Allow for custom chunk/entity view distance and compression threshold without recompiling the server.

src/main/java/net/minestom/server/MinecraftServer.java

@@ -90,9 +90,6 @@ public class MinecraftServer {
     public static final int THREAD_COUNT_PARALLEL_CHUNK_SAVING = 4;
 
     // Config
-    public static final int CHUNK_VIEW_DISTANCE = 10;
-    public static final int ENTITY_VIEW_DISTANCE = 5;
-    public static final int COMPRESSION_THRESHOLD = 256;
     // Can be modified at performance cost when increased
     public static final int TICK_PER_SECOND = 20;
     private static final int MS_TO_SEC = 1000;
@@ -137,6 +134,11 @@ public class MinecraftServer {
     private static MinecraftServer minecraftServer;
 
     // Data
+    private static boolean started;
+
+    private static int chunkViewDistance = 10;
+    private static int entityViewDistance = 5;
+    private static int compressionThreshold = 256;
     private static ResponseDataConsumer responseDataConsumer;
     private static String brandName = "Minestom";
     private static Difficulty difficulty = Difficulty.NORMAL;
@@ -392,6 +394,81 @@ public class MinecraftServer {
         return connectionManager;
     }
 
+    /**
+     * Gets if the server is up and running.
+     *
+     * @return true if the server is started
+     */
+    public static boolean isStarted() {
+        return started;
+    }
+
+    /**
+     * Gets the chunk view distance of the server.
+     *
+     * @return the chunk view distance
+     */
+    public static int getChunkViewDistance() {
+        return chunkViewDistance;
+    }
+
+    /**
+     * Changes the chunk view distance of the server.
+     * <p>
+     * WARNING: this need to be called before {@link #start(String, int, ResponseDataConsumer)}.
+     *
+     * @param chunkViewDistance the new chunk view distance
+     * @throws IllegalStateException if this is called after the server started
+     */
+    public static void setChunkViewDistance(int chunkViewDistance) {
+        Check.stateCondition(started, "The chunk view distance cannot be changed after the server has been started.");
+        MinecraftServer.chunkViewDistance = chunkViewDistance;
+    }
+
+    /**
+     * Gets the entity view distance of the server.
+     *
+     * @return the entity view distance
+     */
+    public static int getEntityViewDistance() {
+        return entityViewDistance;
+    }
+
+    /**
+     * Changes the entity view distance of the server.
+     * <p>
+     * WARNING: this need to be called before {@link #start(String, int, ResponseDataConsumer)}.
+     *
+     * @param entityViewDistance the new entity view distance
+     * @throws IllegalStateException if this is called after the server started
+     */
+    public static void setEntityViewDistance(int entityViewDistance) {
+        Check.stateCondition(started, "The entity view distance cannot be changed after the server has been started.");
+        MinecraftServer.entityViewDistance = entityViewDistance;
+    }
+
+    /**
+     * Gets the compression threshold of the server.
+     *
+     * @return the compression threshold, 0 means that compression is disabled
+     */
+    public static int getCompressionThreshold() {
+        return compressionThreshold;
+    }
+
+    /**
+     * Changes the compression threshold of the server.
+     * <p>
+     * WARNING: this need to be called before {@link #start(String, int, ResponseDataConsumer)}.
+     *
+     * @param compressionThreshold the new compression threshold, 0 to disable compression
+     * @throws IllegalStateException if this is called after the server started
+     */
+    public static void setCompressionThreshold(int compressionThreshold) {
+        Check.stateCondition(started, "The compression threshold cannot be changed after the server has been started.");
+        MinecraftServer.compressionThreshold = compressionThreshold;
+    }
+
     /**
      * Gets the consumer executed to show server-list data.
      *
@@ -485,6 +562,8 @@ public class MinecraftServer {
 
         LOGGER.info("Extensions loaded in " + (t1 + System.nanoTime()) / 1_000_000D + "ms");
         LOGGER.info("Minestom server started successfully.");
+
+        MinecraftServer.started = true;
     }
 
     /**

src/main/java/net/minestom/server/entity/Entity.java

@@ -1032,8 +1032,9 @@ public abstract class Entity implements Viewable, EventHandler, DataContainer {
             ((Player) this).onChunkChange(newChunk); // Refresh loaded chunk
 
