With the *authority-discovery* module an authoritative node makes itself
discoverable and is able to discover other authorities. Once discovered, a node
can directly connect to other authorities instead of multi-hop gossiping
information.
1. **Making itself discoverable**
1. Retrieve its external addresses
2. Adds its network peer id to the addresses
3. Sign the above
4. Put the signature and the addresses on the libp2p Kademlia DHT
2. **Discovering other authorities**
1. Retrieve the current set of authorities
2. Start DHT queries for the ids of the authorities
3. Validate the signatures of the retrieved key value pairs
4. Add the retrieved external addresses as ~reserved~ priority nodes to the
peerset
* node/runtime: Add authority-discovery as session handler
The srml/authority-discovery module implements the OneSessionHandler in
order to keep its authority set in sync. This commit adds the module to
the set of session handlers.
* core/network: Make network worker return Dht events on poll
Instead of network worker implement the Future trait, have it implement
the Stream interface returning Dht events.
For now these events are ignored in build_network_future but will be
used by the core/authority-discovery module in subsequent commits.
* *: Add scaffolding and integration for core/authority-discovery module
* core/authority-discovery: Implement module logic itself
In order to have authorities (validators) discover each other, they need
to publish their public addresses by their ip address on the Kademlia
Dht indexed by their public key. This payload needs to be signed by a
key identifying them as a valid authority.
Code inside `/core` does not know the current set of authorities nor
can it assume what kind of cryptography primitives are currently in use.
Instead it can retrieve its public key and the current set of
authorities from the runtime and have it sign and verify Dht payloads.
This commit enables code in `/core` to do so by introducing a srml
module and runtime api to:
1. Retrieve own public key.
2. Retrieve public keys of current authority set.
3. Sign a Dht payload.
4. Verify a Dht payload.
This commit makes the logic from the previous commit
(`core/consensus/common/primitives.ConsensusApi`)
cf80af9255 obsolete and thus removes it.
Tomasz Drwięga