Fix configurable username check bugs (#572)

* Fix configurable username check bugs * Format * cleanup config load logic
2026-01-06 15:51:31 +00:00 · 2025-12-31 03:41:38 +14:00
parent c7064288f1
commit 8fda84ea96
5 changed files with 162 additions and 36 deletions
--- a/leaf-server/minecraft-patches/features/0096-Configurable-vanilla-username-check.patch
+++ b/leaf-server/minecraft-patches/features/0096-Configurable-vanilla-username-check.patch
@@ -5,7 +5,7 @@ Subject: [PATCH] Configurable vanilla username check


 diff --git a/net/minecraft/server/level/ServerPlayer.java b/net/minecraft/server/level/ServerPlayer.java
-index fb585637383db4592f97f0c9040ffa86afb43c6a..29417442b9379779a078e8fc819035120ddf0108 100644
+index fb585637383db4592f97f0c9040ffa86afb43c6a..5381986c9d283d3b22c59d80acf246dab99771c5 100644
 --- a/net/minecraft/server/level/ServerPlayer.java
 +++ b/net/minecraft/server/level/ServerPlayer.java
@@ -2466,7 +2466,7 @@ public class ServerPlayer extends Player implements ca.spottedleaf.moonrise.patc
@@ -13,50 +13,64 @@ index fb585637383db4592f97f0c9040ffa86afb43c6a..29417442b9379779a078e8fc81903512
             String scoreboardName = getScoreboardName();
             String playerListName = net.kyori.adventure.text.minimessage.MiniMessage.miniMessage().serialize(getBukkitEntity().playerListName());
 -            String[] split = playerListName.split(scoreboardName);
-+            String[] split = playerListName.split(java.util.regex.Pattern.quote(scoreboardName)); // Leaf - Vanilla username check - Sanitize name input
+            String[] split = playerListName.split(java.util.regex.Pattern.quote(scoreboardName)); // Leaf - Configurable vanilla username check - Sanitize name input
             String prefix = (split.length > 0 ? split[0] : "").replace(org.purpurmc.purpur.PurpurConfig.afkTabListPrefix, "");
             String suffix = (split.length > 1 ? split[1] : "").replace(org.purpurmc.purpur.PurpurConfig.afkTabListSuffix, "");
             if (afk) {
 diff --git a/net/minecraft/server/network/ServerLoginPacketListenerImpl.java b/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
-index 6d320ed179393e47398c44f2ba2b2285016f349e..0e7a4d6a3b33a8bd9eebd854b87af269cbec6ea6 100644
+index 6d320ed179393e47398c44f2ba2b2285016f349e..19a56f8c980f739bff54fb067ccf293286f16faf 100644
 --- a/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
 +++ b/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
-@@ -163,10 +163,15 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
+@@ -163,11 +163,20 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
     public void handleHello(ServerboundHelloPacket packet) {
         Validate.validState(this.state == ServerLoginPacketListenerImpl.State.HELLO, "Unexpected hello packet");
         // Paper start - Validate usernames
 -        if (io.papermc.paper.configuration.GlobalConfiguration.get().proxies.isProxyOnlineMode()
-+        if (!org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.removeAllCheck // Leaf - Remove vanilla username check
+        // Leaf start - Configurable vanilla username check
+        boolean allPrevChecksPassed;
+        if (!org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.removeAllCheck
 +            && io.papermc.paper.configuration.GlobalConfiguration.get().proxies.isProxyOnlineMode()
             && io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.performUsernameValidation
             && !this.iKnowThisMayNotBeTheBestIdeaButPleaseDisableUsernameValidation) {
 -            Validate.validState(StringUtil.isReasonablePlayerName(packet.name()), "Invalid characters in username");
-+            // Leaf start - Vanilla username check
+            allPrevChecksPassed = true;
 +            if (!org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) {
 +                Validate.validState(StringUtil.isReasonablePlayerName(packet.name()), "Invalid characters in username");
 +            }
-+            // Leaf end - Vanilla username check
+        } else {
+            allPrevChecksPassed = false;
         }
+        // Leaf end - Configurable vanilla username check
         this.requestedUuid = packet.profileId();
         // Paper end - Validate usernames
-@@ -194,6 +199,15 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
+         this.requestedUsername = packet.name();
+@@ -194,6 +203,15 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
                 authenticatorPool.execute(() -> {
                     try {
                         GameProfile gameprofile = ServerLoginPacketListenerImpl.this.createOfflineProfile(ServerLoginPacketListenerImpl.this.requestedUsername); // Spigot
-+                        // Leaf start - Vanilla username check
+                        // Leaf start - Configurable vanilla username check
 +                        if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) {
 +                            if (server.playerDataStorage.load(gameprofile.getName(), gameprofile.getId().toString(), gameprofile.getId(), net.minecraft.util.ProblemReporter.DISCARDING).orElse(null) != null) {
 +                                server.getPlayerList().playedPlayers.add(packet.name());
-+                            } else {
+                            } else if (allPrevChecksPassed) {
 +                                Validate.validState(StringUtil.isReasonablePlayerName(packet.name()), "Invalid characters in username");
 +                            }
 +                        }
-+                        // Leaf end - Vanilla username check
+                        // Leaf end - Configurable vanilla username check
 
