Server shouldn't crash/lag when receiving a string too big

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

@@ -247,7 +247,7 @@ public final class MinecraftServer {
     }
 
     /**
-     * Gets the max number of packets a client can send over 1 second.
+     * Gets the maximum number of packets a client can send over 1 second.
      *
      * @return the packet count limit over 1 second, 0 if not enabled
      */

src/main/java/net/minestom/server/data/SerializableData.java

@@ -109,7 +109,7 @@ public interface SerializableData extends Data {
         {
             final int dataIndexSize = binaryReader.readVarInt();
             for (int i = 0; i < dataIndexSize; i++) {
-                final String className = binaryReader.readSizedString();
+                final String className = binaryReader.readSizedString(Short.MAX_VALUE);
                 final short classIndex = binaryReader.readShort();
                 typeToIndexMap.put(className, classIndex);
             }

src/main/java/net/minestom/server/data/SerializableDataImpl.java

@@ -149,7 +149,7 @@ public class SerializableDataImpl extends DataImpl implements SerializableData {
             }
 
             // Get the key
-            final String name = reader.readSizedString();
+            final String name = reader.readSizedString(Integer.MAX_VALUE);
 
             // Get the data
             final Object value;

src/main/java/net/minestom/server/data/type/InventoryData.java

@@ -27,8 +27,8 @@ public class InventoryData extends DataType<Inventory> {
     @NotNull
     @Override
     public Inventory decode(@NotNull BinaryReader reader) {
-        final String title = reader.readSizedString();
-        final InventoryType inventoryType = InventoryType.valueOf(reader.readSizedString());
+        final String title = reader.readSizedString(Integer.MAX_VALUE);
+        final InventoryType inventoryType = InventoryType.valueOf(reader.readSizedString(Integer.MAX_VALUE));
         final int size = inventoryType.getAdditionalSlot();
 
         Inventory inventory = new Inventory(inventoryType, title);

src/main/java/net/minestom/server/data/type/StringData.java

@@ -15,6 +15,6 @@ public class StringData extends DataType<String> {
     @NotNull
     @Override
     public String decode(@NotNull BinaryReader reader) {
-        return reader.readSizedString();
+        return reader.readSizedString(Integer.MAX_VALUE);
     }
 }

src/main/java/net/minestom/server/data/type/array/StringArrayData.java

@@ -9,19 +9,12 @@ public class StringArrayData extends DataType<String[]> {
 
     @Override
     public void encode(@NotNull BinaryWriter writer, @NotNull String[] value) {
-        writer.writeVarInt(value.length);
-        for (String val : value) {
-            writer.writeSizedString(val);
-        }
+        writer.writeStringArray(value);
     }
 
     @NotNull
     @Override
     public String[] decode(@NotNull BinaryReader reader) {
-        String[] array = new String[reader.readVarInt()];
-        for (int i = 0; i < array.length; i++) {
-            array[i] = reader.readSizedString();
-        }
-        return array;
+        return reader.readSizedStringArray(Integer.MAX_VALUE);
     }
 }

src/main/java/net/minestom/server/extras/velocity/VelocityProxy.java

@@ -72,7 +72,7 @@ public final class VelocityProxy {
     }
 
     public static InetAddress readAddress(@NotNull BinaryReader reader) {
-        return InetAddresses.forString(reader.readSizedString());
+        return InetAddresses.forString(reader.readSizedString(Integer.MAX_VALUE));
     }
 
 }

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

@@ -31,7 +31,7 @@ public class HandshakePacket implements ClientPreplayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.protocolVersion = reader.readVarInt();
-        this.serverAddress = reader.readSizedString();
+        this.serverAddress = reader.readSizedString(256);
         this.serverPort = reader.readUnsignedShort();
         this.nextState = reader.readVarInt();
     }

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

@@ -88,7 +88,7 @@ public class LoginStartPacket implements ClientPreplayPacket {
 
     @Override
     public void read(@NotNull BinaryReader reader) {
-        this.username = reader.readSizedString();
+        this.username = reader.readSizedString(16);
     }
 
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientAdvancementTabPacket.java

@@ -15,7 +15,7 @@ public class ClientAdvancementTabPacket extends ClientPlayPacket {
         this.action = AdvancementAction.values()[reader.readVarInt()];
 
         if (action == AdvancementAction.OPENED_TAB) {
-            this.tabIdentifier = reader.readSizedString();
+            this.tabIdentifier = reader.readSizedString(256);
         }
     }
 

src/main/java/net/minestom/server/network/packet/client/play/ClientChatMessagePacket.java

@@ -10,6 +10,6 @@ public class ClientChatMessagePacket extends ClientPlayPacket {
 
     @Override
     public void read(@NotNull BinaryReader reader) {
-        this.message = reader.readSizedString();
+        this.message = reader.readSizedString(256);
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientCraftRecipeRequest.java

@@ -13,7 +13,7 @@ public class ClientCraftRecipeRequest extends ClientPlayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.windowId = reader.readByte();
-        this.recipe = reader.readSizedString();
+        this.recipe = reader.readSizedString(256);
         this.makeAll = reader.readBoolean();
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientNameItemPacket.java

@@ -10,6 +10,6 @@ public class ClientNameItemPacket extends ClientPlayPacket {
 
     @Override
     public void read(@NotNull BinaryReader reader) {
-        this.itemName = reader.readSizedString();
+        this.itemName = reader.readSizedString(Short.MAX_VALUE);
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientPluginMessagePacket.java

