assertFalse(InetAddresses.isMappedIPv4Address("::"));
    assertFalse(InetAddresses.isMappedIPv4Address("::ffff"));
    assertFalse(InetAddresses.isMappedIPv4Address("::ffff:0"));
    assertFalse(InetAddresses.isMappedIPv4Address("::fffe:0:0"));
    assertFalse(InetAddresses.isMappedIPv4Address("::1:ffff:0:0"));
    assertFalse(InetAddresses.isMappedIPv4Address("foo"));

 */
internal fun canonicalizeInetAddress(address: ByteArray): ByteArray {
  return when {
    isMappedIpv4Address(address) -> address.sliceArray(12 until 16)
    else -> address
  }
}

/** Returns true for IPv6 addresses like `0000:0000:0000:0000:0000:ffff:XXXX:XXXX`. */
private fun isMappedIpv4Address(address: ByteArray): Boolean {
  if (address.size != 16) return false

  for (i in 0 until 10) {

   * @param ipString {@code String} to be examined for embedded IPv4-mapped IPv6 address format
   * @return {@code true} if the argument is a valid "mapped" address
   * @since 10.0
   */
  public static boolean isMappedIPv4Address(String ipString) {
    byte[] bytes = ipStringToBytes(ipString, null);
    if (bytes != null && bytes.length == 16) {
      for (int i = 0; i < 10; i++) {
        if (bytes[i] != 0) {
          return false;

   * @param ipString {@code String} to be examined for embedded IPv4-mapped IPv6 address format
   * @return {@code true} if the argument is a valid "mapped" address
   * @since 10.0
   */
  public static boolean isMappedIPv4Address(String ipString) {
    byte[] bytes = ipStringToBytes(ipString, null);
    if (bytes != null && bytes.length == 16) {
      for (int i = 0; i < 10; i++) {
        if (bytes[i] != 0) {
          return false;