         // Refresh entity viewable list
-        final long[] lastVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * lastChunk.getChunkX(), 0, 16 * lastChunk.getChunkZ()), MinecraftServer.ENTITY_VIEW_DISTANCE);
-        final long[] updatedVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * newChunk.getChunkX(), 0, 16 * newChunk.getChunkZ()), MinecraftServer.ENTITY_VIEW_DISTANCE);
+        final int entityViewDistance = MinecraftServer.getEntityViewDistance();
+        final long[] lastVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * lastChunk.getChunkX(), 0, 16 * lastChunk.getChunkZ()), entityViewDistance);
+        final long[] updatedVisibleChunksEntity = ChunkUtils.getChunksInRange(new Position(16 * newChunk.getChunkX(), 0, 16 * newChunk.getChunkZ()), entityViewDistance);
 
         // Remove from previous chunks
         final int[] oldChunksEntity = ArrayUtils.getDifferencesBetweenArray(lastVisibleChunksEntity, updatedVisibleChunksEntity);

src/main/java/net/minestom/server/entity/Player.java

@@ -195,7 +195,7 @@ public class Player extends LivingEntity implements CommandSender {
         joinGamePacket.dimensionType = dimensionType;
         joinGamePacket.maxPlayers = 0; // Unused
         joinGamePacket.levelType = levelType;
-        joinGamePacket.viewDistance = MinecraftServer.CHUNK_VIEW_DISTANCE;
+        joinGamePacket.viewDistance = MinecraftServer.getChunkViewDistance();
         joinGamePacket.reducedDebugInfo = false;
         playerConnection.sendPacket(joinGamePacket);
 
@@ -2124,11 +2124,11 @@ public class Player extends LivingEntity implements CommandSender {
 
     /**
      * @return the chunk range of the viewers,
-     * which is {@link MinecraftServer#CHUNK_VIEW_DISTANCE} or {@link PlayerSettings#getViewDistance()}
+     * which is {@link MinecraftServer#getChunkViewDistance()} or {@link PlayerSettings#getViewDistance()}
      * based on which one is the lowest
      */
     public int getChunkRange() {
-        final int serverRange = MinecraftServer.CHUNK_VIEW_DISTANCE;
+        final int serverRange = MinecraftServer.getChunkViewDistance();
         final int playerRange = getSettings().viewDistance;
         if (playerRange == 0) {
             return serverRange; // Didn't receive settings packet yet (is the case on login)

src/main/java/net/minestom/server/extras/mojangAuth/MojangCrypt.java

@@ -2,6 +2,7 @@ package net.minestom.server.extras.mojangAuth;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
 
 import javax.crypto.*;
 import javax.crypto.spec.IvParameterSpec;
@@ -10,83 +11,86 @@ import java.io.UnsupportedEncodingException;
 import java.security.*;
 
 public class MojangCrypt {
-   private static final Logger LOGGER = LogManager.getLogger();
+    private static final Logger LOGGER = LogManager.getLogger();
 
-   public static KeyPair generateKeyPair() {
-      try {
-         KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
-         keyGen.initialize(1024);
-         return keyGen.generateKeyPair();
-      } catch (NoSuchAlgorithmException e) {
-         e.printStackTrace();
-         LOGGER.error("Key pair generation failed!");
-         return null;
-      }
-   }
+    @Nullable
+    public static KeyPair generateKeyPair() {
+        try {
+            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
+            keyGen.initialize(1024);
+            return keyGen.generateKeyPair();
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+            LOGGER.error("Key pair generation failed!");
+            return null;
+        }
+    }
 
-   public static byte[] digestData(String data, PublicKey publicKey, SecretKey secretKey) {
-      try {
-         return digestData("SHA-1", data.getBytes("ISO_8859_1"), secretKey.getEncoded(), publicKey.getEncoded());
-      } catch (UnsupportedEncodingException e) {
-         e.printStackTrace();
-         return null;
-      }
-   }
+    @Nullable
+    public static byte[] digestData(String data, PublicKey publicKey, SecretKey secretKey) {
+        try {
+            return digestData("SHA-1", data.getBytes("ISO_8859_1"), secretKey.getEncoded(), publicKey.getEncoded());
+        } catch (UnsupportedEncodingException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
 
-   private static byte[] digestData(String algorithm, byte[]... data) {
-      try {
-         MessageDigest digest = MessageDigest.getInstance(algorithm);
+    @Nullable
+    private static byte[] digestData(String algorithm, byte[]... data) {
+        try {
+            MessageDigest digest = MessageDigest.getInstance(algorithm);
 
