Fixed ftp.rb so it closes all data sockets

ftp.rb was doing a shutdown without a close on data
(not command) sockets.  This can cause CLOSE_WAIT
for extended periods in certain circumstances-ending
only when msf itself is closed.

Author: bigendiansmalls

lib/msf/core/exploit/ftp.rb

@@ -96,8 +96,14 @@ def data_connect(mode = nil, nsock = self.sock)
   # This method handles disconnecting our data channel
   #
   def data_disconnect
-    self.datasocket.shutdown if self.datasocket
-    self.datasocket = nil
+    begin
+      if datasocket
+        datasocket.shutdown
+        datasocket.close
+      end
+    rescue IOError
+    end
+    datasocket = nil if datasocket
   end
 
   #