Added player sessions.

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

@@ -39,8 +39,7 @@ public class SimpleAuth implements DedicatedServerModInitializer {
 
 	// Boolean for easier checking if player is authenticated
 	public static boolean isAuthenticated(ServerPlayerEntity player) {
-		String uuid = player.getUuidAsString();
+		return !deauthenticatedUsers.containsKey(player.getUuidAsString());
-		return !deauthenticatedUsers.containsKey(uuid);
 	}
 
 	// Getting game directory

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

@@ -14,6 +14,9 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 import org.samo_lego.simpleauth.SimpleAuth;
 
+import java.util.Timer;
+import java.util.TimerTask;
+
 import static net.minecraft.block.NetherPortalBlock.AXIS;
 import static net.minecraft.util.math.Direction.Axis.Z;
 
@@ -33,7 +36,18 @@ public class AuthEventHandler {
 
     // Player joining the server
     public static void onPlayerJoin(ServerPlayerEntity player) {
-        SimpleAuth.deauthenticatePlayer(player);
+        // Checking if session is still valid
+        String uuid = player.getUuidAsString();
+        if(
+            SimpleAuth.deauthenticatedUsers.containsKey(uuid) &&
+            SimpleAuth.deauthenticatedUsers.get(uuid).lastIp.equals(player.getIp()) &&
+            SimpleAuth.deauthenticatedUsers.get(uuid).wasAuthenticated
+        ) {
+            SimpleAuth.deauthenticatedUsers.remove(uuid); // Makes player authenticated
+            return;
+        }
+        else
+            SimpleAuth.deauthenticatePlayer(player);
 
         // Tries to rescue player from nether portal
         if(SimpleAuth.config.main.tryPortalRescue && player.getBlockState().getBlock().equals(Blocks.NETHER_PORTAL)) {
@@ -105,6 +119,27 @@ public class AuthEventHandler {
         }
     }
 
+    public static void onPlayerLeave(ServerPlayerEntity player) {
+        if(!SimpleAuth.isAuthenticated(player) || SimpleAuth.config.main.sessionTimeoutTime == -1)
+            return;
+
+        // Starting session
+        // Putting player to deauthenticated player map
+        SimpleAuth.deauthenticatePlayer(player);
+
+        // Setting that player was actually authenticated before leaving
+        SimpleAuth.deauthenticatedUsers.get(player.getUuidAsString()).wasAuthenticated = true;
+
+        Timer timer = new Timer();
+        timer.schedule(new TimerTask() {
+            @Override
+            public void run() {
+                if(player.removed) // Disproving session
+                    SimpleAuth.deauthenticatedUsers.remove(player.getUuidAsString());
+            }
+        }, SimpleAuth.config.main.sessionTimeoutTime * 1000);
+    }
+
     // Player chatting
     public static ActionResult onPlayerChat(PlayerEntity player, ChatMessageC2SPacket chatMessageC2SPacket) {
         // Getting the message to then be able to check it

src/main/java/org/samo_lego/simpleauth/event/entity/player/PlayerLeaveServerCallback.java

@@ -0,0 +1,15 @@
+package org.samo_lego.simpleauth.event.entity.player;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.event.EventFactory;
+import net.minecraft.server.network.ServerPlayerEntity;
+
+public interface PlayerLeaveServerCallback {
+
+    Event<PlayerLeaveServerCallback> EVENT = EventFactory.createArrayBacked(PlayerLeaveServerCallback.class, listeners -> (player) -> {
+        for (PlayerLeaveServerCallback callback : listeners) {
+            callback.onPlayerLeave(player);
+        }
+    });
+    void onPlayerLeave(ServerPlayerEntity player);
+}

src/main/java/org/samo_lego/simpleauth/mixin/MixinPlayerManager.java

@@ -4,6 +4,7 @@ import net.minecraft.network.ClientConnection;
 import net.minecraft.server.PlayerManager;
 import net.minecraft.server.network.ServerPlayerEntity;
 import org.samo_lego.simpleauth.event.entity.player.PlayerJoinServerCallback;
+import org.samo_lego.simpleauth.event.entity.player.PlayerLeaveServerCallback;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -12,8 +13,13 @@ import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 @Mixin(PlayerManager.class)
 public abstract class MixinPlayerManager {
 
-    @Inject(method = "onPlayerConnect", at = @At("RETURN"))
+    @Inject(method = "onPlayerConnect(Lnet/minecraft/network/ClientConnection;Lnet/minecraft/server/network/ServerPlayerEntity;)V", at = @At("RETURN"))
     private void onPlayerConnect(ClientConnection clientConnection, ServerPlayerEntity serverPlayerEntity, CallbackInfo ci) {
         PlayerJoinServerCallback.EVENT.invoker().onPlayerJoin(serverPlayerEntity);
     }
+
+    @Inject(method = "remove(Lnet/minecraft/server/network/ServerPlayerEntity;)V", at = @At("RETURN"))
+    private void onPlayerLeave(ServerPlayerEntity serverPlayerEntity, CallbackInfo ci) {
+        PlayerLeaveServerCallback.EVENT.invoker().onPlayerLeave(serverPlayerEntity);
+    }
 }

src/main/java/org/samo_lego/simpleauth/storage/AuthConfig.java

@@ -69,6 +69,9 @@ public class AuthConfig {
         // Minimum and maximum length of password. Set -1 to disable max chars
         public int minPasswordChars = 4;
         public int maxPasswordChars = -1;
+        // How long to keep session (auto-logging in the player), in seconds
+        // Set to -1 to disable
+        public int sessionTimeoutTime = 300;
     }
     public static class LangConfig {
         public String enterPassword = "§6You need to enter your password!";