                         gameprofile = ServerLoginPacketListenerImpl.this.callPlayerPreLoginEvents(gameprofile); // Paper - Add more fields to AsyncPlayerPreLoginEvent
                         ServerLoginPacketListenerImpl.LOGGER.info("UUID of player {} is {}", gameprofile.getName(), gameprofile.getId());
+@@ -335,7 +353,7 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
+         server.getPluginManager().callEvent(asyncEvent);
+         profile = asyncEvent.getPlayerProfile();
+         profile.complete(true); // Paper - setPlayerProfileAPI
+-        gameprofile = com.destroystokyo.paper.profile.CraftPlayerProfile.asAuthlibCopy(profile);
+        gameprofile = com.destroystokyo.paper.profile.CraftPlayerProfile.asAuthlibCopyCustomValidation(profile); // Leaf - Configurable vanilla username check
+         playerName = gameprofile.getName();
+         uniqueId = gameprofile.getId();
+         // Paper end - Add more fields to AsyncPlayerPreLoginEvent
 diff --git a/net/minecraft/server/players/GameProfileCache.java b/net/minecraft/server/players/GameProfileCache.java
-index 066f84df5c31242ab542932f1e243369d0e766e2..4faa87d18c2e55d6320f9e8ec91862b9e58d26b5 100644
+index 066f84df5c31242ab542932f1e243369d0e766e2..223f39d2e6d82815af14d437a8c886ae591be597 100644
 --- a/net/minecraft/server/players/GameProfileCache.java
 +++ b/net/minecraft/server/players/GameProfileCache.java
@@ -75,7 +75,7 @@ public class GameProfileCache {
@@ -64,19 +78,19 @@ index 066f84df5c31242ab542932f1e243369d0e766e2..4faa87d18c2e55d6320f9e8ec91862b9
 
     private static Optional<GameProfile> lookupGameProfile(GameProfileRepository profileRepo, String name) {
 -        if (!StringUtil.isValidPlayerName(name)) {
-+        if (!StringUtil.isValidPlayerName(name, false)) { // Leaf start - Remove vanilla username check - Directly return, skip unnecessary following logic
+        if (!StringUtil.isValidPlayerName(name, false)) { // Leaf - Configurable vanilla username check - Directly return, skip unnecessary following logic
             return createUnknownProfile(name);
         } else {
             final boolean shouldLookup = !org.apache.commons.lang3.StringUtils.isBlank(name)  // Paper - Don't lookup a profile with a blank name
 diff --git a/net/minecraft/server/players/PlayerList.java b/net/minecraft/server/players/PlayerList.java
-index 6396083993d248683b887774d2db3f3f03825033..fbf4e548f4377c7155a3a02c3b679a0322ed6bc0 100644
+index 6396083993d248683b887774d2db3f3f03825033..883869d39319e0f98c24d356beab2705d2fa769c 100644
 --- a/net/minecraft/server/players/PlayerList.java
 +++ b/net/minecraft/server/players/PlayerList.java
@@ -136,6 +136,7 @@ public abstract class PlayerList {
     private org.bukkit.craftbukkit.CraftServer cserver;
     private final Map<String,ServerPlayer> playersByName = new java.util.HashMap<>();
     public @Nullable String collideRuleTeamName; // Paper - Configurable player collision
-+    public final List<String> playedPlayers = new java.util.concurrent.CopyOnWriteArrayList<>(); // Leaf - Vanilla username check
+    public final List<String> playedPlayers = new java.util.concurrent.CopyOnWriteArrayList<>(); // Leaf - Configurable vanilla username check
 
