Initial DDC release

internal/guard/addresses.go

@@ -0,0 +1,54 @@
+package guard
+
+import "net/netip"
+
+var blockedPrefixes = []netip.Prefix{
+	netip.MustParsePrefix("0.0.0.0/8"),
+	netip.MustParsePrefix("10.0.0.0/8"),
+	netip.MustParsePrefix("100.64.0.0/10"),
+	netip.MustParsePrefix("127.0.0.0/8"),
+	netip.MustParsePrefix("169.254.0.0/16"),
+	netip.MustParsePrefix("172.16.0.0/12"),
+	netip.MustParsePrefix("192.0.0.0/24"),
+	netip.MustParsePrefix("192.0.2.0/24"),
+	netip.MustParsePrefix("192.88.99.0/24"),
+	netip.MustParsePrefix("192.168.0.0/16"),
+	netip.MustParsePrefix("198.18.0.0/15"),
+	netip.MustParsePrefix("198.51.100.0/24"),
+	netip.MustParsePrefix("203.0.113.0/24"),
+	netip.MustParsePrefix("224.0.0.0/4"),
+	netip.MustParsePrefix("240.0.0.0/4"),
+	netip.MustParsePrefix("::/128"),
+	netip.MustParsePrefix("::1/128"),
+	netip.MustParsePrefix("::ffff:0:0/96"),
+	netip.MustParsePrefix("64:ff9b::/96"),
+	netip.MustParsePrefix("64:ff9b:1::/48"),
+	netip.MustParsePrefix("100::/64"),
+	netip.MustParsePrefix("2001::/32"),
+	netip.MustParsePrefix("2001:db8::/32"),
+	netip.MustParsePrefix("2002::/16"),
+	netip.MustParsePrefix("fc00::/7"),
+	netip.MustParsePrefix("fe80::/10"),
+	netip.MustParsePrefix("fec0::/10"),
+	netip.MustParsePrefix("ff00::/8"),
+}
+
+func IsPublicAddress(address netip.Addr) bool {
+	address = address.Unmap().WithZone("")
+	if !address.IsValid() ||
+		!address.IsGlobalUnicast() ||
+		address.IsPrivate() ||
+		address.IsLoopback() ||
+		address.IsLinkLocalUnicast() ||
+		address.IsMulticast() ||
+		address.IsUnspecified() {
+		return false
+	}
+
+	for _, prefix := range blockedPrefixes {
+		if prefix.Contains(address) {
+			return false
+		}
+	}
+	return true
+}