find_cidr.py

import IPy

def gen_next_net(cidr):
    """
    >>> from IPy import IP
    >>> get_next_net(IP("10.0.0.0/28"))
    IP('10.0.0.16/28')
    >>> reduce(lambda  acc, _: get_next_net(acc), range(10), IP("10.0.0.0/28"))
    IP('10.0.0.160/28')
    """
    return IPy.IP(cidr.broadcast().int() + 1).make_net(cidr.netmask())


def find_next_subnet(subnets):
    """Return next available cidr for subnet.

    :param [string] subnets: cidrs
    :returns: cidr
    :rtype: string
    """
    subnets = map(IPy.IP, subnets)
    subnets_29 = [net for net in subnets if net.len() == 8]
    subnet = IPy.IP("10.194.167.240/29")  # '0xac2a7f0'
    if len(subnets_29) != 0:
        subnet = sorted(subnets_29)[-1]

    def _check_cidr(cidr):
        if cidr.iptype() != 'PRIVATE':
            return False
        for subnet in subnets:
            if subnet.overlaps(cidr):
                return False
        return True

    for _ in range(100):
        subnet = gen_next_net(subnet)
        if _check_cidr(subnet):
            break
    else:
        raise Exception("Can not choose next cidr for subnets.")
    return str(subnet)