Fix validator contract syncing (#4789) (#5011)

* make validator set aware of various states

* fix updater build

* clean up contract call

* failing sync test

* adjust tests

* nicer indent [ci skip]

* revert bound divisor

ethcore/res/authority_round.json

@@ -33,7 +33,7 @@
 		"timestamp": "0x00",
 		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
 		"extraData": "0x",
-		"gasLimit": "0x2fefd8"
+		"gasLimit": "0x222222"
 	},
 	"accounts": {
 		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },

ethcore/res/tendermint.json

@@ -38,7 +38,7 @@
 		"timestamp": "0x00",
 		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
 		"extraData": "0x",
-		"gasLimit": "0x2fefd8"
+		"gasLimit": "0x222222"
 	},
 	"accounts": {
 		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },

ethcore/res/validator_contract.json

@@ -27,7 +27,7 @@
 		"timestamp": "0x00",
 		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
 		"extraData": "0x",
-		"gasLimit": "0x2fefd8"
+		"gasLimit": "0x222222"
 	},
 	"accounts": {
 		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },

ethcore/src/client/client.rs

@@ -253,7 +253,7 @@ impl Client {
 		if let Some(reg_addr) = client.additional_params().get("registrar").and_then(|s| Address::from_str(s).ok()) {
 			trace!(target: "client", "Found registrar at {}", reg_addr);
 			let weak = Arc::downgrade(&client);
-			let registrar = Registry::new(reg_addr, move |a, d| weak.upgrade().ok_or("No client!".into()).and_then(|c| c.call_contract(a, d)));
+			let registrar = Registry::new(reg_addr, move |a, d| weak.upgrade().ok_or("No client!".into()).and_then(|c| c.call_contract(BlockId::Latest, a, d)));
 			*client.registrar.lock() = Some(registrar);
 		}
 		Ok(client)
@@ -1445,7 +1445,7 @@ impl BlockChainClient for Client {
 		}
 	}
 
-	fn call_contract(&self, address: Address, data: Bytes) -> Result<Bytes, String> {
+	fn call_contract(&self, block_id: BlockId, address: Address, data: Bytes) -> Result<Bytes, String> {
 		let from = Address::default();
 		let transaction = Transaction {
 			nonce: self.latest_nonce(&from),
@@ -1456,7 +1456,7 @@ impl BlockChainClient for Client {
 			data: data,
 		}.fake_sign(from);
 
-		self.call(&transaction, BlockId::Latest, Default::default())
+		self.call(&transaction, block_id, Default::default())
 			.map_err(|e| format!("{:?}", e))
 			.map(|executed| {
 				executed.output

ethcore/src/client/test_client.rs

@@ -731,7 +731,7 @@ impl BlockChainClient for TestBlockChainClient {
 		}
 	}
 
-	fn call_contract(&self, _address: Address, _data: Bytes) -> Result<Bytes, String> { Ok(vec![]) }
+	fn call_contract(&self, _id: BlockId, _address: Address, _data: Bytes) -> Result<Bytes, String> { Ok(vec![]) }
 
 	fn transact_contract(&self, address: Address, data: Bytes) -> Result<TransactionImportResult, EthcoreError> {
 		let transaction = Transaction {

ethcore/src/client/traits.rs

@@ -254,7 +254,7 @@ pub trait BlockChainClient : Sync + Send {
 	fn pruning_info(&self) -> PruningInfo;
 
 	/// Like `call`, but with various defaults. Designed to be used for calling contracts.
-	fn call_contract(&self, address: Address, data: Bytes) -> Result<Bytes, String>;
+	fn call_contract(&self, id: BlockId, address: Address, data: Bytes) -> Result<Bytes, String>;
 
 	/// Import a transaction: used for misbehaviour reporting.
 	fn transact_contract(&self, address: Address, data: Bytes) -> Result<TransactionImportResult, EthcoreError>;

ethcore/src/engines/authority_round.rs

@@ -150,12 +150,12 @@ impl AuthorityRound {
 		}
 	}
 
-	fn step_proposer(&self, step: usize) -> Address {
+	fn step_proposer(&self, bh: &H256, step: usize) -> Address {
-		self.validators.get(step)
+		self.validators.get(bh, step)
 	}
 
-	fn is_step_proposer(&self, step: usize, address: &Address) -> bool {
+	fn is_step_proposer(&self, bh: &H256, step: usize, address: &Address) -> bool {
-		self.step_proposer(step) == *address
+		self.step_proposer(bh, step) == *address
 	}
 
 	fn is_future_step(&self, step: usize) -> bool {
@@ -249,7 +249,7 @@ impl Engine for AuthorityRound {
 	}
 
 	fn seals_internally(&self) -> Option<bool> {
-		Some(self.validators.contains(&self.signer.address()))
+		Some(self.signer.address() != Address::default())
 	}
 
 	/// Attempt to seal the block internally.
@@ -260,7 +260,7 @@ impl Engine for AuthorityRound {
 		if self.proposed.load(AtomicOrdering::SeqCst) { return Seal::None; }
 		let header = block.header();
 		let step = self.step.load(AtomicOrdering::SeqCst);
-		if self.is_step_proposer(step, header.author()) {
+		if self.is_step_proposer(header.parent_hash(), step, header.author()) {
 			if let Ok(signature) = self.signer.sign(header.bare_hash()) {
 				trace!(target: "engine", "generate_seal: Issuing a block for step {}.", step);
 				self.proposed.store(true, AtomicOrdering::SeqCst);
@@ -299,32 +299,33 @@ impl Engine for AuthorityRound {
 		}
 	}
 
