mirror of https://github.com/noerw/geo-dht
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232 lines
8.9 KiB
Python
232 lines
8.9 KiB
Python
# -*- coding: utf-8 -*-
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from __future__ import division
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from gevent import socket
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from functools import partial
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from keyspace import Keyspace
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from hashlib import md5
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import json
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from traceback import print_exc
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from topology import GridTopology
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from direction import Direction
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from geohash import Geohash
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class Node(object):
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def __init__(self, own_port=None, keyspace=None):
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self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP
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self.socket.bind(("localhost", own_port or 0)) # 0 Chooses random port
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self.port = self.socket.getsockname()[1]
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self.keyspace = keyspace
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self.hash = {}
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self.neighbours = GridTopology(keyspace)
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# keeps track of queries that were routed to us but that we passed on,
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# so that we can pass the answer to the original queryee
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self.queries = {} # key: query key, value: address of query origin
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self.salt = 'asdndslkf' # TODO: should be proper randomized? must be shared among nodes? 🤔
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self.pepper = 'sdfjsdfoiwefslkf'
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def __str__(self):
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return "node:%s" % self.port
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def address(self):
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return ('127.0.0.1', self.port)
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def join_network(self, entry_port):
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print ("Sending JOIN from %s to port %s." % (self, entry_port))
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self.sendto(("localhost", entry_port), "JOIN")
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def hash_key(self, key):
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return md5(key.encode('utf-8')).hexdigest()
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def key_to_keyspace(self, key):
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''' returns a point within the keyspace corresponding to the given key
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'''
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# keyspace is 2D -> split it
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hashX = self.hash_key(key + self.salt)
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hashY = self.hash_key(key + self.pepper)
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return (
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int(hashX, base=16) / (1 << 128), # convert to keyspace [0,1]
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int(hashY, base=16) / (1 << 128)
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)
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def coord_to_keyspace(self, point):
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'''
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context: Geohash
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hmmm.. what do we want to achieve here?
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- translate between geographic and keyspace coords?
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- translate between hashes and locations?
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- address content by location?
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we should be able to translate between keyspace and a geohash:
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each geohash bitpair divides the space just as we divide our keyspace
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-> longer hash -> smaller keyspace.
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problem: geohash doesnt encode edges but a single point..
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-> keyspace is ID of a node -> can be encoded via interleaved coords, if total size of keyspace is given
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-> neighbour topology can be expressed as DHT? but then we basically have a 2D kademlia?
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-> content IDs (hash of key) can be assigned to node
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'''
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x, y = point
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# TODO
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def sendto(self, address, message):
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if address:
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self.socket.sendto(message.encode('utf-8'), address)
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else: # this was a local query
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print (message)
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def query_others(self, query, origin=None):
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# query is a GET or PUT query, so second element is always a data key
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key = query.split()[1]
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point = self.key_to_keyspace(key)
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address, keyspace = self.neighbours.getNeighbourForPoint(point)
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if address:
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self.sendto(address, query)
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if origin:
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# FIXME: very simplistic; should be a list
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# -> fails when multiple queries for a key are in flight
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self.queries[key] = origin
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else:
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print ('No neighbour found for %s', point)
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def query(self, query, sender=None):
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'''
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query handler. hacky protocol mixed of magic strings and JSON
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queries can be coming from other nodes, or from local input (eg stdin)
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'''
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respond = partial(self.sendto, sender)
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if sender:
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print ("Received \"%s\" from %s." % (query, sender))
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if not query:
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return
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try:
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if query == "JOIN":
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senderKeyspace, splitDirection = self.keyspace.subdivide()
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print ("Own keyspace is now %s" % self.keyspace)
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# pass ourselves and all our neighbours to the new node, except for the opposite splitDirection
