Watch for grandparent ssh termination by default.

[python_utils.git] / arper.py

diff --git a/arper.py b/arper.py
index 4d6a3a2baa8900a4e6f5f535ad846766b2d353d7..a4e8d3e1196a1f683a24a9d43f4ec48fc8890253 100644 (file)
--- a/arper.py
+++ b/arper.py
@@ -6,6 +6,7 @@ import datetime
 import logging
 import os
 from typing import Any, Optional
+import warnings
 
 from overrides import overrides
 
@@ -33,7 +34,7 @@ cfg.add_argument(
 cfg.add_argument(
     '--arper_cache_max_staleness',
     type=argparse_utils.valid_duration,
-    default=datetime.timedelta(seconds=60 * 60),
+    default=datetime.timedelta(seconds=60 * 15),
     metavar='DURATION',
     help='Max acceptable age of the kernel arp table cache'
 )
@@ -48,7 +49,7 @@ cfg.add_argument(
 @persistent.persistent_autoloaded_singleton()
 class Arper(persistent.Persistent):
     def __init__(
-            self, cached_state: Optional[BiDict[str, str]] = None
+            self, cached_state: Optional[BiDict] = None
     ) -> None:
         self.state = BiDict()
         if cached_state is not None:
@@ -56,19 +57,44 @@ class Arper(persistent.Persistent):
             self.state = cached_state
         else:
             logger.debug('No usable cached state; calling /usr/sbin/arp')
-            self.update()
+            self.update_from_arp_scan()
+            self.update_from_arp()
+        if len(self.state) < config.config['arper_min_entries_to_be_valid']:
+            raise Exception('Arper didn\'t find enough entries; only got {len(self.state)}.')
 
-    def update(self):
-        output = exec_utils.cmd(
-            '/usr/sbin/arp -a',
-            timeout_seconds=5.0
-        )
+    def update_from_arp_scan(self):
+        network_spec = site_config.get_config().network
+        try:
+            output = exec_utils.cmd(
+                f'/usr/local/bin/arp-scan --retry=6 --timeout 350 --backoff=1.4 --random --numeric --plain --ignoredups {network_spec}',
+                timeout_seconds=10.0
+            )
+        except Exception as e:
+            logger.exception(e)
+            return
         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:
+            if ip is not None and mac is not None and mac != 'UNKNOWN' and ip != 'UNKNOWN':
                 mac = mac.lower()
-                logger.debug(f'    {mac} => {ip}')
+                logger.debug(f'ARPER: {mac} => {ip}')
+                self.state[mac] = ip
+
+    def update_from_arp(self):
+        try:
+            output = exec_utils.cmd(
+                '/usr/sbin/arp -a',
+                timeout_seconds=10.0
+            )
+        except Exception as e:
+            logger.exception(e)
+            return
+        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':
+                mac = mac.lower()
+                logger.debug(f'ARPER: {mac} => {ip}')
                 self.state[mac] = ip
 
     def get_ip_by_mac(self, mac: str) -> Optional[str]:
@@ -101,11 +127,10 @@ class Arper(persistent.Persistent):
             if len(cached_state) > config.config['arper_min_entries_to_be_valid']:
                 return cls(cached_state)
             else:
-                logger.warning(
-                    f'{cache_file} sucks, only {len(cached_state)} entries.  Deleting it.'
-                )
+                msg = f'{cache_file} is invalid: only {len(cached_state)} entries.  Deleting it.'
+                logger.warning(msg)
+                warnings.warn(msg, stacklevel=2)
                 os.remove(cache_file)
-
         logger.debug('No usable saved state found')
         return None