-	/// Check if the signature belongs to the correct proposer.
+	fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
-	fn verify_block_unordered(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+				Ok(())
-		let header_step = header_step(header)?;
+	}
+
+	/// Do the validator and gas limit validation.
+	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		let step = header_step(header)?;
 		// Give one step slack if step is lagging, double vote is still not possible.
-		if self.is_future_step(header_step) {
+		if self.is_future_step(step) {
 			trace!(target: "engine", "verify_block_unordered: block from the future");
 			self.validators.report_benign(header.author());
 			Err(BlockError::InvalidSeal)?
 		} else {
+			// Check if the signature belongs to a validator, can depend on parent state.
 			let proposer_signature = header_signature(header)?;
-			let correct_proposer = self.step_proposer(header_step);
+			let correct_proposer = self.step_proposer(header.parent_hash(), step);
-			if verify_address(&correct_proposer, &proposer_signature, &header.bare_hash())? {
+			if !verify_address(&correct_proposer, &proposer_signature, &header.bare_hash())? {
-				Ok(())
+				trace!(target: "engine", "verify_block_unordered: bad proposer for step: {}", step);
-			} else {
-				trace!(target: "engine", "verify_block_unordered: bad proposer for step: {}", header_step);
 				Err(EngineError::NotProposer(Mismatch { expected: correct_proposer, found: header.author().clone() }))?
 			}
 		}
-	}
 
-	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		// Do not calculate difficulty for genesis blocks.
 		if header.number() == 0 {
 			return Err(From::from(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() })));
 		}
 
-		let step = header_step(header)?;
 		// Check if parent is from a previous step.
 		if step == header_step(parent)? {
 			trace!(target: "engine", "Multiple blocks proposed for step {}.", step);
@@ -412,7 +413,7 @@ mod tests {
 		let mut header: Header = Header::default();
 		header.set_seal(vec![encode(&H520::default()).to_vec()]);
 
-		let verify_result = engine.verify_block_unordered(&header, None);
+		let verify_result = engine.verify_block_family(&header, &Default::default(), None);
 		assert!(verify_result.is_err());
 	}
 
@@ -450,10 +451,14 @@ mod tests {
 
 	#[test]
 	fn proposer_switching() {
-		let mut header: Header = Header::default();
 		let tap = AccountProvider::transient_provider();
 		let addr = tap.insert_account(Secret::from_slice(&"0".sha3()).unwrap(), "0").unwrap();
-
+		let mut parent_header: Header = Header::default();
+		parent_header.set_seal(vec![encode(&0usize).to_vec()]);
+		parent_header.set_gas_limit(U256::from_str("222222").unwrap());
+		let mut header: Header = Header::default();
+		header.set_number(1);
+		header.set_gas_limit(U256::from_str("222222").unwrap());
 		header.set_author(addr);
 
 		let engine = Spec::new_test_round().engine;
@@ -462,17 +467,22 @@ mod tests {
 		// Two validators.
 		// Spec starts with step 2.
 		header.set_seal(vec![encode(&2usize).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
-		assert!(engine.verify_block_seal(&header).is_err());
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_err());
 		header.set_seal(vec![encode(&1usize).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
-		assert!(engine.verify_block_seal(&header).is_ok());
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
 	}
 
 	#[test]
 	fn rejects_future_block() {
-		let mut header: Header = Header::default();
 		let tap = AccountProvider::transient_provider();
 		let addr = tap.insert_account(Secret::from_slice(&"0".sha3()).unwrap(), "0").unwrap();
 
+		let mut parent_header: Header = Header::default();
+		parent_header.set_seal(vec![encode(&0usize).to_vec()]);
+		parent_header.set_gas_limit(U256::from_str("222222").unwrap());
+		let mut header: Header = Header::default();
+		header.set_number(1);
+		header.set_gas_limit(U256::from_str("222222").unwrap());
 		header.set_author(addr);
 
 		let engine = Spec::new_test_round().engine;
@@ -481,8 +491,8 @@ mod tests {
 		// Two validators.
 		// Spec starts with step 2.
 		header.set_seal(vec![encode(&1usize).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
-		assert!(engine.verify_block_seal(&header).is_ok());
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
 		header.set_seal(vec![encode(&5usize).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
-		assert!(engine.verify_block_seal(&header).is_err());
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_err());
 	}
 }

ethcore/src/engines/basic_authority.rs

@@ -104,14 +104,14 @@ impl Engine for BasicAuthority {
 	}
 
 	fn seals_internally(&self) -> Option<bool> {
-		Some(self.validators.contains(&self.signer.address()))
+		Some(self.signer.address() != Address::default())
 	}
 
 	/// Attempt to seal the block internally.
 	fn generate_seal(&self, block: &ExecutedBlock) -> Seal {
 		let header = block.header();
 		let author = header.author();
-		if self.validators.contains(author) {
+		if self.validators.contains(header.parent_hash(), author) {
 			// account should be pernamently unlocked, otherwise sealing will fail
 			if let Ok(signature) = self.signer.sign(header.bare_hash()) {
 				return Seal::Regular(vec![::rlp::encode(&(&H520::from(signature) as &[u8])).to_vec()]);
@@ -133,20 +133,20 @@ impl Engine for BasicAuthority {
 		Ok(())
 	}
 
-	fn verify_block_unordered(&self, header: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
+	fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
-		use rlp::{UntrustedRlp, View};
-
-		// check the signature is legit.
-		let sig = UntrustedRlp::new(&header.seal()[0]).as_val::<H520>()?;
-		let signer = public_to_address(&recover(&sig.into(), &header.bare_hash())?);
-		if !self.validators.contains(&signer) {
-			return Err(BlockError::InvalidSeal)?;
-		}
 		Ok(())
 	}
 
