* 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.
* Consolidate keypairs in core.
Introduce the concept of a node's identity keypair in libp2p-core,
instead of only the public key:
* New module: libp2p_core::identity with submodules for the currently
supported key types. An identity::Keypair and identity::PublicKey
support the creation and verification of signatures. The public key
supports encoding/decoding according to the libp2p specs.
* The secio protocol is simplified as a result of moving code to libp2p-core.
* The noise protocol is slightly simplified by consolidating ed25519
keypairs in libp2p-core and using x25519-dalek for DH. Furthermore,
Ed25519 to X25519 keypair conversion is now complete and tested.
Generalise over the DH keys in the noise protocol.
Generalise over the DH keys and thus DH parameter in handshake patterns
of the Noise protocol, such that it is easy to support other DH schemes
in the future, e.g. X448.
* Address new review comments.
* Embed the topology in the NetworkBehaviour
* Put topologies inside of Floodsub and Kad
* Fix core tests
* Fix chat example
* More work
* Some cleanup
* Restore external addresses system
* Rework Kademlia for the new design
* Minor work on protocol.rs
* More work
* Remove QueryTarget::FindValue
* Finish work on query
* Query timeout test
* Work on topology
* More work
* Update protocols/kad/src/topology.rs
Co-Authored-By: tomaka <pierre.krieger1708@gmail.com>
* Fix trailing whitespaces
* Use if let
