Added max packet size condition

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

@@ -107,15 +107,14 @@ public final class MinecraftServer {
     @Setter
     private static boolean hardcoreLook = false;
 
-    //Extras
+    // Extras
     @Getter
     @Setter
     private static boolean fixLighting = true;
 
-    //Rate Limiting
+    // Rate Limiting
     private static int rateLimit = 0;
-    // TODO
-    public static final int MAX_PACKET_SIZE = 300_000;
+    private static int maxPacketSize = 30_000;
 
     private static PacketListenerManager packetListenerManager;
     private static NettyServer nettyServer;
@@ -250,7 +249,7 @@ public final class MinecraftServer {
     /**
      * Gets the max number of packets a client can send over 1 second.
      *
-     * @return the packet count limit over 1 second
+     * @return the packet count limit over 1 second, 0 if not enabled
      */
     public static int getRateLimit() {
         return rateLimit;
@@ -265,6 +264,24 @@ public final class MinecraftServer {
         MinecraftServer.rateLimit = rateLimit;
     }
 
+    /**
+     * Gets the maximum packet size (in bytes) that a client can send without getting disconnected.
+     *
+     * @return the maximum packet size
+     */
+    public static int getMaxPacketSize() {
+        return maxPacketSize;
+    }
+
+    /**
+     * Changes the maximum packet size (in bytes) that a client can send without getting disconnected.
+     *
+     * @param maxPacketSize the new max packet size
+     */
+    public static void setMaxPacketSize(int maxPacketSize) {
+        MinecraftServer.maxPacketSize = maxPacketSize;
+    }
+
     /**
      * Gets the server difficulty showed in game option.
      *

src/main/java/net/minestom/server/network/netty/NettyServer.java

@@ -29,7 +29,7 @@ public class NettyServer {
     private String address;
     private int port;
 
-    public NettyServer(PacketProcessor packetProcessor) {
+    public NettyServer(@NotNull PacketProcessor packetProcessor) {
         Class<? extends ServerChannel> channel;
 
         if (Epoll.isAvailable()) {
@@ -55,10 +55,11 @@ public class NettyServer {
 
                 ChannelPipeline pipeline = ch.pipeline();
 
+                // First check should verify if the packet is a legacy ping (from 1.6 version and earlier)
                 pipeline.addLast("legacy-ping", new LegacyPingHandler());
 
                 // Adds packetLength at start | Reads framed bytebuf
-                pipeline.addLast("framer", new PacketFramer());
+                pipeline.addLast("framer", new PacketFramer(packetProcessor));
 
                 // Reads bytebuf and creating inbound packet
                 pipeline.addLast("decoder", new PacketDecoder());

src/main/java/net/minestom/server/network/netty/codec/PacketFramer.java

@@ -4,12 +4,26 @@ import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ByteToMessageCodec;
 import io.netty.handler.codec.CorruptedFrameException;
+import net.minestom.server.MinecraftServer;
+import net.minestom.server.entity.Player;
+import net.minestom.server.network.PacketProcessor;
+import net.minestom.server.network.player.PlayerConnection;
 import net.minestom.server.utils.Utils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.List;
 
 public class PacketFramer extends ByteToMessageCodec<ByteBuf> {
 
+    public final static Logger LOGGER = LoggerFactory.getLogger(PacketFramer.class);
+
+    private final PacketProcessor packetProcessor;
+
+    public PacketFramer(PacketProcessor packetProcessor) {
+        this.packetProcessor = packetProcessor;
+    }
+
     @Override
     protected void encode(ChannelHandlerContext ctx, ByteBuf from, ByteBuf to) {
         final int packetSize = from.readableBytes();
@@ -40,14 +54,29 @@ public class PacketFramer extends ByteToMessageCodec<ByteBuf> {
             if (b >= 0) {
                 buf.resetReaderIndex();
 
-                final int j = Utils.readVarInt(buf);
+                final int packetSize = Utils.readVarInt(buf);
 
-                if (buf.readableBytes() < j) {
+                // Max packet size check
+                if (packetSize >= MinecraftServer.getMaxPacketSize()) {
+                    final PlayerConnection playerConnection = packetProcessor.getPlayerConnection(ctx);
+                    if (playerConnection != null) {
+                        final Player player = playerConnection.getPlayer();
+                        final String identifier = player != null ?
+                                player.getUsername() :
+                                playerConnection.getRemoteAddress().toString();
+                        LOGGER.warn("An user (" + identifier + ") sent a packet over the maximum size (" + packetSize + ")");
+                    } else {
+                        LOGGER.warn("An unregistered user sent a packet over the maximum size (" + packetSize + ")");
+                    }
+                    ctx.close();
+                }
+
+                if (buf.readableBytes() < packetSize) {
                     buf.resetReaderIndex();
                     return;
                 }
 
-                out.add(buf.readRetainedSlice(j));
+                out.add(buf.readRetainedSlice(packetSize));
                 return;
             }
         }

src/main/java/net/minestom/server/network/netty/packet/InboundPacket.java

@@ -1,13 +1,14 @@
 package net.minestom.server.network.netty.packet;
 
 import io.netty.buffer.ByteBuf;
+import org.jetbrains.annotations.NotNull;
 
 public class InboundPacket {
 
     public final int packetId;
     public final ByteBuf body;
 
-    public InboundPacket(int id, ByteBuf body) {
+    public InboundPacket(int id, @NotNull ByteBuf body) {
         this.packetId = id;
         this.body = body;
     }