 	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
-		// we should not calculate difficulty for genesis blocks
+		use rlp::{UntrustedRlp, View};
+		// Check if the signature belongs to a validator, can depend on parent state.
+		let sig = UntrustedRlp::new(&header.seal()[0]).as_val::<H520>()?;
+		let signer = public_to_address(&recover(&sig.into(), &header.bare_hash())?);
+		if !self.validators.contains(header.parent_hash(), &signer) {
+			return Err(BlockError::InvalidSeal)?;
+		}
+
+		// Do not calculate difficulty for genesis blocks.
 		if header.number() == 0 {
 			return Err(From::from(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() })));
 		}
@@ -239,7 +239,7 @@ mod tests {
 		let mut header: Header = Header::default();
 		header.set_seal(vec![::rlp::encode(&H520::default()).to_vec()]);
 
-		let verify_result = engine.verify_block_unordered(&header, None);
+		let verify_result = engine.verify_block_family(&header, &Default::default(), None);
 		assert!(verify_result.is_err());
 	}
 

ethcore/src/engines/tendermint/mod.rs

@@ -95,6 +95,8 @@ pub struct Tendermint {
 	last_lock: AtomicUsize,
 	/// Bare hash of the proposed block, used for seal submission.
 	proposal: RwLock<Option<H256>>,
+	/// Hash of the proposal parent block.
+	proposal_parent: RwLock<H256>,
 	/// Set used to determine the current validators.
 	validators: Box<ValidatorSet + Send + Sync>,
 }
@@ -114,11 +116,12 @@ impl Tendermint {
 				height: AtomicUsize::new(1),
 				view: AtomicUsize::new(0),
 				step: RwLock::new(Step::Propose),
-				votes: VoteCollector::default(),
+				votes: Default::default(),
 				signer: Default::default(),
 				lock_change: RwLock::new(None),
 				last_lock: AtomicUsize::new(0),
 				proposal: RwLock::new(None),
+				proposal_parent: Default::default(),
 				validators: new_validator_set(our_params.validators),
 			});
 		let handler = TransitionHandler::new(Arc::downgrade(&engine) as Weak<Engine>, Box::new(our_params.timeouts));
@@ -232,7 +235,7 @@ impl Tendermint {
 				let height = self.height.load(AtomicOrdering::SeqCst);
 				if let Some(block_hash) = *self.proposal.read() {
 					// Generate seal and remove old votes.
-					if self.is_signer_proposer() {
+					if self.is_signer_proposer(&*self.proposal_parent.read()) {
 						let proposal_step = VoteStep::new(height, view, Step::Propose);
 						let precommit_step = VoteStep::new(proposal_step.height, proposal_step.view, Step::Precommit);
 						if let Some(seal) = self.votes.seal_signatures(proposal_step, precommit_step, &block_hash) {
@@ -254,23 +257,23 @@ impl Tendermint {
 	}
 
 	fn is_authority(&self, address: &Address) -> bool {
-		self.validators.contains(address)
+		self.validators.contains(&*self.proposal_parent.read(), address)
 	}
 
 	fn is_above_threshold(&self, n: usize) -> bool {
-		n > self.validators.count() * 2/3
+		n > self.validators.count(&*self.proposal_parent.read()) * 2/3
 	}
 
 	/// Find the designated for the given view.
-	fn view_proposer(&self, height: Height, view: View) -> Address {
+	fn view_proposer(&self, bh: &H256, height: Height, view: View) -> Address {
 		let proposer_nonce = height + view;
 		trace!(target: "engine", "Proposer nonce: {}", proposer_nonce);
-		self.validators.get(proposer_nonce)
+		self.validators.get(bh, proposer_nonce)
 	}
 
 	/// Check if address is a proposer for given view.
-	fn is_view_proposer(&self, height: Height, view: View, address: &Address) -> Result<(), EngineError> {
+	fn is_view_proposer(&self, bh: &H256, height: Height, view: View, address: &Address) -> Result<(), EngineError> {
-		let proposer = self.view_proposer(height, view);
+		let proposer = self.view_proposer(bh, height, view);
 		if proposer == *address {
 			Ok(())
 		} else {
@@ -279,8 +282,8 @@ impl Tendermint {
 	}
 
 	/// Check if current signer is the current proposer.
-	fn is_signer_proposer(&self) -> bool {
+	fn is_signer_proposer(&self, bh: &H256) -> bool {
-		let proposer = self.view_proposer(self.height.load(AtomicOrdering::SeqCst), self.view.load(AtomicOrdering::SeqCst));
+		let proposer = self.view_proposer(bh, self.height.load(AtomicOrdering::SeqCst), self.view.load(AtomicOrdering::SeqCst));
 		self.signer.is_address(&proposer)
 	}
 
@@ -419,7 +422,7 @@ impl Engine for Tendermint {
 
 	/// Should this node participate.
 	fn seals_internally(&self) -> Option<bool> {
-		Some(self.is_authority(&self.signer.address()))
+		Some(self.signer.address() != Address::default())
 	}
 
 	/// Attempt to seal generate a proposal seal.
@@ -427,7 +430,7 @@ impl Engine for Tendermint {
 		let header = block.header();
 		let author = header.author();
 		// Only proposer can generate seal if None was generated.
-		if !self.is_signer_proposer() || self.proposal.read().is_some() {
+		if !self.is_signer_proposer(header.parent_hash()) || self.proposal.read().is_some() {
 			return Seal::None;
 		}
 
@@ -441,6 +444,7 @@ impl Engine for Tendermint {
 			self.votes.vote(ConsensusMessage::new(signature, height, view, Step::Propose, bh), author);
 			// Remember proposal for later seal submission.
 			*self.proposal.write() = bh;
+			*self.proposal_parent.write() = header.parent_hash().clone();
 			Seal::Proposal(vec![
 				::rlp::encode(&view).to_vec(),
 				::rlp::encode(&signature).to_vec(),
@@ -505,7 +509,12 @@ impl Engine for Tendermint {
 
