* Delay routing table update on new connections.
In order to avoid adding peers to the local routing table
which use a different protocol name and thus a different
overlay network, only update the local routing table
for newly established connections once the associated
connection handler reports that the protocol has been
confirmed.
* Update CHANGELOG.
* Store addresses of provider records.
So far, provider records are stored without their
addresses and the addresses of provider records are
obtained from the routing table on demand. This has
two shortcomings:
1. We can only return provider records whose provider
peers happen to currently be in the local routing table.
2. The local node never returns itself as a provider for
a key, even if it is indeed a provider.
These issues are addressed here by storing the addresses
together with the provider records, falling back to
addresses from the routing table only for backward-compatibility
with existing implementations of `RecordStore` using persistent
storage.
Resolves https://github.com/libp2p/rust-libp2p/issues/1526.
* Update protocols/kad/src/behaviour.rs
Co-authored-by: Max Inden <mail@max-inden.de>
* Remove negligible use of with_capacity.
* Update changelog.
Co-authored-by: Max Inden <mail@max-inden.de>
With 826f513 a `StreamMuxer` can notify that the address of a remote
peer changed. This is needed to support the transport protocol QUIC as
remotes can change their IP addresses within the lifetime of a single
connection.
This commit implements the `NetworkBehaviour::inject_address_change`
handler to update the Kademlia routing table accordingly.
* More control & insight for k-buckets.
1) More control: It is now possible to disable automatic
insertions of peers into the routing table via a new
`KademliaBucketInserts` configuration option. The
default is `OnConnected`, but it can be set to `Manual`,
in which case `add_address` must be called explicitly.
In order to communicate all situations in which a user
of `Kademlia` may want to manually update the routing
table, two new events are introduced:
* `KademliaEvent::RoutablePeer`: When a connection to
a peer with a known listen address is established
which may be added to the routing table. This is
also emitted when automatic inserts are allowed but
the corresponding k-bucket is full.
* `KademliaEvent::PendingRoutablePeer`: When a connection
to a peer with a known listen address is established
which is pending insertion into the routing table
(but may not make it). This is only emitted when
`OnConnected` (i.e. automatic inserts) are used.
These complement the existing `UnroutablePeer` and
`RoutingUpdated` events. It is now also possible to
explicitly remove peers and addresses from the
routing table.
2) More insight: `Kademlia::kbuckets` now gives an
iterator over `KBucketRef`s and `Kademlia::bucket`
a particular `KBucketRef`. A `KBucketRef` in turn
allows iteration over its entries. In this way,
the full contents of the routing table can be
inspected, e.g. in order to decide which peer(s)
to remove.
* Update protocols/kad/src/behaviour.rs
* Update protocols/kad/src/behaviour.rs
Co-authored-by: Max Inden <mail@max-inden.de>
* Update CHANGELOG.
Co-authored-by: Max Inden <mail@max-inden.de>
The extension paper S-Kademlia includes a proposal for lookups over
disjoint paths. Within vanilla Kademlia, queries keep track of the
closest nodes in a single bucket. Any adversary along the path can thus
influence all future paths, in case they can come up with the
next-closest (not overall closest) hops. S-Kademlia tries to solve the
attack above by querying over disjoint paths using multiple buckets.
To adjust the libp2p Kademlia implementation accordingly this change-set
introduces an additional peers iterator: `ClosestDisjointPeersIter`.
This new iterator wraps around a set of `ClosestPeersIter`
`ClosestDisjointPeersIter` enforces that each of the `ClosestPeersIter`
explore disjoint paths by having each peer instantly return that was
queried by a different iterator before.
* [libp2p-kad] Provide more insight and control into Kademlia queries.
More insight: The API allows iterating over the active queries and
inspecting their state and execution statistics.
More control: The API allows aborting queries prematurely
at any time.
To that end, API operations that initiate new queries return the query ID
and multi-phase queries such as `put_record` retain the query ID across all
phases, each phase being executed by a new (internal) query.
* Cleanup
* Cleanup
* Update examples and re-exports.
* Incorporate review feedback.
* Update CHANGELOG
* Update CHANGELOG
Co-authored-by: Max Inden <mail@max-inden.de>
`FixedPeersIter` requires the initial set of peers to be passed as
`PeerId`s and not as `Key<PeerId>`s. This commit removes the unnecessary
conversion.