     public PlayerList(MinecraftServer server, LayeredRegistryAccess<RegistryLayer> registries, PlayerDataStorage playerIo, int maxPlayers) {
         this.cserver = server.server = new org.bukkit.craftbukkit.CraftServer((net.minecraft.server.dedicated.DedicatedServer) server, this);
@@ -84,61 +98,60 @@ index 6396083993d248683b887774d2db3f3f03825033..fbf4e548f4377c7155a3a02c3b679a03
         player.getAdvancements().stopListening();
         this.players.remove(player);
         this.playersByName.remove(player.getScoreboardName().toLowerCase(java.util.Locale.ROOT)); // Spigot
-+        if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) this.playedPlayers.remove(player.getGameProfile().getName()); // Leaf - Vanilla username check
+        if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) this.playedPlayers.remove(player.getGameProfile().getName()); // Leaf - Configurable vanilla username check
         this.removeFromSendAllPlayerInfoBuckets(player); // Gale - Purpur - spread out sending all player info
         this.server.getCustomBossEvents().onPlayerDisconnect(player);
         UUID uuid = player.getUUID();
 diff --git a/net/minecraft/util/StringUtil.java b/net/minecraft/util/StringUtil.java
-index c3a99fe7b49858bc0ca9a7f800b0db40465f6901..2f8a5d0b94b548dfc62f2c40bf10218d34c17574 100644
+index c3a99fe7b49858bc0ca9a7f800b0db40465f6901..d344857a20bfed20d8ffd422c0e6f2bd96b2ae8f 100644
 --- a/net/minecraft/util/StringUtil.java
 +++ b/net/minecraft/util/StringUtil.java
-@@ -64,6 +64,16 @@ public class StringUtil {
+@@ -64,6 +64,15 @@ public class StringUtil {
     }
 
     public static boolean isValidPlayerName(String playerName) {
-+        // Leaf start - Remove vanilla username check
-+        return isValidPlayerName(playerName, org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.removeAllCheck);
+        // Leaf start - Configurable vanilla username check
+        return isValidPlayerName(playerName, org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.shouldSkipNonPlayerNameCheck());
 +    }
 +    public static boolean isValidPlayerNameVanilla(String playerName) {
 +        return playerName.length() <= 16 && playerName.chars().filter(i -> i <= 32 || i >= 127).findAny().isEmpty();
 +    }
 +    public static boolean isValidPlayerName(String playerName, boolean bypassCheck) {
 +        if (bypassCheck) return playerName.length() <= 16;
-+        if (true) return isReasonablePlayerName(playerName); // Leaf - Fix Purpur username validation config
-+        // Leaf end - Remove vanilla username check
+        // Leaf end - Configurable vanilla username check
         return playerName.length() <= 16 && playerName.chars().filter(i -> i <= 32 || i >= 127).findAny().isEmpty();
     }
 
-@@ -87,7 +97,12 @@ public class StringUtil {
+@@ -87,7 +96,12 @@ public class StringUtil {
 
