add authority discovery module (#444)

polkadot/Cargo.lock

@@ -2790,6 +2790,7 @@ dependencies = [
  "sr-staking-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-version 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "srml-authority-discovery 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-authorship 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-babe 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-balances 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -2811,6 +2812,7 @@ dependencies = [
  "srml-system 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-timestamp 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-treasury 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "substrate-authority-discovery-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-client 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-consensus-babe-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-inherents 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -2847,6 +2849,7 @@ dependencies = [
  "srml-babe 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-im-online 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "srml-staking 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "substrate-authority-discovery 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-client 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-client-db 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-consensus-babe 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3746,6 +3749,24 @@ dependencies = [
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
 ]
 
+[[package]]
+name = "srml-authority-discovery"
+version = "0.1.0"
+source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#7a7d641b40b9f9791406d04bd4fc7be2d190fa7b"
+dependencies = [
+ "parity-scale-codec 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.101 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "srml-im-online 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "srml-session 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "srml-support 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "srml-system 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "substrate-application-crypto 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+ "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
+]
+
 [[package]]
 name = "srml-authorship"
 version = "0.1.0"
@@ -6122,6 +6143,7 @@ dependencies = [
 "checksum sr-staking-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
 "checksum sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
 "checksum sr-version 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
+"checksum srml-authority-discovery 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
 "checksum srml-authorship 0.1.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
 "checksum srml-babe 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"
 "checksum srml-balances 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)" = "<none>"

polkadot/runtime/Cargo.toml

@@ -14,6 +14,7 @@ safe-mix = { version = "1.0", default-features = false}
 serde = { version = "1.0", default-features = false }
 serde_derive = { version = "1.0", optional = true }
 
+authority-discovery-primitives = { package = "substrate-authority-discovery-primitives", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 babe-primitives = { package = "substrate-consensus-babe-primitives", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 client = { package = "substrate-client", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 inherents = { package = "substrate-inherents", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
@@ -27,6 +28,7 @@ substrate-serializer = { git = "https://github.com/paritytech/substrate", defaul
 substrate-session = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 version = { package = "sr-version", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 
+authority-discovery = { package = "srml-authority-discovery", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 authorship = { package = "srml-authorship", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 babe = { package = "srml-babe", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 balances = { package = "srml-balances", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
@@ -68,6 +70,8 @@ default = ["std"]
 no_std = []
 only-staking = []
 std = [
+	"authority-discovery-primitives/std",
+	"authority-discovery/std",
 	"bitvec/std",
 	"primitives/std",
 	"rustc-hex/std",

polkadot/runtime/src/lib.rs

@@ -55,7 +55,8 @@ use sr_staking_primitives::SessionIndex;
 use srml_support::{
 	parameter_types, construct_runtime, traits::{SplitTwoWays, Currency}
 };
-use im_online::sr25519::{AuthorityId as ImOnlineId};
+use authority_discovery_primitives::{AuthorityId as EncodedAuthorityId, Signature as EncodedSignature};
+use im_online::sr25519::{AuthorityId as ImOnlineId, AuthoritySignature as ImOnlineSignature};
 use system::offchain::TransactionSubmitter;
 
 #[cfg(feature = "std")]
@@ -242,7 +243,7 @@ parameter_types! {
 	pub const Offset: BlockNumber = 0;
 }
 
-type SessionHandlers = (Grandpa, Babe, ImOnline, Parachains);
+type SessionHandlers = (Grandpa, Babe, ImOnline, AuthorityDiscovery, Parachains);
 impl_opaque_keys! {
 	pub struct SessionKeys {
 		#[id(key_types::GRANDPA)]
@@ -444,6 +445,8 @@ impl im_online::Trait for Runtime {
 	type ReportUnresponsiveness = ();
 }
 
+impl authority_discovery::Trait for Runtime {}
+
 impl grandpa::Trait for Runtime {
 	type Event = Event;
 }
@@ -530,6 +533,7 @@ construct_runtime!(
 		FinalityTracker: finality_tracker::{Module, Call, Inherent},
 		Grandpa: grandpa::{Module, Call, Storage, Config, Event},
 		ImOnline: im_online::{Module, Call, Storage, Event<T>, ValidateUnsigned, Config<T>},
+		AuthorityDiscovery: authority_discovery::{Module, Call, Config<T>},
 
 		// Governance stuff; uncallable initially.
 		Democracy: democracy::{Module, Call, Storage, Config, Event<T>},
@@ -684,6 +688,35 @@ impl_runtime_apis! {
 		}
 	}
 