 	}
 
-	fn verify_block_unordered(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+	fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		Ok(())
+	}
+
+	/// Verify validators and gas limit.
+	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
 		let proposal = ConsensusMessage::new_proposal(header)?;
 		let proposer = proposal.verify()?;
 		if !self.is_authority(&proposer) {
@@ -522,7 +531,7 @@ impl Engine for Tendermint {
 				Some(a) => a,
 				None => public_to_address(&recover(&precommit.signature.into(), &precommit_hash)?),
 			};
-			if !self.validators.contains(&address) {
+			if !self.validators.contains(header.parent_hash(), &address) {
 				Err(EngineError::NotAuthorized(address.to_owned()))?
 			}
 
@@ -545,12 +554,9 @@ impl Engine for Tendermint {
 					found: signatures_len
 				}))?;
 			}
-			self.is_view_proposer(proposal.vote_step.height, proposal.vote_step.view, &proposer)?;
+			self.is_view_proposer(header.parent_hash(), proposal.vote_step.height, proposal.vote_step.view, &proposer)?;
-		}
-		Ok(())
 		}
 
-	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
 		if header.number() == 0 {
 			Err(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() }))?;
 		}
@@ -595,6 +601,7 @@ impl Engine for Tendermint {
 		debug!(target: "engine", "Received a new proposal {:?} from {}.", proposal.vote_step, proposer);
 		if self.is_view(&proposal) {
 			*self.proposal.write() = proposal.block_hash.clone();
+			*self.proposal_parent.write() = header.parent_hash().clone();
 		}
 		self.votes.vote(proposal, &proposer);
 		true
@@ -607,7 +614,7 @@ impl Engine for Tendermint {
 				trace!(target: "engine", "Propose timeout.");
 				if self.proposal.read().is_none() {
 					// Report the proposer if no proposal was received.
-					let current_proposer = self.view_proposer(self.height.load(AtomicOrdering::SeqCst), self.view.load(AtomicOrdering::SeqCst));
+					let current_proposer = self.view_proposer(&*self.proposal_parent.read(), self.height.load(AtomicOrdering::SeqCst), self.view.load(AtomicOrdering::SeqCst));
 					self.validators.report_benign(&current_proposer);
 				}
 				Step::Prevote
@@ -765,20 +772,25 @@ mod tests {
 		let (spec, tap) = setup();
 		let engine = spec.engine;
 
-		let mut header = Header::default();
+		let mut parent_header: Header = Header::default();
-		let validator = insert_and_unlock(&tap, "0");
+		parent_header.set_gas_limit(U256::from_str("222222").unwrap());
-		header.set_author(validator);
-		let seal = proposal_seal(&tap, &header, 0);
-		header.set_seal(seal);
-		// Good proposer.
-		assert!(engine.verify_block_unordered(&header.clone(), None).is_ok());
 
+		let mut header = Header::default();
+		header.set_number(1);
+		header.set_gas_limit(U256::from_str("222222").unwrap());
 		let validator = insert_and_unlock(&tap, "1");
 		header.set_author(validator);
 		let seal = proposal_seal(&tap, &header, 0);
 		header.set_seal(seal);
+		// Good proposer.
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
+
+		let validator = insert_and_unlock(&tap, "0");
+		header.set_author(validator);
+		let seal = proposal_seal(&tap, &header, 0);
+		header.set_seal(seal);
 		// Bad proposer.
-		match engine.verify_block_unordered(&header, None) {
+		match engine.verify_block_family(&header, &parent_header, None) {
 			Err(Error::Engine(EngineError::NotProposer(_))) => {},
 			_ => panic!(),
 		}
@@ -788,7 +800,7 @@ mod tests {
 		let seal = proposal_seal(&tap, &header, 0);
 		header.set_seal(seal);
 		// Not authority.
-		match engine.verify_block_unordered(&header, None) {
+		match engine.verify_block_family(&header, &parent_header, None) {
 			Err(Error::Engine(EngineError::NotAuthorized(_))) => {},
 			_ => panic!(),
 		};
@@ -800,19 +812,24 @@ mod tests {
 		let (spec, tap) = setup();
 		let engine = spec.engine;
 
+		let mut parent_header: Header = Header::default();
+		parent_header.set_gas_limit(U256::from_str("222222").unwrap());
+
 		let mut header = Header::default();
+		header.set_number(2);
+		header.set_gas_limit(U256::from_str("222222").unwrap());
 		let proposer = insert_and_unlock(&tap, "1");
 		header.set_author(proposer);
 		let mut seal = proposal_seal(&tap, &header, 0);
 
-		let vote_info = message_info_rlp(&VoteStep::new(0, 0, Step::Precommit), Some(header.bare_hash()));
+		let vote_info = message_info_rlp(&VoteStep::new(2, 0, Step::Precommit), Some(header.bare_hash()));
 		let signature1 = tap.sign(proposer, None, vote_info.sha3()).unwrap();
 
 		seal[2] = ::rlp::encode(&vec![H520::from(signature1.clone())]).to_vec();
 		header.set_seal(seal.clone());
 
 		// One good signature is not enough.
-		match engine.verify_block_unordered(&header, None) {
+		match engine.verify_block_family(&header, &parent_header, None) {
 			Err(Error::Engine(EngineError::BadSealFieldSize(_))) => {},
 			_ => panic!(),
 		}
@@ -823,7 +840,7 @@ mod tests {
 		seal[2] = ::rlp::encode(&vec![H520::from(signature1.clone()), H520::from(signature0.clone())]).to_vec();
 		header.set_seal(seal.clone());
 
-		assert!(engine.verify_block_unordered(&header, None).is_ok());
+		assert!(engine.verify_block_family(&header, &parent_header, None).is_ok());
 
 		let bad_voter = insert_and_unlock(&tap, "101");
 		let bad_signature = tap.sign(bad_voter, None, vote_info.sha3()).unwrap();
@@ -832,7 +849,7 @@ mod tests {
 		header.set_seal(seal);
 
