val equalsSign = header.delimiterOffset('=', pos, pairEnd)
      val name = header.trimSubstring(pos, equalsSign)
      if (name.startsWith("$")) {
        pos = pairEnd + 1
        continue
      }

      // We have either name=value or just a name.
      var value =
        if (equalsSign < pairEnd) {
          header.trimSubstring(equalsSign + 1, pairEnd)
        } else {
          ""
        }

      if (pairEqualsSign == cookiePairEnd) return null

      val cookieName = setCookie.trimSubstring(endIndex = pairEqualsSign)
      if (cookieName.isEmpty() || cookieName.indexOfControlOrNonAscii() != -1) return null

      val cookieValue = setCookie.trimSubstring(pairEqualsSign + 1, cookiePairEnd)
      if (cookieValue.indexOfControlOrNonAscii() != -1) return null

      var expiresAt = MAX_DATE

      '\t', '\n', '\u000C', '\r', ' ' -> Unit
      else -> return i + 1
    }
  }
  return startIndex
}

/** Equivalent to `string.substring(startIndex, endIndex).trim()`. */
fun String.trimSubstring(
  startIndex: Int = 0,
  endIndex: Int = length,
): String {
  val start = indexOfFirstNonAsciiWhitespace(startIndex, endIndex)
  val end = indexOfLastNonAsciiWhitespace(start, endIndex)