A node receiving a `GetRecord` request first checks whether it has the
given record. If it does have the record it does not return closer
nodes.
A node that knows the record for the given key is likely within a
neighborhood of nodes that know the record as well. In addition the node
likely knows its neighboorhood well.
When querying for a key with a quorum of 1 the above behavior of only
returning the record but not any close peers is fine. Once one queries
with a higher quorum having a node respond with the record as well as
close nodes is likely going to speed up the query, given that the
returned peers probably know the record as well.
* [libp2p-swarm] Make the multiple connections per peer first-class.
This commit makes the notion of multiple connections per peer
first-class in the API of libp2p-swarm, introducing the new
callbacks `inject_connection_established` and
`inject_connection_closed`. The `endpoint` parameter from
`inject_connected` and `inject_disconnected` is removed,
since the first connection to open may not be the last
connection to close, i.e. it cannot be guaranteed,
as was previously the case, that the endpoints passed
to these callbacks match up.
* Have identify track all addresses.
So that identify requests can be answered with the correct
observed address of the connection on which the request
arrives.
* Cleanup
* Cleanup
* Improve the `Peer` state API.
* Remove connection ID from `SwarmEvent::Dialing`.
* Mark `DialPeerCondition` non-exhaustive.
* Re-encapsulate `NetworkConfig`.
To retain the possibility of not re-exposing all
network configuration choices, thereby providing
a more convenient API on the \`SwarmBuilder\`.
* Rework Swarm::dial API.
* Update CHANGELOG.
* Doc formatting tweaks.
Given that the order of `PeerId`s within the `GetProvidersOk.providers`
set is irrelevant but duplication is at best confusing this commit makes
use of a `HashSet` instead of a `Vec` to return unique `PeerId`s only.
* protocols/kad: Do not attempt to store expired record in record store
`Kademlia::record_received` calculates the expiration time of a record
before inserting it into the record store. Instead of inserting the
record into the record store in any case, with this patch the record is
only inserted if it is not expired. If the record is expired a
`KademliaHandlerIn::Reset` for the given (sub) stream is triggered.
This would serve as a tiny defense mechanism against an attacker trying
to fill a node's record store with expired records before the record
store's clean up procedure removes the records.
* protocols/kad: Send regular ack when record discarded due to expiration
With this commit the remote receives a
[`KademliaHandlerIn::PutRecordRes`] even in the case where the record is
discarded due to being expired. Given that the remote sent the local
node a [`KademliaHandlerEvent::PutRecord`] request, the remote perceives
the local node as one node among the k closest nodes to the target.
Returning a [`KademliaHandlerIn::Reset`] instead of an
[`KademliaHandlerIn::PutRecordRes`] to have the remote try another node
would only result in the remote node to contact an even more distant
node. In addition returning [`KademliaHandlerIn::PutRecordRes`] does not
reveal any internal information to a possibly malicious remote node.
* protocols/kad/src/behaviour: Use `now` and reword expiration comment
Co-authored-by: Roman Borschel <romanb@users.noreply.github.com>
* protocols/kad: Add test to reproduce right shift overflow panic
* protocols/kad: Fix right shift overflow panic in record_received
Within `Behaviour::record_received` the exponentially decreasing
expiration based on the distance to the target for a record is
calculated as following:
1. Calculate the amount of nodes between us and the record key beyond
the k replication constant as `n`.
2. Shift the configured record time-to-live `n` times to the right to
calculate an exponentially decreasing expiration.
The configured record time-to-live is a u64. If `n` is larger or equal
to 64 the right shift will lead to an overflow which panics in debug
mode.
This patch uses a checked right shift instead, defaulting to 0 (`now +
0`) for the expiration on overflow.
* protocols/kad: Put attribute below comment
* protocols/kad: Extract shifting logic and rework test
Extract right shift into isolated function and replace complex
regression test with small isolated one.
* protocols/kad/src/behaviour: Refactor exp_decr_expiration
Co-authored-by: Roman Borschel <romanb@users.noreply.github.com>
* Allow multiple connections per peer in libp2p-core.
Instead of trying to enforce a single connection per peer,
which involves quite a bit of additional complexity e.g.
to prioritise simultaneously opened connections and can
have other undesirable consequences [1], we now
make multiple connections per peer a feature.
