Fixing carpet fake player incompatibility. Thanks @sug0

build.gradle

@@ -3,6 +3,13 @@ plugins {
 	id 'maven-publish'
 }
 
+repositories {
+	// Carpet mod
+	maven {
+		url 'https://masa.dy.fi/maven'
+	}
+}
+
 sourceCompatibility = JavaVersion.VERSION_1_8
 targetCompatibility = JavaVersion.VERSION_1_8
 
@@ -36,8 +43,8 @@ dependencies {
 	// JNA lib
 	include 'net.java.dev.jna:jna:5.5.0'
 
-    // PSA: Some older mods, compiled on Loom 0.2.1, might have outdated Maven POMs.
-	// You may need to force-disable transitiveness on them.
+	// carpetMod
+	modImplementation "carpet:fabric-carpet:${project.minecraft_version}-${project.carpet_core_version}"
 }
 
 processResources {

gradle.properties

@@ -13,3 +13,6 @@ fabric_version=0.5.10+build.320-1.16
 	mod_version = 1.4.0
 	maven_group = org.samo_lego
 	archives_base_name = simpleauth
+
+# Dependencies
+carpet_core_version = 1.3.19+v200415

src/main/java/org/samo_lego/simpleauth/SimpleAuth.java

@@ -25,11 +25,16 @@ import java.util.HashMap;
 import java.util.Timer;
 import java.util.TimerTask;
 
+import static org.samo_lego.simpleauth.utils.CarpetHelper.isPlayerCarpetFake;
+
 public class SimpleAuth implements DedicatedServerModInitializer {
 	private static final Logger LOGGER = LogManager.getLogger();
 
     public static SimpleAuthDatabase db = new SimpleAuthDatabase();
 
+    // If server is running carpetmod
+    public static boolean isUsingCarpet;
+
     // HashMap of players that are not authenticated
 	// Rather than storing all the authenticated players, we just store ones that are not authenticated
 	// It stores some data as well, e.g. login tries and user password
@@ -61,6 +66,9 @@ public class SimpleAuth implements DedicatedServerModInitializer {
 		// Connecting to db
 		db.openConnection();
 
+		// Checking if carpetmod is loaded
+		isUsingCarpet = FabricLoader.getInstance().isModLoaded("carpet");
+
 
 		// Registering the commands
 		CommandRegistry.INSTANCE.register(false, dispatcher -> {
@@ -114,7 +122,7 @@ public class SimpleAuth implements DedicatedServerModInitializer {
 
 	// De-authenticates player
 	public static void deauthenticatePlayer(ServerPlayerEntity player) {
-		if(db.isClosed())
+		if(db.isClosed() || isPlayerFake(player))
 			return;
 		// Marking player as not authenticated, (re)setting login tries to zero
 		String uuid = player.getUuidAsString();
@@ -134,4 +142,10 @@ public class SimpleAuth implements DedicatedServerModInitializer {
 			}
 		}, SimpleAuth.config.main.delay * 1000);
 	}
+
+	// Checking is player is a fake (carpetmod) player
+	public static boolean isPlayerFake(PlayerEntity player) {
+		// We ask CarpetHelper class since it has the imports needed
+		return isUsingCarpet ? isPlayerCarpetFake(player) : false;
+	}
 }

src/main/java/org/samo_lego/simpleauth/event/AuthEventHandler.java

@@ -51,7 +51,7 @@ public class AuthEventHandler {
         Pattern pattern = Pattern.compile(regex);
         Matcher matcher = pattern.matcher(incomingPlayerUsername);
 
-        if(onlinePlayer != null && config.experimental.disableAnotherLocationKick) {
+        if((onlinePlayer != null && !isPlayerFake(onlinePlayer)) && config.experimental.disableAnotherLocationKick) {
             // Player needs to be kicked, since there's already a player with that name
             // playing on the server
             return new LiteralText(
@@ -158,7 +158,11 @@ public class AuthEventHandler {
     }
 
     public static void onPlayerLeave(ServerPlayerEntity player) {
-        if(!isAuthenticated(player) || config.main.sessionTimeoutTime == -1)
+        if(
+            !isAuthenticated(player) ||
+            config.main.sessionTimeoutTime == -1 ||
+            isPlayerFake(player)
+        )
             return;
 
         // Starting session

src/main/java/org/samo_lego/simpleauth/utils/CarpetHelper.java

@@ -0,0 +1,12 @@
+package org.samo_lego.simpleauth.utils;
+
+import carpet.patches.EntityPlayerMPFake;
+import net.minecraft.entity.player.PlayerEntity;
+
+public class CarpetHelper {
+    // Checking if player is actually a fake one
+    // This is in its own class since we need carpet classes
+    public static boolean isPlayerCarpetFake(PlayerEntity player) {
+        return player instanceof EntityPlayerMPFake;
+    }
+}