 		// One good and one bad signature.
-		match engine.verify_block_unordered(&header, None) {
+		match engine.verify_block_family(&header, &parent_header, None) {
 			Err(Error::Engine(EngineError::NotAuthorized(_))) => {},
 			_ => panic!(),
 		};

ethcore/src/engines/validator_set/contract.rs

@@ -26,30 +26,30 @@ use super::safe_contract::ValidatorSafeContract;
 /// The validator contract should have the following interface:
 /// [{"constant":true,"inputs":[],"name":"getValidators","outputs":[{"name":"","type":"address[]"}],"payable":false,"type":"function"}]
 pub struct ValidatorContract {
-	validators: Arc<ValidatorSafeContract>,
+	validators: ValidatorSafeContract,
 	provider: RwLock<Option<provider::Contract>>,
 }
 
 impl ValidatorContract {
 	pub fn new(contract_address: Address) -> Self {
 		ValidatorContract {
-			validators: Arc::new(ValidatorSafeContract::new(contract_address)),
+			validators: ValidatorSafeContract::new(contract_address),
 			provider: RwLock::new(None),
 		}
 	}
 }
 
-impl ValidatorSet for Arc<ValidatorContract> {
+impl ValidatorSet for ValidatorContract {
-	fn contains(&self, address: &Address) -> bool {
+	fn contains(&self, bh: &H256, address: &Address) -> bool {
-		self.validators.contains(address)
+		self.validators.contains(bh, address)
 	}
 
-	fn get(&self, nonce: usize) -> Address {
+	fn get(&self, bh: &H256, nonce: usize) -> Address {
-		self.validators.get(nonce)
+		self.validators.get(bh, nonce)
 	}
 
-	fn count(&self) -> usize {
+	fn count(&self, bh: &H256) -> usize {
-		self.validators.count()
+		self.validators.count(bh)
 	}
 
 	fn report_malicious(&self, address: &Address) {
@@ -144,6 +144,7 @@ mod tests {
 	use header::Header;
 	use account_provider::AccountProvider;
 	use miner::MinerService;
+	use types::ids::BlockId;
 	use client::BlockChainClient;
 	use tests::helpers::generate_dummy_client_with_spec_and_accounts;
 	use super::super::ValidatorSet;
@@ -154,8 +155,9 @@ mod tests {
 		let client = generate_dummy_client_with_spec_and_accounts(Spec::new_validator_contract, None);
 		let vc = Arc::new(ValidatorContract::new(Address::from_str("0000000000000000000000000000000000000005").unwrap()));
 		vc.register_contract(Arc::downgrade(&client));
-		assert!(vc.contains(&Address::from_str("7d577a597b2742b498cb5cf0c26cdcd726d39e6e").unwrap()));
+		let last_hash = client.best_block_header().hash();
-		assert!(vc.contains(&Address::from_str("82a978b3f5962a5b0957d9ee9eef472ee55b42f1").unwrap()));
+		assert!(vc.contains(&last_hash, &Address::from_str("7d577a597b2742b498cb5cf0c26cdcd726d39e6e").unwrap()));
+		assert!(vc.contains(&last_hash, &Address::from_str("82a978b3f5962a5b0957d9ee9eef472ee55b42f1").unwrap()));
 	}
 	
 	#[test]
@@ -171,18 +173,21 @@ mod tests {
 
 		client.miner().set_engine_signer(v1, "".into()).unwrap();
 		let mut header = Header::default();
-		let seal = encode(&vec!(5u8)).to_vec();	
+		let seal = vec![encode(&5u8).to_vec(), encode(&(&H520::default() as &[u8])).to_vec()];	
-		header.set_seal(vec!(seal));
+		header.set_seal(seal);
 		header.set_author(v1);
-		header.set_number(1);
+		header.set_number(2);
+		header.set_parent_hash(client.chain_info().best_block_hash);
+		
 		// `reportBenign` when the designated proposer releases block from the future (bad clock).
-		assert!(client.engine().verify_block_unordered(&header, None).is_err());
+		assert!(client.engine().verify_block_family(&header, &header, None).is_err());
 		// Seal a block.
 		client.engine().step();
 		assert_eq!(client.chain_info().best_block_number, 1);
 		// Check if the unresponsive validator is `disliked`.
-		assert_eq!(client.call_contract(validator_contract, "d8f2e0bf".from_hex().unwrap()).unwrap().to_hex(), "0000000000000000000000007d577a597b2742b498cb5cf0c26cdcd726d39e6e");
+		assert_eq!(client.call_contract(BlockId::Latest, validator_contract, "d8f2e0bf".from_hex().unwrap()).unwrap().to_hex(), "0000000000000000000000007d577a597b2742b498cb5cf0c26cdcd726d39e6e");
 		// Simulate a misbehaving validator by handling a double proposal.
+		let header = client.best_block_header().decode();
 		assert!(client.engine().verify_block_family(&header, &header, None).is_err());
 		// Seal a block.
 		client.engine().step();

ethcore/src/engines/validator_set/mod.rs

@@ -21,7 +21,7 @@ mod safe_contract;
 mod contract;
 
 use std::sync::Weak;
-use util::{Address, Arc};
+use util::{Address, H256};
 use ethjson::spec::ValidatorSet as ValidatorSpec;
 use client::Client;
 use self::simple_list::SimpleList;
@@ -32,18 +32,18 @@ use self::safe_contract::ValidatorSafeContract;
 pub fn new_validator_set(spec: ValidatorSpec) -> Box<ValidatorSet + Send + Sync> {
 	match spec {
 		ValidatorSpec::List(list) => Box::new(SimpleList::new(list.into_iter().map(Into::into).collect())),
-		ValidatorSpec::SafeContract(address) => Box::new(Arc::new(ValidatorSafeContract::new(address.into()))),
+		ValidatorSpec::SafeContract(address) => Box::new(ValidatorSafeContract::new(address.into())),
-		ValidatorSpec::Contract(address) => Box::new(Arc::new(ValidatorContract::new(address.into()))),
+		ValidatorSpec::Contract(address) => Box::new(ValidatorContract::new(address.into())),
 	}
 }
 
