new

server/Event.py

@@ -0,0 +1,67 @@
+import md5
+
+class IllegalEventException(Exception):
+    def __init__(self, msg):
+        self.msg = msg
+
+
+class Event(object):
+    @classmethod
+    def setParams(cls, entries, msgTimeCorridor):
+        cls.entries = entries
+        cls.msgTimeCorridor = msgTimeCorridor
+
+    def __init__(self, address, data, receiveTime):
+        self.address = address
+        self.data = data
+        self.receiveTime = receiveTime
+
+    def prepare(self):
+        self.port = self.address[1]
+        self.address = self.address[0]
+        parts = self.data.split(' ')
+        if len(parts) != 3:
+            raise IllegalEventException("data format error 1")
+        (self.dynid, self.msgTime, self.checksum) = self.data.split(' ')
+        try:
+            self.msgTime = int(self.msgTime)
+        except ValueError, e:
+            raise IllegalEventException("data format error 2")
+        self.prepared = True
+
+    def process(self):
+        if not self.prepared:
+            self.prepare()
+
+        if not Event.entries.has_key(self.dynid):
+            raise IllegalEventException("unknown dynid in event %s" % str(self))
+        entry = Event.entries[self.dynid]
+
+        if self.msgTime + Event.msgTimeCorridor < self.receiveTime:
+            raise IllegalEventException("event too old %s" % str(self))
+        if self.msgTime - Event.msgTimeCorridor > self.receiveTime:
+            raise IllegalEventException("event too young %s" % str(self))
+
+
+        if entry.lastEventTime >= self.msgTime:
+            raise IllegalEventException("timing sequence failure in event, possibly replay %s" % str(self))
+
+        di = "%s %s %d" % (self.dynid, entry.sharedSecret, self.msgTime)
+        d = md5.new(di).hexdigest()
+        print "%s, received: %s, calculated: %s" % (di, self.checksum, d)
+        if d != self.checksum:
+            raise IllegalEventException("wrong checksum for event %s" % str(self))
+
+        entry.lastEventTime = self.msgTime
+
+        if entry.address == self.address:
+            print "Same address, nothing to do."
+        else:
+            entry.address = self.address
+            print "Set in DNS: %s -> %s" % (entry.name, entry.address)
+
+
+    def __str__(self):
+        if not self.prepared:
+            self.prepare()
+        return "%s from %s:%d" % (self.data, self.address, self.port)