/**
 * Returns true if the length is not valid for DNS (empty or greater than 253 characters), or if any
 * label is longer than 63 characters. Trailing dots are okay.
 */
internal fun String.containsInvalidLabelLengths(): Boolean {
  if (length !in 1..253) return true

  var labelStart = 0
  while (true) {
    val dot = indexOf('.', startIndex = labelStart)
    val labelLength =
      when (dot) {