From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: BillyGalbreath <blake.galbreath@gmail.com>
Date: Sat, 1 Jan 2022 18:38:58 -0600
Subject: [PATCH] Configurable valid characters for usernames


diff --git a/src/main/java/net/minecraft/util/StringUtil.java b/src/main/java/net/minecraft/util/StringUtil.java
index 0bd191acb9596d3aa21c337230d26f09d26f6888..20211f40aeeade9217ece087688974bdf55afc56 100644
--- a/src/main/java/net/minecraft/util/StringUtil.java
+++ b/src/main/java/net/minecraft/util/StringUtil.java
@@ -69,6 +69,7 @@ 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
         if (name.isEmpty() || name.length() > 16) {
             return false;
         }
diff --git a/src/main/java/org/purpurmc/purpur/PurpurConfig.java b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
index d0683af41c56ed485da11ff2a74f0cf282cf00d4..3032944e7ae61f31ceb72ad688add99f2451f33e 100644
--- a/src/main/java/org/purpurmc/purpur/PurpurConfig.java
+++ b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
@@ -447,4 +447,11 @@ public class PurpurConfig {
     private static void networkSettings() {
         useUPnP = getBoolean("settings.network.upnp-port-forwarding", useUPnP);
     }
+
+    public static java.util.regex.Pattern usernameValidCharactersPattern;
+    private static void usernameValidationSettings() {
+        String defaultPattern = "^[a-zA-Z0-9_.]*$";
+        String setPattern = getString("settings.username-valid-characters", defaultPattern);
+        usernameValidCharactersPattern = java.util.regex.Pattern.compile(setPattern == null || setPattern.isBlank() ? defaultPattern : setPattern);
+    }
 }