Ip utilities module for Python

_ip.pyx

from libc.stdio cimport sprintf
from libc.string cimport strlen, strtok

def reverse_ip(ip):
    cdef int ret
    cdef char *_ip = ip, *p1, *p2, *p3, *p4, rip[16]

    if strlen(_ip) > 15:
        raise ValueError('Invalid IP address')

    p1 = strtok(_ip, '.')
    p2 = strtok(NULL, '.')
    p3 = strtok(NULL, '.')
    p4 = strtok(NULL, '.')

    # Normally using snprintf here would be wise but since there is a
    # previous check for the length of the string we are splitting and
    # reversing it's safe to use sprintf in this instance as it is faster.
    sprintf(rip, "%s.%s.%s.%s", p4, p3, p2, p1)

    return rip