 pub trait ValidatorSet {
 	/// Checks if a given address is a validator.
-	fn contains(&self, address: &Address) -> bool;
+	fn contains(&self, bh: &H256, address: &Address) -> bool;
 	/// Draws an validator nonce modulo number of validators.
-	fn get(&self, nonce: usize) -> Address;
+	fn get(&self, bh: &H256, nonce: usize) -> Address;
 	/// Returns the current number of validators.
-	fn count(&self) -> usize;
+	fn count(&self, bh: &H256) -> usize;
 	/// Notifies about malicious behaviour.
 	fn report_malicious(&self, _validator: &Address) {}
 	/// Notifies about benign misbehaviour.

ethcore/src/engines/validator_set/safe_contract.rs

@@ -17,17 +17,23 @@
 /// Validator set maintained in a contract, updated using `getValidators` method.
 
 use std::sync::Weak;
+use ethabi;
 use util::*;
+use util::cache::MemoryLruCache;
+use types::ids::BlockId;
 use client::{Client, BlockChainClient};
-use client::chain_notify::ChainNotify;
 use super::ValidatorSet;
 use super::simple_list::SimpleList;
 
+const MEMOIZE_CAPACITY: usize = 500;
+const CONTRACT_INTERFACE: &'static [u8] = b"[{\"constant\":true,\"inputs\":[],\"name\":\"getValidators\",\"outputs\":[{\"name\":\"\",\"type\":\"address[]\"}],\"payable\":false,\"type\":\"function\"}]";
+const GET_VALIDATORS: &'static str = "getValidators";
+
 /// The validator contract should have the following interface:
 /// [{"constant":true,"inputs":[],"name":"getValidators","outputs":[{"name":"","type":"address[]"}],"payable":false,"type":"function"}]
 pub struct ValidatorSafeContract {
 	pub address: Address,
-	validators: RwLock<SimpleList>,
+	validators: RwLock<MemoryLruCache<H256, SimpleList>>,
 	provider: RwLock<Option<provider::Contract>>,
 }
 
@@ -35,102 +41,127 @@ impl ValidatorSafeContract {
 	pub fn new(contract_address: Address) -> Self {
 		ValidatorSafeContract {
 			address: contract_address,
-			validators: Default::default(),
+			validators: RwLock::new(MemoryLruCache::new(MEMOIZE_CAPACITY)),
 			provider: RwLock::new(None),
 		}
 	}
 
-	/// Queries the state and updates the set of validators.
+	/// Queries the state and gets the set of validators.
-	pub fn update(&self) {
+	fn get_list(&self, block_hash: H256) -> Option<SimpleList> {
 		if let Some(ref provider) = *self.provider.read() {
-			match provider.get_validators() {
+			match provider.get_validators(BlockId::Hash(block_hash)) {
 				Ok(new) => {
 					debug!(target: "engine", "Set of validators obtained: {:?}", new);
-					*self.validators.write() = SimpleList::new(new);
+					Some(SimpleList::new(new))
+				},
+				Err(s) => {
+					debug!(target: "engine", "Set of validators could not be updated: {}", s);
+					None
 				},
-				Err(s) => warn!(target: "engine", "Set of validators could not be updated: {}", s),
 			}
 		} else {
-			warn!(target: "engine", "Set of validators could not be updated: no provider contract.")
+			warn!(target: "engine", "Set of validators could not be updated: no provider contract.");
+			None
 		}
 	}
 }
 
-/// Checks validators on every block.
+impl ValidatorSet for ValidatorSafeContract {
-impl ChainNotify for ValidatorSafeContract {
+	fn contains(&self, block_hash: &H256, address: &Address) -> bool {
-	fn new_blocks(
+		let mut guard = self.validators.write();
-		&self,
+		let maybe_existing = guard
-		_: Vec<H256>,
+			.get_mut(block_hash)
-		_: Vec<H256>,
+			.map(|list| list.contains(block_hash, address));
-		enacted: Vec<H256>,
+		maybe_existing
-		_: Vec<H256>,
+			.unwrap_or_else(|| self
-		_: Vec<H256>,
+				.get_list(block_hash.clone())
-		_: Vec<Bytes>,
+				.map_or(false, |list| {
-		_duration: u64) {
+					let contains = list.contains(block_hash, address);
-		if !enacted.is_empty() {
+					guard.insert(block_hash.clone(), list);
-			self.update();
+					contains
-		}
+				 }))
-	}
 	}
 
-impl ValidatorSet for Arc<ValidatorSafeContract> {
+	fn get(&self, block_hash: &H256, nonce: usize) -> Address {
-	fn contains(&self, address: &Address) -> bool {
+		let mut guard = self.validators.write();
-		self.validators.read().contains(address)
+		let maybe_existing = guard
+			.get_mut(block_hash)
+			.map(|list| list.get(block_hash, nonce));
+		maybe_existing
+			.unwrap_or_else(|| self
+				.get_list(block_hash.clone())
+				.map_or_else(Default::default, |list| {
+					let address = list.get(block_hash, nonce);
+					guard.insert(block_hash.clone(), list);
+					address
+				 }))
 	}
 
