grandpa: Use storage proofs for Grandpa authorities

Author: jimpo

core/finality-grandpa/primitives/src/lib.rs

@@ -23,9 +23,10 @@ extern crate alloc;
 
 #[cfg(feature = "std")]
 use serde::Serialize;
-use codec::{Encode, Decode, Codec};
+use codec::{Encode, Decode, Input, Codec};
 use sr_primitives::{ConsensusEngineId, RuntimeDebug};
 use client::decl_runtime_apis;
+use rstd::borrow::Cow;
 use rstd::vec::Vec;
 
 mod app {
@@ -46,6 +47,10 @@ pub type AuthoritySignature = app::Signature;
 /// The `ConsensusEngineId` of GRANDPA.
 pub const GRANDPA_ENGINE_ID: ConsensusEngineId = *b"FRNK";
 
+/// The storage key for the current set of weighted Grandpa authorities.
+/// The value stored is an encoded VersionedAuthorityList.
+pub const GRANDPA_AUTHORITIES_KEY: &'static [u8] = b":grandpa_authorities";
+
 /// The weight of an authority.
 pub type AuthorityWeight = u64;
 
@@ -58,12 +63,15 @@ pub type SetId = u64;
 /// The round indicator.
 pub type RoundNumber = u64;
 
+/// A list of Grandpa authorities with associated weights.
+pub type AuthorityList = Vec<(AuthorityId, AuthorityWeight)>;
+
 /// A scheduled change of authority set.
 #[cfg_attr(feature = "std", derive(Serialize))]
 #[derive(Clone, Eq, PartialEq, Encode, Decode, RuntimeDebug)]
 pub struct ScheduledChange<N> {
 	/// The new authorities after the change, along with their respective weights.
-	pub next_authorities: Vec<(AuthorityId, AuthorityWeight)>,
+	pub next_authorities: AuthorityList,
 	/// The number of blocks to delay.
 	pub delay: N,
 }
@@ -154,6 +162,55 @@ pub const PENDING_CHANGE_CALL: &str = "grandpa_pending_change";
 /// WASM function call to get current GRANDPA authorities.
 pub const AUTHORITIES_CALL: &str = "grandpa_authorities";
 
+/// The current version of the stored AuthorityList type. The encoding version MUST be updated any
+/// time the AuthorityList type changes.
+const AUTHORITIES_VERISON: u8 = 1;
+
+/// An AuthorityList that is encoded with a version specifier. The encoding version is updated any
+/// time the AuthorityList type changes. This ensures that encodings of different versions of an
+/// AuthorityList are differentiable. Attempting to decode an authority list with an unknown
+/// version will fail.
+#[derive(Default)]
+pub struct VersionedAuthorityList<'a>(Cow<'a, AuthorityList>);
+
+impl<'a> From<AuthorityList> for VersionedAuthorityList<'a> {
+	fn from(authorities: AuthorityList) -> Self {
+		VersionedAuthorityList(Cow::Owned(authorities))
+	}
+}
+
+impl<'a> From<&'a AuthorityList> for VersionedAuthorityList<'a> {
+	fn from(authorities: &'a AuthorityList) -> Self {
+		VersionedAuthorityList(Cow::Borrowed(authorities))
+	}
+}
+
+impl<'a> Into<AuthorityList> for VersionedAuthorityList<'a> {
+	fn into(self) -> AuthorityList {
+		self.0.into_owned()
+	}
+}
+
+impl<'a> Encode for VersionedAuthorityList<'a> {
+	fn size_hint(&self) -> usize {
+		(AUTHORITIES_VERISON, self.0.as_ref()).size_hint()
+	}
+
+	fn using_encoded<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+		(AUTHORITIES_VERISON, self.0.as_ref()).using_encoded(f)
+	}
+}
+
+impl<'a> Decode for VersionedAuthorityList<'a> {
+	fn decode<I: Input>(value: &mut I) -> Result<Self, codec::Error> {
+		let (version, authorities): (u8, AuthorityList) = Decode::decode(value)?;
+		if version != AUTHORITIES_VERISON {
+			return Err("unknown Grandpa authorities version".into());
+		}
+		Ok(authorities.into())
+	}
+}
+
 decl_runtime_apis! {
 	/// APIs for integrating the GRANDPA finality gadget into runtimes.
 	/// This should be implemented on the runtime side.
@@ -172,6 +229,6 @@ decl_runtime_apis! {
 		/// When called at block B, it will return the set of authorities that should be
 		/// used to finalize descendants of this block (B+1, B+2, ...). The block B itself
 		/// is finalized by the authorities from block B-1.
-		fn grandpa_authorities() -> Vec<(AuthorityId, AuthorityWeight)>;
+		fn grandpa_authorities() -> AuthorityList;
 	}
 }

