instructions

fail2ban-master/fail2ban/server/jailthread.py

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+# emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: t -*-
+# vi: set ft=python sts=4 ts=4 sw=4 noet :
+
+# This file is part of Fail2Ban.
+#
+# Fail2Ban is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# Fail2Ban is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Fail2Ban; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+# Author: Cyril Jaquier
+# 
+
+__author__ = "Cyril Jaquier"
+__copyright__ = "Copyright (c) 2004 Cyril Jaquier"
+__license__ = "GPL"
+
+import sys
+from threading import Thread
+from abc import abstractmethod
+
+from .utils import Utils
+from ..helpers import excepthook, prctl_set_th_name
+
+
+class JailThread(Thread):
+	"""Abstract class for threading elements in Fail2Ban.
+
+	Attributes
+	----------
+	daemon
+	ident
+	name
+	status
+	active : bool
+		Control the state of the thread.
+	idle : bool
+		Control the idle state of the thread.
+	sleeptime : int
+		The time the thread sleeps for in the loop.
+	"""
+
+	def __init__(self, name=None):
+		super(JailThread, self).__init__(name=name)
+		## Should going with main thread also:
+		self.daemon = True
+		## Control the state of the thread (None - was not started, True - active, False - stopped).
+		self.active = None
+		## Control the idle state of the thread.
+		self.idle = False
+		## The time the thread sleeps in the loop.
+		self.sleeptime = Utils.DEFAULT_SLEEP_TIME
+
+		# excepthook workaround for threads, derived from:
+		# http://bugs.python.org/issue1230540#msg91244
+		run = self.run
+
+		def run_with_except_hook(*args, **kwargs):
+			try:
+				run(*args, **kwargs)
+				# call on stop callback to do some finalizations:
+				self.onStop()
+			except Exception as e:
+				# avoid very sporadic error "'NoneType' object has no attribute 'exc_info'" (https://bugs.python.org/issue7336)
+				# only extremely fast systems are affected ATM (2.7 / 3.x), if thread ends nothing is available here.
+				if sys is not None:
+					excepthook(*sys.exc_info())
+				else:
+					print(e)
+		self.run = run_with_except_hook
+
+	def _bootstrap(self):
+		prctl_set_th_name(self.name)
+		return super(JailThread, self)._bootstrap();
+
+	@abstractmethod
+	def status(self, flavor="basic"): # pragma: no cover - abstract
+		"""Abstract - Should provide status information.
+		"""
+		pass
+
+	def start(self):
+		"""Sets active flag and starts thread.
+		"""
+		self.active = True
+		super(JailThread, self).start()
+
+	@abstractmethod
+	def onStop(self): # pragma: no cover - absract
+		"""Abstract - Called when thread ends (after run).
+		"""
+		pass
+
+	def stop(self):
+		"""Sets `active` property to False, to flag run method to return.
+		"""
+		if self.active: self.active = False
+		# normally onStop will be called automatically in thread after its run ends,
+		# but for backwards compatibilities we'll invoke it in caller of stop method.
+		self.onStop()
+		self.onStop = lambda:()
+		self.done()
+
+	def done(self):
+		self.done = lambda:()
+		# if still runniung - wait a bit before initiate clean-up:
+		if self.is_alive():
+			Utils.wait_for(lambda: not self.is_alive(), 5)
+		# now clean-up everything:
+		self.afterStop()
+
+
+	@abstractmethod
+	def run(self): # pragma: no cover - absract
+		"""Abstract - Called when thread starts, thread stops when returns.
+		"""
+		pass
+
+	def afterStop(self):
+		"""Cleanup resources."""
+		pass
+
+	def join(self):
+		""" Safer join, that could be called also for not started (or ended) threads (used for cleanup).
+		"""
+		## if cleanup needed - create derivative and call it before join...
+		self.done()
+		## if was really started - should call join:
+		if self.active is not None:
+			super(JailThread, self).join()
+
+## python 3.9, restore isAlive method:
+if not hasattr(JailThread, 'isAlive'):
+	 JailThread.isAlive = JailThread.is_alive