From 7ec1f487c18791bb8bcec8dd0eb75030968a7347 Mon Sep 17 00:00:00 2001
From: md_5 <git@md-5.net>
Date: Tue, 25 May 2021 18:42:06 +1000
Subject: [PATCH] Remove ipv6 scope from forwarded addresses

Affects forwarding when epoll enabled
---
 .../java/net/md_5/bungee/ServerConnector.java |  3 ++-
 .../net/md_5/bungee/util/AddressUtil.java     | 26 +++++++++++++++++++
 .../net/md_5/bungee/util/AddressUtilTest.java | 19 ++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java
 create mode 100644 proxy/src/test/java/net/md_5/bungee/util/AddressUtilTest.java

diff --git a/proxy/src/main/java/net/md_5/bungee/ServerConnector.java b/proxy/src/main/java/net/md_5/bungee/ServerConnector.java
index fa2ceec5..a87585fb 100644
--- a/proxy/src/main/java/net/md_5/bungee/ServerConnector.java
+++ b/proxy/src/main/java/net/md_5/bungee/ServerConnector.java
@@ -51,6 +51,7 @@ import net.md_5.bungee.protocol.packet.ScoreboardObjective;
 import net.md_5.bungee.protocol.packet.ScoreboardScore;
 import net.md_5.bungee.protocol.packet.SetCompression;
 import net.md_5.bungee.protocol.packet.ViewDistance;
+import net.md_5.bungee.util.AddressUtil;
 import net.md_5.bungee.util.BufUtil;
 import net.md_5.bungee.util.QuietException;
 
@@ -102,7 +103,7 @@ public class ServerConnector extends PacketHandler
 
         if ( BungeeCord.getInstance().config.isIpForward() && user.getSocketAddress() instanceof InetSocketAddress )
         {
-            String newHost = copiedHandshake.getHost() + "\00" + user.getAddress().getHostString() + "\00" + user.getUUID();
+            String newHost = copiedHandshake.getHost() + "\00" + AddressUtil.sanitizeAddress( user.getAddress() ) + "\00" + user.getUUID();
 
             LoginResult profile = user.getPendingConnection().getLoginProfile();
             if ( profile != null && profile.getProperties() != null && profile.getProperties().length > 0 )
diff --git a/proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java b/proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java
new file mode 100644
index 00000000..03dabe01
--- /dev/null
+++ b/proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java
@@ -0,0 +1,26 @@
+package net.md_5.bungee.util;
+
+import java.net.Inet6Address;
+import java.net.InetSocketAddress;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class AddressUtil
+{
+
+    public static String sanitizeAddress(InetSocketAddress addr)
+    {
+        String string = addr.getHostString();
+
+        // Remove IPv6 scope if present
+        if ( addr.getAddress() instanceof Inet6Address )
+        {
+            int strip = string.indexOf( '%' );
+            return ( strip == -1 ) ? string : string.substring( 0, strip );
+        } else
+        {
+            return string;
+        }
+    }
+}
diff --git a/proxy/src/test/java/net/md_5/bungee/util/AddressUtilTest.java b/proxy/src/test/java/net/md_5/bungee/util/AddressUtilTest.java
new file mode 100644
index 00000000..e2a3a481
--- /dev/null
+++ b/proxy/src/test/java/net/md_5/bungee/util/AddressUtilTest.java
@@ -0,0 +1,19 @@
+package net.md_5.bungee.util;
+
+import java.net.InetSocketAddress;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class AddressUtilTest
+{
+
+    @Test
+    public void testScope()
+    {
+        InetSocketAddress addr = new InetSocketAddress( "0:0:0:0:0:0:0:1%0", 25577 );
+        Assert.assertEquals( "0:0:0:0:0:0:0:1", AddressUtil.sanitizeAddress( addr ) );
+
+        InetSocketAddress addr2 = new InetSocketAddress( "0:0:0:0:0:0:0:1", 25577 );
+        Assert.assertEquals( "0:0:0:0:0:0:0:1", AddressUtil.sanitizeAddress( addr2 ) );
+    }
+}