"""Package for interacting on the network at a high level.""" import asyncio import logging import pickle from .crawling import NodeSpiderCrawl, ValueSpiderCrawl from .kad_peerinfo import create_kad_peerinfo from .protocol import KademliaProtocol from .storage import ForgetfulStorage from .utils import digest log = logging.getLogger(__name__) class KademliaServer: """ High level view of a node instance. This is the object that should be created to start listening as an active node on the network. """ protocol_class = KademliaProtocol def __init__(self, ksize=20, alpha=3, node_id=None, storage=None): """ Create a server instance. This will start listening on the given port. Args: ksize (int): The k parameter from the paper alpha (int): The alpha parameter from the paper node_id: The id for this node on the network. storage: An instance that implements :interface:`~kademlia.storage.IStorage` """ self.ksize = ksize self.alpha = alpha self.storage = storage or ForgetfulStorage() self.node = create_kad_peerinfo(node_id) self.transport = None self.protocol = None self.refresh_loop = None self.save_state_loop = None def stop(self): if self.transport is not None: self.transport.close() if self.refresh_loop: self.refresh_loop.cancel() if self.save_state_loop: self.save_state_loop.cancel() def _create_protocol(self): return self.protocol_class(self.node, self.storage, self.ksize) async def listen(self, port, interface="0.0.0.0"): """ Start listening on the given port. Provide interface="::" to accept ipv6 address """ loop = asyncio.get_event_loop() listen = loop.create_datagram_endpoint( self._create_protocol, local_addr=(interface, port) ) log.info("Node %i listening on %s:%i", self.node.xor_id, interface, port) self.transport, self.protocol = await listen # finally, schedule refreshing table self.refresh_table() def refresh_table(self): log.debug("Refreshing routing table") asyncio.ensure_future(self._refresh_table()) loop = asyncio.get_event_loop() self.refresh_loop = loop.call_later(3600, self.refresh_table) async def _refresh_table(self): """Refresh buckets that haven't had any lookups in the last hour (per section 2.3 of the paper).""" results = [] for node_id in self.protocol.get_refresh_ids(): node = create_kad_peerinfo(node_id) nearest = self.protocol.router.find_neighbors(node, self.alpha) spider = NodeSpiderCrawl( self.protocol, node, nearest, self.ksize, self.alpha ) results.append(spider.find()) # do our crawling await asyncio.gather(*results) # now republish keys older than one hour for dkey, value in self.storage.iter_older_than(3600): await self.set_digest(dkey, value) def bootstrappable_neighbors(self): """ Get a :class:`list` of (ip, port) :class:`tuple` pairs suitable for use as an argument to the bootstrap method. The server should have been bootstrapped already - this is just a utility for getting some neighbors and then storing them if this server is going down for a while. When it comes back up, the list of nodes can be used to bootstrap. """ neighbors = self.protocol.router.find_neighbors(self.node) return [tuple(n)[-2:] for n in neighbors] async def bootstrap(self, addrs): """ Bootstrap the server by connecting to other known nodes in the network. Args: addrs: A `list` of (ip, port) `tuple` pairs. Note that only IP addresses are acceptable - hostnames will cause an error. """ log.debug("Attempting to bootstrap node with %i initial contacts", len(addrs)) cos = list(map(self.bootstrap_node, addrs)) gathered = await asyncio.gather(*cos) nodes = [node for node in gathered if node is not None] spider = NodeSpiderCrawl( self.protocol, self.node, nodes, self.ksize, self.alpha ) return await spider.find() async def bootstrap_node(self, addr): result = await self.protocol.ping(addr, self.node.peer_id_bytes) return create_kad_peerinfo(result[1], addr[0], addr[1]) if result[0] else None async def get(self, key): """ Get a key if the network has it. Returns: :class:`None` if not found, the value otherwise. """ log.info("Looking up key %s", key) dkey = digest(key) # if this node has it, return it if self.storage.get(dkey) is not None: return self.storage.get(dkey) node = create_kad_peerinfo(dkey) nearest = self.protocol.router.find_neighbors(node) if not nearest: log.warning("There are no known neighbors to get key %s", key) return None spider = ValueSpiderCrawl(self.protocol, node, nearest, self.ksize, self.alpha) return await spider.find() async def set(self, key, value): """Set the given string key to the given value in the network.""" if not check_dht_value_type(value): raise TypeError("Value must be of type int, float, bool, str, or bytes") log.info("setting '%s' = '%s' on network", key, value) dkey = digest(key) return await self.set_digest(dkey, value) async def provide(self, key): """publish to the network that it provides for a particular key.""" neighbors = self.protocol.router.find_neighbors(self.node) return [ await self.protocol.call_add_provider(n, key, self.node.peer_id_bytes) for n in neighbors ] async def get_providers(self, key): """get the list of providers for a key.""" neighbors = self.protocol.router.find_neighbors(self.node) return [await self.protocol.call_get_providers(n, key) for n in neighbors] async def set_digest(self, dkey, value): """Set the given SHA1 digest key (bytes) to the given value in the network.""" node = create_kad_peerinfo(dkey) nearest = self.protocol.router.find_neighbors(node) if not nearest: log.warning("There are no known neighbors to set key %s", dkey.hex()) return False spider = NodeSpiderCrawl(self.protocol, node, nearest, self.ksize, self.alpha) nodes = await spider.find() log.info("setting '%s' on %s", dkey.hex(), list(map(str, nodes))) # if this node is close too, then store here as well biggest = max([n.distance_to(node) for n in nodes]) if self.node.distance_to(node) < biggest: self.storage[dkey] = value results = [self.protocol.call_store(n, dkey, value) for n in nodes] # return true only if at least one store call succeeded return any(await asyncio.gather(*results)) def save_state(self, fname): """Save the state of this node (the alpha/ksize/id/immediate neighbors) to a cache file with the given fname.""" log.info("Saving state to %s", fname) data = { "ksize": self.ksize, "alpha": self.alpha, "id": self.node.peer_id_bytes, "neighbors": self.bootstrappable_neighbors(), } if not data["neighbors"]: log.warning("No known neighbors, so not writing to cache.") return with open(fname, "wb") as file: pickle.dump(data, file) @classmethod def load_state(cls, fname): """Load the state of this node (the alpha/ksize/id/immediate neighbors) from a cache file with the given fname.""" log.info("Loading state from %s", fname) with open(fname, "rb") as file: data = pickle.load(file) svr = KademliaServer(data["ksize"], data["alpha"], data["id"]) if data["neighbors"]: svr.bootstrap(data["neighbors"]) return svr def save_state_regularly(self, fname, frequency=600): """ Save the state of node with a given regularity to the given filename. Args: fname: File name to save retularly to frequency: Frequency in seconds that the state should be saved. By default, 10 minutes. """ self.save_state(fname) loop = asyncio.get_event_loop() self.save_state_loop = loop.call_later( frequency, self.save_state_regularly, fname, frequency ) def check_dht_value_type(value): """Checks to see if the type of the value is a valid type for placing in the dht.""" typeset = [int, float, bool, str, bytes] return type(value) in typeset