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neighbours = self.neighbours.getNeighbours([
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d for d in Direction.cardinals if d != -splitDirection
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])
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neighbours = [(addr, keysp.serialize()) for addr, keysp in neighbours]
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neighbours.append((self.address(), self.keyspace.serialize()))
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# find content from hashtable that isn't ours anymore
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content = {}
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for k, v in list(self.hash.items()):
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if not self.key_to_keyspace(k) in self.keyspace:
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content[k] = v
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del self.hash[k]
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respond("SETKEYSPACE %s" % json.dumps({
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'content': content,
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'keyspace': senderKeyspace.serialize(),
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'neighbours': neighbours,
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}))
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# notify our neighbours of our changed keyspace
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neighbours = self.neighbours.getNeighbours([
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d for d in Direction.cardinals if d != splitDirection
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])
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for addr, keysp in neighbours:
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self.sendto(addr, 'UPDATE_NEIGHBOURS %s' % json.dumps([
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(self.address(), self.keyspace.serialize())
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]))
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self.neighbours.clearNeighbours([splitDirection]) # get rid of non-adjacent neighbours
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self.neighbours.addNeighbour(sender, senderKeyspace)
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elif query.startswith("STATE"):
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print ("port: %s" % self.port)
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print ("keyspace: %s" % self.keyspace)
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print ("neighbours: %s" % self.neighbours)
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print ("hashtable: %s" % self.hash)
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print ("query routing: %s" % self.queries)
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arg = query.lstrip('STATE ')
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# visualize via matplotlib
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if arg == 'VIZ':
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plt = self.neighbours.visualize()
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for k,v in self.hash.items():
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x,y = self.key_to_keyspace(k)
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plt.plot(x,y)
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plt.annotate('%s:%s' % (k,v), (x, y))
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plt.show() # FIXME: integrate with gevent to avoid blocking?
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elif query.startswith("SETKEYSPACE"):
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data = json.loads(query.lstrip("SETKEYSPACE "))
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self.keyspace = Keyspace.unserialize(data['keyspace'])
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neighbours = [(tuple(address), Keyspace.unserialize(keysp)) for address, keysp in data['neighbours']]
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self.neighbours = GridTopology(self.keyspace, neighbours)
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self.hash = data['content']
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# notify the passed neighbours about the new state
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for n in neighbours:
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addr, keysp = n
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if addr == sender: continue
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self.sendto(addr, 'UPDATE_NEIGHBOURS %s' % json.dumps([
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(self.address(), self.keyspace.serialize()),
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]))
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elif query.startswith("UPDATE_NEIGHBOURS"): # replaces SET_ADDRESS
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neighbours = [(tuple(addr), Keyspace.unserialize(keysp)) for addr, keysp in json.loads(query[18:])]
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for n in neighbours:
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self.neighbours.addNeighbour(n[0], n[1])
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elif query.startswith("GET"):
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key = query.split()[1]
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point = self.key_to_keyspace(key)
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if point in self.keyspace:
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respond('ANSWER %s' % json.dumps({
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'key': key,
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'value': self.hash.get(key, None),
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}))
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else:
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self.query_others(query, sender)
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elif query.startswith("PUT"):
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_, key, value = query.split()
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point = self.key_to_keyspace(key)
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if point in self.keyspace:
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self.hash[key] = value
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respond('ANSWER %s' % json.dumps({
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'key': key,
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'value': value,
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}))
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print ('Own hashtable is now %s' % self.hash)
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else:
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self.query_others(query, sender)
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elif query.startswith("ANSWER"):
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data = json.loads(query.lstrip('ANSWER '))
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key = data['key']
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if key in self.queries:
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# this answer is a reply to a query where we just act as router
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dest = self.queries[key]
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del self.queries[key]
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print ('Routing answer to %s:%s' % dest)
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self.sendto(dest, query)
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else:
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# this response is for our query.
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self.sendto(None, query)
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else:
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print ("Unrecognized query \"%s\"." % query)
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except Exception as err:
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print_exc()
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