def test_routing_table_search():
for table_size, lower_active, upper_active in [(10, 10, 10),
(10_000, 800, 1100)]:
node_id = DHTID.generate()
routing_table = RoutingTable(node_id, bucket_size=20, depth_modulo=5)
num_added = 0
total_nodes = 0
for phony_neighbor_port in random.sample(range(1_000_000), table_size):
routing_table.add_or_update_node(
DHTID.generate(), f'{LOCALHOST}:{phony_neighbor_port}')
new_total = sum(
len(bucket.nodes_to_endpoint)
for bucket in routing_table.buckets)
num_added += new_total > total_nodes
total_nodes = new_total
def test_routing_table_parameters():
for (bucket_size, modulo, min_nbuckets, max_nbuckets) in [
(20, 5, 45, 65),
(50, 5, 35, 45),
(20, 10, 650, 800),
(20, 1, 7, 15),
]:
node_id = DHTID.generate()
routing_table = RoutingTable(node_id,
bucket_size=bucket_size,
depth_modulo=modulo)
for phony_neighbor_port in random.sample(range(1_000_000), 10_000):
routing_table.add_or_update_node(
DHTID.generate(), f'{LOCALHOST}:{phony_neighbor_port}')
for bucket in routing_table.buckets:
assert len(bucket.replacement_nodes) == 0 or len(
bucket.nodes_to_endpoint) <= bucket.size
assert min_nbuckets <= len(routing_table.buckets) <= max_nbuckets, (
f"Unexpected number of buckets: {min_nbuckets} <= {len(routing_table.buckets)} <= {max_nbuckets}"
)
def test_routing_table_basic():
node_id = DHTID.generate()
routing_table = RoutingTable(node_id, bucket_size=20, depth_modulo=5)
added_nodes = []
for phony_neighbor_port in random.sample(range(10000), 100):
phony_id = DHTID.generate()
routing_table.add_or_update_node(phony_id,
f'{LOCALHOST}:{phony_neighbor_port}')
assert phony_id in routing_table
assert f'{LOCALHOST}:{phony_neighbor_port}' in routing_table
assert routing_table[phony_id] == f'{LOCALHOST}:{phony_neighbor_port}'
assert routing_table[f'{LOCALHOST}:{phony_neighbor_port}'] == phony_id
added_nodes.append(phony_id)
assert routing_table.buckets[
0].lower == DHTID.MIN and routing_table.buckets[-1].upper == DHTID.MAX
for bucket in routing_table.buckets:
assert len(
bucket.replacement_nodes
) == 0, "There should be no replacement nodes in a table with 100 entries"
assert 3 <= len(routing_table.buckets) <= 10, len(routing_table.buckets)
random_node = random.choice(added_nodes)
assert routing_table.get(node_id=random_node) == routing_table[random_node]
dummy_node = DHTID.generate()
assert (dummy_node
not in routing_table) == (routing_table.get(node_id=dummy_node) is
None)
for node in added_nodes:
found_bucket_index = routing_table.get_bucket_index(node)
for bucket_index, bucket in enumerate(routing_table.buckets):
if bucket.lower <= node < bucket.upper:
break
else:
raise ValueError(
"Naive search could not find bucket. Universe has gone crazy.")
assert bucket_index == found_bucket_index
class DHTProtocol(dht_grpc.DHTServicer):
# fmt:off
node_id: DHTID
port: int
bucket_size: int
num_replicas: int
wait_timeout: float
node_info: dht_pb2.NodeInfo
channel_options: Optional[Sequence[Tuple[str, Any]]]
server: grpc.experimental.aio.Server
storage: LocalStorage
cache: LocalStorage
routing_table: RoutingTable
rpc_semaphore: asyncio.Semaphore
# fmt:on
@classmethod
async def create(cls,
node_id: DHTID,
bucket_size: int,
depth_modulo: int,
num_replicas: int,
wait_timeout: float,
parallel_rpc: Optional[int] = None,
cache_size: Optional[int] = None,
listen=True,
listen_on='0.0.0.0:*',
channel_options: Optional[Sequence[Tuple[str,
Any]]] = None,
**kwargs) -> DHTProtocol:
"""
A protocol that allows DHT nodes to request keys/neighbors from other DHT nodes.
