#!/usr/bin/python
"""
convert mac addr to ipv6 link local (rfc 4862)
"""

# the mac should become: fe80::2177:02ff:fed2:ff9b
mac='23:77:02:d2:ff:9b'

def mac_to_ipv6_linklocal(mac):

  # remove the most common macaddr delimiters, dots, dashes, etc.
  # cast the hex string to an base-16 int for math safety.
  # use xor of 02 on the 2nd most significant hex char.
  # Remove/slice the '0x' off the begining from using hex().

  m = hex(int(mac.translate(None,' .:-'),16)^0x020000000000)[2:]
  return 'fe80::%s:%sff:fe%s:%s' %(m[:4],m[4:6],m[6:8],m[8:12])


print mac_to_ipv6_linklocal(mac)

>>> mac_value = 0x237702d2ff9b
>>> format(mac_value, '012x')
'237702d2ff9b'
>>> format(42, '012x')
'00000000002a'

def mac_to_ipv6_linklocal(mac):
    # Remove the most common delimiters; dots, dashes, etc.
    mac_value = int(mac.translate(None, ' .:-'), 16)

    # Split out the bytes that slot into the IPv6 address
    # XOR the most significant byte with 0x02, inverting the
    # Universal / Local bit
    high2 = mac_value >> 32 & 0xffff ^ 0x0200
    high1 = mac_value >> 24 & 0xff
    low1 = mac_value >> 16 & 0xff
    low2 = mac_value & 0xffff

    return 'fe80::{:04x}:{:02x}ff:fe{:02x}:{:04x}'.format(
        high2, high1, low1, low2)