feat(node): expose the GRANDPA RPC so external verifiers can prove Orbinum finality

Cargo.toml

@@ -109,6 +109,7 @@ sc-client-db = { version = "0.54.0", default-features = false }
 sc-consensus = { version = "0.57.0" }
 sc-consensus-aura = { version = "0.58.0" }
 sc-consensus-grandpa = { version = "0.43.0" }
+sc-consensus-grandpa-rpc = { version = "0.44.0" }
 sc-consensus-manual-seal = { version = "0.59.0" }
 sc-executor = { version = "0.50.0" }
 sc-keystore = { version = "42.0.0" }

template/node/Cargo.toml

@@ -33,6 +33,7 @@ sc-client-api = { workspace = true }
 sc-consensus = { workspace = true }
 sc-consensus-aura = { workspace = true }
 sc-consensus-grandpa = { workspace = true }
+sc-consensus-grandpa-rpc = { workspace = true }
 sc-consensus-manual-seal = { workspace = true }
 sc-executor = { workspace = true }
 sc-network = { workspace = true }

template/node/src/rpc/mod.rs

@@ -19,7 +19,7 @@ use sp_consensus_aura::sr25519::AuthorityId as AuraId;
 use sp_core::H256;
 use sp_inherents::CreateInherentDataProviders;
 use sp_keystore::Keystore;
-use sp_runtime::traits::Block as BlockT;
+use sp_runtime::traits::{Block as BlockT, NumberFor};
 // Runtime
 use orbinum_runtime::{AccountId, Balance, Hash, Nonce};
 
@@ -30,6 +30,29 @@ pub use self::eth::{create_eth, EthDeps, LogsJournalConfig};
 use self::relayer_author::{RelayerAuthor, RelayerAuthorApiServer};
 use self::storage_override::EeSuffixStorageOverride;
 
+/// GRANDPA-specific dependencies.
+///
+/// Wiring these is what lets a chain be verified from the outside: Hyperbridge's relayer
+/// builds Orbinum finality proofs through `grandpa_proveFinality`, and without the RPC it
+/// reports the method as missing rather than as unauthorised.
+///
+/// Everything here serves finality data for blocks that are already final — public by
+/// definition, and independently verifiable against the authority set. No keys, no
+/// private state. `sc-consensus-grandpa-rpc` marks none of the three methods `unsafe`,
+/// so they are served under the `--rpc-methods Safe` the public endpoint runs with.
+pub struct GrandpaDeps<B: BlockT, BE> {
+	/// Shared with the voter, not a fresh empty one: a detached state makes
+	/// `grandpa_roundState` answer with zeroed rounds instead of failing, which reads as
+	/// "working" while telling the caller nothing.
+	pub shared_voter_state: sc_consensus_grandpa::SharedVoterState,
+	/// Current authority set, for `grandpa_roundState`.
+	pub shared_authority_set: sc_consensus_grandpa::SharedAuthoritySet<B::Hash, NumberFor<B>>,
+	/// Justification notifications, for `grandpa_subscribeJustifications`.
+	pub justification_stream: sc_consensus_grandpa::GrandpaJustificationStream<B>,
+	/// Serves `grandpa_proveFinality`.
+	pub finality_provider: Arc<sc_consensus_grandpa::FinalityProofProvider<BE, B>>,
+}
+
 /// Full client dependencies.
 pub struct FullDeps<B: BlockT, C, P, BE, CT, CIDP> {
 	/// The client instance to use.
@@ -45,6 +68,8 @@ pub struct FullDeps<B: BlockT, C, P, BE, CT, CIDP> {
 	pub keystore: Arc<dyn Keystore>,
 	/// Ethereum-compatibility specific dependencies.
 	pub eth: EthDeps<B, C, P, CT, CIDP>,
+	/// GRANDPA finality RPC dependencies.
+	pub grandpa: GrandpaDeps<B, BE>,
 }
 
