socket.address()
返回操作系统报告的 socket 的地址、地址族和端口。返回的对象有三个属性，例如：
{ port: 12346, family: 'IPv4', address: '127.0.0.1' }
- Returns: <Object>
Returns the bound address, the address family name and port of the
socket as reported by the operating system:
{ port: 12346, family: 'IPv4', address: '127.0.0.1' }