dhcp-lease-stats

#! /usr/bin/env python
#
"""
Print statistics about the DHCP leases.
"""
__docformat__ = 'reStructuredText'


from collections import defaultdict
from datetime import datetime


## main: run tests

# Example:
#
# lease 130.60.240.55 {
#   starts 3 2010/04/14 14:54:38;
#   ends 3 2010/04/14 17:54:38;
#   tstp 3 2010/04/14 17:54:38;
#   cltt 3 2010/04/14 14:54:38;
#   binding state free;
#   hardware ethernet 00:03:93:c1:8f:48;
#   uid "\001\000\003\223\301\217H";
# }
#

def parse_dhcpd_leases(path='/var/lib/dhcp/dhcpd.leases'):
    leases = defaultdict(dict)
    file = open(path, 'r')
    for line in file:
        line = line.strip()
        if line.startswith('lease'):
            _, addr, _ = line.split(None, 2)
            a1, a2, a3, a4 = addr.split('.')
            prefix = ("%s.%s.%s" % (a1, a2, a3))
            addr = a4
        elif line.startswith('starts'):
            _, _, timestamp  = line.split(None, 2)
            start = datetime.strptime(timestamp, '%Y/%m/%d %H:%M:%S;')
        elif line.startswith('ends never'):
            end = datetime(9999, 12, 31, 23, 59, 00)
        elif line.startswith('ends'):
            _, _, timestamp  = line.split(None, 2)
            end = datetime.strptime(timestamp, '%Y/%m/%d %H:%M:%S;')
        elif line.startswith('binding state'):
            _, _, state = line.split()
            if state.startswith('free'):
                state = 'free'
            else:
                state = 'used'
        elif line.startswith('}'):
            # commit values gathered so far
            if start < datetime.now() < end:
                leases[prefix][addr] = state
    return leases


def count(D):
    counts = defaultdict(int)
    for v in D.values():
        counts[v] += 1
    return counts


def main():
    leases = parse_dhcpd_leases()
    for netprefix in leases.keys():
        print ("%s:" % netprefix)
        counts = count(leases[netprefix])
        for state, num in counts.items():
            print ("  %s: %d" % (state, num))


if "__main__" == __name__:
    main()