As a side-effect, DHTProtocol also maintains a routing table as described in
https://pdos.csail.mit.edu/~petar/papers/maymounkov-kademlia-lncs.pdf
See DHTNode (node.py) for a more detailed description.
:note: the rpc_* methods defined in this class will be automatically exposed to other DHT nodes,
for instance, def rpc_ping can be called as protocol.call_ping(endpoint, dht_id) from a remote machine
Only the call_* methods are meant to be called publicly, e.g. from DHTNode
Read more: https://github.com/bmuller/rpcudp/tree/master/rpcudp
"""
self = cls(_initialized_with_create=True)
self.node_id, self.bucket_size, self.num_replicas = node_id, bucket_size, num_replicas
self.wait_timeout, self.channel_options = wait_timeout, channel_options
self.storage, self.cache = LocalStorage(), LocalStorage(
maxsize=cache_size)
self.routing_table = RoutingTable(node_id, bucket_size, depth_modulo)
self.rpc_semaphore = asyncio.Semaphore(
parallel_rpc if parallel_rpc is not None else float('inf'))
if listen: # set up server to process incoming rpc requests
grpc.experimental.aio.init_grpc_aio()
self.server = grpc.experimental.aio.server(**kwargs)
dht_grpc.add_DHTServicer_to_server(self, self.server)
found_port = self.server.add_insecure_port(listen_on)
assert found_port != 0, f"Failed to listen to {listen_on}"
self.node_info = dht_pb2.NodeInfo(node_id=node_id.to_bytes(),
rpc_port=found_port)
self.port = found_port
await self.server.start()
else: # not listening to incoming requests, client-only mode
# note: use empty node_info so peers wont add you to their routing tables
self.node_info, self.server, self.port = dht_pb2.NodeInfo(
), None, None
if listen_on != '0.0.0.0:*' or len(kwargs) != 0:
warn(
f"DHTProtocol has no server (due to listen=False), listen_on"
f"and kwargs have no effect (unused kwargs: {kwargs})")
return self
def __init__(self, *, _initialized_with_create=False):
""" Internal init method. Please use DHTProtocol.create coroutine to spawn new protocol instances """
assert _initialized_with_create, " Please use DHTProtocol.create coroutine to spawn new protocol instances "
super().__init__()
async def shutdown(self, timeout=None):
""" Process existing requests, close all connections and stop the server """
if self.server:
await self.server.stop(timeout)
else:
warn(
"DHTProtocol has no server (due to listen=False), it doesn't need to be shut down"
)
def _get(self, peer: Endpoint) -> dht_grpc.DHTStub:
""" get a DHTStub that sends requests to a given peer """
channel = grpc.experimental.aio.insecure_channel(
peer, options=self.channel_options)
return dht_grpc.DHTStub(channel)
async def call_ping(self, peer: Endpoint) -> Optional[DHTID]:
"""
Get peer's node id and add him to the routing table. If peer doesn't respond, return None
:param peer: string network address, e.g. 123.123.123.123:1337 or [2a21:6с8:b192:2105]:8888
:note: if DHTProtocol was created with listen=True, also request peer to add you to his routing table
:return: node's DHTID, if peer responded and decided to send his node_id
"""
try:
async with self.rpc_semaphore:
peer_info = await self._get(peer).rpc_ping(
self.node_info, timeout=self.wait_timeout)
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to ping {peer}: {error.code()}")
peer_info = None
responded = bool(peer_info and peer_info.node_id)
peer_id = DHTID.from_bytes(peer_info.node_id) if responded else None
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=responded))
return peer_id
async def rpc_ping(self, peer_info: dht_pb2.NodeInfo,
context: grpc.ServicerContext):
""" Some node wants us to add it to our routing table. """
if peer_info.node_id and peer_info.rpc_port:
sender_id = DHTID.from_bytes(peer_info.node_id)
rpc_endpoint = replace_port(context.peer(),
new_port=peer_info.rpc_port)
asyncio.create_task(
self.update_routing_table(sender_id, rpc_endpoint))
return self.node_info
async def call_store(
self,
peer: Endpoint,
keys: Sequence[DHTID],
values: Sequence[BinaryDHTValue],
expiration_time: Union[DHTExpiration, Sequence[DHTExpiration]],
in_cache: Optional[Union[bool,
Sequence[bool]]] = None) -> Sequence[bool]:
"""
Ask a recipient to store several (key, value : expiration_time) items or update their older value
