Rewrite the spawn player packet's uuid to support skins on non ip-fowarded servers

proxy/src/main/java/net/md_5/bungee/BungeeCord.java

@@ -26,6 +26,7 @@ import java.net.InetSocketAddress;
 import java.text.MessageFormat;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
@@ -33,6 +34,7 @@ import java.util.MissingResourceException;
 import java.util.ResourceBundle;
 import java.util.Timer;
 import java.util.TimerTask;
+import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
@@ -101,6 +103,11 @@ public class BungeeCord extends ProxyServer
      */
     private final Map<String, UserConnection> connections = new CaseInsensitiveMap<>();
     private final ReadWriteLock connectionLock = new ReentrantReadWriteLock();
+    /**
+     * Skin support for servers that don't support ip-forwarding
+     */
+    private final Map<String, String> uuidMap = new HashMap<>();
+    private final ReadWriteLock uuidLock = new ReentrantReadWriteLock();
     /**
      * Plugin manager.
      */
@@ -538,6 +545,42 @@ public class BungeeCord extends ProxyServer
         }
     }
 
+    public void addUUID(String offlineUUID, String actualUUID)
+    {
+        uuidLock.writeLock().lock();
+        try
+        {
+            uuidMap.put( offlineUUID, actualUUID );
+        } finally
+        {
+            uuidLock.writeLock().unlock();
+        }
+    }
+
+    public void removeUUID(String offlineUUID)
+    {
+        uuidLock.writeLock().lock();
+        try
+        {
+            uuidMap.remove( offlineUUID );
+        } finally
+        {
+            uuidLock.writeLock().unlock();
+        }
+    }
+
+    public String getActualUUID(String offlineUUID)
+    {
+        uuidLock.readLock().lock();
+        try
+        {
+            return uuidMap.get( offlineUUID );
+        } finally
+        {
+            uuidLock.readLock().unlock();
+        }
+    }
+
     @Override
     public CustomTabList customTabList(ProxiedPlayer player)
     {

proxy/src/main/java/net/md_5/bungee/EntityMap.java

@@ -16,8 +16,12 @@ public class EntityMap
     private final boolean[] serverboundInts = new boolean[ 256 ];
     private final boolean[] serverboundVarInts = new boolean[ 256 ];
 
+    private final int version;
+
     public EntityMap(int version)
     {
+        this.version = version;
+
         clientboundInts[0x04] = true; // Entity Equipment
         clientboundInts[0x0A] = true; // Use bed
         clientboundVarInts[0x0B] = true; // Animation
@@ -137,6 +141,22 @@ public class EntityMap
                     }
                 }
             }
+        } else if ( packetId == 0x0C /* Spawn Player */ && version == 5 )
+        {
+            DefinedPacket.readVarInt( packet );
+            int idLength = packet.readerIndex() - readerIndex - packetIdLength;
+            String uuid = DefinedPacket.readString( packet );
+            if ( uuid.length() == 36 ) {
+                String actualUUID = BungeeCord.getInstance().getActualUUID( uuid );
+                if ( actualUUID != null )
+                {
+                    packet.readerIndex( readerIndex );
+                    int writerIndex = packet.writerIndex();
+                    packet.writerIndex( readerIndex + packetIdLength + idLength );
+                    DefinedPacket.writeString( actualUUID, packet );
+                    packet.writerIndex( writerIndex );
+                }
+            }
         }
         packet.readerIndex( readerIndex );
     }

proxy/src/main/java/net/md_5/bungee/connection/InitialHandler.java

@@ -83,6 +83,8 @@ public class InitialHandler extends PacketHandler implements PendingConnection
     private InetSocketAddress virtualHost;
     @Getter
     private UUID uniqueId;
+    @Getter
+    private UUID offlineId;
 
     private enum State
     {
@@ -367,10 +369,12 @@ public class InitialHandler extends PacketHandler implements PendingConnection
                     {
                         if ( ch.getHandle().isActive() )
                         {
+                            offlineId = java.util.UUID.nameUUIDFromBytes( ( "OfflinePlayer:" + getName() ).getBytes( Charsets.UTF_8 ) );
                             if ( uniqueId == null )
                             {
-                                uniqueId = java.util.UUID.nameUUIDFromBytes( ( "OfflinePlayer:" + getName() ).getBytes( Charsets.UTF_8 ) );
+                                uniqueId = offlineId;
                             }
+                            BungeeCord.getInstance().addUUID( offlineId.toString(), uniqueId.toString() );
                             // Version 5 == 1.7.6. This is a screwup as 1.7.6 was also a snapshot.
                             if ( getVersion() == 5 )
                             {

proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java

@@ -52,6 +52,7 @@ public class UpstreamBridge extends PacketHandler
         bungee.getPluginManager().callEvent( event );
         con.getTabList().onDisconnect();
         BungeeCord.getInstance().removeConnection( con );
+        BungeeCord.getInstance().removeUUID( con.getPendingConnection().getOfflineId().toString() );
 
         if ( con.getServer() != null )
         {