core/finality-grandpa/src/authorities.rs

@@ -22,7 +22,7 @@ use grandpa::voter_set::VoterSet;
 use codec::{Encode, Decode};
 use log::{debug, info};
 use substrate_telemetry::{telemetry, CONSENSUS_INFO};
-use fg_primitives::AuthorityId;
+use fg_primitives::{AuthorityId, AuthorityList};
 
 use std::cmp::Ord;
 use std::fmt::Debug;
@@ -86,7 +86,7 @@ pub(crate) struct Status<H, N> {
 /// A set of authorities.
 #[derive(Debug, Clone, Encode, Decode, PartialEq)]
 pub(crate) struct AuthoritySet<H, N> {
-	pub(crate) current_authorities: Vec<(AuthorityId, u64)>,
+	pub(crate) current_authorities: AuthorityList,
 	pub(crate) set_id: u64,
 	// Tree of pending standard changes across forks. Standard changes are
 	// enacted on finality and must be enacted (i.e. finalized) in-order across
@@ -103,7 +103,7 @@ where H: PartialEq,
 	  N: Ord,
 {
 	/// Get a genesis set with given authorities.
-	pub(crate) fn genesis(initial: Vec<(AuthorityId, u64)>) -> Self {
+	pub(crate) fn genesis(initial: AuthorityList) -> Self {
 		AuthoritySet {
 			current_authorities: initial,
 			set_id: 0,
@@ -390,7 +390,7 @@ pub(crate) enum DelayKind<N> {
 #[derive(Debug, Clone, Encode, PartialEq)]
 pub(crate) struct PendingChange<H, N> {
 	/// The new authorities and weights to apply.
-	pub(crate) next_authorities: Vec<(AuthorityId, u64)>,
+	pub(crate) next_authorities: AuthorityList,
 	/// How deep in the chain the announcing block must be
 	/// before the change is applied.
 	pub(crate) delay: N,

core/finality-grandpa/src/aux_schema.rs

@@ -25,7 +25,7 @@ use fork_tree::ForkTree;
 use grandpa::round::State as RoundState;
 use sr_primitives::traits::{Block as BlockT, NumberFor};
 use log::{info, warn};
-use fg_primitives::{AuthorityId, AuthorityWeight, SetId, RoundNumber};
+use fg_primitives::{AuthorityList, SetId, RoundNumber};
 
 use crate::authorities::{AuthoritySet, SharedAuthoritySet, PendingChange, DelayKind};
 use crate::consensus_changes::{SharedConsensusChanges, ConsensusChanges};
@@ -55,15 +55,15 @@ type V0VoterSetState<H, N> = (RoundNumber, RoundState<H, N>);
 
 #[derive(Debug, Clone, Encode, Decode, PartialEq)]
 struct V0PendingChange<H, N> {
-	next_authorities: Vec<(AuthorityId, AuthorityWeight)>,
+	next_authorities: AuthorityList,
 	delay: N,
 	canon_height: N,
 	canon_hash: H,
 }
 