-	fn get(&self, nonce: usize) -> Address {
+	fn count(&self, block_hash: &H256) -> usize {
-		self.validators.read().get(nonce)
+		let mut guard = self.validators.write();
-	}
+		let maybe_existing = guard
-
+			.get_mut(block_hash)
-	fn count(&self) -> usize {
+			.map(|list| list.count(block_hash));
-		self.validators.read().count()
+		maybe_existing
+			.unwrap_or_else(|| self
+				.get_list(block_hash.clone())
+				.map_or_else(usize::max_value, |list| {
+					let address = list.count(block_hash);
+					guard.insert(block_hash.clone(), list);
+					address
+				 }))
 	}
 
 	fn register_contract(&self, client: Weak<Client>) {
-		if let Some(c) = client.upgrade() {
+		trace!(target: "engine", "Setting up contract caller.");
-			c.add_notify(self.clone());
+		let contract = ethabi::Contract::new(ethabi::Interface::load(CONTRACT_INTERFACE).expect("JSON interface is valid; qed"));
-		}
+		let call = contract.function(GET_VALIDATORS.into()).expect("Method name is valid; qed");
-		{
+		let data = call.encode_call(vec![]).expect("get_validators does not take any arguments; qed");
-			*self.provider.write() = Some(provider::Contract::new(self.address, move |a, d| client.upgrade().ok_or("No client!".into()).and_then(|c| c.call_contract(a, d))));
+		let contract_address = self.address.clone();
-		}
+		let do_call = move |id| client
-		self.update();
+			.upgrade()
+			.ok_or("No client!".into())
+			.and_then(|c| c.call_contract(id, contract_address.clone(), data.clone()))
+			.map(|raw_output| call.decode_output(raw_output).expect("ethabi is correct; qed"));
+		*self.provider.write() = Some(provider::Contract::new(do_call));
 	}
 }
 
 mod provider {
-	// Autogenerated from JSON contract definition using Rust contract convertor.
-	#![allow(unused_imports)]
 	use std::string::String;
 	use std::result::Result;
-	use std::fmt;
 	use {util, ethabi};
-	use util::{FixedHash, Uint};
+	use types::ids::BlockId;
 
 	pub struct Contract {
-		contract: ethabi::Contract,
+		do_call: Box<Fn(BlockId) -> Result<Vec<ethabi::Token>, String> + Send + Sync + 'static>,
-		address: util::Address,
-		do_call: Box<Fn(util::Address, Vec<u8>) -> Result<Vec<u8>, String> + Send + Sync + 'static>,
 	}
+
 	impl Contract {
-		pub fn new<F>(address: util::Address, do_call: F) -> Self where F: Fn(util::Address, Vec<u8>) -> Result<Vec<u8>, String> + Send + Sync + 'static {
+		pub fn new<F>(do_call: F) -> Self where F: Fn(BlockId) -> Result<Vec<ethabi::Token>, String> + Send + Sync + 'static {
 			Contract {
-				contract: ethabi::Contract::new(ethabi::Interface::load(b"[{\"constant\":true,\"inputs\":[],\"name\":\"getValidators\",\"outputs\":[{\"name\":\"\",\"type\":\"address[]\"}],\"payable\":false,\"type\":\"function\"}]").expect("JSON is autogenerated; qed")),
-				address: address,
 				do_call: Box::new(do_call),
 			}
 		}
-		fn as_string<T: fmt::Debug>(e: T) -> String { format!("{:?}", e) }
 
-		/// Auto-generated from: `{"constant":true,"inputs":[],"name":"getValidators","outputs":[{"name":"","type":"address[]"}],"payable":false,"type":"function"}`
+		/// Gets validators from contract with interface: `{"constant":true,"inputs":[],"name":"getValidators","outputs":[{"name":"","type":"address[]"}],"payable":false,"type":"function"}`
-		#[allow(dead_code)]
+		pub fn get_validators(&self, id: BlockId) -> Result<Vec<util::Address>, String> {
-		pub fn get_validators(&self) -> Result<Vec<util::Address>, String> {
+			Ok((self.do_call)(id)?
-			let call = self.contract.function("getValidators".into()).map_err(Self::as_string)?;
+				 .into_iter()
-			let data = call.encode_call(
+				 .rev()
-				vec![]
+				 .collect::<Vec<_>>()
-			).map_err(Self::as_string)?;
+				 .pop()
-			let output = call.decode_output((self.do_call)(self.address.clone(), data)?).map_err(Self::as_string)?;
+				 .expect("get_validators returns one argument; qed")
-			let mut result = output.into_iter().rev().collect::<Vec<_>>();
+				 .to_array()
-			Ok(({ let r = result.pop().ok_or("Invalid return arity")?; let r = r.to_array().and_then(|v| v.into_iter().map(|a| a.to_address()).collect::<Option<Vec<[u8; 20]>>>()).ok_or("Invalid type returned")?; r.into_iter().map(|a| util::Address::from(a)).collect::<Vec<_>>() }))
+				 .and_then(|v| v
+					 .into_iter()
+					 .map(|a| a.to_address())
+					 .collect::<Option<Vec<[u8; 20]>>>())
+				 .expect("get_validators returns a list of addresses; qed")
+				 .into_iter()
+				 .map(util::Address::from)
+				 .collect::<Vec<_>>()
+			)
 		}
 	}
 }
@@ -138,13 +169,14 @@ mod provider {
 #[cfg(test)]
 mod tests {
 	use util::*;
+	use types::ids::BlockId;
 	use spec::Spec;
 	use account_provider::AccountProvider;
 	use transaction::{Transaction, Action};
 	use client::{BlockChainClient, EngineClient};
 	use ethkey::Secret;
 	use miner::MinerService;
-	use tests::helpers::generate_dummy_client_with_spec_and_accounts;
+	use tests::helpers::{generate_dummy_client_with_spec_and_accounts, generate_dummy_client_with_spec_and_data};
 	use super::super::ValidatorSet;
 	use super::ValidatorSafeContract;
 
