prevents to stop processing after first unhandled exception inside processLineAndAdd (filter going idle after 100th error);

fail2ban/server/filter.py

@@ -85,6 +85,8 @@ class Filter(JailThread):
 		self.__lastDate = None
 		## External command
 		self.__ignoreCommand = False
+		## Error counter
+		self.__errors = 0
 
 		self.dateDetector = DateDetector()
 		self.dateDetector.addDefaultTemplate()
@@ -414,6 +416,7 @@ class Filter(JailThread):
 	def processLineAndAdd(self, line, date=None):
 		"""Processes the line for failures and populates failManager
 		"""
+		try:
 			for element in self.processLine(line, date)[1]:
 				ip = element[1]
 				unixTime = element[2]
@@ -434,6 +437,18 @@ class Filter(JailThread):
 				)
 				tick = FailTicket(ip, unixTime, lines, data=fail)
 				self.failManager.addFailure(tick)
+			# reset (halve) error counter (successfully processed line):
+			if self.__errors:
+				self.__errors //= 2
+		except Exception as e:
+			logSys.error("Failed to process line: %r, caught exception: %r", line, e,
+				exc_info=logSys.getEffectiveLevel()<=logging.DEBUG)
+			# incr error counter, stop processing this :
+			self.__errors += 1
+			if self.__errors >= 100:
+				logSys.error("Too many errors at once (%s), going idle", self.__errors)
+				self.__errors //= 2
+				self.idle = True
 
 	##
 	# Returns true if the line should be ignored.

fail2ban/tests/filtertestcase.py

@@ -604,6 +604,27 @@ class LogFileMonitor(LogCaptureTestCase):
 		self.filter.getFailures(self.name)
 		self.assertLogged('Unable to open %s' % self.name)
 
+	def testErrorProcessLine(self):
+		## produce error with not callable processLine:
+		_org_processLine = self.filter.processLine
+		self.filter.processLine = None
+		for i in range(100):
+			self.file.write("line%d\n" % 1)
+		self.file.flush()
+		for i in range(100):
+			self.filter.getFailures(self.name)
+		self.assertLogged('Failed to process line:')
+		self.assertLogged('Too many errors at once')
+		self.pruneLog()
+		self.assertTrue(self.filter.idle)
+		self.filter.idle = False
+		self.filter.getFailures(self.name)
+		self.filter.processLine = _org_processLine
+		self.file.write("line%d\n" % 1)
+		self.file.flush()
+		self.filter.getFailures(self.name)
+		self.assertNotLogged('Failed to process line:')
+
 	def testRemovingFailRegex(self):
 		self.filter.delFailRegex(0)
 		self.assertNotLogged('Cannot remove regular expression. Index 0 is not valid')