reverse_ipv6.py

# Python 3
def reverse_dotted_ipv6(address):
    ADDR_HEX_LEN = 32
    GROUP_LEN = 4
    
    try:
        splitted = address.replace('::', ':0000:').split(':') # check for grouping format
        if len([x for x in splitted if len(x) != GROUP_LEN]) != 0:
            return '(╯°□°）╯︵ ┻━┻)'
        bytearray.fromhex(address.replace(':', '')) # check for non-hex character
    except (AttributeError, ValueError):
        return '(╯°□°）╯︵ ┻━┻)'
    
    nhex = len([x for x in address if x != ':'])
    nmissing = ADDR_HEX_LEN - nhex
    stripped_addr = address.replace('::', nmissing * '0').replace(':', '')
    if len(stripped_addr) != ADDR_HEX_LEN: # check for correct address length
        return '(╯°□°）╯︵ ┻━┻)'
        
    return '.'.join(reversed(stripped_addr))
    
print(reverse_dotted_ipv6('FE80::0202:B3FF:FE1E:8329')) # 9.2.3.8.E.1.E.F.F.F.3.B.2.0.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.E.F
print(reverse_dotted_ipv6('FE80::0202:B3FF:FE1E:8329:DEAD:BEEF:DEAD:CAFE')) # (╯°□°）╯︵ ┻━┻)
print(reverse_dotted_ipv6('FE80::0202:B3FF:FE1E:8329:xxxx')) # (╯°□°）╯︵ ┻━┻)
print(reverse_dotted_ipv6('FE80:0202:B3FF:FE1E:8329')) # (╯°□°）╯︵ ┻━┻)
print(reverse_dotted_ipv6('192::168:2:1')) # (╯°□°）╯︵ ┻━┻)
print(reverse_dotted_ipv6(123)) # (╯°□°）╯︵ ┻━┻)