The gist of these changes is as follows:
The concept of a "node" with an implicit 1-1 correspondence
to a connection has been replaced with the "first-class"
concept of a "connection". The code from `src/nodes` has moved
(with varying degrees of modification) to `src/connection`.
A `HandledNode` has become a `Connection`, a `NodeHandler` a
`ConnectionHandler`, the `CollectionStream` was the basis for
the new `connection::Pool`, and so forth.
Conceptually, a `Network` contains a `connection::Pool` which
in turn internally employs the `connection::Manager` for
handling the background `connection::manager::Task`s, one
per connection, as before. These are all considered implementation
details. On the public API, `Peer`s are managed as before through
the `Network`, except now the API has changed with the shift of focus
to (potentially multiple) connections per peer. The `NetworkEvent`s have
accordingly also undergone changes.
The Swarm APIs remain largely unchanged, except for the fact that
`inject_replaced` is no longer called. It may now practically happen
that multiple `ProtocolsHandler`s are associated with a single
`NetworkBehaviour`, one per connection. If implementations of
`NetworkBehaviour` rely somehow on communicating with exactly
one `ProtocolsHandler`, this may cause issues, but it is unlikely.
[1]: https://github.com/paritytech/substrate/issues/4272
* Fix intra-rustdoc links.
* Update core/src/connection/pool.rs
Co-Authored-By: Max Inden <mail@max-inden.de>
* Address some review feedback and fix doc links.
* Allow responses to be sent on the same connection.
* Remove unnecessary remainders of inject_replaced.
* Update swarm/src/behaviour.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Update swarm/src/lib.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Update core/src/connection/manager.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Update core/src/connection/manager.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Update core/src/connection/pool.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Incorporate more review feedback.
* Move module declaration below imports.
* Update core/src/connection/manager.rs
Co-Authored-By: Toralf Wittner <tw@dtex.org>
* Update core/src/connection/manager.rs
Co-Authored-By: Toralf Wittner <tw@dtex.org>
* Simplify as per review.
* Fix rustoc link.
* Add try_notify_handler and simplify.
* Relocate DialingConnection and DialingAttempt.
For better visibility constraints.
* Small cleanup.
* Small cleanup. More robust EstablishedConnectionIter.
* Clarify semantics of `DialingPeer::connect`.
* Don't call inject_disconnected on InvalidPeerId.
To preserve the previous behavior and ensure calls to
`inject_disconnected` are always paired with calls to
`inject_connected`.
* Provide public ConnectionId constructor.
Mainly needed for testing purposes, e.g. in substrate.
* Move the established connection limit check to the right place.
* Clean up connection error handling.
Separate connection errors into those occuring during
connection setup or upon rejecting a newly established
connection (the `PendingConnectionError`) and those
errors occurring on previously established connections,
i.e. for which a `ConnectionEstablished` event has
been emitted by the connection pool earlier.
* Revert change in log level and clarify an invariant.
* Remove inject_replaced entirely.
* Allow notifying all connection handlers.
Thereby simplify by introducing a new enum `NotifyHandler`,
used with a single constructor `NetworkBehaviourAction::NotifyHandler`.
* Finishing touches.
Small API simplifications and code deduplication.
Some more useful debug logging.
Co-authored-by: Max Inden <mail@max-inden.de>
Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>
Co-authored-by: Toralf Wittner <tw@dtex.org>
The `QueryId` type should be exported as it is used in the
`NetworkBehaviour::ProtocolsHandler` type of `Kademlia`.
`Kademlia::protocol_name` is added for convenience.
* Replace some remaining `AsRef` constraints for DHT keys with `Borrow`.
* Add a bit of debug/trace logging.
* Tiny refactoring and a debug assertion for the `bucket` module.
* Fix broken links in rustdoc
This fixes all of the rustdoc warnings on nightly.
* Check documentation intra-link
* Fix config
* Fix bad indent
* Make nightly explicit
* More links fixes
* Fix link broken after master merge
Co-authored-by: Demi Obenour <48690212+DemiMarie-parity@users.noreply.github.com>
* Simplify trait bounds requirements
* More work
* Moar
* Finish
* Fix final tests
* More simplification
* Use separate traits for Inbound/Outbound
* Update gossipsub and remove warnings
* Add documentation to swarm
* Remove BoxSubstream
* Fix tests not compiling
* Fix stack overflow
* Address concerns
* For some reason my IDE ignored libp2p-kad
* Implement Debug for (ed25519|secp256k1)::(Keypair|SecretKey) (#1285)
* Fix possible arithmetic overflow in libp2p-kad. (#1291)
When the number of active queries exceeds the (internal)
JOBS_MAX_QUERIES limit, which is only supposed to bound
the number of concurrent queries relating to background
jobs, an arithmetic overflow occurs. This is fixed by
using saturating subtraction.
