Waterfall/BungeeCord-Patches/0039-Fix-potion-race-condition-on-Forge-1.8.9.patch

From 7b94bf37323209f817606573449e0c52ed04f7e9 Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Thu, 15 Sep 2016 22:38:37 +0200
Subject: [PATCH] Fix potion race condition on Forge 1.8.9


diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/AbstractPacketHandler.java b/protocol/src/main/java/net/md_5/bungee/protocol/AbstractPacketHandler.java
index 6f782c8f..2d5fc487 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/AbstractPacketHandler.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/AbstractPacketHandler.java
@@ -1,6 +1,8 @@
 package net.md_5.bungee.protocol;
 
 import net.md_5.bungee.protocol.packet.BossBar;
+import net.md_5.bungee.protocol.packet.EntityEffect;
+import net.md_5.bungee.protocol.packet.EntityRemoveEffect;
 import net.md_5.bungee.protocol.packet.KeepAlive;
 import net.md_5.bungee.protocol.packet.ClientSettings;
 import net.md_5.bungee.protocol.packet.ClientStatus;
@@ -148,4 +150,13 @@ public abstract class AbstractPacketHandler
     public void handle(BossBar bossBar) throws Exception
     {
     }
+    // Waterfall start
+    public void handle(EntityEffect entityEffect) throws Exception
+    {
+    }
+
+    public void handle(EntityRemoveEffect removeEffect) throws Exception
+    {
+    }
+    // Waterfall end
 }
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/Protocol.java b/protocol/src/main/java/net/md_5/bungee/protocol/Protocol.java
index a2eeb024..18c99076 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/Protocol.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/Protocol.java
@@ -16,6 +16,8 @@ import net.md_5.bungee.protocol.packet.Chat;
 import net.md_5.bungee.protocol.packet.ClientSettings;
 import net.md_5.bungee.protocol.packet.EncryptionRequest;
 import net.md_5.bungee.protocol.packet.EncryptionResponse;
+import net.md_5.bungee.protocol.packet.EntityEffect;
+import net.md_5.bungee.protocol.packet.EntityRemoveEffect;
 import net.md_5.bungee.protocol.packet.Handshake;
 import net.md_5.bungee.protocol.packet.KeepAlive;
 import net.md_5.bungee.protocol.packet.Kick;
@@ -86,6 +88,22 @@ public enum Protocol
                     map( ProtocolConstants.MINECRAFT_1_9, 0x0C ),
                     map( ProtocolConstants.MINECRAFT_1_12, 0x0C )
             );
+            // Waterfall start
+            TO_CLIENT.registerPacket(
+                    EntityEffect.class,
+                    map(ProtocolConstants.MINECRAFT_1_8, 0x1D),
+                    map(ProtocolConstants.MINECRAFT_1_9, 0x4C),
+                    map(ProtocolConstants.MINECRAFT_1_9_4, 0x4B),
+                    map(ProtocolConstants.MINECRAFT_1_10, 0x4B),
+                    map(ProtocolConstants.MINECRAFT_1_12, 0x4E)
+            );
+            TO_CLIENT.registerPacket(
+                    EntityRemoveEffect.class,
+                    map(ProtocolConstants.MINECRAFT_1_8, 0x1E),
+                    map(ProtocolConstants.MINECRAFT_1_9, 0x31),
+                    map(ProtocolConstants.MINECRAFT_1_12, 0x32)
+            );
+            // Waterfall end
             TO_CLIENT.registerPacket(
                     PlayerListItem.class, // PlayerInfo
                     map( ProtocolConstants.MINECRAFT_1_8, 0x38 ),
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityEffect.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityEffect.java
new file mode 100644
index 00000000..d11a9ea9
--- /dev/null
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityEffect.java
@@ -0,0 +1,45 @@
+package net.md_5.bungee.protocol.packet;
+
+import io.netty.buffer.ByteBuf;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+import net.md_5.bungee.protocol.AbstractPacketHandler;
+import net.md_5.bungee.protocol.DefinedPacket;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@EqualsAndHashCode(callSuper = false)
+public class EntityEffect extends DefinedPacket {
+
+    private int entityId;
+    private int effectId;
+    private int amplifier;
+    private int duration;
+    private boolean hideParticles;
+
+    @Override
+    public void read(ByteBuf buf) {
+        this.entityId = readVarInt(buf);
+        this.effectId = buf.readUnsignedByte();
+        this.amplifier = buf.readUnsignedByte();
+        this.duration = readVarInt(buf);
+        this.hideParticles = buf.readBoolean();
+    }
+
+    @Override
+    public void write(ByteBuf buf) {
+        writeVarInt(this.entityId, buf);
+        buf.writeByte(this.effectId);
+        buf.writeByte(this.amplifier);
+        writeVarInt(this.duration, buf);
+        buf.writeBoolean(this.hideParticles);
+    }
+
+    @Override
+    public void handle(AbstractPacketHandler handler) throws Exception {
+        handler.handle(this);
+    }
+}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityRemoveEffect.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityRemoveEffect.java
new file mode 100644
index 00000000..7ed2dc3a
--- /dev/null
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EntityRemoveEffect.java
@@ -0,0 +1,36 @@
+package net.md_5.bungee.protocol.packet;
+
+import io.netty.buffer.ByteBuf;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+import net.md_5.bungee.protocol.AbstractPacketHandler;
+import net.md_5.bungee.protocol.DefinedPacket;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+@EqualsAndHashCode(callSuper = false)
+public class EntityRemoveEffect extends DefinedPacket {
+
+    private int entityId;
+    private int effectId;
+
+    @Override
+    public void read(ByteBuf buf) {
+        this.entityId = readVarInt(buf);
+        this.effectId = buf.readUnsignedByte();
+    }
+
+    @Override
+    public void write(ByteBuf buf) {
+        writeVarInt(this.entityId, buf);
+        buf.writeByte(effectId);
+    }
+
+    @Override
+    public void handle(AbstractPacketHandler handler) throws Exception {
+        handler.handle(this);
+    }
+}
diff --git a/proxy/src/main/java/net/md_5/bungee/UserConnection.java b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
index 23e03ca2..e1aa8213 100644
--- a/proxy/src/main/java/net/md_5/bungee/UserConnection.java
+++ b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
@@ -2,7 +2,9 @@ package net.md_5.bungee;
 
