v4mask         = IPMask{255, 255, 255, 0}
	v4mappedv6mask = IPMask{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 255, 255, 255, 0}
	v6mask         = IPMask{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0}
	badaddr        = IP{192, 168, 0}
	badmask        = IPMask{255, 255, 0}
	v4maskzero     = IPMask{0, 0, 0, 0}
)

// IPv4 mask a.b.c.d.
func IPv4Mask(a, b, c, d byte) IPMask {
	p := make(IPMask, IPv4len)
	p[0] = a
	p[1] = b
	p[2] = c
	p[3] = d
	return p
}

// CIDRMask returns an [IPMask] consisting of 'ones' 1 bits
// followed by 0s up to a total length of 'bits' bits.
// For a mask of this form, CIDRMask is the inverse of [IPMask.Size].
func CIDRMask(ones, bits int) IPMask {
	if bits != 8*IPv4len && bits != 8*IPv6len {
		return nil

					if i == _RTAX_NETMASK {
						nmrsa = rsa
					}
					if i == _RTAX_IFA {
						iprsa = rsa
					}
					off += (uint(rsa.Len) + 3) &^ 3
				}
				if iprsa != nil && nmrsa != nil {
					var mask IPMask
					var ip IP

					switch iprsa.Family {
					case syscall.AF_INET:
						ipsa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(iprsa))
						nmsa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(nmrsa))

		case *route.InterfaceAddrMessage:
			if index != 0 && index != m.Index {
				continue
			}
			var mask IPMask
			switch sa := m.Addrs[syscall.RTAX_NETMASK].(type) {
			case *route.Inet4Addr:
				mask = IPv4Mask(sa.IP[0], sa.IP[1], sa.IP[2], sa.IP[3])
			case *route.Inet6Addr:
				mask = make(IPMask, IPv6len)
				copy(mask, sa.IP[:])
			}
			var ip IP
			switch sa := m.Addrs[syscall.RTAX_IFA].(type) {

	if ifi != nil {
		name = ifi.Name
	}
	as, err := lif.Addrs(syscall.AF_UNSPEC, name)
	if err != nil {
		return nil, err
	}
	var ifat []Addr
	for _, a := range as {
		var ip IP
		var mask IPMask
		switch a := a.(type) {
		case *lif.Inet4Addr:
			ip = IPv4(a.IP[0], a.IP[1], a.IP[2], a.IP[3])
			mask = CIDRMask(a.PrefixLen, 8*IPv4len)
		case *lif.Inet6Addr:
			ip = make(IP, IPv6len)
			copy(ip, a.IP[:])

			maskfld := fields[1]
			maskfld = maskfld[1:]
			pfxlen, _, ok := dtoi(maskfld)
			if !ok {
				return nil, errors.New("cannot parse network mask for interface: " + status)
			}
			var mask IPMask
			if ip.To4() != nil { // IPv4 or IPv6 IPv4-mapped address
				mask = CIDRMask(pfxlen-8*len(v4InV6Prefix), 8*IPv4len)
			}
			if ip.To16() != nil && ip.To4() == nil { // IPv6 address

	// caches the mask size to avoid the penalty of calling clusterCIDR.Mask.Size()
	clusterMaskSize int
	// nodeMask is the network mask assigned to the nodes
	nodeMask net.IPMask
	// nodeMaskSize is the mask size, in bits,assigned to the nodes
	// caches the mask size to avoid the penalty of calling nodeMask.Size()
	nodeMaskSize int
	// maxCIDRs is the maximum number of CIDRs that can be allocated

}

type IpAddressString struct {
	String [16]byte
}

type IpMaskString IpAddressString

type IpAddrString struct {
	Next      *IpAddrString
	IpAddress IpAddressString
	IpMask    IpMaskString
	Context   uint32
}

const MAX_ADAPTER_NAME_LENGTH = 256
const MAX_ADAPTER_DESCRIPTION_LENGTH = 128
const MAX_ADAPTER_ADDRESS_LENGTH = 8

type IpAdapterInfo struct {

				}

				if !isValidIPMask(mask) {
					return nil, nil, nil, nil, fmt.Errorf("x509: IP constraint contained invalid mask %x", mask)
				}

				ips = append(ips, &net.IPNet{IP: net.IP(ip), Mask: net.IPMask(mask)})

			case emailTag:
				constraint := string(value)
				if err := isIA5String(constraint); err != nil {
					return nil, nil, nil, nil, errors.New("x509: invalid constraint value: " + err.Error())
				}

}

type IpAddressString struct {
	String [16]byte
}

type IpMaskString IpAddressString

type IpAddrString struct {
	Next      *IpAddrString
	IpAddress IpAddressString
	IpMask    IpMaskString
	Context   uint32
}

const MAX_ADAPTER_NAME_LENGTH = 256
const MAX_ADAPTER_DESCRIPTION_LENGTH = 128
const MAX_ADAPTER_ADDRESS_LENGTH = 8

type IpAdapterInfo struct {