     // Paper start - Username validation
     public static boolean isReasonablePlayerName(final String name) {
 -        if (true) return org.purpurmc.purpur.PurpurConfig.usernameValidCharactersPattern.matcher(name).matches(); // Purpur - Configurable valid characters for usernames
-+        // Leaf start - Vanilla username check
-+        if (true) {
+        // Leaf start - Configurable vanilla username check
 +        if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin && net.minecraft.server.MinecraftServer.getServer().getPlayerList().playedPlayers.contains(name)) return true;
-+            return org.purpurmc.purpur.PurpurConfig.usernameValidCharactersPattern.matcher(name).matches() && name.length() <= 16; // Purpur - Configurable valid characters for usernames // Leaf - Fix Purpur username validation config - Add length check
+        if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.useUsernameRegex) {
+            return org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.usernameRegex.matcher(name).matches() && name.length() <= 16; // Purpur - Configurable valid characters for usernames // Leaf - use our own config
 +        }
-+        // Leaf end - Vanilla username check
+        // Leaf end - Configurable vanilla username check
         if (name.isEmpty() || name.length() > 16) {
             return false;
         }
 diff --git a/net/minecraft/world/item/component/ResolvableProfile.java b/net/minecraft/world/item/component/ResolvableProfile.java
-index 48517612ff40c83069a52b817a1af9e6ef180db5..5e6441196a697be73f79e4776209791627a5ecc2 100644
+index 48517612ff40c83069a52b817a1af9e6ef180db5..c1937cc39c75c03896f37ea1b516cc5b72e74969 100644
 --- a/net/minecraft/world/item/component/ResolvableProfile.java
 +++ b/net/minecraft/world/item/component/ResolvableProfile.java
@@ -39,6 +39,15 @@ public record ResolvableProfile(Optional<String> name, Optional<UUID> id, Proper
         ResolvableProfile::new
     );
 
-+    // Leaf start - Vanilla username check - Enforce skull validation
+    // Leaf start - Configurable vanilla username check - Enforce skull validation
 +    public ResolvableProfile {
 +        name = sanitizePlayerName(name);
 +    }
 +    private static Optional<String> sanitizePlayerName(Optional<String> name) {
 +        return org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.enforceSkullValidation && !net.minecraft.util.StringUtil.isValidPlayerNameVanilla(name.orElse("NULL_OWNER")) ? Optional.of("INVALID_OWNER") : name;
 +    }
-+    // Leaf end - Vanilla username check - Enforce skull validation
+    // Leaf end - Configurable vanilla username check - Enforce skull validation
 +
     public ResolvableProfile(Optional<String> name, Optional<UUID> id, PropertyMap properties) {
         this(name, id, properties, createGameProfile(id, name, properties));
--- a/leaf-server/minecraft-patches/features/0110-Leaves-Replay-Mod-API.patch
+++ b/leaf-server/minecraft-patches/features/0110-Leaves-Replay-Mod-API.patch
@@ -342,7 +342,7 @@ index 1d128d0613d92eb95a753be33a1134c857d0e388..c50cb9bfcd06ec54c0a43d013aa074fb
                 ServerLevel.this.updateSleepingPlayerList();
             }
 diff --git a/net/minecraft/server/players/PlayerList.java b/net/minecraft/server/players/PlayerList.java
-index 76785d9b11593cc9304e3d16962ddddba2ff8834..e0ae31621ececc54b9e38e524c2b56ffb02949a1 100644
+index 4fbe3d2a7e157f1f06bd0929ee10efd87426554d..fdd2ad453192cfac8dd5310266cbab3bdb5743c6 100644
 --- a/net/minecraft/server/players/PlayerList.java
 +++ b/net/minecraft/server/players/PlayerList.java
@@ -131,6 +131,7 @@ public abstract class PlayerList {
@@ -532,7 +532,7 @@ index 76785d9b11593cc9304e3d16962ddddba2ff8834..e0ae31621ececc54b9e38e524c2b56ff
         this.players.remove(player);
 +        this.realPlayers.remove(player); // Leaves - replay api
         this.playersByName.remove(player.getScoreboardName().toLowerCase(java.util.Locale.ROOT)); // Spigot
-         if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) this.playedPlayers.remove(player.getGameProfile().getName()); // Leaf - Vanilla username check
+         if (org.dreeam.leaf.config.modules.misc.VanillaUsernameCheck.allowOldPlayersJoin) this.playedPlayers.remove(player.getGameProfile().getName()); // Leaf - Configurable vanilla username check
         this.removeFromSendAllPlayerInfoBuckets(player); // Gale - Purpur - spread out sending all player info
@@ -1011,10 +1158,10 @@ public abstract class PlayerList {
     }
--- a/leaf-server/minecraft-patches/features/0229-Async-switch-connection-state.patch
+++ b/leaf-server/minecraft-patches/features/0229-Async-switch-connection-state.patch
@@ -110,10 +110,10 @@ index 7f3379a617932f1e0b0344df75566d2dc6612359..99d9d5048440e535ed6be33df39bf7ae
         try {
             PlayerList playerList = this.server.getPlayerList();
 diff --git a/net/minecraft/server/network/ServerLoginPacketListenerImpl.java b/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
-index 970c6f20a3e995dc1b82c3fbabd6ab01a51f22c0..35e8ac5e7a2e4719d407bdc61579d0bc14cc4712 100644
+index a485b708858b6bb87a7ae6ca7f0b2a13dc3b07ed..565870996264ba5bd93b6eaf93b9c9fd8a3ce433 100644
 --- a/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
 +++ b/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
-@@ -429,11 +429,31 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
+@@ -433,11 +433,31 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
         this.disconnect(ServerCommonPacketListenerImpl.DISCONNECT_UNEXPECTED_QUERY);
     }
 