@@ -153,12 +185,13 @@ mod tests {
 		let client = generate_dummy_client_with_spec_and_accounts(Spec::new_validator_safe_contract, None);
 		let vc = Arc::new(ValidatorSafeContract::new(Address::from_str("0000000000000000000000000000000000000005").unwrap()));
 		vc.register_contract(Arc::downgrade(&client));
-		assert!(vc.contains(&Address::from_str("7d577a597b2742b498cb5cf0c26cdcd726d39e6e").unwrap()));
+		let last_hash = client.best_block_header().hash();
-		assert!(vc.contains(&Address::from_str("82a978b3f5962a5b0957d9ee9eef472ee55b42f1").unwrap()));
+		assert!(vc.contains(&last_hash, &Address::from_str("7d577a597b2742b498cb5cf0c26cdcd726d39e6e").unwrap()));
+		assert!(vc.contains(&last_hash, &Address::from_str("82a978b3f5962a5b0957d9ee9eef472ee55b42f1").unwrap()));
 	}
 
 	#[test]
-	fn updates_validators() {
+	fn knows_validators() {
 		let tap = Arc::new(AccountProvider::transient_provider());
 		let s0 = Secret::from_slice(&"1".sha3()).unwrap();
 		let v0 = tap.insert_account(s0.clone(), "").unwrap();
@@ -212,5 +245,14 @@ mod tests {
 		client.update_sealing();
 		// Able to seal again.
 		assert_eq!(client.chain_info().best_block_number, 3);
+
+		// Check syncing.
+		let sync_client = generate_dummy_client_with_spec_and_data(Spec::new_validator_safe_contract, 0, 0, &[]);
+		sync_client.engine().register_client(Arc::downgrade(&sync_client));
+		for i in 1..4 {
+			sync_client.import_block(client.block(BlockId::Number(i)).unwrap().into_inner()).unwrap();
+		}
+		sync_client.flush_queue();
+		assert_eq!(sync_client.chain_info().best_block_number, 3);
 	}
 }

ethcore/src/engines/validator_set/simple_list.rs

@@ -16,7 +16,7 @@
 
 /// Preconfigured validator list.
 
-use util::Address;
+use util::{H256, Address, HeapSizeOf};
 use super::ValidatorSet;
 
 #[derive(Debug, PartialEq, Eq, Default)]
@@ -34,16 +34,22 @@ impl SimpleList {
 	}
 }
 
+impl HeapSizeOf for SimpleList {
+	fn heap_size_of_children(&self) -> usize {
+		self.validators.heap_size_of_children() + self.validator_n.heap_size_of_children()
+	}
+}
+
 impl ValidatorSet for SimpleList {
-	fn contains(&self, address: &Address) -> bool {
+	fn contains(&self, _bh: &H256, address: &Address) -> bool {
 		self.validators.contains(address)
 	}
 
-	fn get(&self, nonce: usize) -> Address {
+	fn get(&self, _bh: &H256, nonce: usize) -> Address {
 		self.validators.get(nonce % self.validator_n).expect("There are validator_n authorities; taking number modulo validator_n gives number in validator_n range; qed").clone()
 	}
 
-	fn count(&self) -> usize {
+	fn count(&self, _bh: &H256) -> usize {
 		self.validator_n
 	}
 }
@@ -60,9 +66,9 @@ mod tests {
 		let a1 = Address::from_str("cd1722f3947def4cf144679da39c4c32bdc35681").unwrap();
 		let a2 = Address::from_str("0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6").unwrap();
 		let list = SimpleList::new(vec![a1.clone(), a2.clone()]);
-		assert!(list.contains(&a1));
+		assert!(list.contains(&Default::default(), &a1));
-		assert_eq!(list.get(0), a1);
+		assert_eq!(list.get(&Default::default(), 0), a1);
-		assert_eq!(list.get(1), a2);
+		assert_eq!(list.get(&Default::default(), 1), a2);
-		assert_eq!(list.get(2), a1);
+		assert_eq!(list.get(&Default::default(), 2), a1);
 	}
 }

ethcore/src/miner/service_transaction_checker.rs

@@ -14,6 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity. If not, see <http://www.gnu.org/licenses/>.
 
+use types::ids::BlockId;
 use client::MiningBlockChainClient;
 use transaction::SignedTransaction;
 use util::{U256, Uint, Mutex};
@@ -45,7 +46,7 @@ impl ServiceTransactionChecker {
 		debug_assert_eq!(tx.gas_price, U256::zero());
 
 		if let Some(ref contract) = *self.contract.lock() {
-			let do_call = |a, d| client.call_contract(a, d);
+			let do_call = |a, d| client.call_contract(BlockId::Latest, a, d);
 			contract.certified(&do_call, &tx.sender())
 		} else {
 			Err("contract is not configured".to_owned())

updater/src/updater.rs

@@ -247,7 +247,7 @@ impl Updater {
 			if let Some(ops_addr) = self.client.upgrade().and_then(|c| c.registry_address("operations".into())) {
 				trace!(target: "updater", "Found operations at {}", ops_addr);
 				let client = self.client.clone();
-				*self.operations.lock() = Some(Operations::new(ops_addr, move |a, d| client.upgrade().ok_or("No client!".into()).and_then(|c| c.call_contract(a, d))));
+				*self.operations.lock() = Some(Operations::new(ops_addr, move |a, d| client.upgrade().ok_or("No client!".into()).and_then(|c| c.call_contract(BlockId::Latest, a, d))));
 			} else {
 				// No Operations contract - bail.
 				return;
@@ -340,7 +340,7 @@ impl fetch::urlhint::ContractClient for Updater {
 
 	fn call(&self, address: Address, data: Bytes) -> Result<Bytes, String> {
 		self.client.upgrade().ok_or_else(|| "Client not available".to_owned())?
-			.call_contract(address, data)
+			.call_contract(BlockId::Latest, address, data)
 	}
 }