lints/lint_subject_contains_reserved_arpa_ip.go
func reversedLabelsToIPv4(labels []string) net.IP {
	var buf strings.Builder

	// If there aren't the right number of labels, it isn't an IPv4 address.
	if len(labels) != rdnsIPv4Labels {
		return nil
	}

	// An IPv4 address is represented as four groups of bytes separated by '.'
	for i := len(labels) - 1; i >= 0; i-- {
		buf.WriteString(labels[i])
		if i != 0 {
			buf.WriteString(".")
		}
	}
	return net.ParseIP(buf.String())
}
func reversedLabelsToIPv4(labels []string) net.IP {
	var buf strings.Builder

	// If there aren't the right number of labels, it isn't an IPv4 address.
	if len(labels) != rdnsIPv4Labels {
		return nil
	}

	// An IPv4 address is represented as four groups of bytes separated by '.'
	for i := len(labels) - 1; i >= 0; i-- {
		buf.WriteString(labels[i])
		if i != 0 {
			buf.WriteString(".")
		}
	}
	return net.ParseIP(buf.String())
}
// reversedLabelsToIPv4 reverses the provided labels (assumed to be 4 labels,
// one per byte of the IPv6 address) and constructs an IPv4 address, returning
// the result of calling net.ParseIP for the constructed address.