Dispute distribution implementation (#3282)

* Dispute protocol.

* Dispute distribution protocol.

* Get network requests routed.

* WIP: Basic dispute sender logic.

* Basic validator determination logic.

* WIP: Getting things to typecheck.

* Slightly larger timeout.

* More typechecking stuff.

* Cleanup.

* Finished most of the sending logic.

* Handle active leaves updates

- Cleanup dead disputes
- Update sends for new sessions
- Retry on errors

* Pass sessions in already.

* Startup dispute sending.

* Provide incoming decoding facilities

and use them in statement-distribution.

* Relaxed runtime util requirements.

We only need a `SubsystemSender` not a full `SubsystemContext`.

* Better usability of incoming requests.

Make it possible to consume stuff without clones.

* Add basic receiver functionality.

* Cleanup + fixes for sender.

* One more sender fix.

* Start receiver.

* Make sure to send responses back.

* WIP: Exposed authority discovery

* Make tests pass.

* Fully featured receiver.

* Decrease cost of `NotAValidator`.

* Make `RuntimeInfo` LRU cache size configurable.

* Cache more sessions.

* Fix collator protocol.

* Disable metrics for now.

* Make dispute-distribution a proper subsystem.

* Fix naming.

* Code style fixes.

* Factored out 4x copied mock function.

* WIP: Tests.

* Whitespace cleanup.

* Accessor functions.

* More testing.

* More Debug instances.

* Fix busy loop.

* Working tests.

* More tests.

* Cleanup.

* Fix build.

* Basic receiving test.

* Non validator message gets dropped.

* More receiving tests.

* Test nested and subsequent imports.

* Fix spaces.

* Better formatted imports.

* Import cleanup.

* Metrics.

* Message -> MuxedMessage

* Message -> MuxedMessage

* More review remarks.

* Add missing metrics.rs.

* Fix flaky test.

* Dispute coordinator - deliver confirmations.

* Send out `DisputeMessage` on issue local statement.

* Unwire dispute distribution.

* Review remarks.

* Review remarks.

* Better docs.

polkadot/node/network/protocol/src/authority_discovery.rs

@@ -0,0 +1,48 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Authority discovery service interfacing.
+
+use std::fmt::Debug;
+
+use async_trait::async_trait;
+
+use sc_authority_discovery::Service as AuthorityDiscoveryService;
+
+use polkadot_primitives::v1::AuthorityDiscoveryId;
+use sc_network::{Multiaddr, PeerId};
+
+/// An abstraction over the authority discovery service.
+///
+/// Needed for mocking in tests mostly.
+#[async_trait]
+pub trait AuthorityDiscovery: Send + Debug + 'static {
+	/// Get the addresses for the given [`AuthorityId`] from the local address cache.
+	async fn get_addresses_by_authority_id(&mut self, authority: AuthorityDiscoveryId) -> Option<Vec<Multiaddr>>;
+	/// Get the [`AuthorityId`] for the given [`PeerId`] from the local address cache.
+	async fn get_authority_id_by_peer_id(&mut self, peer_id: PeerId) -> Option<AuthorityDiscoveryId>;
+}
+
+#[async_trait]
+impl AuthorityDiscovery for AuthorityDiscoveryService {
+	async fn get_addresses_by_authority_id(&mut self, authority: AuthorityDiscoveryId) -> Option<Vec<Multiaddr>> {
+		AuthorityDiscoveryService::get_addresses_by_authority_id(self, authority).await
+	}
+
+	async fn get_authority_id_by_peer_id(&mut self, peer_id: PeerId) -> Option<AuthorityDiscoveryId> {
+		AuthorityDiscoveryService::get_authority_id_by_peer_id(self, peer_id).await
+	}
+}