用P2P技术设计的一个简易聊天程序，要求不使用专用的主服务器，只要将好友添加到好友列表中就能检测好友是否在线，并相互发送聊天信息-Using P2P technology, design a simple chat program, asked not to use a dedicated master server, as long as the friend added to the Friends list will be able to detect friends are online