:param peer: request this peer to store the data
:param keys: a list of N keys digested by DHTID.generate(source=some_dict_key)
:param values: a list of N serialized values (bytes) for each respective key
:param expiration_time: a list of N expiration timestamps for each respective key-value pair (see get_dht_time())
:param in_cache: a list of booleans, True = store i-th key in cache, value = store i-th key locally
:note: the difference between storing normally and in cache is that normal storage is guaranteed to be stored
until expiration time (best-effort), whereas cached storage can be evicted early due to limited cache size
:return: list of [True / False] True = stored, False = failed (found newer value or no response)
if peer did not respond (e.g. due to timeout or congestion), returns None
"""
if isinstance(expiration_time, DHTExpiration):
expiration_time = [expiration_time] * len(keys)
in_cache = in_cache if in_cache is not None else [False] * len(
keys) # default value (None)
in_cache = [in_cache] * len(keys) if isinstance(
in_cache, bool) else in_cache # single bool
keys, values, expiration_time, in_cache = map(
list, [keys, values, expiration_time, in_cache])
assert len(keys) == len(values) == len(expiration_time) == len(
in_cache), "Data is not aligned"
store_request = dht_pb2.StoreRequest(keys=list(
map(DHTID.to_bytes, keys)),
values=values,
expiration_time=expiration_time,
in_cache=in_cache,
peer=self.node_info)
try:
async with self.rpc_semaphore:
response = await self._get(peer).rpc_store(
store_request, timeout=self.wait_timeout)
if response.peer and response.peer.node_id:
peer_id = DHTID.from_bytes(response.peer.node_id)
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=True))
return response.store_ok
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to store at {peer}: {error.code()}")
asyncio.create_task(
self.update_routing_table(
self.routing_table.get(endpoint=peer),
peer,
responded=False))
return [False] * len(keys)
async def rpc_store(
self, request: dht_pb2.StoreRequest,
context: grpc.ServicerContext) -> dht_pb2.StoreResponse:
""" Some node wants us to store this (key, value) pair """
if request.peer: # if requested, add peer to the routing table
asyncio.create_task(self.rpc_ping(request.peer, context))
assert len(request.keys) == len(request.values) == len(
request.expiration_time) == len(request.in_cache)
response = dht_pb2.StoreResponse(store_ok=[], peer=self.node_info)
for key_bytes, value_bytes, expiration_time, in_cache in zip(
request.keys, request.values, request.expiration_time,
request.in_cache):
local_memory = self.cache if in_cache else self.storage
response.store_ok.append(
local_memory.store(DHTID.from_bytes(key_bytes), value_bytes,
expiration_time))
return response
async def call_find(self, peer: Endpoint, keys: Collection[DHTID]) -> \
Optional[Dict[DHTID, Tuple[Optional[BinaryDHTValue], Optional[DHTExpiration], Dict[DHTID, Endpoint]]]]:
"""
Request keys from a peer. For each key, look for its (value, expiration time) locally and
k additional peers that are most likely to have this key (ranked by XOR distance)
:returns: A dict key => Tuple[optional value, optional expiration time, nearest neighbors]
value: value stored by the recipient with that key, or None if peer doesn't have this value
expiration time: expiration time of the returned value, None if no value was found
neighbors: a dictionary[node_id : endpoint] containing nearest neighbors from peer's routing table
If peer didn't respond, returns None
"""
keys = list(keys)
find_request = dht_pb2.FindRequest(keys=list(map(DHTID.to_bytes,
keys)),
peer=self.node_info)
try:
async with self.rpc_semaphore:
response = await self._get(peer).rpc_find(
find_request, timeout=self.wait_timeout)
if response.peer and response.peer.node_id:
peer_id = DHTID.from_bytes(response.peer.node_id)
asyncio.create_task(
self.update_routing_table(peer_id, peer, responded=True))
assert len(response.values) == len(response.expiration_time) == len(response.nearest) == len(keys), \
"DHTProtocol: response is not aligned with keys and/or expiration times"
output = {} # unpack data without special NOT_FOUND_* values
