解析linux-dhcp服务器IP分配情况python脚本

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客户这里有一台linux服务器，作为dhcp服务器使用。每次需要查询dhcp地址分配记录的默认只能在 cat /var/lib/dhcpd/dhcpd.leases这个文件查看，查询起来非常不方便
就像这样

后来自己尝试编写脚本来解析，但是处理得不是很好。但是在githup搜寻到有一个大佬写的python脚本，可以完成解析统计，人性化了很多，就像这样

脚本如下：

`
#!/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/dhcpd/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('+------------------------------------------------------------------------------')

`

感觉运维工作，又轻松了点。。。

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