ip_utils.py

# -*- coding: utf-8 -*-
import random


def ip_to_num(ip):
    """Takes an IP string and returns its decimal equivalent"""
    octects = ip.split(".")
    if len(octects) == 4:
        num = sum([int(octects[i]) << ((3-i)*8) for i in range(0, 4)])
        if num < 0 or num > 0xFFFFFFFF:
            return None
        else:
            return num
    else:
        return None


def num_to_ip(num):
    """Takes an decimal representation of an IP and converts to a string"""
    if num < 0 or num > 0xFFFFFFFF:
        return None
    else:
        return ".".join([str((num >> ((3-i)*8)) & 0xFF) for i in range(0, 4)])


def _gen_rand():
    return random.randint(0, 255)


def gen_pub_ip():
    """generate a random ip"""
    not_valid = [10, 127, 169, 172, 192]
    first = _gen_rand()
    while first in not_valid:
        first = _gen_rand()

    rand_strs = [str(first)]
    for _ in range(3):
        rand_strs.append(str(_gen_rand()))

    return '.'.join(rand_strs)


if __name__ == '__main__':
    print gen_pub_ip()