initial commit, source from a stackoverflow post

leases.py

@@ -0,0 +1,203 @@
+#!/usr/bin/python
+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('+------------------------------------------------------------------------------')

src.loc

@@ -0,0 +1 @@
+https://askubuntu.com/questions/219609/how-do-i-show-active-dhcp-leases