package privacy

import "net"

// Documentation, benchmarking, and well-known example addresses that carry no
// site information even though they are globally routable.
var nonSensitiveNets = func() []*net.IPNet {
	cidrs := []string{
		"192.0.2.0/24",    // RFC 5737 TEST-NET-1
		"198.51.100.0/24", // RFC 5737 TEST-NET-2
		"203.0.113.0/24",  // RFC 5737 TEST-NET-3
		"198.18.0.0/15",   // RFC 2544 benchmarking
		"100.64.0.0/10",   // RFC 6598 CGNAT
		"192.88.99.0/24",  // RFC 7526 6to4 relay anycast
	}
	out := make([]*net.IPNet, 0, len(cidrs))
	for _, c := range cidrs {
		if _, n, err := net.ParseCIDR(c); err == nil {
			out = append(out, n)
		}
	}
	return out
}()

var nonSensitiveExact = map[string]struct{}{
	"8.8.8.8": {}, "8.8.4.4": {}, "1.1.1.1": {}, "1.0.0.1": {},
	"4.2.2.2": {}, "4.2.2.1": {}, "9.9.9.9": {}, "1.2.3.4": {},
	"208.67.222.222": {}, "208.67.220.220": {},
}

// isSensitiveIP reports whether s is a routable address that could identify the
// customer's provider or site. Private (RFC1918/ULA), loopback, link-local,
// multicast, and the example/benchmark ranges above are not sensitive.
func isSensitiveIP(s string) bool {
	ip := net.ParseIP(s)
	if ip == nil {
		return false
	}
	if _, ok := nonSensitiveExact[s]; ok {
		return false
	}
	if ip.IsLoopback() || ip.IsPrivate() || ip.IsUnspecified() ||
		ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() ||
		ip.IsMulticast() || ip.IsInterfaceLocalMulticast() {
		return false
	}
	if !ip.IsGlobalUnicast() {
		return false
	}
	if v4 := ip.To4(); v4 != nil && (v4[0] == 0 || v4[0] == 255 || v4[0] >= 240) {
		return false
	}
	for _, n := range nonSensitiveNets {
		if n.Contains(ip) {
			return false
		}
	}
	return true
}