--- a/leaf-server/paper-patches/features/0061-Configurable-vanilla-username-check.patch
+++ b/leaf-server/paper-patches/features/0061-Configurable-vanilla-username-check.patch
@@ -0,0 +1,78 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Dreeam <61569423+Dreeam-qwq@users.noreply.github.com>
+Date: Wed, 12 Oct 2022 14:36:58 -0400
+Subject: [PATCH] Configurable vanilla username check
+
+
+diff --git a/src/main/java/com/destroystokyo/paper/profile/CraftPlayerProfile.java b/src/main/java/com/destroystokyo/paper/profile/CraftPlayerProfile.java
+index db43329d57144471d0c9ce0eed92d2f1bd05f120..d65bde85ecae29104c5c34380f164252df9e4515 100644
+--- a/src/main/java/com/destroystokyo/paper/profile/CraftPlayerProfile.java
+++ b/src/main/java/com/destroystokyo/paper/profile/CraftPlayerProfile.java
+@@ -62,6 +62,14 @@ public class CraftPlayerProfile implements PlayerProfile, SharedPlayerProfile {
+         copyProfileProperties(resolvableProfile.gameProfile(), this.profile);
+     }
+ 
+    // Leaf start - Configurable vanilla username check
+    public CraftPlayerProfile(UUID id, String name, boolean useCustomValidation) {
+        this.profile = createAuthLibProfile(id, name, useCustomValidation);
+        this.emptyName = name == null;
+        this.emptyUUID = id == null;
+    }
+    // Leaf end - Configurable vanilla username check
+
+     @Override
+     public boolean hasProperty(String property) {
+         return profile.getProperties().containsKey(property);
+@@ -195,6 +203,14 @@ public class CraftPlayerProfile implements PlayerProfile, SharedPlayerProfile {
+         return clone;
+     }
+ 
+    // Leaf start - Configurable vanilla username check
+    public CraftPlayerProfile cloneCustom() {
+        CraftPlayerProfile clone = new CraftPlayerProfile(this.getId(), this.getName(), true);
+        clone.setProperties(getProperties());
+        return clone;
+    }
+    // Leaf end - Configurable vanilla username check
+
+     @Override
+     public boolean isComplete() {
+         return this.getId() != null && StringUtils.isNotBlank(this.getName());
+@@ -369,15 +385,21 @@ public class CraftPlayerProfile implements PlayerProfile, SharedPlayerProfile {
+         }
+     }
+ 
+-    private static GameProfile createAuthLibProfile(UUID uniqueId, String name) {
+    // Leaf start - Configurable vanilla username check
+    private static GameProfile createAuthLibProfile(UUID uniqueId, String name, boolean useCustomValidation) {
+         Preconditions.checkArgument(name == null || name.length() <= 16, "Name cannot be longer than 16 characters");
+-        Preconditions.checkArgument(name == null || StringUtil.isValidPlayerName(name), "The name of the profile contains invalid characters: %s", name);
+        Preconditions.checkArgument(name == null || (useCustomValidation ? StringUtil.isReasonablePlayerName(name) : StringUtil.isValidPlayerName(name)), "The name of the profile contains invalid characters: %s", name);
+         return new GameProfile(
+             uniqueId != null ? uniqueId : Util.NIL_UUID,
+             name != null ? name : ""
+         );
+     }
+ 
+    private static GameProfile createAuthLibProfile(UUID uniqueId, String name) {
+        return createAuthLibProfile(uniqueId, name, false);
+    }
+    // Leaf end - Configurable vanilla username check
+
+     private static ProfileProperty toBukkit(Property property) {
+         return new ProfileProperty(property.name(), property.value(), property.signature());
+     }
+@@ -401,6 +423,13 @@ public class CraftPlayerProfile implements PlayerProfile, SharedPlayerProfile {
+         return asAuthlib(craft.clone());
+     }
+ 
+    // Leaf start - Configurable vanilla username check
+    public static GameProfile asAuthlibCopyCustomValidation(PlayerProfile profile) {
+        CraftPlayerProfile craft = ((CraftPlayerProfile) profile);
+        return asAuthlib(craft.cloneCustom());
+    }
+    // Leaf end - Configurable vanilla username check
+
+     public static GameProfile asAuthlib(PlayerProfile profile) {
+         CraftPlayerProfile craft = ((CraftPlayerProfile) profile);
+         return craft.getGameProfile();
--- a/leaf-server/src/main/java/org/dreeam/leaf/config/modules/misc/VanillaUsernameCheck.java
+++ b/leaf-server/src/main/java/org/dreeam/leaf/config/modules/misc/VanillaUsernameCheck.java
@@ -2,19 +2,28 @@ package org.dreeam.leaf.config.modules.misc;