 #[derive(Debug, Clone, Encode, Decode, PartialEq)]
 struct V0AuthoritySet<H, N> {
-	current_authorities: Vec<(AuthorityId, AuthorityWeight)>,
+	current_authorities: AuthorityList,
 	set_id: SetId,
 	pending_changes: Vec<V0PendingChange<H, N>>,
 }
@@ -266,7 +266,7 @@ pub(crate) fn load_persistent<Block: BlockT, B, G>(
 	-> ClientResult<PersistentData<Block>>
 	where
 		B: AuxStore,
-		G: FnOnce() -> ClientResult<Vec<(AuthorityId, AuthorityWeight)>>,
+		G: FnOnce() -> ClientResult<AuthorityList>,
 {
 	let version: Option<u32> = load_decode(backend, VERSION_KEY)?;
 	let consensus_changes = load_decode(backend, CONSENSUS_CHANGES_KEY)?
@@ -426,6 +426,7 @@ pub(crate) fn load_authorities<B: AuxStore, H: Decode, N: Decode>(backend: &B)
 
 #[cfg(test)]
 mod test {
+	use fg_primitives::AuthorityId;
 	use primitives::H256;
 	use test_client;
 	use super::*;

core/finality-grandpa/src/communication/tests.rs

@@ -28,6 +28,7 @@ use codec::Encode;
 use sr_primitives::traits::NumberFor;
 
 use crate::environment::SharedVoterSetState;
+use fg_primitives::AuthorityList;
 use super::gossip::{self, GossipValidator};
 use super::{AuthorityId, VoterSet, Round, SetId};
 
@@ -200,7 +201,7 @@ fn make_test_network() -> (
 	)
 }
 
-fn make_ids(keys: &[Ed25519Keyring]) -> Vec<(AuthorityId, u64)> {
+fn make_ids(keys: &[Ed25519Keyring]) -> AuthorityList {
 	keys.iter()
 		.map(|key| key.clone().public().into())
 		.map(|id| (id, 1))

core/finality-grandpa/src/finality_proof.rs

@@ -34,23 +34,24 @@
 //! finality proof (that finalizes some block C that is ancestor of the B and descendant
 //! of the U) could be returned.
 
+use std::iter;
 use std::sync::Arc;
 use log::{trace, warn};
 
 use client::{
 	backend::Backend, blockchain::Backend as BlockchainBackend, CallExecutor, Client,
 	error::{Error as ClientError, Result as ClientResult},
-	light::fetcher::{FetchChecker, RemoteCallRequest, StorageProof}, ExecutionStrategy,
+	light::fetcher::{FetchChecker, RemoteReadRequest, StorageProof},
 };
 use codec::{Encode, Decode};
 use grandpa::BlockNumberOps;
 use sr_primitives::{
 	Justification, generic::BlockId,
 	traits::{NumberFor, Block as BlockT, Header as HeaderT, One},
 };
-use primitives::{H256, Blake2Hasher};
+use primitives::{H256, Blake2Hasher, storage::StorageKey};
 use substrate_telemetry::{telemetry, CONSENSUS_INFO};
-use fg_primitives::AuthorityId;
+use fg_primitives::{AuthorityId, AuthorityList, VersionedAuthorityList, GRANDPA_AUTHORITIES_KEY};
 
 use crate::justification::GrandpaJustification;
 
@@ -59,9 +60,9 @@ const MAX_FRAGMENTS_IN_PROOF: usize = 8;
 
 /// GRANDPA authority set related methods for the finality proof provider.
 pub trait AuthoritySetForFinalityProver<Block: BlockT>: Send + Sync {
-	/// Call GrandpaApi::grandpa_authorities at given block.
-	fn authorities(&self, block: &BlockId<Block>) -> ClientResult<Vec<(AuthorityId, u64)>>;
-	/// Prove call of GrandpaApi::grandpa_authorities at given block.
+	/// Read GRANDPA_AUTHORITIES_KEY from storage at given block.
+	fn authorities(&self, block: &BlockId<Block>) -> ClientResult<AuthorityList>;
+	/// Prove storage read of GRANDPA_AUTHORITIES_KEY at given block.
 	fn prove_authorities(&self, block: &BlockId<Block>) -> ClientResult<StorageProof>;
 }
 
