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