Add an option to disable compression for Geyser clients

bootstrap/spigot/src/main/java/org/geysermc/geyser/platform/spigot/GeyserSpigotCompressionDisabler.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2019-2021 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.platform.spigot;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelOutboundHandlerAdapter;
+import io.netty.channel.ChannelPromise;
+import org.bukkit.Bukkit;
+import org.geysermc.connector.GeyserConnector;
+
+/**
+ * Disables the compression packet (and the compression handlers from being added to the pipeline) for Geyser clients
+ * that won't be receiving the data over the network.
+ *
+ * As of 1.8 - 1.17.1, compression is enabled in the Netty pipeline by adding a listener after a packet is written.
+ * If we simply "cancel" or don't forward the packet, then the listener is never called.
+ */
+public class GeyserSpigotCompressionDisabler extends ChannelOutboundHandlerAdapter {
+    public static final boolean ENABLED;
+
+    private static final Class<?> COMPRESSION_PACKET_CLASS;
+    private static final Class<?> LOGIN_SUCCESS_PACKET_CLASS;
+    private static final boolean PROTOCOL_SUPPORT_INSTALLED;
+
+    static {
+        PROTOCOL_SUPPORT_INSTALLED = Bukkit.getPluginManager().getPlugin("ProtocolSupport") != null;
+
+        Class<?> compressionPacketClass = null;
+        Class<?> loginSuccessPacketClass = null;
+        boolean enabled = false;
+        try {
+            compressionPacketClass = findCompressionPacket();
+            loginSuccessPacketClass = findLoginSuccessPacket();
+            enabled = true;
+        } catch (Exception e) {
+            GeyserConnector.getInstance().getLogger().error("Could not initialize compression disabler!", e);
+        }
+        COMPRESSION_PACKET_CLASS = compressionPacketClass;
+        LOGIN_SUCCESS_PACKET_CLASS = loginSuccessPacketClass;
+        ENABLED = enabled;
+    }
+
+    public GeyserSpigotCompressionDisabler() {
+        if (!ENABLED) {
+            throw new RuntimeException("Geyser compression disabler cannot be initialized in its current state!");
+        }
+    }
+
+    @Override
+    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
+        Class<?> msgClass = msg.getClass();
+        // Don't let any compression packet get through
+        if (!COMPRESSION_PACKET_CLASS.isAssignableFrom(msgClass)) {
+            if (LOGIN_SUCCESS_PACKET_CLASS.isAssignableFrom(msgClass)) {
+                if (PROTOCOL_SUPPORT_INSTALLED) {
+                    // ProtocolSupport must send the compression packet, so let's remove what it did before it does damage
+                    if (ctx.pipeline().get("compress") != null) {
+                        ctx.pipeline().remove("compress");
+                    }
+                    if (ctx.pipeline().get("decompress") != null) {
+                        ctx.pipeline().remove("decompress");
+                    }
+                }
+                // We're past the point that a compression packet can be sent, so we can safely yeet ourselves away
+                ctx.channel().pipeline().remove(this);
+            }
+            super.write(ctx, msg, promise);
+        } else if (PROTOCOL_SUPPORT_INSTALLED) {
+            // We must indicate it "succeeded" or ProtocolSupport will time us out
+            promise.setSuccess();
+        }
+    }
+
+    private static Class<?> findCompressionPacket() throws ClassNotFoundException {
+        try {
+            return Class.forName("net.minecraft.network.protocol.login.PacketLoginOutSetCompression");
+        } catch (ClassNotFoundException e) {
+            String prefix = Bukkit.getServer().getClass().getPackage().getName().replace("org.bukkit.craftbukkit", "net.minecraft.server");
+            return Class.forName(prefix + ".PacketLoginOutSetCompression");
+        }
+    }
+
+    private static Class<?> findLoginSuccessPacket() throws ClassNotFoundException {
+        try {
+            return Class.forName("net.minecraft.network.protocol.login.PacketLoginOutSuccess");
+        } catch (ClassNotFoundException e) {
+            String prefix = Bukkit.getServer().getClass().getPackage().getName().replace("org.bukkit.craftbukkit", "net.minecraft.server");
+            return Class.forName(prefix + ".PacketLoginOutSuccess");
+        }
+    }
+}

bootstrap/spigot/src/main/java/org/geysermc/geyser/platform/spigot/GeyserSpigotInjector.java

@@ -115,10 +115,14 @@ public class GeyserSpigotInjector extends GeyserInjector {
 
         ChannelFuture channelFuture = (new ServerBootstrap()
                 .channel(LocalServerChannelWrapper.class)
-                .childHandler(new ChannelInitializer<Channel>() {
+                .childHandler(new ChannelInitializer<>() {
                     @Override
                     protected void initChannel(Channel ch) throws Exception {
                         initChannel.invoke(childHandler, ch);
+
+                        if (bootstrap.getGeyserConfig().isDisableCompression() && GeyserSpigotCompressionDisabler.ENABLED) {
+                            ch.pipeline().addAfter("encoder", "geyser-compression-disabler", new GeyserSpigotCompressionDisabler());
+                        }
                     }
                 })
                 // Set to MAX_PRIORITY as MultithreadEventLoopGroup#newDefaultThreadFactory which DefaultEventLoopGroup implements does by default