Question

Im trying to validate the input to see if it a valid IP address(could be a partial one).

Acceptable input : 172, 172.112, 172.112.113, 172.112.113.114

Unacceptable input: 1724,172.11113 etc etc

Heres a function that I created to check it (however it validates unacceptable input like 1724 which I cant seem to fix..please help)

def ipcheck(ip):
    ippattern_str = '(([1-2]?[\d]{1,2}\.?){0,1}(\.[1-2]?[\d]{1,2}){0,1}(\.[1-2]?[\d]{1,2}\.){0,1}(([1-2]?[\d]{1,2}[\D\W]*)'
    ippattern = re.compile(ippattern_str)
    # ippattern is now used to call match, passing only the ip string
    global matchip
    matchip = ippattern.match(ip)
    return matchip


ip = sys.argv[1]
ipcheck(ip)

print matchip

I feel like maybe I need to use anchors properly? Ive tried everything to my best knowledge, any help would be appreciated.

Answer 1

This regex would do the trick:

^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){0,3}$

It ensures that the given numbers are in the correct range (0-255) and can have 1-4 parts.

You can see it in action here: http://regexr.com?2va3j