoop());
       }
-      switchFuture.thenAcceptAsync((unused) -> {
-        smc.write(new LoginAcknowledged());
-        // Sync backend
-        smc.setActiveSessionHandler(StateRegistry.CONFIG,
-            new ConfigSessionHandler(server, serverConn, resultFuture));
-        smc.setAutoReading(true);
-      }, smc.eventLoop());
     }
 
     return true;

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

@@ -22,6 +22,7 @@ import static com.velocitypowered.proxy.connection.forge.legacy.LegacyForgeHands
 
 import com.velocitypowered.api.event.player.ServerConnectedEvent;
 import com.velocitypowered.api.event.player.ServerPostConnectEvent;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.ConnectionTypes;
@@ -104,7 +105,7 @@ public class TransitionSessionHandler implements MinecraftSessionHandler {
       player.sendKeepAlive();
 
       // Reset Tablist header and footer to prevent desync
-      player.clearHeaderAndFooter();
+      player.clearPlayerListHeaderAndFooter();
     }
 
     // The goods are in hand! We got JoinGame. Let's transition completely to the new state.
@@ -143,7 +144,9 @@ public class TransitionSessionHandler implements MinecraftSessionHandler {
           // Now set the connected server.
           serverConn.getPlayer().setConnectedServer(serverConn);
 
-          if (player.getClientSettingsPacket() != null) {
+          // Send client settings. In 1.20.2+ this is done in the config state.
+          if (smc.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_20_2) < 0
+              && player.getClientSettingsPacket() != null) {
             serverConn.ensureConnected().write(player.getClientSettingsPacket());
           }
 

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

@@ -482,12 +482,13 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       // Send keep alive to try to avoid timeouts
       player.sendKeepAlive();
 
-      // Reset Tablist header and footer to prevent desync
+      // Config state clears everything in the client. No need to clear later.
-      player.clearHeaderAndFooter();
+      spawned = false;
+      serverBossBars.clear();
+      player.clearPlayerListHeaderAndFooterSilent();
+      player.getTabList().clearAllSilent();
     }
 
-    spawned = false;
-
     player.switchToConfigState();
 
     return configSwitchFuture;

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

@@ -544,8 +544,16 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
   }
 
   @Override
-  public void clearHeaderAndFooter() {
+  public void clearPlayerListHeaderAndFooter() {
-    tabList.clearHeaderAndFooter();
+    clearPlayerListHeaderAndFooterSilent();
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
+      this.connection.write(HeaderAndFooter.reset());
+    }
+  }
+
+  public void clearPlayerListHeaderAndFooterSilent() {
+    this.playerListHeader = Component.empty();
+    this.playerListFooter = Component.empty();
   }
 
   @Override

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

@@ -35,4 +35,6 @@ public interface InternalTabList extends TabList {
 
   default void processRemove(RemovePlayerInfo infoPacket) {
   }
+
+  void clearAllSilent();
 }

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

@@ -26,7 +26,6 @@ import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.protocol.packet.HeaderAndFooter;
 import com.velocitypowered.proxy.protocol.packet.LegacyPlayerListItem;
 import com.velocitypowered.proxy.protocol.packet.chat.RemoteChatSession;
 import java.util.ArrayList;
@@ -70,7 +69,7 @@ public class KeyedVelocityTabList implements InternalTabList {
 
   @Override
   public void clearHeaderAndFooter() {
-    connection.write(HeaderAndFooter.reset());
+    this.player.clearPlayerListHeaderAndFooter();
   }
 
   @Override
@@ -131,10 +130,15 @@ public class KeyedVelocityTabList implements InternalTabList {
     for (TabListEntry value : listEntries) {
       items.add(LegacyPlayerListItem.Item.from(value));
     }
-    entries.clear();
+    clearAllSilent();
     connection.delayedWrite(new LegacyPlayerListItem(LegacyPlayerListItem.REMOVE_PLAYER, items));
   }
 
+  @Override
+  public void clearAllSilent() {
+    entries.clear();
+  }
+
   @Override
   public Collection<TabListEntry> getEntries() {
     return Collections.unmodifiableCollection(this.entries.values());

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

@@ -25,7 +25,6 @@ import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.console.VelocityConsole;
-import com.velocitypowered.proxy.protocol.packet.HeaderAndFooter;
 import com.velocitypowered.proxy.protocol.packet.RemovePlayerInfo;
 import com.velocitypowered.proxy.protocol.packet.UpsertPlayerInfo;
 import com.velocitypowered.proxy.protocol.packet.chat.RemoteChatSession;
@@ -74,7 +73,7 @@ public class VelocityTabList implements InternalTabList {
 
   @Override
   public void clearHeaderAndFooter() {
-    connection.write(HeaderAndFooter.reset());
+    this.player.clearPlayerListHeaderAndFooter();
   }
 
   @Override
@@ -175,6 +174,11 @@ public class VelocityTabList implements InternalTabList {
   @Override
   public void clearAll() {
     this.connection.delayedWrite(new RemovePlayerInfo(new ArrayList<>(this.entries.keySet())));
+    clearAllSilent();
+  }
+
+  @Override
+  public void clearAllSilent() {
     this.entries.clear();
   }
 

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

@@ -71,6 +71,11 @@ public class VelocityTabListLegacy extends KeyedVelocityTabList {
       connection.delayedWrite(new LegacyPlayerListItem(LegacyPlayerListItem.REMOVE_PLAYER,
           Collections.singletonList(LegacyPlayerListItem.Item.from(value))));
     }
+    clearAllSilent();
+  }
+
+  @Override
+  public void clearAllSilent() {
     entries.clear();
     nameMapping.clear();
   }