mirror of
https://github.com/fail2ban/fail2ban.git
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303 lines
8.9 KiB
Python
303 lines
8.9 KiB
Python
# emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: t -*-
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# vi: set ft=python sts=4 ts=4 sw=4 noet :
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# This file is part of Fail2Ban.
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#
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# Fail2Ban is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# Fail2Ban is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Fail2Ban; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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__author__ = "Cyril Jaquier"
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__copyright__ = "Copyright (c) 2004 Cyril Jaquier"
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__license__ = "GPL"
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import re
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import sre_constants
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import sys
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from .ipdns import IPAddr
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##
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# Regular expression class.
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#
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# This class represents a regular expression with its compiled version.
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class Regex:
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##
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# Constructor.
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#
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# Creates a new object. This method can throw RegexException in order to
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# avoid construction of invalid object.
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# @param value the regular expression
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def __init__(self, regex, **kwargs):
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self._matchCache = None
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# Perform shortcuts expansions.
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# Resolve "<HOST>" tag using default regular expression for host:
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regex = Regex._resolveHostTag(regex, **kwargs)
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# Replace "<SKIPLINES>" with regular expression for multiple lines.
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regexSplit = regex.split("<SKIPLINES>")
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regex = regexSplit[0]
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for n, regexLine in enumerate(regexSplit[1:]):
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regex += "\n(?P<skiplines%i>(?:(.*\n)*?))" % n + regexLine
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if regex.lstrip() == '':
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raise RegexException("Cannot add empty regex")
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try:
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self._regexObj = re.compile(regex, re.MULTILINE)
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self._regex = regex
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except sre_constants.error:
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raise RegexException("Unable to compile regular expression '%s'" %
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regex)
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def __str__(self):
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return "%s(%r)" % (self.__class__.__name__, self._regex)
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##
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# Replaces "<HOST>", "<IP4>", "<IP6>", "<FID>" with default regular expression for host
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#
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# (see gh-1374 for the discussion about other candidates)
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# @return the replaced regular expression as string
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@staticmethod
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def _resolveHostTag(regex, useDns="yes"):
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# separated ipv4:
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r_host = []
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r = r"""(?:::f{4,6}:)?(?P<ip4>%s)""" % (IPAddr.IP_4_RE,)
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regex = regex.replace("<IP4>", r); # self closed
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regex = regex.replace("<F-IP4/>", r); # closed
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r_host.append(r)
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# separated ipv6:
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r = r"""(?P<ip6>%s)""" % (IPAddr.IP_6_RE,)
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regex = regex.replace("<IP6>", r); # self closed
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regex = regex.replace("<F-IP6/>", r); # closed
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r_host.append(r"""\[?%s\]?""" % (r,)); # enclose ipv6 in optional [] in host-regex
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# 2 address groups instead of <ADDR> - in opposition to `<HOST>`,
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# for separate usage of 2 address groups only (regardless of `usedns`), `ip4` and `ip6` together
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regex = regex.replace("<ADDR>", "(?:%s)" % ("|".join(r_host),))
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# separated dns:
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r = r"""(?P<dns>[\w\-.^_]*\w)"""
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regex = regex.replace("<DNS>", r); # self closed
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regex = regex.replace("<F-DNS/>", r); # closed
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if useDns not in ("no",):
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r_host.append(r)
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# 3 groups instead of <HOST> - separated ipv4, ipv6 and host (dns)
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regex = regex.replace("<HOST>", "(?:%s)" % ("|".join(r_host),))
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# default failure-id as no space tag:
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regex = regex.replace("<F-ID/>", r"""(?P<fid>\S+)"""); # closed
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# default failure port, like 80 or http :
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regex = regex.replace("<F-PORT/>", r"""(?P<port>\w+)"""); # closed
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# default failure groups (begin / end tag) for customizable expressions:
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for o,r in (('IP4', 'ip4'), ('IP6', 'ip6'), ('DNS', 'dns'), ('ID', 'fid'), ('PORT', 'fport')):
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regex = regex.replace("<F-%s>" % o, "(?P<%s>" % r); # open tag
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regex = regex.replace("</F-%s>" % o, ")"); # close tag
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return regex
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##
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# Gets the regular expression.
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#
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# The effective regular expression used is returned.
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# @return the regular expression
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def getRegex(self):
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return self._regex
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##
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# Searches the regular expression.
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#
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# Sets an internal cache (match object) in order to avoid searching for
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# the pattern again. This method must be called before calling any other
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# method of this object.
