Sync ethereum headers using unsigned (substrate) transactions (parity…

…tech#45)

* reward submitters on finalization

* PoA -> Substrate: unsigned_import_header API

* fix grumble

* make submitter part of ImportContext

* verify using next validators set + tests

* fix nostd compilation

* add sub-tx-mode argument

* support sub-tx-mode

* impl ValidateUnsigned for Runtime

* do not submit too much transactions to the pool

* cargo fmt

* fix bad merge

* revert license fix

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Hernando Castano <[email protected]>

* Update modules/ethereum/src/verification.rs

Co-Authored-By: Hernando Castano <[email protected]>

* updated comment

* validate receipts before accepting unsigned tx to pool

* cargo fmt

* fix comment

* fix grumbles

* Update modules/ethereum/src/verification.rs

Co-Authored-By: Hernando Castano <[email protected]>

* cargo fmt --all

* struct ChangeToEnact

* updated doc

* fix doc

* add docs to the code method

* simplify fn ancestry

* finish incomplete docs

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* Update modules/ethereum/src/lib.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* return err from unsigned_import_header

* get header once

* Update relays/ethereum/src/ethereum_sync.rs

Co-Authored-By: Tomasz Drwięga <[email protected]>

* fix

* UnsignedTooFarInTheFuture -> Custom(err.code())

* updated ImportContext::last_signal_block

* cargo fmt --all

* rename runtime calls

Co-authored-by: Hernando Castano <[email protected]>
Co-authored-by: Tomasz Drwięga <[email protected]>

bridges/bin/node/runtime/src/lib.rs

@@ -247,7 +247,7 @@ construct_runtime!(
 		Balances: pallet_balances::{Module, Call, Storage, Config<T>, Event<T>},
 		TransactionPayment: pallet_transaction_payment::{Module, Storage},
 		Sudo: pallet_sudo::{Module, Call, Config<T>, Storage, Event<T>},
-		BridgeEthPoA: pallet_bridge_eth_poa::{Module, Call, Config, Storage},
+		BridgeEthPoA: pallet_bridge_eth_poa::{Module, Call, Config, Storage, ValidateUnsigned},
 	}
 );
 

bridges/modules/ethereum/src/error.rs

@@ -17,45 +17,49 @@
 use sp_runtime::RuntimeDebug;
 
 /// Header import error.
-#[derive(RuntimeDebug)]
+#[derive(Clone, Copy, RuntimeDebug)]
 #[cfg_attr(feature = "std", derive(PartialEq))]
 pub enum Error {
-	/// The header is beyound last finalized and can not be imported.
-	AncientHeader,
+	/// The header is beyond last finalized and can not be imported.
+	AncientHeader = 0,
 	/// The header is already imported.
-	KnownHeader,
+	KnownHeader = 1,
 	/// Seal has an incorrect format.
-	InvalidSealArity,
+	InvalidSealArity = 2,
 	/// Block number isn't sensible.
-	RidiculousNumber,
+	RidiculousNumber = 3,
 	/// Block has too much gas used.
-	TooMuchGasUsed,
+	TooMuchGasUsed = 4,
 	/// Gas limit header field is invalid.
-	InvalidGasLimit,
+	InvalidGasLimit = 5,
 	/// Extra data is of an invalid length.
-	ExtraDataOutOfBounds,
+	ExtraDataOutOfBounds = 6,
 	/// Timestamp header overflowed.
-	TimestampOverflow,
+	TimestampOverflow = 7,
 	/// The parent header is missing from the blockchain.
-	MissingParentBlock,
+	MissingParentBlock = 8,
 	/// The header step is missing from the header.
-	MissingStep,
+	MissingStep = 9,
 	/// The header signature is missing from the header.
-	MissingSignature,
+	MissingSignature = 10,
 	/// Empty steps are missing from the header.
-	MissingEmptySteps,
+	MissingEmptySteps = 11,
 	/// The same author issued different votes at the same step.
-	DoubleVote,
+	DoubleVote = 12,
 	/// Validation proof insufficient.
-	InsufficientProof,
+	InsufficientProof = 13,
 	/// Difficulty header field is invalid.
-	InvalidDifficulty,
+	InvalidDifficulty = 14,
 	/// The received block is from an incorrect proposer.
-	NotValidator,
+	NotValidator = 15,
 	/// Missing transaction receipts for the operation.
-	MissingTransactionsReceipts,
+	MissingTransactionsReceipts = 16,
+	/// Redundant transaction receipts are provided.
+	RedundantTransactionsReceipts = 17,
 	/// Provided transactions receipts are not matching the header.
-	TransactionsReceiptsMismatch,
+	TransactionsReceiptsMismatch = 18,
+	/// Can't accept unsigned header from the far future.
+	UnsignedTooFarInTheFuture = 19,
 }
 
