#
# subnet_allocator.py by Eli Fulkerson
#
# http://www.elifulkerson.com
#

import string

def drawsubnet (draw_from, draw_to, interesting, networknumber, count=0):

        spacer = " " * count
        antispacer = " " * (20 - count)

        number_of_hosts = num_hosts(32 - draw_from) + " hosts"
        
        networks_under = pow(2,(draw_to - draw_from))
        if networks_under > 1:
            networks_under = str(networks_under)
            networks_under = " - (" + networks_under + " /" + str(draw_to) + "'s under)"
        else:
            networks_under = ""

        net = base10_to_ip(networknumber)
        mask = subnetmask(draw_from)

        allocatee = whats_allocated(net,mask)

        if (draw_from <= draw_to or draw_from == interesting or allocatee):

            if not allocatee:
                allocatee = ""
            else:
                allocatee = " - " + allocatee
                
            print spacer + "/" +  str(draw_from) + antispacer + net + " - " + mask +" - "+ number_of_hosts + allocatee + networks_under

        if (draw_from < 30):
                drawsubnet(draw_from+1, draw_to, interesting, networknumber + 0, count+1)
                drawsubnet(draw_from+1, draw_to, interesting, networknumber + pow(2, (32-draw_from))/2, count+1)


def whats_allocated(networknumber, subnetmask):
    "Dirty little hack to stick some generic data into the output"
    n = networknumber
    m = subnetmask

    if (n == "172.20.128.0" and m == "255.255.252.0"):
        return "New York /22"
    elif (n == "172.20.132.0" and m == "255.255.252.0"):
        return "Los Angeles /22"
    elif (n == "172.20.136.0" and m == "255.255.252.0"):
        return "Chicago /22"
    elif (n == "172.20.255.0" and m == "255.255.255.0"):
        return "Management Networks"
    elif (n == "172.20.255.0" and m == "255.255.255.248"):
        return "Management network A"
    elif (n == "172.20.255.8" and m == "255.255.255.248"):
        return "Management network B"
    elif (n == "172.20.252.0" and m == "255.255.252.0"):
        return "Administrivia"

    else:
        return 0
    

def num_hosts(bits):
    return str(pow(2,bits)-2)

def subnetmask(bits):
    "Convert.. for instance, 24 to '255.255.255.0'"
    ones = bits
    zeros = 32 - bits
    mask = ("1" * ones) + ("0" * zeros)
    mask = int(mask, 2)
    mask = base10_to_ip(mask)
    return mask

def ip_to_base10(ip):
    "Given an IP address, convert to base10 integer"
    octets = string.split(ip, ".")

    total = 0
    total += int(octets[3])
    total += int(octets[2]) * 256
    total += int(octets[1]) * 65536
    total += int(octets[0]) * 16777216

    return total


def base10_to_ip(num):
    "Given an integer, convert to base2 dotted quad"
    oct1 = num / 16777216
    num = num % 16777216

    oct2 = num / 65536
    num = num % 65536

    oct3 = num / 256
    num = num % 256
    
    oct4 = num

    return str(oct1) + "." + str(oct2) + "." + str(oct3) + "." + str(oct4)



#The network number to start with...
start = ip_to_base10("172.20.128.0")

#An 'interesting' network size will always be shown, regardless if its used
interesting = 22

#The network size to start drawing from ( 0 to 30)
draw_from = 17

#the network size to stop drawing at (0 to 30, should be smaller (in size... /0 is largest, /30 smallest) than draw_from)
draw_to = 18

#OK, draw it
drawsubnet(draw_from, draw_to, interesting, start)

#start = ip_to_base10("192.168.0.0")
#drawsubnet(20,24, start)