diff --git a/files/dhcpleases b/files/dhcpleases new file mode 100644 index 0000000..40465c2 --- /dev/null +++ b/files/dhcpleases @@ -0,0 +1,260 @@ +#!/usr/bin/python +# source: http://askubuntu.com/revisions/fb67e8e2-efd4-4d0e-bb2f-416855fd8369/view-source +# by http://askubuntu.com/users/499043/dfsmith +import datetime, bisect + +def parse_timestamp(raw_str): + tokens = raw_str.split() + + if len(tokens) == 1: + if tokens[0].lower() == 'never': + return 'never'; + + else: + raise Exception('Parse error in timestamp') + + elif len(tokens) == 3: + return datetime.datetime.strptime(' '.join(tokens[1:]), + '%Y/%m/%d %H:%M:%S') + + else: + raise Exception('Parse error in timestamp') + + +def timestamp_is_ge(t1, t2): + if t1 == 'never': + return True + + elif t2 == 'never': + return False + + else: + return t1 >= t2 + + +def timestamp_is_lt(t1, t2): + if t1 == 'never': + return False + + elif t2 == 'never': + return t1 != 'never' + + else: + return t1 < t2 + + +def timestamp_is_between(t, tstart, tend): + return timestamp_is_ge(t, tstart) and timestamp_is_lt(t, tend) + + +def parse_hardware(raw_str): + tokens = raw_str.split() + + if len(tokens) == 2: + return tokens[1] + + else: + raise Exception('Parse error in hardware') + + +def strip_endquotes(raw_str): + return raw_str.strip('"') + + +def identity(raw_str): + return raw_str + + +def parse_binding_state(raw_str): + tokens = raw_str.split() + + if len(tokens) == 2: + return tokens[1] + + else: + raise Exception('Parse error in binding state') + + +def parse_next_binding_state(raw_str): + tokens = raw_str.split() + + if len(tokens) == 3: + return tokens[2] + + else: + raise Exception('Parse error in next binding state') + + +def parse_rewind_binding_state(raw_str): + tokens = raw_str.split() + + if len(tokens) == 3: + return tokens[2] + + else: + raise Exception('Parse error in next binding state') + + +def parse_leases_file(leases_file): + valid_keys = { + 'starts': parse_timestamp, + 'ends': parse_timestamp, + 'tstp': parse_timestamp, + 'tsfp': parse_timestamp, + 'atsfp': parse_timestamp, + 'cltt': parse_timestamp, + 'hardware': parse_hardware, + 'binding': parse_binding_state, + 'next': parse_next_binding_state, + 'rewind': parse_rewind_binding_state, + 'uid': strip_endquotes, + 'client-hostname': strip_endquotes, + 'option': identity, + 'set': identity, + 'on': identity, + 'abandoned': None, + 'bootp': None, + 'reserved': None, + } + + leases_db = {} + + lease_rec = {} + in_lease = False + in_failover = False + + for line in leases_file: + if line.lstrip().startswith('#'): + continue + + tokens = line.split() + + if len(tokens) == 0: + continue + + key = tokens[0].lower() + + if key == 'lease': + if not in_lease: + ip_address = tokens[1] + + lease_rec = {'ip_address' : ip_address} + in_lease = True + + else: + raise Exception('Parse error in leases file') + + elif key == 'failover': + in_failover = True + elif key == '}': + if in_lease: + for k in valid_keys: + if callable(valid_keys[k]): + lease_rec[k] = lease_rec.get(k, '') + else: + lease_rec[k] = False + + ip_address = lease_rec['ip_address'] + + if ip_address in leases_db: + leases_db[ip_address].insert(0, lease_rec) + + else: + leases_db[ip_address] = [lease_rec] + + lease_rec = {} + in_lease = False + + elif in_failover: + in_failover = False + continue + else: + raise Exception('Parse error in leases file') + + elif key in valid_keys: + if in_lease: + value = line[(line.index(key) + len(key)):] + value = value.strip().rstrip(';').rstrip() + + if callable(valid_keys[key]): + lease_rec[key] = valid_keys[key](value) + else: + lease_rec[key] = True + + else: + raise Exception('Parse error in leases file') + + else: + if in_lease: + raise Exception('Parse error in leases file') + + if in_lease: + raise Exception('Parse error in leases file') + + return leases_db + + +def round_timedelta(tdelta): + return datetime.timedelta(tdelta.days, + tdelta.seconds + (0 if tdelta.microseconds < 500000 else 1)) + + +def timestamp_now(): + n = datetime.datetime.utcnow() + return datetime.datetime(n.year, n.month, n.day, n.hour, n.minute, + n.second + (0 if n.microsecond < 500000 else 1)) + + +def lease_is_active(lease_rec, as_of_ts): + return timestamp_is_between(as_of_ts, lease_rec['starts'], + lease_rec['ends']) + + +def ipv4_to_int(ipv4_addr): + parts = ipv4_addr.split('.') + return (int(parts[0]) << 24) + (int(parts[1]) << 16) + \ + (int(parts[2]) << 8) + int(parts[3]) + + +def select_active_leases(leases_db, as_of_ts): + retarray = [] + sortedarray = [] + + for ip_address in leases_db: + lease_rec = leases_db[ip_address][0] + + if lease_is_active(lease_rec, as_of_ts): + ip_as_int = ipv4_to_int(ip_address) + insertpos = bisect.bisect(sortedarray, ip_as_int) + sortedarray.insert(insertpos, ip_as_int) + retarray.insert(insertpos, lease_rec) + + return retarray + + +############################################################################## + + +myfile = open('/var/lib/dhcp/dhcpd.leases', 'r') +leases = parse_leases_file(myfile) +myfile.close() + +now = timestamp_now() +report_dataset = select_active_leases(leases, now) + +print('+------------------------------------------------------------------------------') +print('| DHCPD ACTIVE LEASES REPORT') +print('+-----------------+-------------------+----------------------+-----------------') +print('| IP Address | MAC Address | Expires (days,H:M:S) | Client Hostname ') +print('+-----------------+-------------------+----------------------+-----------------') + +for lease in report_dataset: + print('| ' + format(lease['ip_address'], '<15') + ' | ' + \ + format(lease['hardware'], '<17') + ' | ' + \ + format(str((lease['ends'] - now) if lease['ends'] != 'never' else 'never'), '>20') + ' | ' + \ + lease['client-hostname']) + +print('+-----------------+-------------------+----------------------+-----------------') +print('| Total Active Leases: ' + str(len(report_dataset))) +print('| Report generated (UTC): ' + str(now)) +print('+------------------------------------------------------------------------------')