'socket' 事件

• socket <stream.Duplex>

除非用户指定 <net.Socket> 以外的套接字类型，否则此事件保证传入 <net.Socket> 类（<stream.Duplex> 的子类）的实例。

• socket <stream.Duplex>

This event is guaranteed to be passed an instance of the <net.Socket> class, a subclass of <stream.Duplex>, unless the user specifies a socket type other than <net.Socket>.