 import com.google.common.base.Objects;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Multimap;
 import io.netty.bootstrap.Bootstrap;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFuture;
@@ -127,6 +129,10 @@ public final class UserConnection implements ProxiedPlayer
     private final Scoreboard serverSentScoreboard = new Scoreboard();
     @Getter
     private final Collection<UUID> sentBossBars = new HashSet<>();
+    // Waterfall start
+    @Getter
+    private final Multimap<Integer, Integer> potions = HashMultimap.create();
+    // Waterfall end
     /*========================================================================*/
     @Getter
     private String displayName;
diff --git a/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java b/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
index 1cdfb995..30ee7d16 100644
--- a/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
+++ b/proxy/src/main/java/net/md_5/bungee/connection/DownstreamBridge.java
@@ -31,6 +31,8 @@ import net.md_5.bungee.netty.PacketHandler;
 import net.md_5.bungee.protocol.DefinedPacket;
 import net.md_5.bungee.protocol.PacketWrapper;
 import net.md_5.bungee.protocol.packet.BossBar;
+import net.md_5.bungee.protocol.packet.EntityEffect;
+import net.md_5.bungee.protocol.packet.EntityRemoveEffect;
 import net.md_5.bungee.protocol.packet.KeepAlive;
 import net.md_5.bungee.protocol.packet.PlayerListItem;
 import net.md_5.bungee.protocol.packet.Respawn;
@@ -520,6 +522,32 @@ public class DownstreamBridge extends PacketHandler
         }
     }
 
+    // Waterfall start
+    @Override
+    public void handle(EntityEffect entityEffect) throws Exception
+    {
+        // Don't send any potions when switching between servers (which involves a handshake), which can trigger a race
+        // condition on the client.
+        if (this.con.getForgeClientHandler().isForgeUser() && !this.con.getForgeClientHandler().isHandshakeComplete()) {
+            throw CancelSendSignal.INSTANCE;
+        }
+        con.getPotions().put(rewriteEntityId(entityEffect.getEntityId()), entityEffect.getEffectId());
+    }
+
+    @Override
+    public void handle(EntityRemoveEffect removeEffect) throws Exception
+    {
+        con.getPotions().remove(rewriteEntityId(removeEffect.getEntityId()), removeEffect.getEffectId());
+    }
+
+    private int rewriteEntityId(int entityId) {
+        if (entityId == con.getServerEntityId()) {
+            return con.getClientEntityId();
+        }
+        return entityId;
+    }
+    // Waterfall end
+
     @Override
     public void handle(Respawn respawn)
     {
diff --git a/proxy/src/main/java/net/md_5/bungee/forge/ForgeClientHandler.java b/proxy/src/main/java/net/md_5/bungee/forge/ForgeClientHandler.java
index 673497e5..17e250d4 100644
--- a/proxy/src/main/java/net/md_5/bungee/forge/ForgeClientHandler.java
+++ b/proxy/src/main/java/net/md_5/bungee/forge/ForgeClientHandler.java
@@ -8,6 +8,8 @@ import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.Setter;
 import net.md_5.bungee.UserConnection;
+import net.md_5.bungee.protocol.ProtocolConstants;
+import net.md_5.bungee.protocol.packet.EntityRemoveEffect;
 import net.md_5.bungee.protocol.packet.PluginMessage;
 
 /**
@@ -90,9 +92,23 @@ public class ForgeClientHandler
     public void resetHandshake()
     {
         state = ForgeClientHandshakeState.HELLO;
+
+        // This issue only exists in Forge 1.8.9
+        if (this.con.getPendingConnection().getVersion() == ProtocolConstants.MINECRAFT_1_8) {
+            this.resetAllThePotions(con);
+        }
+
         con.unsafe().sendPacket( ForgeConstants.FML_RESET_HANDSHAKE );
     }
 
+    private void resetAllThePotions(UserConnection con) {
+        // Just to be sure
+        for (Map.Entry<Integer, Integer> entry: con.getPotions().entries()) {
+            con.unsafe().sendPacket(new EntityRemoveEffect(entry.getKey(), entry.getValue()));
+        }
+        con.getPotions().clear();
+    }
+
     /**
      * Sends the server mod list to the client, or stores it for sending later.
      *
-- 
2.13.0.windows.1