code: func (p PortBinding) HostAddr() (net.Addr, error) {
  	switch p.Proto {
  	case UDP:
  		return &net.UDPAddr{IP: p.HostIP, Port: int(p.HostPort)}, nil
  	case TCP:
  		return &net.TCPAddr{IP: p.HostIP, Port: int(p.HostPort)}, nil
  	case SCTP:
  		return &sctp.SCTPAddr{IP: []net.IP{p.HostIP}, Port: int(p.HostPort)}, nil
  	default:
  		return nil, ErrInvalidProtocolBinding(p.Proto.String())
  	}
  }
docs: // HostAddr returns the host side transport address