Muduo Non-blocking Address Resolver using UDNS
https://github.com/chenshuo/muduo-udns

Copyright (C) 2012  Chen Shuo <chenshuo@chenshuo.com>
This file is part of muduo-udns library, a non-blocking DNS
stub resolver built on top of UDNS (www.corpit.ru/mjt/udns.html)
and Muduo (code.google.com/p/muduo).
Requires Muduo 0.3.2 and above.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library, in file named COPYING.LGPL; if not,
write to the Free Software Foundation, Inc., 59 Temple Place,
Suite 330, Boston, MA  02111-1307  USA

Note: muduo-udns is LGPL, because it redistributes UDNS, and UDNS is LGPL.