# 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.

# Original author: Cyril Jaquier

__author__ = "Cyril Jaquier, Lee Clemens, Yaroslav Halchenko"
__copyright__ = "Copyright (c) 2004 Cyril Jaquier, 2011-2012 Lee Clemens, 2012 Yaroslav Halchenko"
__license__ = "GPL"

from distutils.version import LooseVersion

from failmanager import FailManagerEmpty
from filter import FileFilter
from mytime import MyTime

import time, logging, pyinotify

if not hasattr(pyinotify, '__version__') \
  or LooseVersion(pyinotify.__version__) < '0.8.3':
  raise ImportError("Fail2Ban requires pyinotify >= 0.8.3")

from os.path import dirname, sep as pathsep

# Gets the instance of the logger.
logSys = logging.getLogger("fail2ban.filter")

##
# Log reader class.
#
# This class reads a log file and detects login failures or anything else
# that matches a given regular expression. This class is instantiated by
# a Jail object.

class FilterPyinotify(FileFilter):
	##
	# Constructor.
	#
	# Initialize the filter object with default values.
	# @param jail the jail object

	def __init__(self, jail):
		FileFilter.__init__(self, jail)
		self.__modified = False
		# Pyinotify watch manager
		self.__monitor = pyinotify.WatchManager()
		self.__watches = dict()
		logSys.debug("Created FilterPyinotify")


	def callback(self, event, origin=''):
		logSys.debug("%sCallback for Event: %s", origin, event)
		path = event.pathname
		if event.mask & pyinotify.IN_CREATE:
			# skip directories altogether
			if event.mask & pyinotify.IN_ISDIR:
				logSys.debug("Ignoring creation of directory %s", path)
				return
			# check if that is a file we care about
			if not path in self.__watches:
				logSys.debug("Ignoring creation of %s we do not monitor", path)
				return
			else:
				# we need to substitute the watcher with a new one, so first
				# remove old one
				self._delFileWatcher(path)
				# place a new one
				self._addFileWatcher(path)

		self._process_file(path)


	def _process_file(self, path):
		"""Process a given file

		TODO -- RF:
		this is a common logic and must be shared/provided by FileFilter
		"""
		self.getFailures(path)
		try:
			while True:
				ticket = self.failManager.toBan()
				self.jail.putFailTicket(ticket)
		except FailManagerEmpty:
			self.failManager.cleanup(MyTime.time())
		self.dateDetector.sortTemplate()
		self.__modified = False


	def _addFileWatcher(self, path):
		wd = self.__monitor.add_watch(path, pyinotify.IN_MODIFY)
		self.__watches.update(wd)
		logSys.debug("Added file watcher for %s", path)
		# process the file since we did get even
		self._process_file(path)


	def _delFileWatcher(self, path):
		wdInt = self.__watches[path]
		wd = self.__monitor.rm_watch(wdInt)
		if wd[wdInt]:
			del self.__watches[path]
			logSys.debug("Removed file watcher for %s", path)
			return True
		else:
			return False

	##
	# Add a log file path
	#
	# @param path log file path

	def _addLogPath(self, path):
		path_dir = dirname(path)
		if not (path_dir in self.__watches):
			# we need to watch also  the directory for IN_CREATE
			self.__watches.update(
				self.__monitor.add_watch(path_dir, pyinotify.IN_CREATE))
			logSys.debug("Added monitor for the parent directory %s", path_dir)

		self._addFileWatcher(path)


    ##
	# Delete a log path
	#
	# @param path the log file to delete

	def _delLogPath(self, path):
		if not self._delFileWatcher(path):
			logSys.error("Failed to remove watch on path: %s", path)

		path_dir = dirname(path)
		if not len([k for k in self.__watches
					if k.startswith(path_dir + pathsep)]):
			# Remove watches for the directory
			# since there is no other monitored file under this directory
			wdInt = self.__watches.pop(path_dir)
			_ = self.__monitor.rm_watch(wdInt)
			logSys.debug("Removed monitor for the parent directory %s", path_dir)


	##
	# Main loop.
	#
	# Since all detection is offloaded to pyinotifier -- no manual
	# loop is necessary

	def run(self):
		self.setActive(True)
		self.__notifier = pyinotify.ThreadedNotifier(self.__monitor,
			ProcessPyinotify(self))
		self.__notifier.start()
		logSys.debug("pyinotifier started for %s.", self.jail.getName())
		# TODO: verify that there is nothing really to be done for
		#       idle jails
		return True

	##
	# Call super.stop() and then stop the 'Notifier'

	def stop(self):
		super(FilterPyinotify, self).stop()

		# Stop the notifier thread
		self.__notifier.stop()
		self.__notifier.join()			# to not exit before notifier does
		self.__cleanup()				# for pedantic ones

	##
	# Deallocates the resources used by pyinotify.

	def __cleanup(self):
		self.__notifier = None
		self.__monitor = None


class ProcessPyinotify(pyinotify.ProcessEvent):
	def __init__(self, FileFilter, **kargs):
		#super(ProcessPyinotify, self).__init__(**kargs)
		# for some reason root class _ProcessEvent is old-style (is
		# not derived from object), so to play safe let's avoid super
		# for now, and call superclass directly
		pyinotify.ProcessEvent.__init__(self, **kargs)
		self.__FileFilter = FileFilter
		pass

	# just need default, since using mask on watch to limit events
	def process_default(self, event):
		self.__FileFilter.callback(event, origin='Default ')