import re

ipv4MatchStr = r'[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
ipv6MatchChars = 'A-Fa-f0-9:.'

MATCH2 = '((?<!::[Ff]{4}:)%s)|((?<=::[Ff]{4}:)%s)' % (ipv4MatchStr, ipv4MatchStr)
MATCH3 = '|((?<=[^%s])[%s]+)' % (ipv6MatchChars, ipv6MatchChars)

HOST_IP_RE_2 = re.compile(MATCH2)
HOST_IP_RE_3 = re.compile(MATCH2 + MATCH3)

text = '[::ffff:208.123.4.22'

mo = HOST_IP_RE_2.search(text)
if mo:
    print(mo.group(0))

mo = HOST_IP_RE_3.search(text)
if mo:
    print(mo.group(0))