68 lines
2.3 KiB
Python
68 lines
2.3 KiB
Python
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import md5
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class IllegalEventException(Exception):
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def __init__(self, msg):
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self.msg = msg
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class Event(object):
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@classmethod
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def setParams(cls, entries, msgTimeCorridor):
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cls.entries = entries
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cls.msgTimeCorridor = msgTimeCorridor
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def __init__(self, address, data, receiveTime):
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self.address = address
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self.data = data
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self.receiveTime = receiveTime
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def prepare(self):
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self.port = self.address[1]
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self.address = self.address[0]
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parts = self.data.split(' ')
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if len(parts) != 3:
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raise IllegalEventException("data format error 1")
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(self.dynid, self.msgTime, self.checksum) = self.data.split(' ')
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try:
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self.msgTime = int(self.msgTime)
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except ValueError, e:
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raise IllegalEventException("data format error 2")
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self.prepared = True
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def process(self):
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if not self.prepared:
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self.prepare()
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if not Event.entries.has_key(self.dynid):
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raise IllegalEventException("unknown dynid in event %s" % str(self))
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entry = Event.entries[self.dynid]
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if self.msgTime + Event.msgTimeCorridor < self.receiveTime:
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raise IllegalEventException("event too old %s" % str(self))
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if self.msgTime - Event.msgTimeCorridor > self.receiveTime:
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raise IllegalEventException("event too young %s" % str(self))
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if entry.lastEventTime >= self.msgTime:
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raise IllegalEventException("timing sequence failure in event, possibly replay %s" % str(self))
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di = "%s %s %d" % (self.dynid, entry.sharedSecret, self.msgTime)
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d = md5.new(di).hexdigest()
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print "%s, received: %s, calculated: %s" % (di, self.checksum, d)
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if d != self.checksum:
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raise IllegalEventException("wrong checksum for event %s" % str(self))
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entry.lastEventTime = self.msgTime
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if entry.address == self.address:
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print "Same address, nothing to do."
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else:
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entry.address = self.address
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print "Set in DNS: %s -> %s" % (entry.name, entry.address)
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def __str__(self):
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if not self.prepared:
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self.prepare()
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return "%s from %s:%d" % (self.data, self.address, self.port)
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