* protocols/plaintext: Add example on how to upgrade with PlainTextConfig1 (#1286)
* [mdns] - Support for long mDNS names (Bug #1232) (#1287)
* Dead code -- commenting out with a note referencing future implementation
* Adding "std" feature so that cargo can build in other directories (notably `misc/mdns`, so that I could run these tests)
* Permitting `PeerID` to be built from an `Identity` multihash
* The length limit for DNS labels is 63 characters, as per RFC1035
* Allocates the vector with capacity for the service name plus additional QNAME encoding bytes
* Added support for encoding/decoding peer IDs with an encoded length greater than 63 characters
* Removing "std" from ring features
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Retaining MAX_INLINE_KEY_LENGTH with comment about future usage
* `segment_peer_id` consumes `peer_id` ... plus an early return for IDs that don't need to be segmented
* Fixing logic
* Bump most dependencies (#1268)
* Bump most dependencies
This actually builds 😊.
* Bump all dependencies
Includes the excellent work of @rschulman in #1265.
* Remove use of ed25519-dalek fork
* Monomorphize more dependencies
* Add compatibility hack for rand
Cargo allows a crate to depend on multiple versions of another, but
`cargo-web` panics in that situation. Use a wrapper crate to work
around the panic.
* Use @tomaka’s idea for using a newer `rand`
instead of my own ugly hack.
* Switch to Parity master
as its dependency-bumping PR has been merged.
* Update some depenendencies again
* Remove unwraps and `#[allow(deprecated)]`.
* Remove spurious changes to dependencies
Bumping minor or patch versions is not needed, and increases likelyhood
of merge conflicts.
* Remove some redundant Cargo.toml changes
* Replace a retry loop with an expect
`ed25519::SecretKey::from_bytes` will never fail for 32-byte inputs.
* Revert changes that don’t belong in this PR
* Remove using void to bypass ICE (#1295)
* Publish 0.13.0 (#1294)
* Remove pending RPCs on query completion.
Ensure that any still pending RPCs related to a query are removed
once the query terminates (successfully or through timeout) by
scoping pending RPCs to the lifetime of a query.
* Cleanup.
* Somewhat complete the implementation of Kademlia records.
This commit relates to [libp2p-146] and [libp2p-1089].
* All records expire (by default, configurable).
* Provider records are also stored in the RecordStore, and the RecordStore
API extended.
* Background jobs for periodic (re-)replication and (re-)publication
of records. Regular (value-)records are subject to re-replication and
re-publication as per standard Kademlia. Provider records are only
subject to re-publication.
* For standard Kademlia value lookups (quorum = 1), the record is cached
at the closest peer to the key that did not return the value, as per
standard Kademlia.
* Expiration times of regular (value-)records is computed exponentially
inversely proportional to the number of nodes between the local node
and the closest node known to the key (beyond the k closest), as per
standard Kademlia.
The protobuf messages are extended with two fields: `ttl` and `publisher`
in order to implement the different semantics of re-replication (by any
of the k closest peers to the key, not affecting expiry) and re-publication
(by the original publisher, resetting the expiry). This is not done yet in
other libp2p Kademlia implementations, see e.g. [libp2p-go-323]. The new protobuf fields
have been given somewhat unique identifiers to prevent future collision.
Similarly, periodic re-publication of provider records does not seem to
be done yet in other implementations, see e.g. [libp2p-js-98].
[libp2p-146]: https://github.com/libp2p/rust-libp2p/issues/146
[libp2p-1089]: https://github.com/libp2p/rust-libp2p/issues/1089
[libp2p-go-323]: https://github.com/libp2p/go-libp2p-kad-dht/issues/323
[libp2p-js-98]: https://github.com/libp2p/js-libp2p-kad-dht/issues/98
* Tweak kad-ipfs example.
* Add missing files.
* Ensure new delays are polled immediately.
To ensure task notification, since `NotReady` is returned right after.
* Fix ipfs-kad example and use wasm_timer.
* Small cleanup.
* Incorporate some feedback.
