class IntegrityHandler(object):
__result = False
__sequence_handler = None
def __init__(self):
self.__sequence_handler = SequenceHandler()
def __isIntegrityValid(self, afdxPacket):
rsn = afdxPacket.getFrameSequenceNumber()
if rsn == None:
return False
vlId = afdxPacket.getDestinedVl()
prsn = self.__sequence_handler.getPRSN(vlId)
prsn_next_1 = self.__sequence_handler.getNextSequenceNumber(prsn,
SEQUENCE_FRAME)
prsn_next_2 = self.__sequence_handler.getNextSequenceNumber(prsn_next_1,
SEQUENCE_FRAME)
if (rsn in (prsn_next_1, prsn_next_2)) or (prsn == -1) or \
(rsn == 0 and prsn != 0):
if (rsn == 0 and prsn != 0):
self.__sequence_handler.setASN(vlId, 0)
self.__sequence_handler.setRSN(vlId, rsn)
return True
return False
def doCheck(self, afdxPacket):
self.__result = False
if not self.__isIntegrityValid(afdxPacket):
if afdxPacket[IP] != None:
print "Integrity check failed for packet with ip id", \
afdxPacket[IP].id
#afdxLogger.error("The packet failed integrity check")
return
self.__result = True
#afdxLogger.info("The packet has passed the integrity check")
def getResult(self):
return self.__result
def reset(self):
self.__sequence_handler = SequenceHandler()
class RedundancyHandler(object):
__result = False
__sequence_handler = None
_accepted_sns = dict()
def __init__(self):
self.__sequence_handler = SequenceHandler()
def __addAcceptedSN(self, vlId, sn):
if self._accepted_sns.has_key(vlId):
if len(self._accepted_sns[vlId]) > 10:
self._accepted_sns[vlId] = self._accepted_sns[vlId][5:]
self._accepted_sns[vlId].append(sn)
else:
self._accepted_sns[vlId] = [sn]
def __getLatestAcceptedSNs(self, vlId):
if self._accepted_sns.has_key(vlId):
sns = self._accepted_sns[vlId]
return sns[-5:]
return tuple()
def __checkForRedundancy(self, afdxPacket):
rsn = afdxPacket.getFrameSequenceNumber()
if rsn == None:
return False
vlId = afdxPacket.getDestinedVl()
pasn = self.__sequence_handler.getPASN(vlId)
# the below condition is as per the specification
#acceptable_asn = [self.__sequence_handler.getNextSequenceNumber(
# pasn + i, SEQUENCE_FRAME) \
# for i in range(0, 66)]
# this condition is as per what kailash has thought of.
# the dict "_accepted_sns" contains list of 5 recently accepted
# sequence numbers for a vl. If the rsn is in any of the received
# sn's then the packet is a redundant packet, hence reject else
# accept and proceed forward
acceptable_asn = self.__getLatestAcceptedSNs(vlId)
#print pasn, rsn, acceptable_asn, vlId, rsn in acceptable_asn
if (pasn == -1) or (rsn not in acceptable_asn):
#print 'accepted'
self.__sequence_handler.setASN(vlId, rsn)
self.__addAcceptedSN(vlId, rsn)
return True
return False
def doCheck(self, afdxPacket):
self.__result = False
if not self.__checkForRedundancy(afdxPacket):
print 'Redundancy check failed for packet with ip id', \
afdxPacket[IP].id
#afdxLogger.error("The packet failed with redundancy check")
return
self.__result = True
#afdxLogger.info("The packet has passed the redundancy check")
def getResult(self):
return self.__result
def reset(self):
self._accepted_sns.clear()
self.__result = False
