If possible, user Paper internal injection method

bukkit/src/main/java/com/viaversion/viaversion/bukkit/handlers/BukkitChannelInitializer.java

@@ -51,20 +51,23 @@ public class BukkitChannelInitializer extends ChannelInitializer<SocketChannel>
 
     @Override
     protected void initChannel(SocketChannel socketChannel) throws Exception {
-        UserConnection info = new UserConnectionImpl(socketChannel);
-        // init protocol
-        new ProtocolPipelineImpl(info);
         // Add originals
         this.method.invoke(this.original, socketChannel);
+        afterChannelInitialize(socketChannel);
+    }
+
+    public static void afterChannelInitialize(Channel channel) {
+        UserConnection connection = new UserConnectionImpl(channel);
+        new ProtocolPipelineImpl(connection);
 
-        HandlerConstructor constructor = ClassGenerator.getConstructor();
         // Add our transformers
-        MessageToByteEncoder encoder = constructor.newEncodeHandler(info, (MessageToByteEncoder) socketChannel.pipeline().get("encoder"));
+        HandlerConstructor constructor = ClassGenerator.getConstructor();
-        ByteToMessageDecoder decoder = constructor.newDecodeHandler(info, (ByteToMessageDecoder) socketChannel.pipeline().get("decoder"));
+        MessageToByteEncoder encoder = constructor.newEncodeHandler(connection, (MessageToByteEncoder) channel.pipeline().get("encoder"));
-        BukkitPacketHandler chunkHandler = new BukkitPacketHandler(info);
+        ByteToMessageDecoder decoder = constructor.newDecodeHandler(connection, (ByteToMessageDecoder) channel.pipeline().get("decoder"));
 
-        socketChannel.pipeline().replace("encoder", "encoder", encoder);
+        BukkitPacketHandler chunkHandler = new BukkitPacketHandler(connection);
-        socketChannel.pipeline().replace("decoder", "decoder", decoder);
+        channel.pipeline().replace("encoder", "encoder", encoder);
-        socketChannel.pipeline().addAfter("packet_handler", "viaversion_packet_handler", chunkHandler);
+        channel.pipeline().replace("decoder", "decoder", decoder);
+        channel.pipeline().addAfter("packet_handler", "viaversion_packet_handler", chunkHandler);
     }
 }

bukkit/src/main/java/com/viaversion/viaversion/bukkit/platform/BukkitViaInjector.java

@@ -45,11 +45,15 @@ public class BukkitViaInjector implements ViaInjector {
     private final List<ChannelFuture> injectedFutures = new ArrayList<>();
     private final List<Pair<Field, Object>> injectedLists = new ArrayList<>();
 
-    private final boolean modernPaper = hasServerProtocolMethod();
     private boolean protocolLib;
 
     @Override
     public void inject() throws Exception {
+        if (PaperViaInjector.PAPER_INJECTION_METHOD) {
+            PaperViaInjector.setPaperChannelInitializeListener();
+            return;
+        }
+
         try {
             Object connection = getServerConnection();
             if (connection == null) {
@@ -189,7 +193,7 @@ public class BukkitViaInjector implements ViaInjector {
 
     @Override
     public int getServerProtocolVersion() throws Exception {
-        if (modernPaper) {
+        if (PaperViaInjector.PAPER_PROTOCOL_METHOD) {
             // *Trust me, it's safe*
             return Bukkit.getUnsafe().getProtocolVersion();
         }
@@ -266,6 +270,7 @@ public class BukkitViaInjector implements ViaInjector {
     }
 
     public static boolean isBinded() {
+        if (PaperViaInjector.PAPER_INJECTION_METHOD) return true;
         try {
             Object connection = getServerConnection();
             if (connection == null) {
@@ -354,6 +359,8 @@ public class BukkitViaInjector implements ViaInjector {
     }
 
     public static void patchLists() throws Exception {
+        if (PaperViaInjector.PAPER_INJECTION_METHOD) return;
+
         Object connection = getServerConnection();
         if (connection == null) {
             Via.getPlatform().getLogger().warning("We failed to find the core component 'ServerConnection', please file an issue on our GitHub.");
@@ -375,17 +382,4 @@ public class BukkitViaInjector implements ViaInjector {
     public void setProtocolLib(boolean protocolLib) {
         this.protocolLib = protocolLib;
     }
-
-    public boolean isModernPaper() {
-        return modernPaper;
-    }
-
-    private static boolean hasServerProtocolMethod() {
-        try {
-            Class.forName("org.bukkit.UnsafeValues").getDeclaredMethod("getProtocolVersion");
-            return true;
-        } catch (ReflectiveOperationException e) {
-            return false;
-        }
-    }
 }

bukkit/src/main/java/com/viaversion/viaversion/bukkit/platform/PaperViaInjector.java

@@ -0,0 +1,51 @@
+package com.viaversion.viaversion.bukkit.platform;
+
+import com.viaversion.viaversion.bukkit.handlers.BukkitChannelInitializer;
+import io.netty.channel.Channel;
+import net.kyori.adventure.key.Key;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+public final class PaperViaInjector {
+    public static final boolean PAPER_INJECTION_METHOD = hasPaperInjectionMethod();
+    public static final boolean PAPER_PROTOCOL_METHOD = hasServerProtocolMethod();
+
+    private PaperViaInjector() {
+    }
+
+    public static void setPaperChannelInitializeListener() throws ReflectiveOperationException {
+        // Call io.papermc.paper.network.ChannelInitializeListenerHolder.addListener(net.kyori.adventure.key.Key, io.papermc.paper.network.ChannelInitializeListener)
+        // Create an interface proxy of ChannelInitializeListener
+        Class<?> listenerClass = Class.forName("io.papermc.paper.network.ChannelInitializeListener");
+        Object channelInitializeListener = Proxy.newProxyInstance(BukkitViaInjector.class.getClassLoader(), new Class[]{listenerClass}, (proxy, method, args) -> {
+            if (method.getName().equals("afterInitChannel")) {
+                BukkitChannelInitializer.afterChannelInitialize((Channel) args[0]);
+                return null;
+            }
+            return method.invoke(proxy, args);
+        });
+
+        Class<?> holderClass = Class.forName("io.papermc.paper.network.ChannelInitializeListenerHolder");
+        Method addListenerMethod = holderClass.getDeclaredMethod("addListener", Key.class, listenerClass);
+        addListenerMethod.invoke(null, Key.key("viaversion", "injector"), channelInitializeListener);
+    }
+
+    private static boolean hasServerProtocolMethod() {
+        try {
+            Class.forName("org.bukkit.UnsafeValues").getDeclaredMethod("getProtocolVersion");
+            return true;
+        } catch (ReflectiveOperationException e) {
+            return false;
+        }
+    }
+
+    private static boolean hasPaperInjectionMethod() {
+        try {
+            Class.forName("io.papermc.paper.network.ChannelInitializeListener");
+            return true;
+        } catch (ReflectiveOperationException e) {
+            return false;
+        }
+    }
+}