Bridges subtree update (#2602)

## Summary

This PR aligns Rococo/Westend bridge with latest Bridges repo
development:
- https://github.com/paritytech/parity-bridges-common/pull/2727
- https://github.com/paritytech/parity-bridges-common/pull/2728
- https://github.com/paritytech/parity-bridges-common/pull/2729




Part of: https://github.com/paritytech/parity-bridges-common/issues/2452

bridges/primitives/header-chain/src/justification/mod.rs

@@ -82,8 +82,8 @@ impl<H: HeaderT> GrandpaJustification<H> {
 			.saturating_add(BlockNumberOf::<C>::max_encoded_len().saturated_into())
 			.saturating_add(HashOf::<C>::max_encoded_len().saturated_into());
 
-		let max_expected_votes_ancestries_size = C::REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY
-			.saturating_mul(C::AVERAGE_HEADER_SIZE_IN_JUSTIFICATION);
+		let max_expected_votes_ancestries_size =
+			C::REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY.saturating_mul(C::AVERAGE_HEADER_SIZE);
 
 		// justification is round number (u64=8b), a signed GRANDPA commit and the
 		// `votes_ancestries` vector

bridges/primitives/header-chain/src/lib.rs

@@ -266,23 +266,28 @@ pub trait ChainWithGrandpa: Chain {
 	/// to submitter.
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32;
 
-	/// Maximal size of the chain header. The header may be the header that enacts new GRANDPA
-	/// authorities set (so it has large digest inside).
+	/// Maximal size of the mandatory chain header. Mandatory header is the header that enacts new
+	/// GRANDPA authorities set (so it has large digest inside).
 	///
 	/// This isn't a strict limit. The relay may submit larger headers and the pallet will accept
 	/// the call. The limit is only used to compute maximal refund amount and doing calls which
 	/// exceed the limit, may be costly to submitter.
-	const MAX_HEADER_SIZE: u32;
+	const MAX_MANDATORY_HEADER_SIZE: u32;
 
-	/// Average size of the chain header from justification ancestry. We don't expect to see there
-	/// headers that change GRANDPA authorities set (GRANDPA will probably be able to finalize at
-	/// least one additional header per session on non test chains), so this is average size of
-	/// headers that aren't changing the set.
+	/// Average size of the chain header. We don't expect to see there headers that change GRANDPA
+	/// authorities set (GRANDPA will probably be able to finalize at least one additional header
+	/// per session on non test chains), so this is average size of headers that aren't changing the
+	/// set.
 	///
-	/// This isn't a strict limit. The relay may submit justifications with larger headers in its
-	/// ancestry and the pallet will accept the call. The limit is only used to compute maximal
-	/// refund amount and doing calls which exceed the limit, may be costly to submitter.
-	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32;
+	/// This isn't a strict limit. The relay may submit justifications with larger headers and the
+	/// pallet will accept the call. However, if the total size of all `submit_finality_proof`
+	/// arguments exceeds the maximal size, computed using this average size, relayer will only get
+	/// partial refund.
+	///
+	/// We expect some headers on production chains that are above this size. But they are rare and
+	/// if rellayer cares about its profitability, we expect it'll select other headers for
+	/// submission.
+	const AVERAGE_HEADER_SIZE: u32;
 }
 
 impl<T> ChainWithGrandpa for T
@@ -295,7 +300,67 @@ where
 	const MAX_AUTHORITIES_COUNT: u32 = <T::Chain as ChainWithGrandpa>::MAX_AUTHORITIES_COUNT;
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 =
 		<T::Chain as ChainWithGrandpa>::REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
-	const MAX_HEADER_SIZE: u32 = <T::Chain as ChainWithGrandpa>::MAX_HEADER_SIZE;
-	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 =
-		<T::Chain as ChainWithGrandpa>::AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const MAX_MANDATORY_HEADER_SIZE: u32 =
+		<T::Chain as ChainWithGrandpa>::MAX_MANDATORY_HEADER_SIZE;
+	const AVERAGE_HEADER_SIZE: u32 = <T::Chain as ChainWithGrandpa>::AVERAGE_HEADER_SIZE;
+}
+
+/// Returns maximal expected size of `submit_finality_proof` call arguments.
+pub fn max_expected_submit_finality_proof_arguments_size<C: ChainWithGrandpa>(
+	is_mandatory_finality_target: bool,
+	precommits: u32,
+) -> u32 {
+	let max_expected_justification_size =
+		GrandpaJustification::<HeaderOf<C>>::max_reasonable_size::<C>(precommits);
+
+	// call arguments are header and justification
+	let max_expected_finality_target_size = if is_mandatory_finality_target {
+		C::MAX_MANDATORY_HEADER_SIZE
+	} else {
+		C::AVERAGE_HEADER_SIZE
+	};
+	max_expected_finality_target_size.saturating_add(max_expected_justification_size)
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use frame_support::weights::Weight;
+	use sp_runtime::{testing::H256, traits::BlakeTwo256, MultiSignature};
+
+	struct TestChain;
+
+	impl Chain for TestChain {
+		type BlockNumber = u32;
+		type Hash = H256;
+		type Hasher = BlakeTwo256;
+		type Header = sp_runtime::generic::Header<u32, BlakeTwo256>;
+		type AccountId = u64;
+		type Balance = u64;
+		type Nonce = u64;
+		type Signature = MultiSignature;
+
+		fn max_extrinsic_size() -> u32 {
+			0
+		}
+		fn max_extrinsic_weight() -> Weight {
+			Weight::zero()
+		}
+	}
+
+	impl ChainWithGrandpa for TestChain {
+		const WITH_CHAIN_GRANDPA_PALLET_NAME: &'static str = "Test";
+		const MAX_AUTHORITIES_COUNT: u32 = 128;
+		const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 2;
+		const MAX_MANDATORY_HEADER_SIZE: u32 = 100_000;
+		const AVERAGE_HEADER_SIZE: u32 = 1_024;
+	}
+
+	#[test]
+	fn max_expected_submit_finality_proof_arguments_size_respects_mandatory_argument() {
+		assert!(
+			max_expected_submit_finality_proof_arguments_size::<TestChain>(true, 100) >
+				max_expected_submit_finality_proof_arguments_size::<TestChain>(false, 100),
+		);
+	}
 }