add test case to cover gh-2277, testOverflowedIPCache testing overflow of IP-cache multi-threaded (2 "parasite" threads flooding cache)

fail2ban/tests/filtertestcase.py

@@ -1753,6 +1753,44 @@ class DNSUtilsTests(unittest.TestCase):
 		# here the whole cache should be empty:
 		self.assertEqual(len(c), 0)
 		
+	def testOverflowedIPCache(self):
+		# test overflow of IP-cache multi-threaded (2 "parasite" threads flooding cache):
+		from threading import Thread
+		from random import shuffle
+		# save original cache and use smaller cache during the test here:
+		_org_cache = IPAddr.CACHE_OBJ
+		cache = IPAddr.CACHE_OBJ = Utils.Cache(maxCount=5, maxTime=60)
+		result = list()
+		count = 1 if unittest.F2B.fast else 50
+		try:
+			# tester procedure of worker:
+			def _TestCacheStr2IP(forw=True, result=[], random=False):
+				try:
+					c = count
+					while c:
+						c -= 1
+						s = xrange(0, 256, 1) if forw else xrange(255, -1, -1)
+						if random: shuffle([i for i in s])
+						for i in s:
+							IPAddr('192.0.2.'+str(i), IPAddr.FAM_IPv4)
+							IPAddr('2001:db8::'+str(i), IPAddr.FAM_IPv6)
+					result.append(None)
+				except Exception as e:
+					DefLogSys.debug(e, exc_info=True)
+					result.append(e)
+
+			# 2 workers flooding it forwards and backwards:
+			th1 = Thread(target=_TestCacheStr2IP, args=(True,  result)); th1.start()
+			th2 = Thread(target=_TestCacheStr2IP, args=(False, result)); th2.start()
+			# and here we flooding it with random IPs too:
+			_TestCacheStr2IP(True, result, True)
+		finally:
+			# wait for end of threads and restore cache:
+			th1.join()
+			th2.join()
+			IPAddr.CACHE_OBJ = _org_cache
+		self.assertEqual(result, [None]*3) # no errors
+		self.assertTrue(len(cache) <= cache.maxCount)
 
 
 class DNSUtilsNetworkTests(unittest.TestCase):