164 lines
6.3 KiB
Python
164 lines
6.3 KiB
Python
#!/usr/bin/env python
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#
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# This is a basic single-node example of how to use the Entangled
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# DHT. It creates a Node and (optionally) joins an existing DHT. It
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# then does a Kademlia store and find, and then it deletes the stored
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# value (non-Kademlia method).
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#
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# No tuple space functionality is demonstrated by this script.
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#
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# To test it properly, start a multi-node Kademlia DHT with the "create_network.py"
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# script and point this node to that, e.g.:
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# $python create_network.py 10 127.0.0.1
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#
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# $python basic_example.py 5000 127.0.0.1 4000
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#
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# This library is free software, distributed under the terms of
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# the GNU Lesser General Public License Version 3, or any later version.
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# See the COPYING file included in this archive
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#
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# Thanks to Paul Cannon for IP-address resolution functions (taken from aspn.activestate.com)
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import binascii
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import random
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import twisted.internet.reactor
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from lbrynet.dht.node import Node
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from lbrynet.core.cryptoutils import get_lbry_hash_obj
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# The Entangled DHT node; instantiated in the main() method
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node = None
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# The key to use for this example when storing/retrieving data
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h = get_lbry_hash_obj()
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h.update("key")
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KEY = h.digest()
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# The value to store
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VALUE = random.randint(10000, 20000)
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lbryid = KEY
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def storeValue(key, value):
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""" Stores the specified value in the DHT using the specified key """
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global node
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print '\nStoring value; Key: %s, Value: %s' % (key, value)
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# Store the value in the DHT. This method returns a Twisted
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# Deferred result, which we then add callbacks to
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deferredResult = node.announceHaveHash(key, value)
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# Add our callback; this method is called when the operation completes...
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deferredResult.addCallback(storeValueCallback)
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# ...and for error handling, add an "error callback" as well.
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#
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# For this example script, I use a generic error handler; usually
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# you would need something more specific
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deferredResult.addErrback(genericErrorCallback)
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def storeValueCallback(*args, **kwargs):
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""" Callback function that is invoked when the storeValue() operation succeeds """
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print 'Value has been stored in the DHT'
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# Now that the value has been stored, schedule that the value is read again after 2.5 seconds
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print 'Scheduling retrieval in 2.5 seconds'
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twisted.internet.reactor.callLater(2.5, getValue)
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def genericErrorCallback(failure):
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""" Callback function that is invoked if an error occurs during any of the DHT operations """
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print 'An error has occurred:', failure.getErrorMessage()
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twisted.internet.reactor.callLater(0, stop)
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def getValue():
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""" Retrieves the value of the specified key (KEY) from the DHT """
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global node, KEY
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# Get the value for the specified key (immediately returns a Twisted deferred result)
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print ('\nRetrieving value from DHT for key "%s"' %
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binascii.unhexlify("f7d9dc4de674eaa2c5a022eb95bc0d33ec2e75c6"))
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deferredResult = node.iterativeFindValue(
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binascii.unhexlify("f7d9dc4de674eaa2c5a022eb95bc0d33ec2e75c6"))
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# Add a callback to this result; this will be called as soon as the operation has completed
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deferredResult.addCallback(getValueCallback)
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# As before, add the generic error callback
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deferredResult.addErrback(genericErrorCallback)
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def getValueCallback(result):
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""" Callback function that is invoked when the getValue() operation succeeds """
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# Check if the key was found (result is a dict of format {key:
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# value}) or not (in which case a list of "closest" Kademlia
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# contacts would be returned instead")
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print "Got the value"
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print result
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# Either way, schedule a "delete" operation for the key
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print 'Scheduling shutdown in 2.5 seconds'
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twisted.internet.reactor.callLater(2.5, stop)
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def stop():
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""" Stops the Twisted reactor, and thus the script """
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print '\nStopping Kademlia node and terminating script'
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twisted.internet.reactor.stop()
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if __name__ == '__main__':
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import sys
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if len(sys.argv) < 2:
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print 'Usage:\n%s UDP_PORT [KNOWN_NODE_IP KNOWN_NODE_PORT]' % sys.argv[0]
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print 'or:\n%s UDP_PORT [FILE_WITH_KNOWN_NODES]' % sys.argv[0]
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print
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print 'If a file is specified, it should containg one IP address and UDP port'
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print 'per line, seperated by a space.'
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sys.exit(1)
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try:
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int(sys.argv[1])
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except ValueError:
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print '\nUDP_PORT must be an integer value.\n'
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print 'Usage:\n%s UDP_PORT [KNOWN_NODE_IP KNOWN_NODE_PORT]' % sys.argv[0]
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print 'or:\n%s UDP_PORT [FILE_WITH_KNOWN_NODES]' % sys.argv[0]
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print
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print 'If a file is specified, it should contain one IP address and UDP port'
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print 'per line, seperated by a space.'
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sys.exit(1)
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if len(sys.argv) == 4:
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knownNodes = [(sys.argv[2], int(sys.argv[3]))]
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elif len(sys.argv) == 3:
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knownNodes = []
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f = open(sys.argv[2], 'r')
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lines = f.readlines()
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f.close()
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for line in lines:
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ipAddress, udpPort = line.split()
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knownNodes.append((ipAddress, int(udpPort)))
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else:
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knownNodes = None
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print '\nNOTE: You have not specified any remote DHT node(s) to connect to'
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print 'It will thus not be aware of any existing DHT, but will still function as'
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print ' a self-contained DHT (until another node contacts it).'
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print 'Run this script without any arguments for info.\n'
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# Set up SQLite-based data store (you could use an in-memory store instead, for example)
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#
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# Create the Entangled node. It extends the functionality of a
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# basic Kademlia node (but is fully backwards-compatible with a
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# Kademlia-only network)
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#
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# If you wish to have a pure Kademlia network, use the
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# entangled.kademlia.node.Node class instead
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print 'Creating Node'
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node = Node(udpPort=int(sys.argv[1]), lbryid=lbryid)
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# Schedule the node to join the Kademlia/Entangled DHT
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node.joinNetwork(knownNodes)
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# Schedule the "storeValue() call to be invoked after 2.5 seconds,
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# using KEY and VALUE as arguments
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twisted.internet.reactor.callLater(2.5, getValue)
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# Start the Twisted reactor - this fires up all networking, and
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# allows the scheduled join operation to take place
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print 'Twisted reactor started (script will commence in 2.5 seconds)'
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twisted.internet.reactor.run()
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