Avoid resets

src/main/java/org/adde0109/ambassador/forge/ForgeHandshake.java

@@ -2,25 +2,19 @@ package org.adde0109.ambassador.forge;
 
 import org.adde0109.ambassador.forge.packet.ModListPacket;
 import org.adde0109.ambassador.forge.packet.ModListReplyPacket;
+import org.adde0109.ambassador.forge.packet.RegistryPacket;
 
 import java.util.List;
+import java.util.zip.Adler32;
+import java.util.zip.Checksum;
 
 public class ForgeHandshake {
-
-    private ModListPacket modListPacket;
     private ModListReplyPacket modListReplyPacket;
+    private final Checksum registryChecksum = new Adler32();
 
     public ForgeHandshake() {
     }
 
-    public ModListPacket getModListPacket() {
-        return modListPacket;
-    }
-
-    public void setModListPacket(ModListPacket modListPacket) {
-        this.modListPacket = modListPacket;
-    }
-
     public ModListReplyPacket getModListReplyPacket() {
         return modListReplyPacket;
     }
@@ -28,4 +22,12 @@ public class ForgeHandshake {
     public void setModListReplyPacket(ModListReplyPacket modListReplyPacket) {
         this.modListReplyPacket = modListReplyPacket;
     }
+
+    public void addRegistry(RegistryPacket packet) {
+        registryChecksum.update(packet.getSnapshot());
+    }
+
+    public Checksum getRegistryChecksum() {
+        return registryChecksum;
+    }
 }

src/main/java/org/adde0109/ambassador/forge/VelocityForgeBackendConnectionPhase.java

@@ -9,10 +9,15 @@ import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommands;
 import com.velocitypowered.proxy.protocol.packet.LoginPluginMessage;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
-import org.adde0109.ambassador.forge.packet.Context;
-import org.adde0109.ambassador.forge.packet.IForgeLoginWrapperPacket;
+import org.adde0109.ambassador.forge.packet.*;
 import org.adde0109.ambassador.forge.pipeline.CommandDecoderErrorCatcher;
 import org.adde0109.ambassador.forge.pipeline.ForgeLoginWrapperCodec;
+import org.checkerframework.checker.units.qual.A;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.zip.Adler32;
+import java.util.zip.Checksum;
 
 public enum VelocityForgeBackendConnectionPhase implements BackendConnectionPhase {
   NOT_STARTED() {
@@ -54,7 +59,8 @@ public enum VelocityForgeBackendConnectionPhase implements BackendConnectionPhas
     }
   };
 
-
+  public Checksum registryChecksum;
+  CountDownLatch remainingRegistries;
 
   VelocityForgeBackendConnectionPhase() {
   }
@@ -66,17 +72,46 @@ public enum VelocityForgeBackendConnectionPhase implements BackendConnectionPhas
 
     //Reset client if not ready to receive new handshake
     VelocityForgeClientConnectionPhase clientPhase = (VelocityForgeClientConnectionPhase) player.getPhase();
-    if (clientPhase != VelocityForgeClientConnectionPhase.NOT_STARTED) {
+    if (clientPhase == VelocityForgeClientConnectionPhase.RESETTABLE) {
       //Initial Forge
       //Forge -> Forge
       clientPhase.resetConnectionPhase(player);
-      if (clientPhase == VelocityForgeClientConnectionPhase.COMPLETE)
-      {
-        //Do not continue if the client can't reset.
-        return;
+    }
+
+    if (clientPhase != VelocityForgeClientConnectionPhase.COMPLETE) {
+      if (message instanceof ModListPacket modListPacket) {
+        clientPhase.forgeHandshake = new ForgeHandshake();
+      }
+      if (message instanceof RegistryPacket registryPacket) {
+        clientPhase.forgeHandshake.addRegistry(registryPacket);
+      }
+      player.getConnection().write(message);
+    } else {
+      if (message instanceof ModListPacket modListPacket) {
+        registryChecksum = new Adler32();
+        remainingRegistries = new CountDownLatch(modListPacket.getRegistries().size());
+        CompletableFuture.runAsync(() -> {
+          try {
+            remainingRegistries.await();
+          } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+          }
+        }).thenAcceptAsync((v) -> {
+          if (clientPhase.forgeHandshake.getRegistryChecksum().getValue() == registryChecksum.getValue()) {
+            server.ensureConnected().write(clientPhase.forgeHandshake.getModListReplyPacket());
+          } else {
+            //Player needs to be kicked in order to continue.
+           server.disconnect();
+          }
+        }, server.ensureConnected().eventLoop());
+      } else if (message instanceof RegistryPacket registryPacket) {
+        server.getConnection().write(new ACKPacket(Context.createContext(message.getContext().getResponseID(), true)));
+        registryChecksum.update(registryPacket.getSnapshot());
+        remainingRegistries.countDown();
+      } else if (message instanceof ConfigDataPacket) {
+        server.getConnection().write(new ACKPacket(Context.createContext(message.getContext().getResponseID(), true)));
       }
     }
-    player.getConnection().write(message);
     //Forge server
     //To avoid unnecessary resets, we wait until we get the handshake even if we know that we should
     //reset because that the previous server was Forge.