@@ -72,33 +73,28 @@ impl<B, E, Block: BlockT<Hash=H256>, RA> AuthoritySetForFinalityProver<Block> fo
 		E: CallExecutor<Block, Blake2Hasher> + 'static + Clone + Send + Sync,
 		RA: Send + Sync,
 {
-	fn authorities(&self, block: &BlockId<Block>) -> ClientResult<Vec<(AuthorityId, u64)>> {
-		self.executor().call(
-			block,
-			"GrandpaApi_grandpa_authorities",
-			&[],
-			ExecutionStrategy::NativeElseWasm,
-			None,
-		).and_then(|call_result| Decode::decode(&mut &call_result[..])
-			.map_err(|err| ClientError::CallResultDecode(
-				"failed to decode GRANDPA authorities set proof".into(), err
-			)))
+	fn authorities(&self, block: &BlockId<Block>) -> ClientResult<AuthorityList> {
+		let storage_key = StorageKey(GRANDPA_AUTHORITIES_KEY.to_vec());
+		self.storage(block, &storage_key)?
+			.and_then(|encoded| VersionedAuthorityList::decode(&mut encoded.0.as_slice()).ok())
+			.map(|versioned| versioned.into())
+			.ok_or(ClientError::InvalidAuthoritiesSet)
 	}
 
 	fn prove_authorities(&self, block: &BlockId<Block>) -> ClientResult<StorageProof> {
-		self.execution_proof(block, "GrandpaApi_grandpa_authorities",&[]).map(|(_, proof)| proof)
+		self.read_proof(block, iter::once(GRANDPA_AUTHORITIES_KEY))
 	}
 }
 
 /// GRANDPA authority set related methods for the finality proof checker.
 pub trait AuthoritySetForFinalityChecker<Block: BlockT>: Send + Sync {
-	/// Check execution proof of Grandpa::grandpa_authorities at given block.
+	/// Check storage read proof of GRANDPA_AUTHORITIES_KEY at given block.
 	fn check_authorities_proof(
 		&self,
 		hash: Block::Hash,
 		header: Block::Header,
 		proof: StorageProof,
-	) -> ClientResult<Vec<(AuthorityId, u64)>>;
+	) -> ClientResult<AuthorityList>;
 }
 
 /// FetchChecker-based implementation of AuthoritySetForFinalityChecker.
@@ -108,22 +104,30 @@ impl<Block: BlockT> AuthoritySetForFinalityChecker<Block> for Arc<dyn FetchCheck
 		hash: Block::Hash,
 		header: Block::Header,
 		proof: StorageProof,
-	) -> ClientResult<Vec<(AuthorityId, u64)>> {
-		let request = RemoteCallRequest {
+	) -> ClientResult<AuthorityList> {
+		let storage_key = GRANDPA_AUTHORITIES_KEY.to_vec();
+		let request = RemoteReadRequest {
 			block: hash,
 			header,
-			method: "GrandpaApi_grandpa_authorities".into(),
-			call_data: vec![],
+			keys: vec![storage_key.clone()],
 			retry_count: None,
 		};
 
-		self.check_execution_proof(&request, proof)
-			.and_then(|authorities| {
-				let authorities: Vec<(AuthorityId, u64)> = Decode::decode(&mut &authorities[..])
-					.map_err(|err| ClientError::CallResultDecode(
-						"failed to decode GRANDPA authorities set proof".into(), err
-					))?;
-				Ok(authorities.into_iter().collect())
+		self.check_read_proof(&request, proof)
+			.and_then(|results| {
+				let maybe_encoded = results.get(&storage_key)
+					.expect(
+						"storage_key is listed in the request keys; \
+						check_read_proof must return a value for each requested key;
+						qed"
+					);
+				maybe_encoded
+					.as_ref()
+					.and_then(|encoded| {
+						VersionedAuthorityList::decode(&mut encoded.as_slice()).ok()
+					})
+					.map(|versioned| versioned.into())
+					.ok_or(ClientError::InvalidAuthoritiesSet)
 			})
 	}
 }
@@ -189,7 +193,7 @@ pub struct FinalityEffects<Header: HeaderT> {
 	/// New authorities set id that should be applied starting from block.
 	pub new_set_id: u64,
 	/// New authorities set that should be applied starting from block.
-	pub new_authorities: Vec<(AuthorityId, u64)>,
+	pub new_authorities: AuthorityList,
 }
 
