Increase packet limits for multiple connected clients playing from one IP address (#5351)

* Fix https://github.com/GeyserMC/Geyser/issues/4926

* Extend the RakServerRateLimiter, now that it is possible

* Update core/src/main/java/org/geysermc/geyser/network/netty/handler/RakGeyserRateLimiter.java

* cast to int

core/src/main/java/org/geysermc/geyser/network/netty/GeyserServer.java

@@ -59,6 +59,7 @@ import org.geysermc.geyser.network.CIDRMatcher;
 import org.geysermc.geyser.network.GameProtocol;
 import org.geysermc.geyser.network.GeyserServerInitializer;
 import org.geysermc.geyser.network.netty.handler.RakConnectionRequestHandler;
+import org.geysermc.geyser.network.netty.handler.RakGeyserRateLimiter;
 import org.geysermc.geyser.network.netty.handler.RakPingHandler;
 import org.geysermc.geyser.network.netty.proxy.ProxyServerHandler;
 import org.geysermc.geyser.ping.GeyserPingInfo;
@@ -175,6 +176,9 @@ public final class GeyserServer {
         if (Boolean.parseBoolean(System.getProperty("Geyser.RakRateLimitingDisabled", "false")) || isWhitelistedProxyProtocol) {
             // We would already block any non-whitelisted IP addresses in onConnectionRequest so we can remove the rate limiter
             channel.pipeline().remove(RakServerRateLimiter.NAME);
+        } else {
+            // Use our own rate limiter to allow multiple players from the same IP
+            channel.pipeline().replace(RakServerRateLimiter.NAME, RakGeyserRateLimiter.NAME, new RakGeyserRateLimiter(channel));
         }
     }
 

core/src/main/java/org/geysermc/geyser/network/netty/handler/RakGeyserRateLimiter.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2019-2025 GeyserMC. http://geysermc.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @author GeyserMC
+ * @link https://github.com/GeyserMC/Geyser
+ */
+
+package org.geysermc.geyser.network.netty.handler;
+
+import io.netty.channel.Channel;
+import org.cloudburstmc.netty.channel.raknet.RakServerChannel;
+import org.cloudburstmc.netty.handler.codec.raknet.server.RakServerRateLimiter;
+import org.geysermc.geyser.GeyserImpl;
+import org.geysermc.geyser.session.SessionManager;
+
+import java.net.InetAddress;
+
+public class RakGeyserRateLimiter extends RakServerRateLimiter {
+    public static final String NAME = "rak-geyser-rate-limiter";
+    private final SessionManager sessionManager;
+
+    public RakGeyserRateLimiter(Channel channel) {
+        super((RakServerChannel) channel);
+        this.sessionManager = GeyserImpl.getInstance().getSessionManager();
+    }
+
+    @Override
+    protected int getAddressMaxPacketCount(InetAddress address) {
+        // Using a factor of 0.8 for now, as the default packet count is already padded for multiple
+        return (int) (super.getAddressMaxPacketCount(address) * sessionManager.getAddressMultiplier(address) * 0.8);
+    }
+}

core/src/main/java/org/geysermc/geyser/session/SessionManager.java

@@ -32,8 +32,15 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.geysermc.geyser.text.GeyserLocale;
 
-import java.util.*;
+import java.net.InetAddress;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
 
 public final class SessionManager {
     /**
@@ -47,6 +54,13 @@ public final class SessionManager {
     @Getter
     private final Map<UUID, GeyserSession> sessions = new ConcurrentHashMap<>();
 
+    /**
+     * Stores the number of connected sessions per address they're connected from.
+     * Used to raise per-IP connection limits.
+     */
+    @Getter(AccessLevel.PACKAGE)
+    private final Map<InetAddress, AtomicInteger> connectedClients = new ConcurrentHashMap<>();
+
     /**
      * Called once the player has successfully authenticated to the Geyser server.
      */
@@ -60,6 +74,14 @@ public final class SessionManager {
     public void addSession(UUID uuid, GeyserSession session) {
         pendingSessions.remove(session);
         sessions.put(uuid, session);
+        connectedClients.compute(session.getSocketAddress().getAddress(), (key, count) -> {
+            if (count == null) {
+                return new AtomicInteger(0);
+            }
+
+            count.getAndIncrement();
+            return count;
+        });
     }
 
     public void removeSession(GeyserSession session) {
@@ -68,6 +90,17 @@ public final class SessionManager {
             // Connection was likely pending
             pendingSessions.remove(session);
         }
+        connectedClients.computeIfPresent(session.getSocketAddress().getAddress(), (key, count) -> {
+            if (count.decrementAndGet() <= 0) {
+                return null;
+            }
+            return count;
+        });
+    }
+
+    public int getAddressMultiplier(InetAddress ip) {
+        AtomicInteger atomicInteger = connectedClients.get(ip);
+        return atomicInteger == null ? 1 : atomicInteger.get();
     }
 
     public @Nullable GeyserSession sessionByXuid(@NonNull String xuid) {

gradle/libs.versions.toml

@@ -13,7 +13,7 @@ websocket = "1.5.1"
 protocol-connection = "3.0.0.Beta6-20250212.131009-3"
 protocol-common = "3.0.0.Beta6-20250212.131009-3"
 protocol-codec = "3.0.0.Beta6-20250212.131009-3"
-raknet = "1.0.0.CR3-20250128.101054-17"
+raknet = "1.0.0.CR3-20250218.160705-18"
 minecraftauth = "4.1.1"
 mcprotocollib = "1.21.4-20250218.175633-22"
 adventure = "4.14.0"