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/server/network/ServerLoginPacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
index ab1443048b3a4292be45b253c24eccf0de8b364d..f7f085a2dc5dc8d09bc665a371afac04b0e118fc 100644
--- a/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
@@ -220,6 +220,8 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener,
             return false;
         }
 
+        if (true) return org.purpurmc.purpur.PurpurConfig.usernameValidCharactersPattern.matcher(in).matches(); // Purpur
+
         for (int i = 0, len = in.length(); i < len; ++i) {
             char c = in.charAt(i);
 
diff --git a/src/main/java/org/purpurmc/purpur/PurpurConfig.java b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
index 32769f726d3200478e13b5b31756d2139aac40b7..0394e3150daebc8e63165faafb8362ce7a0d8641 100644
--- a/src/main/java/org/purpurmc/purpur/PurpurConfig.java
+++ b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
@@ -455,4 +455,11 @@ 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);
+    }
 }