-         for(byte[] bytes : data) {
-            digest.update(bytes);
-         }
+            for (byte[] bytes : data) {
+                digest.update(bytes);
+            }
 
-         return digest.digest();
-      } catch (NoSuchAlgorithmException e) {
-         e.printStackTrace();
-         return null;
-      }
-   }
+            return digest.digest();
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
 
-   public static SecretKey decryptByteToSecretKey(PrivateKey privateKey, byte[] bytes) {
-      return new SecretKeySpec(decryptUsingKey(privateKey, bytes), "AES");
-   }
+    public static SecretKey decryptByteToSecretKey(PrivateKey privateKey, byte[] bytes) {
+        return new SecretKeySpec(decryptUsingKey(privateKey, bytes), "AES");
+    }
 
-   public static byte[] decryptUsingKey(Key key, byte[] bytes) {
-      return cipherData(2, key, bytes);
-   }
+    public static byte[] decryptUsingKey(Key key, byte[] bytes) {
+        return cipherData(2, key, bytes);
+    }
 
-   private static byte[] cipherData(int mode, Key key, byte[] data) {
-      try {
-         return setupCipher(mode, key.getAlgorithm(), key).doFinal(data);
-      } catch (IllegalBlockSizeException | BadPaddingException var4) {
-         var4.printStackTrace();
-      }
+    private static byte[] cipherData(int mode, Key key, byte[] data) {
+        try {
+            return setupCipher(mode, key.getAlgorithm(), key).doFinal(data);
+        } catch (IllegalBlockSizeException | BadPaddingException var4) {
+            var4.printStackTrace();
+        }
 
-      LOGGER.error("Cipher data failed!");
-      return null;
-   }
+        LOGGER.error("Cipher data failed!");
+        return null;
+    }
 
-   private static Cipher setupCipher(int mode, String transformation, Key key) {
-      try {
-         Cipher cipher4 = Cipher.getInstance(transformation);
-         cipher4.init(mode, key);
-         return cipher4;
-      } catch (InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException var4) {
-         var4.printStackTrace();
-      }
+    private static Cipher setupCipher(int mode, String transformation, Key key) {
+        try {
+            Cipher cipher4 = Cipher.getInstance(transformation);
+            cipher4.init(mode, key);
+            return cipher4;
+        } catch (InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException var4) {
+            var4.printStackTrace();
+        }
 
-      LOGGER.error("Cipher creation failed!");
-      return null;
-   }
+        LOGGER.error("Cipher creation failed!");
+        return null;
+    }
 
-   public static Cipher getCipher(int mode, Key key) {
-      try {
-         Cipher cipher3 = Cipher.getInstance("AES/CFB8/NoPadding");
-         cipher3.init(mode, key, new IvParameterSpec(key.getEncoded()));
-         return cipher3;
-      } catch (GeneralSecurityException e) {
-         throw new RuntimeException(e);
-      }
-   }
+    public static Cipher getCipher(int mode, Key key) {
+        try {
+            Cipher cipher3 = Cipher.getInstance("AES/CFB8/NoPadding");
+            cipher3.init(mode, key, new IvParameterSpec(key.getEncoded()));
+            return cipher3;
+        } catch (GeneralSecurityException e) {
+            throw new RuntimeException(e);
+        }
+    }
 }

src/main/java/net/minestom/server/instance/Instance.java

@@ -824,7 +824,8 @@ public abstract class Instance implements BlockModifier, EventHandler, DataConta
         }
         AddEntityToInstanceEvent event = new AddEntityToInstanceEvent(this, entity);
         callCancellableEvent(AddEntityToInstanceEvent.class, event, () -> {
-            final long[] visibleChunksEntity = ChunkUtils.getChunksInRange(entity.getPosition(), MinecraftServer.ENTITY_VIEW_DISTANCE);
+            final Position entityPosition = entity.getPosition();
+            final long[] visibleChunksEntity = ChunkUtils.getChunksInRange(entityPosition, MinecraftServer.getEntityViewDistance());
             final boolean isPlayer = entity instanceof Player;
 
             if (isPlayer) {
@@ -846,7 +847,6 @@ public abstract class Instance implements BlockModifier, EventHandler, DataConta
                 });
             }
 
