add allowlist processing

src/main/java/com/loohp/limbo/network/ClientConnection.java

@@ -19,6 +19,7 @@
 
 package com.loohp.limbo.network;
 
+import com.loohp.limbo.Console;
 import com.loohp.limbo.Limbo;
 import com.loohp.limbo.events.player.PlayerJoinEvent;
 import com.loohp.limbo.events.player.PlayerSpawnEvent;
@@ -88,6 +89,7 @@ import com.loohp.limbo.utils.MojangAPIUtils.SkinResponse;
 import com.loohp.limbo.utils.NamespacedKey;
 import com.loohp.limbo.world.BlockPosition;
 import com.loohp.limbo.world.World;
+
 import net.kyori.adventure.text.Component;
 import net.md_5.bungee.api.ChatColor;
 import net.md_5.bungee.api.chat.BaseComponent;
@@ -96,11 +98,14 @@ import net.md_5.bungee.api.chat.TranslatableComponent;
 import org.json.simple.JSONArray;
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;
+import org.json.simple.parser.ParseException;
 
 import java.io.ByteArrayOutputStream;
 import java.io.DataInput;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
 import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.net.InetAddress;
@@ -108,6 +113,7 @@ import java.net.Socket;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
 import java.util.Random;
@@ -294,6 +300,84 @@ public class ClientConnection extends Thread {
         });
     }
 
+    public boolean uuidAllowed(UUID uuid, boolean verbose) {
+        Console console = Limbo.getInstance().getConsole();
+
+        try {
+            JSONParser parser = new JSONParser();
+            Object obj = parser.parse(new FileReader("allowlist.json"));
+
+            if (!(obj instanceof JSONArray)) {
+                if (verbose) {
+                    console.sendMessage("allowlist: expected [] got {}");
+                }
+                return false;
+            }
+
+            JSONArray array = (JSONArray) obj;
+
+            Iterator<?> iter = array.iterator();
+            while (iter.hasNext()) {
+                Object o = iter.next();
+                if (!(o instanceof JSONObject)) {
+                    if (verbose) {
+                        console.sendMessage("allowlist: array element is not an object");
+                    }
+                    continue;
+                }
+
+                JSONObject element = (JSONObject) o;
+                o = element.get("uuid");
+                if (o == null) {
+                    if (verbose) {
+                        console.sendMessage("allowlist: missing uuid attribute");
+                    }
+                    continue;
+                }
+                if (!(o instanceof String)) {
+                    if (verbose) {
+                        console.sendMessage("allowlist: uuid is not a string");
+                    }
+                    continue;
+                }
+                String uuidStr = (String) o;
+
+                UUID allowedUuid = UUID.fromString(uuidStr);
+                if (uuid.equals(allowedUuid)) {
+                    if(verbose) {
+                        console.sendMessage(String.format("allowlist: %s allowed", uuid.toString()));
+                    }
+                    return true;
+                }
+            }
+        } catch (IllegalArgumentException e) {
+            if (verbose) {
+                console.sendMessage(e.toString());
+            }
+            return false;
+        } catch (FileNotFoundException e) {
+            if (verbose) {
+                console.sendMessage(String.format("allowlist: no allowlist: %s allowed", uuid.toString()));
+            }
+            return true;
+        } catch (IOException e) {
+            if (verbose) {
+                console.sendMessage(String.format("allowlist: %s", e.toString()));
+            }
+            return false;
+        } catch (ParseException e) {
+            if (verbose) {
+                console.sendMessage(String.format(" allowlist: parse: %s", e.toString()));
+            }
+            return false;
+        }
+
+        if (verbose) {
+            console.sendMessage(String.format("allowlist: %s is not allowed", uuid.toString()));
+        }
+        return false;
+    }
+
     @SuppressWarnings("deprecation")
     @Override
     public void run() {
@@ -360,9 +444,9 @@ public class ClientConnection extends Thread {
                         break;
                     case LOGIN:
                         state = ClientState.LOGIN;
+                        ServerProperties properties = Limbo.getInstance().getServerProperties();
 
                         if (isBungeecord || isBungeeGuard) {
-                            ServerProperties properties = Limbo.getInstance().getServerProperties();
                             try {
                                 String[] data = bungeeForwarding.split("\\x00");
                                 String host = "";
@@ -469,6 +553,11 @@ public class ClientConnection extends Thread {
 
                                 UUID uuid = isBungeecord || isBungeeGuard ? bungeeUUID : UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes(StandardCharsets.UTF_8));
 
+                                if (!uuidAllowed(uuid, !properties.isReducedDebugInfo())) {
+                                    disconnectDuringLogin(TextComponent.fromLegacyText("You are not invited to this server"));
+                                    break;
+                                }
+
                                 PacketLoginOutLoginSuccess success = new PacketLoginOutLoginSuccess(uuid, username);
                                 sendPacket(success);