src/main/java/org/adde0109/ambassador/forge/VelocityForgeClientConnectionPhase.java

@@ -22,6 +22,7 @@ import org.adde0109.ambassador.velocity.client.FML2CRPMResetCompleteDecoder;
 import org.adde0109.ambassador.velocity.client.OutboundSuccessHolder;
 import org.adde0109.ambassador.velocity.client.ClientPacketQueue;
 
+import javax.swing.*;
 import java.nio.charset.StandardCharsets;
 import java.util.concurrent.TimeUnit;
 
@@ -144,18 +145,20 @@ public enum VelocityForgeClientConnectionPhase implements ClientConnectionPhase
     public boolean consideredComplete() {
       return true;
     }
+
+    public void complete(ConnectedPlayer player, boolean resettable) {  }
+
   };
 
-  public ModListReplyPacket clientModList;
+  public ForgeHandshake forgeHandshake = new ForgeHandshake();
 
   public boolean handle(ConnectedPlayer player, IForgeLoginWrapperPacket<Context.ClientContext> msg, VelocityServerConnection server) {
-    player.setPhase(nextPhase());
 
     if (msg instanceof ModListReplyPacket replyPacket) {
       ModInfo modInfo = new ModInfo("FML2", replyPacket.getMods().stream().map(
               (v) -> new ModInfo.Mod(v,"1")).toList());
       player.setModInfo(modInfo);
-      this.clientModList = replyPacket;
+      forgeHandshake.setModListReplyPacket(replyPacket);
       if (!(server.getConnection().getType() instanceof ForgeFMLConnectionType)) {
         complete(player);
         player.getConnectionInFlight().getConnection().getChannel().config().setAutoRead(true);
@@ -165,6 +168,10 @@ public enum VelocityForgeClientConnectionPhase implements ClientConnectionPhase
     }
 
     player.getConnectionInFlight().getConnection().write(msg);
+
+    player.setPhase(nextPhase());
+    nextPhase().forgeHandshake = this.forgeHandshake;
+
     return true;
   }
 
@@ -181,11 +188,11 @@ public enum VelocityForgeClientConnectionPhase implements ClientConnectionPhase
     if (resettable) {
       player.setPhase(RESETTABLE);
       RESETTABLE.onTransitionToNewPhase(player);
-      RESETTABLE.clientModList = clientModList;
+      RESETTABLE.forgeHandshake = forgeHandshake;
     } else {
       player.setPhase(COMPLETE);
       COMPLETE.onTransitionToNewPhase(player);
-      COMPLETE.clientModList = clientModList;
+      COMPLETE.forgeHandshake = forgeHandshake;
     }
   }
 

src/main/java/org/adde0109/ambassador/forge/packet/ModListPacket.java

@@ -95,5 +95,8 @@ public class ModListPacket implements IForgeLoginWrapperPacket<Context> {
         return channels;
     }
 
+    public List<String> getRegistries() {
+        return registries;
+    }
 
 }

src/main/java/org/adde0109/ambassador/forge/packet/RegistryPacket.java

@@ -7,6 +7,7 @@ import io.netty.buffer.Unpooled;
 public class RegistryPacket implements IForgeLoginWrapperPacket<Context> {
 
   private final String registryName;
+
   private final byte[] snapshot;
 
   private final Context context;
@@ -48,4 +49,8 @@ public class RegistryPacket implements IForgeLoginWrapperPacket<Context> {
   public Context getContext() {
     return context;
   }
+
+  public byte[] getSnapshot() {
+    return snapshot;
+  }
 }