* Adjustments after rebase.
* Distinguish events further.
In order for a user to easily distinguish the result of e.g.
a `put_record` operation from the result of a later republication,
different event constructors are used. Furthermore, for now,
re-replication and "caching" of records (at the closest peer to
the key that did not return a value during a successful lookup)
do not yield events for now as they are less interesting.
* Speed up tests for CI.
* Small refinements and more documentation.
* Guard a node against overriding records for which it considers
itself to be the publisher.
* Document the jobs module more extensively.
* More inline docs around removal of "unreachable" addresses.
* Remove wildcard re-exports.
* Use NonZeroUsize for the constants.
* Re-add method lost on merge.
* Add missing 'pub'.
* Further increase the timeout in the ipfs-kad example.
* Readd log dependency to libp2p-kad.
* Simplify RecordStore API slightly.
* Some more commentary.
* Change Addresses::remove to return Result<(),()>.
Change the semantics of `Addresses::remove` so that the error case
is unambiguous, instead of the success case. Use the `Result` for
clearer semantics to that effect.
* Add some documentation to .
* Adds a retain method to kademlia.
* Add a store_mut getter to Kademlia
* Removes a blank line
* Changes store_mut comment appropriately
* Fixes build
* Return a type, not a trait
* Address some TODOs, refactor queries and public API.
The following left-over issues are addressed:
* The key for FIND_NODE requests is generalised to any Multihash,
instead of just peer IDs.
* All queries get a (configurable) timeout.
* Finishing queries as soon as enough results have been received is simplified
to avoid code duplication.
* No more panics in provider-API-related code paths. The provider API is
however still untested and (I think) still incomplete (e.g. expiration
of provider records).
* Numerous smaller TODOs encountered in the code.
The following public API changes / additions are made:
* Introduce a `KademliaConfig` with new configuration options for
the replication factor and query timeouts.
* Rename `find_node` to `get_closest_peers`.
* Rename `get_value` to `get_record` and `put_value` to `put_record`,
introducing a `Quorum` parameter for both functions, replacing the
existing `num_results` parameter with clearer semantics.
* Rename `add_providing` to `start_providing` and `remove_providing`
to `stop_providing`.
* Add a `bootstrap` function that implements a (almost) standard
Kademlia bootstrapping procedure.
* Rename `KademliaOut` to `KademliaEvent` with an updated list of
constructors (some renaming). All events that report query results
now report a `Result` to uniformly permit reporting of errors.
The following refactorings are made:
* Introduce some constants.
* Consolidate `query.rs` and `write.rs` behind a common query interface
to reduce duplication and facilitate better code reuse, introducing
the notion of a query peer iterator. `query/peers/closest.rs`
contains the code that was formerly in `query.rs`. `query/peers/fixed.rs` contains
a modified variant of `write.rs` (which is removed). The new `query.rs`
provides an interface for working with a collection of queries, taking
over some code from `behaviour.rs`.
* Reduce code duplication in tests and use the current_thread runtime for
polling swarms to avoid spurious errors in the test output due to aborted
connections when a test finishes prematurely (e.g. because a quorum of
results has been collected).
* Some additions / improvements to the existing tests.
* Fix test.
* Fix rebase.
* Tweak kad-ipfs example.
* Incorporate some feedback.
* Provide easy access and conversion to keys in error results.
Refactoring of iterative queries (`query.rs`) to improve both
correctness and performance (for larger DHTs):
Correctness:
1. Queries no longer terminate prematurely due to counting results
from peers farther from the target while results from closer
peers are still pending. (#1105).
2. Queries no longer ignore reported closer peers that are not duplicates
just because they are currently not among the `num_results` closest.
The currently `max_results` closest may contain peers marked as failed
or pending / waiting. Hence all reported closer peers that are not
duplicates must be considered candidates that may still end up
among the `num_results` closest that successfully responded.
3. Bounded parallelism based on the `active_counter` was not working
correctly, as new (not yet contacted) peers closer to the target
may be discovered at any time and thus appear in `closer_peers`
before the already active / pending peers.
