Strip hostname from InetSocketAddress (#679)

BungeeCord-Patches/0061-Strip-hostname-from-InetSocketAddress.patch

@@ -0,0 +1,55 @@
+From 1b1107674563adebad11d00b6625bf8f6cbb97d1 Mon Sep 17 00:00:00 2001
+From: mibac138 <5672750+mibac138@users.noreply.github.com>
+Date: Tue, 20 Jul 2021 00:47:59 +0200
+Subject: [PATCH] Strip hostname from InetSocketAddress
+
+Recently PaperSpigot added a host check that doesn't allow hostnames
+in ip addresses and if a hostname is present then it kicks the player
+with a configure ip forwarding in bungee to connect error message.
+By default Bungee doesn't actually include the hostname (as to include
+it you need to call getHostName which triggers reverse service lookups
+that add the hostname info). However, the only thing a bungee plugin
+needs to do is to call addr.getHostName() in PlayerLoginEvent to
+trigger this and block the player from joining any recent paper servers.
+This change strips the hostname from the ip address sent to the proxied
+server thus fixing this issue. Example address sent before:
+`123.123.123.123.ipv4.supernova.orange.pl`
+after:
+`123.123.123.123`.
+
+Context:
+hi! i have a papermc 1.16.5 and bungeecord server. i updated papermc and
+the server started rejecting me saying i need to configure If you wish
+to use IP forwarding, please enable it in your BungeeCord config as
+well but everything in config was good. so i started digging and
+found out papermc added a host_check like this
+Pattern HOST_PATTERN = Pattern.compile("[0-9a-f\\.:]{0,45}");
+If this pattern doesn't match the hostname in
+PacketHandshakeSetProtocol, the server kicks the user with the above
+message. In debug I saw that my hostname looks like this:
+123.123.123.123.ipv4.supernova.orange.pl. I messaged papermc about this
+and they said an dns resolved ip like this should not be possible.
+I started digging in bungeecord and found out an innocent plugin that
+called getConnection().getAddress().getHostName() caused the address to
+gain the ipv4..... suffix (getHostName does that under the hood).
+I once again contacted paper devs about this and was told this is a
+bungeecord issue, and its not on their side. So, long story short,
+when connecting to a proxied server you need to make sure not to send
+the host name
+
+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
+index 03dabe01..464acc6c 100644
+--- a/proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java
++++ b/proxy/src/main/java/net/md_5/bungee/util/AddressUtil.java
+@@ -11,7 +11,7 @@ public class AddressUtil
+
+     public static String sanitizeAddress(InetSocketAddress addr)
+     {
+-        String string = addr.getHostString();
++        String string = addr.getAddress().getHostAddress(); // Waterfall
+
+         // Remove IPv6 scope if present
+         if ( addr.getAddress() instanceof Inet6Address )
+--
+2.25.1
+