 /// Single fragment of proof-of-finality.
@@ -408,7 +412,7 @@ pub(crate) fn prove_finality<Block: BlockT<Hash=H256>, B: BlockchainBackend<Bloc
 pub(crate) fn check_finality_proof<Block: BlockT<Hash=H256>, B>(
 	blockchain: &B,
 	current_set_id: u64,
-	current_authorities: Vec<(AuthorityId, u64)>,
+	current_authorities: AuthorityList,
 	authorities_provider: &dyn AuthoritySetForFinalityChecker<Block>,
 	remote_proof: Vec<u8>,
 ) -> ClientResult<FinalityEffects<Block::Header>>
@@ -427,7 +431,7 @@ pub(crate) fn check_finality_proof<Block: BlockT<Hash=H256>, B>(
 fn do_check_finality_proof<Block: BlockT<Hash=H256>, B, J>(
 	blockchain: &B,
 	current_set_id: u64,
-	current_authorities: Vec<(AuthorityId, u64)>,
+	current_authorities: AuthorityList,
 	authorities_provider: &dyn AuthoritySetForFinalityChecker<Block>,
 	remote_proof: Vec<u8>,
 ) -> ClientResult<FinalityEffects<Block::Header>>
@@ -522,12 +526,12 @@ fn check_finality_proof_fragment<Block: BlockT<Hash=H256>, B, J>(
 
 /// Authorities set from initial authorities set or finality effects.
 enum AuthoritiesOrEffects<Header: HeaderT> {
-	Authorities(u64, Vec<(AuthorityId, u64)>),
+	Authorities(u64, AuthorityList),
 	Effects(FinalityEffects<Header>),
 }
 
 impl<Header: HeaderT> AuthoritiesOrEffects<Header> {
-	pub fn extract_authorities(self) -> (u64, Vec<(AuthorityId, u64)>) {
+	pub fn extract_authorities(self) -> (u64, AuthorityList) {
 		match self {
 			AuthoritiesOrEffects::Authorities(set_id, authorities) => (set_id, authorities),
 			AuthoritiesOrEffects::Effects(effects) => (effects.new_set_id, effects.new_authorities),
@@ -581,10 +585,10 @@ pub(crate) mod tests {
 
 	impl<GetAuthorities, ProveAuthorities> AuthoritySetForFinalityProver<Block> for (GetAuthorities, ProveAuthorities)
 		where
-			GetAuthorities: Send + Sync + Fn(BlockId<Block>) -> ClientResult<Vec<(AuthorityId, u64)>>,
+			GetAuthorities: Send + Sync + Fn(BlockId<Block>) -> ClientResult<AuthorityList>,
 			ProveAuthorities: Send + Sync + Fn(BlockId<Block>) -> ClientResult<StorageProof>,
 	{
-		fn authorities(&self, block: &BlockId<Block>) -> ClientResult<Vec<(AuthorityId, u64)>> {
+		fn authorities(&self, block: &BlockId<Block>) -> ClientResult<AuthorityList> {
 			self.0(*block)
 		}
 
@@ -597,14 +601,14 @@ pub(crate) mod tests {
 
 	impl<Closure> AuthoritySetForFinalityChecker<Block> for ClosureAuthoritySetForFinalityChecker<Closure>
 		where
-			Closure: Send + Sync + Fn(H256, Header, StorageProof) -> ClientResult<Vec<(AuthorityId, u64)>>,
+			Closure: Send + Sync + Fn(H256, Header, StorageProof) -> ClientResult<AuthorityList>,
 	{
 		fn check_authorities_proof(
 			&self,
 			hash: H256,
 			header: Header,
-			proof: StorageProof,
-		) -> ClientResult<Vec<(AuthorityId, u64)>> {
+			proof: StorageProof
+		) -> ClientResult<AuthorityList> {
 			self.0(hash, header, proof)
 		}
 	}