 import org.dreeam.leaf.config.ConfigModules;
 import org.dreeam.leaf.config.EnumConfigCategory;
+import org.dreeam.leaf.config.LeafConfig;
 import org.dreeam.leaf.config.annotations.Experimental;

+import java.util.regex.Pattern;
+
 public class VanillaUsernameCheck extends ConfigModules {

    public String getBasePath() {
        return EnumConfigCategory.MISC.getBaseKeyName() + ".vanilla-username-check";
    }

-    @Experimental
+    @Deprecated
    public static boolean removeAllCheck = false;
    public static boolean enforceSkullValidation = true;
    @Experimental
    public static boolean allowOldPlayersJoin = false;
+    public static boolean useUsernameRegex = false;
+    private static final String defaultRegexString = "^[a-zA-Z0-9_.]*$";
+    public static Pattern usernameRegex = Pattern.compile(defaultRegexString);
+    public static boolean shouldSkipNonPlayerNameCheck() { // helper
+        return removeAllCheck || useUsernameRegex;
+    }

    @Override
    public void onLoaded() {
@@ -38,5 +47,31 @@ public class VanillaUsernameCheck extends ConfigModules {
            """
                允许老玩家加入修改用户名验证正则后的服务器,
                即使他们的用户名不满足修改后的正则."""));
+        useUsernameRegex = config.getBoolean(getBasePath() + ".use-username-regex", useUsernameRegex, config.pickStringRegionBased("""
+                Use username regex to validate usernames,
+                allowing only characters specified in the regex.""",
+            """
+                使用用户名正则来验证用户名,
+                只允许正则指定的字符."""));
+        String regexString = config.getString(getBasePath() + ".username-regex", defaultRegexString, config.pickStringRegionBased(
+            """
+            Username regex,
+            specifying the characters allowed in usernames.
+            Default: %s""".formatted(defaultRegexString),
+            """
+            用户名正则,
+            指定允许在用户名中使用的字符.
+            默认: %s""".formatted(defaultRegexString)));
+        if (!regexString.isBlank()) {
+            try {
+                usernameRegex = Pattern.compile(regexString);
+            } catch (Exception e) {
+                LeafConfig.LOGGER.error("Invalid username regex {} found, falling back to default.", regexString, e);
+            }
+        }
+        if (useUsernameRegex && removeAllCheck) {
+            LeafConfig.LOGGER.warn("Found conflicting configuration, remove-all-check and use-username-regex cannot be enabled at same time, ignoring remove-all-check...");
+            removeAllCheck = false;
+        }
    }
 }