+	impl authority_discovery_primitives::AuthorityDiscoveryApi<Block> for Runtime {
+		fn authorities() -> Vec<EncodedAuthorityId> {
+			AuthorityDiscovery::authorities().into_iter()
+				.map(|id| id.encode())
+				.map(EncodedAuthorityId)
+				.collect()
+		}
+
+		fn sign(payload: &Vec<u8>) -> Option<(EncodedSignature, EncodedAuthorityId)> {
+			AuthorityDiscovery::sign(payload).map(|(sig, id)| {
+				(EncodedSignature(sig.encode()), EncodedAuthorityId(id.encode()))
+			})
+		}
+
+		fn verify(payload: &Vec<u8>, signature: &EncodedSignature, authority_id: &EncodedAuthorityId) -> bool {
+			let signature = match ImOnlineSignature::decode(&mut &signature.0[..]) {
+				Ok(s) => s,
+				_ => return false,
+			};
+
+			let authority_id = match ImOnlineId::decode(&mut &authority_id.0[..]) {
+				Ok(id) => id,
+				_ => return false,
+			};
+
+			AuthorityDiscovery::verify(payload, signature, authority_id)
+		}
+	}
+
 	impl substrate_session::SessionKeys<Block> for Runtime {
 		fn generate_session_keys(seed: Option<Vec<u8>>) -> Vec<u8> {
 			let seed = seed.as_ref().map(|s| rstd::str::from_utf8(&s).expect("Seed is an utf8 string"));

polkadot/service/Cargo.toml

@@ -36,5 +36,6 @@ substrate-keystore = { git = "https://github.com/paritytech/substrate", branch =
 srml-babe = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 srml-staking = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 im-online = { package = "srml-im-online", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
+authority-discovery = { package = "substrate-authority-discovery", git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
 babe = { package = "substrate-consensus-babe", git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
 babe-primitives = { package = "substrate-consensus-babe-primitives", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }

polkadot/service/src/chain_spec.rs

@@ -148,6 +148,7 @@ fn staging_testnet_config_genesis() -> GenesisConfig {
 		babe: Some(Default::default()),
 		grandpa: Some(Default::default()),
 		im_online: Some(Default::default()),
+		authority_discovery: Some(Default::default()),
 		parachains: Some(ParachainsConfig {
 			authorities: vec![],
 			parachains: vec![],
@@ -285,6 +286,7 @@ pub fn testnet_genesis(
 		babe: Some(Default::default()),
 		grandpa: Some(Default::default()),
 		im_online: Some(Default::default()),
+		authority_discovery: Some(Default::default()),
 		parachains: Some(ParachainsConfig {
 			authorities: vec![],
 			parachains: vec![],

polkadot/service/src/lib.rs

@@ -19,6 +19,7 @@
 pub mod chain_spec;
 
 use futures::prelude::*;
+use futures::sync::mpsc;
 use client::LongestChain;
 use std::sync::Arc;
 use std::time::Duration;
@@ -138,6 +139,8 @@ pub fn new_full(config: Configuration<CustomConfiguration, GenesisConfig>)
 		CallExecutor = impl CallExecutor<Block, Blake2Hasher> + Clone + Send + Sync + 'static,
 	>, ServiceError>
 {
+	use substrate_network::DhtEvent;
+
 	let is_authority = config.roles.is_authority();
 	let is_collator = config.custom.collating_for.is_some();
 	let force_authoring = config.force_authoring;
@@ -148,11 +151,19 @@ pub fn new_full(config: Configuration<CustomConfiguration, GenesisConfig>)
 
 	let (builder, mut import_setup, inherent_data_providers) = new_full_start!(config);
 
+	// Dht event channel from the network to the authority discovery module. Use
+	// bounded channel to ensure back-pressure. Authority discovery is triggering one
+	// event per authority within the current authority set. This estimates the
+	// authority set size to be somewhere below 10 000 thereby setting the channel
+	// buffer size to 10 000.
+	let (dht_event_tx, dht_event_rx) = mpsc::channel::<DhtEvent>(10000);
+
 	let service = builder
 		.with_network_protocol(|config| Ok(PolkadotProtocol::new(config.custom.collating_for.clone())))?
 		.with_finality_proof_provider(|client, backend|
 			Ok(Arc::new(GrandpaFinalityProofProvider::new(backend, client)) as _)
 		)?
+		.with_dht_event_tx(dht_event_tx)?
 		.build()?;
 
 	let (block_import, link_half, babe_link) = import_setup.take()
@@ -258,6 +269,13 @@ pub fn new_full(config: Configuration<CustomConfiguration, GenesisConfig>)
 		let babe = start_babe(babe_config)?;
 		let select = babe.select(service.on_exit()).then(|_| Ok(()));
 		service.spawn_essential_task(Box::new(select));
+
+		let authority_discovery = authority_discovery::AuthorityDiscovery::new(
+			service.client(),
+			service.network(),
+			dht_event_rx,
+		);
+		service.spawn_task(authority_discovery);
 	} else {
 		network_gossip::register_non_authority_validator(service.network());
 	}