-            final Position entityPosition = entity.getPosition();
             final Chunk chunk = getChunkAt(entityPosition);
             Check.notNull(chunk, "You tried to spawn an entity in an unloaded chunk, " + entityPosition);
             addEntityToChunk(entity, chunk);

src/main/java/net/minestom/server/network/ConnectionManager.java

@@ -216,7 +216,7 @@ public final class ConnectionManager {
      * Adds a new {@link Player} in the players list.
      * Is currently used at
      * {@link LoginStartPacket#process(PlayerConnection)}
-     * and in {@link FakePlayer#initPlayer(UUID, String, Consumer)}
+     * and in {@link FakePlayer#initPlayer(UUID, String, Consumer)}.
      *
      * @param player the player to add
      */

src/main/java/net/minestom/server/network/packet/client/ClientPreplayPacket.java

@@ -3,15 +3,16 @@ package net.minestom.server.network.packet.client;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.network.ConnectionManager;
 import net.minestom.server.network.player.PlayerConnection;
+import org.jetbrains.annotations.NotNull;
 
 public interface ClientPreplayPacket extends ClientPacket {
 
     ConnectionManager CONNECTION_MANAGER = MinecraftServer.getConnectionManager();
 
     /**
-     * Called when this packet is received
+     * Called when the packet is received.
      *
      * @param connection the connection who sent the packet
      */
-    void process(PlayerConnection connection);
+    void process(@NotNull PlayerConnection connection);
 }

src/main/java/net/minestom/server/network/packet/client/handshake/HandshakePacket.java

@@ -9,6 +9,7 @@ import net.minestom.server.network.packet.server.login.LoginDisconnect;
 import net.minestom.server.network.player.NettyPlayerConnection;
 import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 public class HandshakePacket implements ClientPreplayPacket {
 
@@ -31,7 +32,7 @@ public class HandshakePacket implements ClientPreplayPacket {
     }
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
         switch (nextState) {
             case 1:
                 connection.setConnectionState(ConnectionState.STATUS);

src/main/java/net/minestom/server/network/packet/client/login/EncryptionResponsePacket.java

@@ -11,6 +11,7 @@ import net.minestom.server.network.packet.server.login.LoginSuccessPacket;
 import net.minestom.server.network.player.NettyPlayerConnection;
 import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 import javax.crypto.SecretKey;
 import java.math.BigInteger;
@@ -20,28 +21,45 @@ import java.util.concurrent.atomic.AtomicInteger;
 public class EncryptionResponsePacket implements ClientPreplayPacket {
 
     private final static String THREAD_NAME = "Mojang Auth Thread";
-    private static AtomicInteger UNIQUE_THREAD_ID = new AtomicInteger(0);
+    private static final AtomicInteger UNIQUE_THREAD_ID = new AtomicInteger(0);
     private byte[] sharedSecret;
     private byte[] verifyToken;
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
+
+        // Encryption is only support for netty connection
+        if (!(connection instanceof NettyPlayerConnection)) {
+            return;
+        }
+
         new Thread(THREAD_NAME + " #" + UNIQUE_THREAD_ID.incrementAndGet()) {
 
             public void run() {
                 try {
                     if (!Arrays.equals(connection.getNonce(), getNonce())) {
-                        System.out.println(connection.getLoginUsername() + " tried to login with an invalid nonce!");
+                        MinecraftServer.getLOGGER().error(connection.getLoginUsername() + " tried to login with an invalid nonce!");
                         return;
                     }
                     if (!connection.getLoginUsername().isEmpty()) {
-                        final String string3 = new BigInteger(MojangCrypt.digestData("", MinecraftServer.getKeyPair().getPublic(), getSecretKey())).toString(16);
-                        final GameProfile gameProfile = MinecraftServer.getSessionService().hasJoinedServer(new GameProfile(null, connection.getLoginUsername()), string3);
-                        ((NettyPlayerConnection) connection).setEncryptionKey(getSecretKey());
-                        final int threshold = MinecraftServer.COMPRESSION_THRESHOLD;
+                        final NettyPlayerConnection nettyConnection = (NettyPlayerConnection) connection;
 
