import random import asyncio import logging from rpcudp.protocol import RPCProtocol from .kad_peerinfo import create_kad_peerinfo from .routing import RoutingTable log = logging.getLogger(__name__) class KademliaProtocol(RPCProtocol): """ There are four main RPCs in the Kademlia protocol PING, STORE, FIND_NODE, FIND_VALUE PING probes if a node is still online STORE instructs a node to store (key, value) FIND_NODE takes a 160-bit ID and gets back (ip, udp_port, node_id) for k closest nodes to target FIND_VALUE behaves like FIND_NODE unless a value is stored """ def __init__(self, source_node, storage, ksize): RPCProtocol.__init__(self) self.router = RoutingTable(self, ksize, source_node) self.storage = storage self.source_node = source_node def get_refresh_ids(self): """ Get ids to search for to keep old buckets up to date. """ ids = [] for bucket in self.router.lonely_buckets(): rid = random.randint(*bucket.range).to_bytes(20, byteorder="big") ids.append(rid) return ids def rpc_stun(self, sender): return sender def rpc_ping(self, sender, nodeid): source = create_kad_peerinfo(nodeid, sender[0], sender[1]) self.welcome_if_new(source) return self.source_node.peer_id_bytes def rpc_store(self, sender, nodeid, key, value): source = create_kad_peerinfo(nodeid, sender[0], sender[1]) self.welcome_if_new(source) log.debug( "got a store request from %s, storing '%s'='%s'", sender, key.hex(), value ) self.storage[key] = value return True def rpc_find_node(self, sender, nodeid, key): log.info("finding neighbors of %i in local table", int(nodeid.hex(), 16)) source = create_kad_peerinfo(nodeid, sender[0], sender[1]) self.welcome_if_new(source) node = create_kad_peerinfo(key) neighbors = self.router.find_neighbors(node, exclude=source) return list(map(tuple, neighbors)) def rpc_find_value(self, sender, nodeid, key): source = create_kad_peerinfo(nodeid, sender[0], sender[1]) self.welcome_if_new(source) value = self.storage.get(key, None) if value is None: return self.rpc_find_node(sender, nodeid, key) return {"value": value} def rpc_add_provider(self, sender, nodeid, key, provider_id): """ rpc when receiving an add_provider call should validate received PeerInfo matches sender nodeid if it does, receipient must store a record in its datastore we store a map of content_id to peer_id (non xor) """ if nodeid == provider_id: log.info( "adding provider %s for key %s in local table", provider_id, str(key) ) self.storage[key] = provider_id return True return False def rpc_get_providers(self, sender, key): """ rpc when receiving a get_providers call should look up key in data store and respond with records plus a list of closer peers in its routing table """ providers = [] record = self.storage.get(key, None) if record: providers.append(record) keynode = create_kad_peerinfo(key) neighbors = self.router.find_neighbors(keynode) for neighbor in neighbors: if neighbor.peer_id_bytes != record: providers.append(neighbor.peer_id_bytes) return providers async def call_find_node(self, node_to_ask, node_to_find): address = (node_to_ask.ip, node_to_ask.port) result = await self.find_node( address, self.source_node.peer_id_bytes, node_to_find.peer_id_bytes ) return self.handle_call_response(result, node_to_ask) async def call_find_value(self, node_to_ask, node_to_find): address = (node_to_ask.ip, node_to_ask.port) result = await self.find_value( address, self.source_node.peer_id_bytes, node_to_find.peer_id_bytes ) return self.handle_call_response(result, node_to_ask) async def call_ping(self, node_to_ask): address = (node_to_ask.ip, node_to_ask.port) result = await self.ping(address, self.source_node.peer_id_bytes) return self.handle_call_response(result, node_to_ask) async def call_store(self, node_to_ask, key, value): address = (node_to_ask.ip, node_to_ask.port) result = await self.store(address, self.source_node.peer_id_bytes, key, value) return self.handle_call_response(result, node_to_ask) async def call_add_provider(self, node_to_ask, key, provider_id): address = (node_to_ask.ip, node_to_ask.port) result = await self.add_provider( address, self.source_node.peer_id_bytes, key, provider_id ) return self.handle_call_response(result, node_to_ask) async def call_get_providers(self, node_to_ask, key): address = (node_to_ask.ip, node_to_ask.port) result = await self.get_providers(address, key) return self.handle_call_response(result, node_to_ask) def welcome_if_new(self, node): """ Given a new node, send it all the keys/values it should be storing, then add it to the routing table. @param node: A new node that just joined (or that we just found out about). Process: For each key in storage, get k closest nodes. If newnode is closer than the furtherst in that list, and the node for this server is closer than the closest in that list, then store the key/value on the new node (per section 2.5 of the paper) """ if not self.router.is_new_node(node): return log.info("never seen %s before, adding to router", node) for key, value in self.storage: keynode = create_kad_peerinfo(key) neighbors = self.router.find_neighbors(keynode) if neighbors: last = neighbors[-1].distance_to(keynode) new_node_close = node.distance_to(keynode) < last first = neighbors[0].distance_to(keynode) this_closest = self.source_node.distance_to(keynode) < first if not neighbors or (new_node_close and this_closest): asyncio.ensure_future(self.call_store(node, key, value)) self.router.add_contact(node) def handle_call_response(self, result, node): """ If we get a response, add the node to the routing table. If we get no response, make sure it's removed from the routing table. """ if not result[0]: log.warning("no response from %s, removing from router", node) self.router.remove_contact(node) return result log.info("got successful response from %s", node) self.welcome_if_new(node) return result