4. The `Frozen` query mechanism allowed all remaining not-yet contacted
peers to be contacted, but their results were discarded, because
`inject_rpc_result` would only incorporate results while the
query is `Iterating`. The `Frozen` state has been reworked into
a `Stalled` state that implements a slightly more permissive
variant of the following from the paper / specs: "If a round of
FIND_NODEs fails to return a node any closer than the closest
already seen, the initiator resends the FIND_NODE to all of the
k closest nodes it has not already queried.". Importantly, though
not explicitly mentioned, the query can move back to `Iterating`
if it makes further progress again as a result of these requests.
The `Stalled` state thus allows (temporarily) higher parallelism
in an effort to make progress and bring the query to an end.
Performance:
1. Repeated distance calculations between the same peers and the
target is avoided.
2. Enabled by #1108, use of a more appropriate data structure (`BTreeMap`) for
the incrementally updated list of closer peers. The data structure needs
efficient lookups (to avoid duplicates) and insertions at any position,
both of which large(r) vectors are not that good at. Unscientific benchmarks
showed a ~40-60% improvement in somewhat pathological scenarios with at least
20 healthy nodes, each possibly returning a distinct list of closer 20 peers
to the requestor. A previous assumption may have been that the vector always
stays very small, but that is not the case in larger clusters: Even if the
lists of closer peers reported by the 20 contacted peers are heavily overlapping,
typically a lot more than 20 peers have to be (at least temporarily) considered
as closest peers until the query completes. See also issue (2) above.
New tests are added for:
* Query termination conditions.
* Bounded parallelism.
* Absence of duplicates.
* initial implementation of the records
* move to multihash keys
* correctly process query results
* comments and formatting
* correctly return closer_peers in query
* checking wrong peer id in test
* Apply suggestions from code review
Co-Authored-By: Roman Borschel <romanb@users.noreply.github.com>
* Fix changes from suggestions
* Send responses to PUT_VALUE requests
* Shortcut in get_value
* Update protocols/kad/src/behaviour.rs
Co-Authored-By: Roman Borschel <romanb@users.noreply.github.com>
* Revert "Update protocols/kad/src/behaviour.rs"
This reverts commit 579ce742a7f4c94587f1e1f0866d2a3a37418efb.
* Remove duplicate insertion
* Adds a record to a PUT_VALUE response
* Fix a racy put_value test
* Store value ourselves only if we are in K closest
* Abstract over storage
* Revert "Abstract over storage": bad take
This reverts commit eaebf5b6d915712eaf3b05929577fdf697f204d8.
* Abstract over records storage using hashmap as default
* Constructor for custom records
* New Record type and its traits
* Fix outdated storage name
* Fixes returning an event
* Change FindNodeReq key type to Multihash
* WriteState for a second stage of a PUT_VALUE request
* GET_VALUE should not have a record
* Refactor a match arm
* Add successes and failures counters to PutValueRes
* If value is found no need to return closer peers
* Remove a custo storage from tests
* Rename a test to get_value_not_found
* Adds a TODO to change FindNode request key to Multihash
Co-Authored-By: Roman Borschel <romanb@users.noreply.github.com>
* Move MemoryRecordStorage to record.rs
* Return a Cow-ed Record from get
* Fix incorrect GET_VALUE parsing
* Various fixes with review
* Fixes get_value_not_found
* Fix peerids names in test
* another fix
* PutValue correctly distributes values
* Simplify the test
* Check that results are actually the closest
* Reverts changes to tests
* Fix the test topology and checking the results
* Run put_value test ten times
* Adds a get_value test
* Apply suggestions from code review
Co-Authored-By: Roman Borschel <romanb@users.noreply.github.com>
* Make Record fields public
* Moves WriteState to write.rs
* A couple of minor fixes
* Another few fixes of review
* Simplify the put_value test
* Dont synchronously return an error from put_value
* Formatting fixes and comments
* Collect a bunch of results
* Take exactly as much elements as neede
* Check if the peer is still connected
* Adds a multiple GetValueResults results number test
* Unnecessary mut iterators in put_value
* Ask for num_results in get_value
* Dont allocate twice in get_value
* Dont count same errored peer multiple times
* Apply suggestions from code review
Co-Authored-By: Roman Borschel <romanb@users.noreply.github.com>
* Fix another review
* Apply suggestions from code review
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Bring back FromIterator and improve a panic message
* Update protocols/kad/src/behaviour.rs
Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
* Kademlia: Optimise iteration over closest entries.
The current implementation for finding the entries whose keys are closest
to some target key in the Kademlia routing table involves copying the
keys of all buckets into a new `Vec` which is then sorted based on the
distances to the target and turned into an iterator from which only a
small number of elements (by default 20) are drawn.