-                        if (threshold > 0 && connection instanceof NettyPlayerConnection) {
-                            ((NettyPlayerConnection) connection).enableCompression(threshold);
+                        final byte[] digestedData = MojangCrypt.digestData("", MinecraftServer.getKeyPair().getPublic(), getSecretKey());
+
+                        if (digestedData == null) {
+                            // Incorrect key, probably because of the client
+                            MinecraftServer.getLOGGER().error("Connection " + nettyConnection.getRemoteAddress() + " failed initializing encryption.");
+                            connection.disconnect();
+                            return;
+                        }
+
+                        final String string3 = new BigInteger(digestedData).toString(16);
+                        final GameProfile gameProfile = MinecraftServer.getSessionService().hasJoinedServer(new GameProfile(null, connection.getLoginUsername()), string3);
+                        nettyConnection.setEncryptionKey(getSecretKey());
+                        final int threshold = MinecraftServer.getCompressionThreshold();
+
+                        if (threshold > 0) {
+                            nettyConnection.enableCompression(threshold);
                         }
 
                         LoginSuccessPacket loginSuccessPacket = new LoginSuccessPacket(gameProfile.getId(), gameProfile.getName());

src/main/java/net/minestom/server/network/packet/client/login/LoginStartPacket.java

@@ -12,6 +12,7 @@ import net.minestom.server.network.packet.server.login.LoginSuccessPacket;
 import net.minestom.server.network.player.NettyPlayerConnection;
 import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.UUID;
 
@@ -23,7 +24,7 @@ public class LoginStartPacket implements ClientPreplayPacket {
     public String username;
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
         if (MojangAuth.isUsingMojangAuth()) {
             if (CONNECTION_MANAGER.getPlayer(username) != null) {
                 connection.sendPacket(new LoginDisconnect(ALREADY_CONNECTED_JSON));
@@ -38,7 +39,7 @@ public class LoginStartPacket implements ClientPreplayPacket {
         } else {
             final UUID playerUuid = CONNECTION_MANAGER.getPlayerConnectionUuid(connection, username);
 
-            final int threshold = MinecraftServer.COMPRESSION_THRESHOLD;
+            final int threshold = MinecraftServer.getCompressionThreshold();
 
             if (threshold > 0 && connection instanceof NettyPlayerConnection) {
                 ((NettyPlayerConnection) connection).enableCompression(threshold);

src/main/java/net/minestom/server/network/packet/client/status/LegacyServerListPingPacket.java

@@ -3,13 +3,14 @@ package net.minestom.server.network.packet.client.status;
 import net.minestom.server.network.packet.client.ClientPreplayPacket;
 import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 public class LegacyServerListPingPacket implements ClientPreplayPacket {
 
     private byte payload;
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
 
     }
 

src/main/java/net/minestom/server/network/packet/client/status/PingPacket.java

@@ -4,13 +4,14 @@ import net.minestom.server.network.packet.client.ClientPreplayPacket;
 import net.minestom.server.network.packet.server.status.PongPacket;
 import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 public class PingPacket implements ClientPreplayPacket {
 
     private long number;
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
         PongPacket pongPacket = new PongPacket(number);
         connection.sendPacket(pongPacket);
         connection.disconnect();

src/main/java/net/minestom/server/network/packet/client/status/StatusRequestPacket.java

@@ -7,11 +7,12 @@ import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.ping.ResponseData;
 import net.minestom.server.ping.ResponseDataConsumer;
 import net.minestom.server.utils.binary.BinaryReader;
+import org.jetbrains.annotations.NotNull;
 
 public class StatusRequestPacket implements ClientPreplayPacket {
 
     @Override
-    public void process(PlayerConnection connection) {
+    public void process(@NotNull PlayerConnection connection) {
         ResponseDataConsumer consumer = MinecraftServer.getResponseDataConsumer();
         ResponseData responseData = new ResponseData();
 

src/main/java/net/minestom/server/utils/entity/EntityUtils.java

@@ -23,7 +23,7 @@ public final class EntityUtils {
 
         final Chunk chunk = ent1.getInstance().getChunkAt(ent1.getPosition());
 
-        long[] visibleChunksEntity = ChunkUtils.getChunksInRange(ent2.getPosition(), MinecraftServer.ENTITY_VIEW_DISTANCE);
+        final long[] visibleChunksEntity = ChunkUtils.getChunksInRange(ent2.getPosition(), MinecraftServer.getEntityViewDistance());
         for (long visibleChunk : visibleChunksEntity) {
             final int chunkX = ChunkUtils.getChunkCoordX(visibleChunk);
             final int chunkZ = ChunkUtils.getChunkCoordZ(visibleChunk);