private fun String.asciiToLowercase(): String {
    return when {
      isAscii() -> lowercase(Locale.US) // This is an ASCII string.
      else -> this
    }
  }

  /** Returns true if the [String] is ASCII encoded (0-127). */
  private fun String.isAscii() = length == utf8Size().toInt()

  /**
   * Returns true if [hostname] matches the domain name [pattern].
   *
   * @param hostname lower-case host name.

	0x70,
	0x71,
	0x72,
	0xfc,
	0x73,
	0xfd,
	0x1ffb,
	0x7fff0,
	0x1ffc,
	0x3ffc,
	0x22,
	0x7ffd,
	0x3,
	0x23,
	0x4,
	0x24,
	0x5,
	0x25,
	0x26,
	0x27,
	0x6,
	0x74,
	0x75,
	0x28,
	0x29,
	0x2a,
	0x7,
	0x2b,
	0x76,
	0x2c,
	0x8,
	0x9,
	0x2d,
	0x77,
	0x78,
	0x79,
	0x7a,
	0x7b,
	0x7ffe,
	0x7fc,

	return ip.Equal(IPv4zero) || ip.Equal(IPv6unspecified)
}

// IsLoopback reports whether ip is a loopback address.
func (ip IP) IsLoopback() bool {
	if ip4 := ip.To4(); ip4 != nil {
		return ip4[0] == 127
	}
	return ip.Equal(IPv6loopback)
}

// IsPrivate reports whether ip is a private address, according to
// RFC 1918 (IPv4 addresses) and RFC 4193 (IPv6 addresses).
func (ip IP) IsPrivate() bool {

	IFT_SIPTG                         = 0xcb
	IFT_SLIP                          = 0x1c
	IFT_SMDSDXI                       = 0x2b
	IFT_SMDSICIP                      = 0x34
	IFT_SONET                         = 0x27
	IFT_SONETOVERHEADCHANNEL          = 0xb9
	IFT_SONETPATH                     = 0x32
	IFT_SONETVT                       = 0x33
	IFT_SRP                           = 0x97
	IFT_SS7SIGLINK                    = 0x9c

	IFT_SIPTG                         = 0xcb
	IFT_SLIP                          = 0x1c
	IFT_SMDSDXI                       = 0x2b
	IFT_SMDSICIP                      = 0x34
	IFT_SONET                         = 0x27
	IFT_SONETOVERHEADCHANNEL          = 0xb9
	IFT_SONETPATH                     = 0x32
	IFT_SONETVT                       = 0x33
	IFT_SRP                           = 0x97
	IFT_SS7SIGLINK                    = 0x9c

	AF_SIP                         = 0x18
	AF_SLOW                        = 0x21
	AF_SNA                         = 0xb
	AF_UNIX                        = 0x1
	AF_UNSPEC                      = 0x0
	AF_VENDOR00                    = 0x27
	AF_VENDOR01                    = 0x29
	AF_VENDOR02                    = 0x2b
	AF_VENDOR03                    = 0x2d
	AF_VENDOR04                    = 0x2f
	AF_VENDOR05                    = 0x31

	IFT_SIPTG                         = 0xcb
	IFT_SLIP                          = 0x1c
	IFT_SMDSDXI                       = 0x2b
	IFT_SMDSICIP                      = 0x34
	IFT_SONET                         = 0x27
	IFT_SONETOVERHEADCHANNEL          = 0xb9
	IFT_SONETPATH                     = 0x32
	IFT_SONETVT                       = 0x33
	IFT_SRP                           = 0x97
	IFT_SS7SIGLINK                    = 0x9c

	IFT_SIPTG                         = 0xcb
	IFT_SLIP                          = 0x1c
	IFT_SMDSDXI                       = 0x2b
	IFT_SMDSICIP                      = 0x34
	IFT_SONET                         = 0x27
	IFT_SONETOVERHEADCHANNEL          = 0xb9
	IFT_SONETPATH                     = 0x32
	IFT_SONETVT                       = 0x33
	IFT_SRP                           = 0x97
	IFT_SS7SIGLINK                    = 0x9c

	0xd2, 0xb4, 0xee, 0x4c, 0x30, 0x3e, 0x71, 0x7a, 0x2c, 0xa0, 0xe1, 0xd8, 0x1c, 0xf6, 0x3d, 0x45,
	0x0a, 0x69, 0xc4, 0xe3, 0xd0, 0xa1, 0xff, 0xc4, 0x8a, 0x4c, 0x9f, 0x0a, 0x32, 0x2b, 0x97, 0xf9,
	0x27, 0x56, 0x18, 0x07, 0x82, 0xf9, 0xe5, 0x34, 0x77, 0xff, 0x46, 0x88, 0x9c, 0x1e, 0xf5, 0xc9,
	0xef, 0xbc, 0xee, 0xb7, 0x2a, 0xac, 0x3d, 0x1b, 0xd1, 0xb0, 0x47, 0x89, 0x8b, 0x4e, 0x01, 0xac,

00000290  d4 db fe 3d 13 60 84 5c  21 d3 3b e9 fa e7 16 03  |...=.`.\!.;.....|
000002a0  03 00 cd 0c 00 00 c9 03  00 17 41 04 1e 18 37 ef  |..........A...7.|
000002b0  0d 19 51 88 35 75 71 b5  e5 54 5b 12 2e 8f 09 67  |..Q.5uq..T[....g|
000002c0  fd a7 24 20 3e b2 56 1c  ce 97 28 5e f8 2b 2d 4f  |..$ >.V...(^.+-O|
000002d0  9e f1 07 9f 6c 4b 5b 83  56 e2 32 42 e9 58 b6 d7  |....lK[.V.2B.X..|