La Vita è Bella

This script will convert a line contains start and end IP separated by space like:

221.192.0.0 221.199.207.255

Into IP mask format (with comment) like:

#221.192.0.0 - 221.199.207.255
221.192.0.0/14
221.196.0.0/15
221.198.0.0/16
221.199.0.0/17
221.199.128.0/18
221.199.192.0/20

The script is:

 1 #!/usr/bin/env python
 2
 3 import sys
 4 import re
 5
 6 def ip2int(ip) :
 7         ret = 0
 8         match = re.match("(\d*)\.(\d*)\.(\d*)\.(\d*)", ip)
 9         if not match : return 0
10         for i in xrange(4) : ret = (ret << 8) + int(match.groups()[i])
11         return ret
12
13 def int2ip(ipnum) :
14         ip1 = ipnum >> 24
15         ip2 = ipnum >> 16 & 0xFF
16         ip3 = ipnum >> 8 & 0xFF
17         ip4 = ipnum & 0xFF
18         return "%d.%d.%d.%d" % (ip1, ip2, ip3, ip4)
19
20 def printrange(startip, endip) :
21         bits = 1
22         mask = 1
23         while bits < 32 :
24                 newip = startip | mask
25                 if (newip>endip) or (((startip>>bits) << bits) != startip) :
26                         bits = bits - 1
27                         mask = mask >> 1
28                         break
29                 bits = bits + 1
30                 mask = (mask<<1) + 1
31         newip = startip | mask
32         bits = 32 - bits
33         print "%s/%d" % (int2ip(startip), bits)
34         if newip < endip :
35                 printrange(newip + 1, endip)
36
37 while 1 :
38         line = sys.stdin.readline().strip()
39         if not line : break
40         chars = line.split(" ")
41         print "#%s - %s" % (chars[0], chars[1])
42         ip1 = ip2int(chars[0])
43         ip2 = ip2int(chars[1])
44         printrange(ip1, ip2)
45