package cidr import ( "fmt" "net" ) func NewCIDRRanger(cidr string) (CIDRRanger, error) { nIP, nIPNet, err := net.ParseCIDR(cidr) if nil != err { return nil, err } switch len(nIP) { case net.IPv4len: cr := &cidrRangeIPv4{ cidrNet: nIPNet, } return cr, nil case net.IPv6len: cr := &cidrRangeIPv6{ cidrNet: nIPNet, } return cr, nil default: return nil, fmt.Errorf("Net: not supported IP length") } } type CIDRRanger interface { Contains(ip net.IP) bool First() net.IP Last() net.IP Range() []net.IP Broadcast() net.IP Network() net.IP }