"""A caching layer around the kernel's network mapping between IPs and MACs"""
+
import datetime
import logging
import os
-from typing import Any, Optional
import warnings
+from typing import Any, Optional
from overrides import overrides
import argparse_utils
-from collect.bidict import BiDict
import config
import exec_utils
import file_utils
import persistent
-import string_utils
import site_config
+import string_utils
+from collect.bidict import BiDict
logger = logging.getLogger(__name__)
)
cfg.add_argument(
'--arper_cache_location',
- default=f'{os.environ["HOME"]}/cache/.arp_table_cache',
+ default=site_config.get_config().arper_cache_file,
metavar='FILENAME',
help='Where to cache the kernel ARP table',
)
+cfg.add_argument(
+ '--arper_supplimental_cache_location',
+ default=site_config.get_config(site_config.other_location()).arper_cache_file,
+ metavar='FILENAME',
+ help='Where someone else is caching the kernel ARP table',
+)
cfg.add_argument(
'--arper_cache_max_staleness',
type=argparse_utils.valid_duration,
)
class Arper(persistent.Persistent):
- def __init__(self, cached_state: Optional[BiDict] = None) -> None:
+ def __init__(
+ self,
+ cached_local_state: Optional[BiDict] = None,
+ cached_supplimental_state: Optional[BiDict] = None,
+ ) -> None:
self.state = BiDict()
- if cached_state is not None:
- logger.debug('Loading Arper map from cached state.')
- self.state = cached_state
+ if cached_local_state is not None:
+ logger.debug('Loading Arper map from cached local state.')
+ self.state = cached_local_state
else:
logger.debug('No usable cached state; calling /usr/sbin/arp')
self.update_from_arp_scan()
self.update_from_arp()
if len(self.state) < config.config['arper_min_entries_to_be_valid']:
- raise Exception(
- f'Arper didn\'t find enough entries; only got {len(self.state)}.'
- )
+ raise Exception(f'Arper didn\'t find enough entries; only got {len(self.state)}.')
+ if cached_supplimental_state is not None:
+ logger.debug(f'Also added {len(cached_supplimental_state)} supplimental entries.')
+ for mac, ip in cached_supplimental_state.items():
+ self.state[mac] = ip
+ for mac, ip in self.state.items():
+ logger.debug(f'{mac} <-> {ip}')
def update_from_arp_scan(self):
network_spec = site_config.get_config().network
for line in output.split('\n'):
ip = string_utils.extract_ip_v4(line)
mac = string_utils.extract_mac_address(line)
- if (
- ip is not None
- and mac is not None
- and mac != 'UNKNOWN'
- and ip != 'UNKNOWN'
- ):
+ if ip is not None and mac is not None and mac != 'UNKNOWN' and ip != 'UNKNOWN':
mac = mac.lower()
logger.debug(f'ARPER: {mac} => {ip}')
self.state[mac] = ip
for line in output.split('\n'):
ip = string_utils.extract_ip_v4(line)
mac = string_utils.extract_mac_address(line)
- if (
- ip is not None
- and mac is not None
- and mac != 'UNKNOWN'
- and ip != 'UNKNOWN'
- ):
+ if ip is not None and mac is not None and mac != 'UNKNOWN' and ip != 'UNKNOWN':
mac = mac.lower()
logger.debug(f'ARPER: {mac} => {ip}')
self.state[mac] = ip
return self.state.inverse.get(ip, None)
@classmethod
- @overrides
- def load(cls) -> Any:
- cache_file = config.config['arper_cache_location']
+ def load_state(cls, cache_file: str, freshness_threshold_sec: int, state: BiDict):
+ if not file_utils.file_is_readable(cache_file):
+ logger.debug(f'Can\'t read {cache_file}')
+ return None
if persistent.was_file_written_within_n_seconds(
cache_file,
- config.config['arper_cache_max_staleness'].total_seconds(),
+ freshness_threshold_sec,
):
logger.debug(f'Loading state from {cache_file}')
- cached_state = BiDict()
+ count = 0
with open(cache_file, 'r') as rf:
contents = rf.readlines()
for line in contents:
mac = mac.strip()
mac = mac.lower()
ip = ip.strip()
- cached_state[mac] = ip
- if (
- len(cached_state)
- > config.config['arper_min_entries_to_be_valid']
- ):
- return cls(cached_state)
- else:
- msg = f'{cache_file} is invalid: only {len(cached_state)} entries. Deleting it.'
- logger.warning(msg)
- warnings.warn(msg, stacklevel=2)
+ state[mac] = ip
+ count += 1
+ else:
+ logger.debug(f'{cache_file} is too stale.')
+
+ @classmethod
+ @overrides
+ def load(cls) -> Any:
+ local_state = BiDict()
+ cache_file = config.config['arper_cache_location']
+ max_staleness = config.config['arper_cache_max_staleness'].total_seconds()
+ logger.debug(f'Trying to load main arper cache from {cache_file}...')
+ cls.load_state(cache_file, max_staleness, local_state)
+ if len(local_state) <= config.config['arper_min_entries_to_be_valid']:
+ msg = f'{cache_file} is invalid: only {len(local_state)} entries. Deleting it.'
+ logger.warning(msg)
+ warnings.warn(msg, stacklevel=2)
+ try:
os.remove(cache_file)
- logger.debug('No usable saved state found')
+ except Exception:
+ pass
+
+ supplimental_state = BiDict()
+ cache_file = config.config['arper_supplimental_cache_location']
+ max_staleness = config.config['arper_cache_max_staleness'].total_seconds()
+ logger.debug(f'Trying to suppliment arper state from {cache_file}...')
+ cls.load_state(cache_file, max_staleness, supplimental_state)
+ if len(supplimental_state) == 0:
+ supplimental_state = None
+
+ if len(local_state) > 0:
+ return cls(local_state, supplimental_state)
return None
@overrides
def save(self) -> bool:
if len(self.state) > config.config['arper_min_entries_to_be_valid']:
- logger.debug(
- f'Persisting state to {config.config["arper_cache_location"]}'
- )
- with file_utils.FileWriter(
- config.config['arper_cache_location']
- ) as wf:
+ logger.debug(f'Persisting state to {config.config["arper_cache_location"]}')
+ with file_utils.FileWriter(config.config['arper_cache_location']) as wf:
for (mac, ip) in self.state.items():
mac = mac.lower()
print(f'{mac}, {ip}', file=wf)
projects / python_utils.git / blobdiff