func hasRoutableIP(network string, ifi *net.Interface) (net.IP, bool) {
	ifat, err := ifi.Addrs()
	if err != nil {
		return nil, false
	}
	for _, ifa := range ifat {
		switch ifa := ifa.(type) {
		case *net.IPAddr:
			if ip, ok := routableIP(network, ifa.IP); ok {
				return ip, true
			}
		case *net.IPNet:
			if ip, ok := routableIP(network, ifa.IP); ok {
				return ip, true
			}
		}
	}

	"os"
)

// A FatFile is a Mach-O universal binary that contains at least one architecture.
type FatFile struct {
	Magic  uint32
	Arches []FatArch
	closer io.Closer
}

// A FatArchHeader represents a fat header for a specific image architecture.
type FatArchHeader struct {
	Cpu    Cpu
	SubCpu uint32
	Offset uint32
	Size   uint32
	Align  uint32
}

const fatArchHeaderSize = 5 * 4

func p521Polynomial(y2, x *fiat.P521Element) *fiat.P521Element {
	y2.Square(x)
	y2.Mul(y2, x)

	threeX := new(fiat.P521Element).Add(x, x)
	threeX.Add(threeX, x)
	y2.Sub(y2, threeX)

	return y2.Add(y2, p521B())
}

func p521CheckOnCurve(x, y *fiat.P521Element) error {
	// y² = x³ - 3x + b
	rhs := p521Polynomial(new(fiat.P521Element), x)
	lhs := new(fiat.P521Element).Square(y)

	// prime order elliptic curves" (https://eprint.iacr.org/2015/1060), §A.2.

	t0 := new(fiat.P224Element).Mul(p1.x, p2.x)  // t0 := X1 * X2
	t1 := new(fiat.P224Element).Mul(p1.y, p2.y)  // t1 := Y1 * Y2
	t2 := new(fiat.P224Element).Mul(p1.z, p2.z)  // t2 := Z1 * Z2
	t3 := new(fiat.P224Element).Add(p1.x, p1.y)  // t3 := X1 + Y1
	t4 := new(fiat.P224Element).Add(p2.x, p2.y)  // t4 := X2 + Y2

	y2.Square(x)
	y2.Mul(y2, x)

	threeX := new(fiat.P384Element).Add(x, x)
	threeX.Add(threeX, x)
	y2.Sub(y2, threeX)

	return y2.Add(y2, p384B())
}

func p384CheckOnCurve(x, y *fiat.P384Element) error {
	// y² = x³ - 3x + b
	rhs := p384Polynomial(new(fiat.P384Element), x)
	lhs := new(fiat.P384Element).Square(y)
	if rhs.Equal(lhs) != 1 {

	// prime order elliptic curves" (https://eprint.iacr.org/2015/1060), §A.2.

	t0 := new(fiat.P256Element).Mul(p1.x, p2.x)  // t0 := X1 * X2
	t1 := new(fiat.P256Element).Mul(p1.y, p2.y)  // t1 := Y1 * Y2
	t2 := new(fiat.P256Element).Mul(p1.z, p2.z)  // t2 := Z1 * Z2
	t3 := new(fiat.P256Element).Add(p1.x, p1.y)  // t3 := X1 + Y1
	t4 := new(fiat.P256Element).Add(p2.x, p2.y)  // t4 := X2 + Y2

	r.Mul(r, t0)

	// v = x^(2^127-1)^2 * x
	v := new(fiat.P224Element).Square(r)
	v.Mul(v, x)

	// r = x^(2^127-1) * x
	r.Mul(r, x)

	// for i = n-1 down to 1:
	//     w = v^(2^(i-1))
	//     if w == -1 then:
	//         v <- v*GG[n-i]
	//         r <- r*GG[n-i-1]

	var p224MinusOne = new(fiat.P224Element).Sub(
		new(fiat.P224Element), new(fiat.P224Element).One())

	for i := 96 - 1; i >= 1; i-- {

	rtm.parse = rtm.parseRouteMessage
	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrDragonFlyBSD4}
	ifm.parse = ifm.parseInterfaceMessage
	ifam := &wireFormat{extOff: sizeofIfaMsghdrDragonFlyBSD4, bodyOff: sizeofIfaMsghdrDragonFlyBSD4}
	ifam.parse = ifam.parseInterfaceAddrMessage
	ifmam := &wireFormat{extOff: sizeofIfmaMsghdrDragonFlyBSD4, bodyOff: sizeofIfmaMsghdrDragonFlyBSD4}

	ifm.parse = ifm.parseInterfaceMessage
	ifm2 := &wireFormat{extOff: 32, bodyOff: sizeofIfMsghdr2Darwin15}
	ifm2.parse = ifm2.parseInterfaceMessage
	ifam := &wireFormat{extOff: sizeofIfaMsghdrDarwin15, bodyOff: sizeofIfaMsghdrDarwin15}
	ifam.parse = ifam.parseInterfaceAddrMessage
	ifmam := &wireFormat{extOff: sizeofIfmaMsghdrDarwin15, bodyOff: sizeofIfmaMsghdrDarwin15}
	ifmam.parse = ifmam.parseInterfaceMulticastAddrMessage

	rtm.parse = rtm.parseRouteMessage
	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrNetBSD7}
	ifm.parse = ifm.parseInterfaceMessage
	ifam := &wireFormat{extOff: sizeofIfaMsghdrNetBSD7, bodyOff: sizeofIfaMsghdrNetBSD7}
	ifam.parse = ifam.parseInterfaceAddrMessage
	ifanm := &wireFormat{extOff: sizeofIfAnnouncemsghdrNetBSD7, bodyOff: sizeofIfAnnouncemsghdrNetBSD7}
	ifanm.parse = ifanm.parseInterfaceAnnounceMessage