for key, value, expiration_time, nearest in zip(
keys, response.values, response.expiration_time,
response.nearest):
value = value if value != _NOT_FOUND_VALUE else None
expiration_time = expiration_time if expiration_time != _NOT_FOUND_EXPIRATION else None
nearest = dict(
zip(map(DHTID.from_bytes, nearest.node_ids),
nearest.endpoints))
output[key] = (value, expiration_time, nearest)
return output
except grpc.experimental.aio.AioRpcError as error:
logger.warning(
f"DHTProtocol failed to find at {peer}: {error.code()}")
asyncio.create_task(
self.update_routing_table(
self.routing_table.get(endpoint=peer),
peer,
responded=False))
async def rpc_find(self, request: dht_pb2.FindRequest,
context: grpc.ServicerContext) -> dht_pb2.FindResponse:
"""
Someone wants to find keys in the DHT. For all keys that we have locally, return value and expiration
Also return :bucket_size: nearest neighbors from our routing table for each key (whether or not we found value)
"""
if request.peer: # if requested, add peer to the routing table
asyncio.create_task(self.rpc_ping(request.peer, context))
response = dht_pb2.FindResponse(values=[],
expiration_time=[],
nearest=[],
peer=self.node_info)
for key_id in map(DHTID.from_bytes, request.keys):
maybe_value, maybe_expiration_time = self.storage.get(key_id)
cached_value, cached_expiration_time = self.cache.get(key_id)
if (cached_expiration_time or
-float('inf')) > (maybe_expiration_time or -float('inf')):
maybe_value, maybe_expiration_time = cached_value, cached_expiration_time
nearest_neighbors = self.routing_table.get_nearest_neighbors(
key_id,
k=self.bucket_size,
exclude=DHTID.from_bytes(request.peer.node_id))
if nearest_neighbors:
peer_ids, endpoints = zip(*nearest_neighbors)
else:
peer_ids, endpoints = [], []
response.values.append(
maybe_value if maybe_value is not None else _NOT_FOUND_VALUE)
response.expiration_time.append(
maybe_expiration_time
if maybe_expiration_time else _NOT_FOUND_EXPIRATION)
response.nearest.append(
dht_pb2.Peers(node_ids=list(map(DHTID.to_bytes, peer_ids)),
endpoints=endpoints))
return response
async def update_routing_table(self,
node_id: Optional[DHTID],
peer_endpoint: Endpoint,
responded=True):
"""
This method is called on every incoming AND outgoing request to update the routing table
:param peer_endpoint: sender endpoint for incoming requests, recipient endpoint for outgoing requests
:param node_id: sender node id for incoming requests, recipient node id for outgoing requests
:param responded: for outgoing requests, this indicated whether recipient responded or not.
For incoming requests, this should always be True
"""
node_id = node_id if node_id is not None else self.routing_table.get(
endpoint=peer_endpoint)
if responded: # incoming request or outgoing request with response
if node_id not in self.routing_table:
# we just met a new node, maybe we know some values that it *should* store
data_to_send: List[Tuple[DHTID, BinaryDHTValue,
DHTExpiration]] = []
for key, value, expiration_time in list(self.storage.items()):
neighbors = self.routing_table.get_nearest_neighbors(
key, self.num_replicas, exclude=self.node_id)
if neighbors:
nearest_distance = neighbors[0][0].xor_distance(key)
farthest_distance = neighbors[-1][0].xor_distance(key)
new_node_should_store = node_id.xor_distance(
key) < farthest_distance
this_node_is_responsible = self.node_id.xor_distance(
key) < nearest_distance
if not neighbors or (new_node_should_store
and this_node_is_responsible):
data_to_send.append((key, value, expiration_time))
if data_to_send:
asyncio.create_task(
self.call_store(peer_endpoint,
*zip(*data_to_send),
in_cache=False))
maybe_node_to_ping = self.routing_table.add_or_update_node(
node_id, peer_endpoint)
if maybe_node_to_ping is not None:
# we couldn't add new node because the table was full. Check if existing peers are alive (Section 2.2)
# ping one least-recently updated peer: if it won't respond, remove it from the table, else update it
asyncio.create_task(self.call_ping(maybe_node_to_ping[1])
) # [1]-th element is that node's endpoint
else: # we sent outgoing request and peer did not respond
if node_id is not None and node_id in self.routing_table:
del self.routing_table[node_id]