This commit introduces an iterator over buckets for finding the closest
keys to a target that visits the buckets in the optimal order, based on
the information contained in the distance bit-string representing the
distance between the local key and the target.
Correctness is tested against full-table scans.
Also included:
* Updated documentation.
* The `Entry` API was moved to the `kbucket::entry` sub-module for
ease of maintenance.
* The pending node handling has been slightly refactored in order to
bring code and documentation in agreement and clarify the semantics
a little.
* Rewrite pending node handling and add tests.
There are two issues with the current definition and use of Kademlia's
XOR metric:
1. The distance is currently equated with the bucket index, i.e.
`distance(a,b) - 1` is the index of the bucket into which either
peer is put by the other. The result is a metric that is not
unidirectional, as defined in the Kademlia paper and as implemented
in e.g. libp2p-go and libp2p-js, which is to interpret the result
of the XOR as an integer in its entirety.
2. The current `KBucketsPeerId` trait and its instances allow computing
distances between types with differing bit lengths as well as between
types that hash all inputs again (i.e. `KadHash`) and "plain" `PeerId`s
or `Multihash`es. This can result in computed distances that are either
incorrect as per the requirement of the libp2p specs that all distances
are to be computed from the XOR of the SHA256 of the input keys, or
even fall outside of the image of the metric used for the `KBucketsTable`.
In the latter case, such distances are not currently used as a bucket index
- they can only occur in the context of comparing distances for the purpose
of sorting peers - but that still seems undesirable.
These issues are addressed here as follows:
* Unidirectionality of the XOR metric is restored by keeping the "full"
integer representation of the bitwise XOR. The result is an XOR metric
as defined in the paper. This also opens the door to avoiding the
"full table scan" when searching for the keys closest to a given key -
the ideal order in which to visit the buckets can be computed with the
help of the distance bit string.
* As a simplification and to make it easy to "do the right thing", the
XOR metric is only defined on an opaque `kbucket::Key` type, partially
derived from the current `KadHash`. `KadHash` and `KBucketsPeerId`
are removed.
Although not explicitly mentioned in the paper, it seems clear that
including an entry for the requesting peer in a FIND_NODE response
never gives useful information and just occupies a result slot that may
have been better filled with another peer that the requestor may not
know about.
There is one explicit mention that this is the desired behavior
in a somewhat dated design document of another p2p framework [1]:
"The recipient of a FIND_NODE should never return a triple containing
the nodeID of the requestor."
The same reasoning supposedly applies to the libp2p-specific `GET_PROVIDERS`
request.
[1] http://xlattice.sourceforge.net/components/protocol/kademlia/specs.html#FIND_NODE
* Fix self-dialing in Kademlia.
Addresses https://github.com/libp2p/rust-libp2p/issues/341 which is the cause
for one of the observations made in https://github.com/libp2p/rust-libp2p/issues/1053.
However, the latter is not assumed to be fully addressed by these changes and
needs further investigation.
Currently, whenever a search for a key yields a response containing the initiating
peer as one of the closest peers known to the remote, the local node
would attempt to dial itself. That attempt is ignored by the Swarm, but
the Kademlia behaviour now believes it still has a query ongoing which is
always doomed to time out. That timeout delays successful completion of the query.
Hence, any query where a remote responds with the ID of the local node takes at
least as long as the `rpc_timeout` to complete, which possibly affects almost
all queries in smaller clusters where every node knows about every other.
This problem is fixed here by ensuring that Kademlia never tries to dial the local node.
Furthermore, `Discovered` events are no longer emitted for the local node
and it is not inserted into the `untrusted_addresses` from discovery, as described
in #341.
This commit also includes a change to the condition for freezing / terminating
a Kademlia query upon receiving a response. Specifically, the condition is
tightened such that it only applies if in addition to `parallelism`
consecutive responses that failed to yield a peer closer to the target, the
last response must also either not have reported any new peer or the
number of collected peers has already reached the number of desired results.
In effect, a Kademlia query now tries harder to actually return `k`
closest peers.
Tests have been refactored and expanded.
* Add another comment.
* Some k-buckets improvements
* Apply suggestions from code review
Co-Authored-By: tomaka <pierre.krieger1708@gmail.com>
* Use NonZeroUsize for the distance
* Update TODO comment
