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