Waterfall/BungeeCord-Patches/0029-Fix-potion-race-condition-on-Forge-1.8.9.patch

From f5c341bf2e3a268299c88c9fe9726111194e498d 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 8d91211b..e2221010 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
@@ -278,4 +278,14 @@ public abstract class AbstractPacketHandler
     public void handle(ServerLinks serverLinks) throws Exception
     {
     }
+
+    // Waterfall start
+    public void handle(net.md_5.bungee.protocol.packet.EntityEffect entityEffect) throws Exception
+    {
+    }
+
+    public void handle(net.md_5.bungee.protocol.packet.EntityRemoveEffect removeEffect) throws Exception
+    {
+    }
+    // Waterfall end
 }
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 d8f7bc95..d15f2bcc 100644
--- a/proxy/src/main/java/net/md_5/bungee/UserConnection.java
+++ b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
@@ -1,7 +1,9 @@
 package net.md_5.bungee;
 
 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;
@@ -129,6 +131,10 @@ 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
     @Setter
     private String lastCommandTabbed;
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 d4036c5d..ad9fc042 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
@@ -753,6 +753,32 @@ public class DownstreamBridge extends PacketHandler
         }
     }
 
+    // Waterfall start
+    @Override
+    public void handle(net.md_5.bungee.protocol.packet.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(net.md_5.bungee.protocol.packet.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 d15044f4..bea2bbff 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
@@ -9,6 +9,8 @@ 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;
 
 /**
@@ -94,9 +96,23 @@ 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.
      *
-- 
2.45.1