 impl Error {
@@ -78,7 +82,14 @@ impl Error {
 			Error::InvalidDifficulty => "Header has invalid difficulty",
 			Error::NotValidator => "Header is sealed by unexpected validator",
 			Error::MissingTransactionsReceipts => "The import operation requires transactions receipts",
+			Error::RedundantTransactionsReceipts => "Redundant transactions receipts are provided",
 			Error::TransactionsReceiptsMismatch => "Invalid transactions receipts provided",
+			Error::UnsignedTooFarInTheFuture => "The unsigned header is too far in future",
 		}
 	}
+
+	/// Return unique error code.
+	pub fn code(&self) -> u8 {
+		*self as u8
+	}
 }

bridges/modules/ethereum/src/finality.rs

@@ -15,15 +15,18 @@
 // along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::error::Error;
-use crate::{ancestry, Storage};
+use crate::Storage;
 use primitives::{public_to_address, Address, Header, SealedEmptyStep, H256};
 use sp_io::crypto::secp256k1_ecdsa_recover;
-use sp_std::collections::{
-	btree_map::{BTreeMap, Entry},
-	btree_set::BTreeSet,
-	vec_deque::VecDeque,
-};
 use sp_std::prelude::*;
+use sp_std::{
+	collections::{
+		btree_map::{BTreeMap, Entry},
+		btree_set::BTreeSet,
+		vec_deque::VecDeque,
+	},
+	iter::from_fn,
+};
 
 /// Tries to finalize blocks when given block is imported.
 ///
@@ -190,6 +193,24 @@ fn empty_step_signer(empty_step: &SealedEmptyStep, parent_hash: &H256) -> Option
 		.map(|public| public_to_address(&public))
 }
 
+/// Return iterator of given header ancestors.
+pub(crate) fn ancestry<'a, S: Storage>(
+	storage: &'a S,
+	header: &Header,
+) -> impl Iterator<Item = (H256, Header, Option<S::Submitter>)> + 'a {
+	let mut parent_hash = header.parent_hash.clone();
+	from_fn(move || {
+		let (header, submitter) = storage.header(&parent_hash)?;
+		if header.number == 0 {
+			return None;
+		}
+
+		let hash = parent_hash.clone();
+		parent_hash = header.parent_hash.clone();
+		Some((hash, header, submitter))
+	})
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;

bridges/modules/ethereum/src/import.rs

@@ -17,8 +17,8 @@
 use crate::error::Error;
 use crate::finality::finalize_blocks;
 use crate::validators::{Validators, ValidatorsConfiguration};
-use crate::verification::verify_aura_header;
-use crate::{AuraConfiguration, Storage};
+use crate::verification::{is_importable_header, verify_aura_header};
+use crate::{AuraConfiguration, ChangeToEnact, Storage};
 use primitives::{Header, Receipt, H256};
 use sp_std::{collections::btree_map::BTreeMap, prelude::*};
 
@@ -105,16 +105,22 @@ pub fn import_header<S: Storage>(
 	let (scheduled_change, enacted_change) = validators.extract_validators_change(&header, receipts)?;
 
 	// check if block finalizes some other blocks and corresponding scheduled validators
+	let validators_set = import_context.validators_set();
 	let finalized_blocks = finalize_blocks(
 		storage,
 		&prev_finalized_hash,
-		(import_context.validators_start(), import_context.validators()),
+		(&validators_set.enact_block, &validators_set.validators),
 		&hash,
 		import_context.submitter(),
 		&header,
 		aura_config.two_thirds_majority_transition,
 	)?;
-	let enacted_change = enacted_change.or_else(|| validators.finalize_validators_change(storage, &finalized_blocks));
+	let enacted_change = enacted_change
+		.map(|validators| ChangeToEnact {
+			signal_block: None,
+			validators,
+		})
+		.or_else(|| validators.finalize_validators_change(storage, &finalized_blocks));
 
 	// NOTE: we can't return Err() from anywhere below this line
 	// (because otherwise we'll have inconsistent storage if transaction will fail)
@@ -157,24 +163,6 @@ pub fn header_import_requires_receipts<S: Storage>(
 		.unwrap_or(false)
 }
 
-/// Checks that we are able to ***try to** import this header.
-/// Returns error if we should not try to import this block.
-/// Returns hash of the header and number of the last finalized block.
-fn is_importable_header<S: Storage>(storage: &S, header: &Header) -> Result<(H256, H256), Error> {
-	// we never import any header that competes with finalized header
-	let (finalized_block_number, finalized_block_hash) = storage.finalized_block();
-	if header.number <= finalized_block_number {
-		return Err(Error::AncientHeader);
-	}
-	// we never import any header with known hash
-	let hash = header.hash();
-	if storage.header(&hash).is_some() {
-		return Err(Error::KnownHeader);
-	}
-
-	Ok((hash, finalized_block_hash))
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;