source: genesis/nodes/getrange.py@ 5688

# zoek de eerste vrije (== niet in een wleiden.conf gedefinieerde) interlink
# range
# lodewijk@wirelessleiden.nl
import popen2
import re
import sys

size = 30
if len(sys.argv) > 1:
        size = int(sys.argv[1])
numaddrs = 1 << (32 - size)

ipre = re.compile("^IP=(172\.16\.[0-9]+\.[0-9]+)/([0-9]+) *")

def parseaddr(s):
        f = s.split('.')
        return (long(f[0]) << 24L) + \
                (long(f[1]) << 16L) + \
                (long(f[2]) << 8L) + \
                long(f[3])

def showaddr(a):
        return "%d.%d.%d.%d" % ((a >> 24) & 0xff, (a >> 16) & 0xff, (a >> 8) & 0xff, a & 0xff)

bezet = {}

(cout, cin) = popen2.popen2("cat */wleiden.conf | grep ^IP | grep 172.16\...*\/[28\|29\|30]")
cin.close()
for l in cout.readlines():
        l = l[:-1]
        match = ipre.match(l)
        if match == None:
                print "'" + l + "'"
        addr = parseaddr(match.group(1))
        mask = int(match.group(2))
        addr = addr & ~((1 << (32 - mask)) - 1)
        bezet[addr] = 1

i = 0xffffffffL
for k in bezet.keys():
        if k < i:
                i = k

if size == 24:
        i = 0xac110000

while bezet.has_key(i):
        i = i + numaddrs

print "%s/%d:" % (showaddr(i), size),
print " en ".join([showaddr(i) for i in range(i + 1, i + numaddrs - 1)])