@@ -11,7 +11,7 @@ public class ClientPluginMessagePacket extends ClientPlayPacket {
 
     @Override
     public void read(@NotNull BinaryReader reader) {
-        this.channel = reader.readSizedString();
+        this.channel = reader.readSizedString(256);
         this.data = reader.getRemainingBytes();
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientRecipeBookData.java

@@ -25,7 +25,7 @@ public class ClientRecipeBookData extends ClientPlayPacket {
 
         switch (type) {
             case 0:
-                this.recipeId = reader.readSizedString();
+                this.recipeId = reader.readSizedString(256);
                 break;
             case 1:
                 this.craftingRecipeBookOpen = reader.readBoolean();

src/main/java/net/minestom/server/network/packet/client/play/ClientSettingsPacket.java

@@ -16,7 +16,7 @@ public class ClientSettingsPacket extends ClientPlayPacket {
 
     @Override
     public void read(@NotNull BinaryReader reader) {
-        this.locale = reader.readSizedString();
+        this.locale = reader.readSizedString(128);
         this.viewDistance = reader.readByte();
         this.chatMode = Player.ChatMode.values()[reader.readVarInt()];
         this.chatColors = reader.readBoolean();

src/main/java/net/minestom/server/network/packet/client/play/ClientTabCompletePacket.java

@@ -12,6 +12,6 @@ public class ClientTabCompletePacket extends ClientPlayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.transactionId = reader.readVarInt();
-        this.text = reader.readSizedString();
+        this.text = reader.readSizedString(Short.MAX_VALUE);
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientUpdateCommandBlockMinecartPacket.java

@@ -13,7 +13,7 @@ public class ClientUpdateCommandBlockMinecartPacket extends ClientPlayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.entityId = reader.readVarInt();
-        this.command = reader.readSizedString();
+        this.command = reader.readSizedString(Short.MAX_VALUE);
         this.trackOutput = reader.readBoolean();
     }
 }

src/main/java/net/minestom/server/network/packet/client/play/ClientUpdateCommandBlockPacket.java

@@ -15,7 +15,7 @@ public class ClientUpdateCommandBlockPacket extends ClientPlayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.blockPosition = reader.readBlockPosition();
-        this.command = reader.readSizedString();
+        this.command = reader.readSizedString(Short.MAX_VALUE);
         this.mode = Mode.values()[reader.readVarInt()];
         this.flags = reader.readByte();
     }

src/main/java/net/minestom/server/network/packet/client/play/ClientUpdateSignPacket.java

@@ -16,10 +16,10 @@ public class ClientUpdateSignPacket extends ClientPlayPacket {
     @Override
     public void read(@NotNull BinaryReader reader) {
         this.blockPosition = reader.readBlockPosition();
-        this.line1 = reader.readSizedString();
-        this.line2 = reader.readSizedString();
-        this.line3 = reader.readSizedString();
-        this.line4 = reader.readSizedString();
+        this.line1 = reader.readSizedString(384);
+        this.line2 = reader.readSizedString(384);
+        this.line3 = reader.readSizedString(384);
+        this.line4 = reader.readSizedString(384);
 
     }
 }

src/main/java/net/minestom/server/utils/binary/BinaryReader.java

@@ -10,6 +10,7 @@ import net.minestom.server.utils.BlockPosition;
 import net.minestom.server.utils.NBTUtils;
 import net.minestom.server.utils.SerializerUtils;
 import net.minestom.server.utils.Utils;
+import net.minestom.server.utils.validate.Check;
 import org.jglrxavpok.hephaistos.nbt.NBT;
 import org.jglrxavpok.hephaistos.nbt.NBTException;
 import org.jglrxavpok.hephaistos.nbt.NBTReader;
@@ -76,8 +77,21 @@ public class BinaryReader extends InputStream {
         return buffer.readDouble();
     }
 
-    public String readSizedString() {
+    /**
+     * Reads a string size by a var-int.
+     * <p>
+     * If the string length is higher than {@code maxLength},
+     * the code throws an exception and the string bytes are not read.
+     *
+     * @param maxLength the max length of the string
+     * @return the string
+     * @throws IllegalStateException if the string length is higher than {@code maxLength}
+     */
+    public String readSizedString(int maxLength) {
         final int length = readVarInt();
+        Check.stateCondition(length >= maxLength,
+                "String length (" + length + ") was higher than the max length of " + maxLength);
+
         final byte[] bytes = readBytes(length);
         return new String(bytes);
     }
@@ -96,11 +110,11 @@ public class BinaryReader extends InputStream {
         return bytes;
     }
 
-    public String[] readSizedStringArray() {
+    public String[] readSizedStringArray(int maxLength) {
         final int size = readVarInt();
         String[] strings = new String[size];
         for (int i = 0; i < size; i++) {
-            strings[i] = readSizedString();
+            strings[i] = readSizedString(maxLength);
         }
         return strings;
     }
@@ -133,8 +147,8 @@ public class BinaryReader extends InputStream {
         return NBTUtils.readItemStack(this);
     }
 
-    public JsonMessage readJsonMessage() {
-        final String string = readSizedString();
+    public JsonMessage readJsonMessage(int maxLength) {
+        final String string = readSizedString(maxLength);
         final JsonObject jsonObject = JsonParser.parseString(string).getAsJsonObject();
         return new JsonMessage.RawJsonMessage(jsonObject);
     }