fail2ban/server/regex.py

# 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# Author: Cyril Jaquier
# 
# $Revision: 589 $

__author__ = "Cyril Jaquier"
__version__ = "$Revision: 589 $"
__date__ = "$Date: 2007-06-25 23:43:25 +0200 (Mon, 25 Jun 2007) $"
__copyright__ = "Copyright (c) 2004 Cyril Jaquier"
__license__ = "GPL"

import re, sre_constants

##
# Regular expression class.
#
# This class represents a regular expression with its compiled version.

class Regex:

	##
	# Constructor.
	#
	# Creates a new object. This method can throw RegexException in order to
	# avoid construction of invalid object.
	# @param value the regular expression
	
	def __init__(self, regex):
		self._matchCache = None
		# Perform shortcuts expansions.
		# Replace "<HOST>" with default regular expression for host.
		regex = regex.replace("<HOST>", "(?:::f{4,6}:)?(?P<host>\S+)")
		if regex.lstrip() == '':
			raise RegexException("Cannot add empty regex")
		try:
			self._regexObj = re.compile(regex)
			self._regex = regex
		except sre_constants.error:
			raise RegexException("Unable to compile regular expression '%s'" %
								 regex)
	
	##
	# Gets the regular expression.
	#
	# The effective regular expression used is returned.
	# @return the regular expression
	
	def getRegex(self):
		return self._regex
	
	##
	# Searches the regular expression.
	#
	# Sets an internal cache (match object) in order to avoid searching for
	# the pattern again. This method must be called before calling any other
	# method of this object.
	# @param value the line
	
	def search(self, value):
		self._matchCache = self._regexObj.search(value)
	
	##
	# Checks if the previous call to search() matched.
	#
	# @return True if a match was found, False otherwise
	
	def hasMatched(self):
		if self._matchCache:
			return True
		else:
			return False


##
# Exception dedicated to the class Regex.

class RegexException(Exception):
	pass