source: genesis/nodes/getrange.py@ 4149

# zoek de eerste vrije (== niet in een wleiden.conf gedefinieerde) /30
# lvoge@cs.vu.nl
import popen2
import re

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\\\\..*\/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

while bezet.has_key(i):
        i = i + 4

print "%s/30: %s en %s\n" % (showaddr(i), showaddr(i + 1), showaddr(i + 2))