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# @param a list of tupples. The tupples are ( prematch, datematch, postdatematch )
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def search(self, tupleLines):
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self._matchCache = self._regexObj.search(
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"\n".join("".join(value[::2]) for value in tupleLines) + "\n")
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if self.hasMatched():
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# Find start of the first line where the match was found
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try:
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self._matchLineStart = self._matchCache.string.rindex(
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"\n", 0, self._matchCache.start() +1 ) + 1
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except ValueError:
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self._matchLineStart = 0
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# Find end of the last line where the match was found
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try:
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self._matchLineEnd = self._matchCache.string.index(
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"\n", self._matchCache.end() - 1) + 1
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except ValueError:
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self._matchLineEnd = len(self._matchCache.string)
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lineCount1 = self._matchCache.string.count(
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"\n", 0, self._matchLineStart)
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lineCount2 = self._matchCache.string.count(
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"\n", 0, self._matchLineEnd)
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self._matchedTupleLines = tupleLines[lineCount1:lineCount2]
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self._unmatchedTupleLines = tupleLines[:lineCount1]
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n = 0
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for skippedLine in self.getSkippedLines():
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for m, matchedTupleLine in enumerate(
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self._matchedTupleLines[n:]):
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if "".join(matchedTupleLine[::2]) == skippedLine:
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self._unmatchedTupleLines.append(
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self._matchedTupleLines.pop(n+m))
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n += m
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break
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self._unmatchedTupleLines.extend(tupleLines[lineCount2:])
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# Checks if the previous call to search() matched.
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#
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# @return True if a match was found, False otherwise
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def hasMatched(self):
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if self._matchCache:
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return True
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else:
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return False
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##
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# Returns skipped lines.
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#
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# This returns skipped lines captured by the <SKIPLINES> tag.
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# @return list of skipped lines
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def getSkippedLines(self):
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if not self._matchCache:
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return []
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skippedLines = ""
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n = 0
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while True:
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try:
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if self._matchCache.group("skiplines%i" % n) is not None:
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skippedLines += self._matchCache.group("skiplines%i" % n)
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n += 1
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except IndexError:
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break
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# KeyError is because of PyPy issue1665 affecting pypy <= 2.2.1
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except KeyError:
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if 'PyPy' not in sys.version: # pragma: no cover - not sure this is even reachable
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raise
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break
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return skippedLines.splitlines(False)
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##
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# Returns unmatched lines.
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#
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# This returns unmatched lines including captured by the <SKIPLINES> tag.
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# @return list of unmatched lines
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def getUnmatchedTupleLines(self):
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if not self.hasMatched():
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return []
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else:
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return self._unmatchedTupleLines
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def getUnmatchedLines(self):
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if not self.hasMatched():
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return []
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else:
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return ["".join(line) for line in self._unmatchedTupleLines]
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##
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# Returns matched lines.
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#
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# This returns matched lines by excluding those captured
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# by the <SKIPLINES> tag.
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# @return list of matched lines
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def getMatchedTupleLines(self):
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if not self.hasMatched():
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return []
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else:
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return self._matchedTupleLines
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def getMatchedLines(self):
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if not self.hasMatched():
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return []
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else:
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return ["".join(line) for line in self._matchedTupleLines]
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##
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# Exception dedicated to the class Regex.
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class RegexException(Exception):
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pass
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##
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# Groups used as failure identifier.
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#
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# The order of this tuple is important while searching for failure-id
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#
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FAILURE_ID_GROPS = ("fid", "ip4", "ip6", "dns")
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##
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# Regular expression class.
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#
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# This class represents a regular expression with its compiled version.
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class FailRegex(Regex):
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##
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# Constructor.
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#
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# Creates a new object. This method can throw RegexException in order to
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# avoid construction of invalid object.
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# @param value the regular expression
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def __init__(self, regex, **kwargs):
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# Initializes the parent.
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Regex.__init__(self, regex, **kwargs)
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# Check for group "dns", "ip4", "ip6", "fid"
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if not [grp for grp in FAILURE_ID_GROPS if grp in self._regexObj.groupindex]:
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raise RegexException("No failure-id group in '%s'" % self._regex)
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##
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# Returns all matched groups.
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#
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def getGroups(self):
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return self._matchCache.groupdict()
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##
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# Returns the matched failure id.
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#
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# This corresponds to the pattern matched by the named group from given groups.
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# @return the matched failure-id
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def getFailID(self, groups=FAILURE_ID_GROPS):
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fid = None
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for grp in groups:
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try:
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fid = self._matchCache.group(grp)
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except (IndexError, KeyError):
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continue
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if fid is not None:
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break
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if fid is None:
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# Gets a few information.
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s = self._matchCache.string
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r = self._matchCache.re
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raise RegexException("No group found in '%s' using '%s'" % (s, r))
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return str(fid)
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##
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# Returns the matched host.
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#
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# This corresponds to the pattern matched by the named group "ip4", "ip6" or "dns".
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# @return the matched host
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def getHost(self):
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return self.getFailID(("ip4", "ip6", "dns"))
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