 pub struct DefaultEthConfig<C, BE>(std::marker::PhantomData<(C, BE)>);
@@ -94,11 +119,13 @@ where
 	u64: From<<<B as BlockT>::Header as sp_runtime::traits::Header>::Number>,
 	CIDP: CreateInherentDataProviders<B, ()> + Send + 'static,
 	CT: fp_rpc::ConvertTransaction<<B as BlockT>::Extrinsic> + Send + Sync + 'static,
+	NumberFor<B>: sc_consensus_grandpa::BlockNumberOps,
 {
 	use pallet_ismp_rpc::{IsmpApiServer, IsmpRpcHandler};
 	use pallet_relayer_rpc::{Relayer, RelayerApiServer};
 	use pallet_transaction_payment_rpc::{TransactionPayment, TransactionPaymentApiServer};
 	use pallet_zk_verifier_rpc::{ZkVerifier, ZkVerifierApiServer};
+	use sc_consensus_grandpa_rpc::{Grandpa, GrandpaApiServer};
 	use sc_consensus_manual_seal::rpc::{ManualSeal, ManualSealApiServer};
 	use substrate_frame_rpc_system::{System, SystemApiServer};
 
@@ -113,9 +140,20 @@ where
 		command_sink,
 		keystore,
 		eth,
+		grandpa,
 	} = deps;
 
 	io.merge(System::new(client.clone(), pool.clone()).into_rpc())?;
+	io.merge(
+		Grandpa::new(
+			subscription_task_executor.clone(),
+			grandpa.shared_authority_set,
+			grandpa.shared_voter_state,
+			grandpa.justification_stream,
+			grandpa.finality_provider,
+		)
+		.into_rpc(),
+	)?;
 	io.merge(TransactionPayment::new(client.clone()).into_rpc())?;
 	io.merge(ZkVerifier::new(client.clone()).into_rpc())?;
 	io.merge(Relayer::new(client.clone()).into_rpc())?;

template/node/src/service.rs

@@ -438,8 +438,24 @@ where
 
 	let evm_key = crate::evm_relay_key::resolve(&config);
 
+	// GRANDPA pieces for the RPC, pulled out before `grandpa_link` is moved into the
+	// voter below. `shared_voter_state` is created here rather than at the voter so both
+	// sides hold the same one — a detached state leaves `grandpa_roundState` reporting
+	// zeroed rounds forever.
+	let shared_voter_state = sc_consensus_grandpa::SharedVoterState::empty();
+	let grandpa_shared_authority_set = grandpa_link.shared_authority_set().clone();
+	let grandpa_justification_stream = grandpa_link.justification_stream().clone();
+	let grandpa_finality_provider = sc_consensus_grandpa::FinalityProofProvider::new_for_service(
+		backend.clone(),
+		Some(grandpa_shared_authority_set.clone()),
+	);
+
 	let rpc_builder = {
 		let client = client.clone();
+		let shared_voter_state = shared_voter_state.clone();
+		let grandpa_shared_authority_set = grandpa_shared_authority_set.clone();
+		let grandpa_justification_stream = grandpa_justification_stream.clone();
+		let grandpa_finality_provider = grandpa_finality_provider.clone();
 		// Cloned before the closure takes ownership: the outer `backend` is still
 		// needed after this point (see the mapping-sync setup below).
 		let rpc_backend = backend.clone();
@@ -522,6 +538,12 @@ where
 				},
 				keystore: keystore.clone(),
 				eth: eth_deps,
+				grandpa: crate::rpc::GrandpaDeps {
+					shared_voter_state: shared_voter_state.clone(),
+					shared_authority_set: grandpa_shared_authority_set.clone(),
+					justification_stream: grandpa_justification_stream.clone(),
+					finality_provider: grandpa_finality_provider.clone(),
+				},
 			};
 			crate::rpc::create_full(
 				deps,
@@ -677,7 +699,7 @@ where
 				notification_service: grandpa_notification_service,
 				voting_rule: sc_consensus_grandpa::VotingRulesBuilder::default().build(),
 				prometheus_registry,
-				shared_voter_state: sc_consensus_grandpa::SharedVoterState::empty(),
+				shared_voter_state,
 				telemetry: telemetry.as_ref().map(|x| x.handle()),
 				offchain_tx_pool_factory: OffchainTransactionPoolFactory::new(transaction_pool),
 			})?;