separate constants for average and worst case relay headers (#2728)

* separate constants for average and worst case relay headers

* fix compilation

modules/grandpa/src/mock.rs

@@ -93,6 +93,7 @@ impl ChainWithGrandpa for TestBridgedChain {
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 8;
 	const MAX_HEADER_SIZE: u32 = 256;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
 }
 
 /// Return test externalities to use in tests.

modules/messages/src/tests/mock.rs

@@ -136,6 +136,7 @@ impl ChainWithGrandpa for BridgedChain {
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 4;
 	const MAX_HEADER_SIZE: u32 = 4096;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 4096;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 8192;
 }
 
 impl ChainWithMessages for BridgedChain {

modules/parachains/src/mock.rs

@@ -274,6 +274,7 @@ impl ChainWithGrandpa for TestBridgedChain {
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 8;
 	const MAX_HEADER_SIZE: u32 = 256;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
 }
 
 #[derive(Debug)]
@@ -309,6 +310,7 @@ impl ChainWithGrandpa for OtherBridgedChain {
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 8;
 	const MAX_HEADER_SIZE: u32 = 256;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
 }
 
 /// Return test externalities to use in tests.

modules/relayers/src/mock.rs

@@ -148,6 +148,7 @@ impl ChainWithGrandpa for BridgedUnderlyingChain {
 	const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 8;
 	const MAX_HEADER_SIZE: u32 = 256;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 64;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 128;
 }
 
 impl ChainWithMessages for BridgedUnderlyingChain {

primitives/chain-kusama/src/lib.rs

@@ -60,6 +60,7 @@ impl ChainWithGrandpa for Kusama {
 		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
 	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }
 
 // The SignedExtension used by Kusama.

primitives/chain-polkadot-bulletin/src/lib.rs

@@ -46,6 +46,7 @@ pub use bp_polkadot_core::{
 	AccountAddress, AccountId, Balance, Block, BlockNumber, Hash, Hasher, Header, Nonce, Signature,
 	SignedBlock, UncheckedExtrinsic, AVERAGE_HEADER_SIZE_IN_JUSTIFICATION,
 	EXTRA_STORAGE_PROOF_SIZE, MAX_HEADER_SIZE, REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY,
+	WORST_HEADER_SIZE_IN_JUSTIFICATION,
 };
 
 /// Maximal number of GRANDPA authorities at Polkadot Bulletin chain.
@@ -215,6 +216,7 @@ impl ChainWithGrandpa for PolkadotBulletin {
 		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
 	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }
 
 impl ChainWithMessages for PolkadotBulletin {

primitives/chain-polkadot/src/lib.rs

@@ -62,6 +62,7 @@ impl ChainWithGrandpa for Polkadot {
 		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
 	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }
 
 /// The SignedExtension used by Polkadot.

primitives/chain-rococo/src/lib.rs

@@ -60,6 +60,7 @@ impl ChainWithGrandpa for Rococo {
 		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
 	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }
 
 // The SignedExtension used by Rococo.

primitives/chain-westend/src/lib.rs

@@ -60,6 +60,7 @@ impl ChainWithGrandpa for Westend {
 		REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY;
 	const MAX_HEADER_SIZE: u32 = MAX_HEADER_SIZE;
 	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = AVERAGE_HEADER_SIZE_IN_JUSTIFICATION;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }
 
 // The SignedExtension used by Westend.

primitives/header-chain/src/lib.rs

@@ -284,9 +284,22 @@ pub trait ChainWithGrandpa: Chain {
 	/// 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 fee, paid
+	/// by the user at the sending chain. It covers most of cases, but if the actual header,
+	/// submitted with the messages transaction will be larger than the
+	/// `AVERAGE_HEADER_SIZE_IN_JUSTIFICATION`, the difference (`WORST_HEADER_SIZE_IN_JUSTIFICATION`
+	/// - `AVERAGE_HEADER_SIZE_IN_JUSTIFICATION`) must be covered by the sending chain.
+	const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32;
+
+	/// Worst-case 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 the worst-case
+	/// 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;
+	const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32;
 }
 
 impl<T> ChainWithGrandpa for T
@@ -302,4 +315,6 @@ where
 	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 WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 =
+		<T::Chain as ChainWithGrandpa>::WORST_HEADER_SIZE_IN_JUSTIFICATION;
 }

primitives/polkadot-core/src/lib.rs

@@ -73,7 +73,16 @@ pub const MAX_AUTHORITIES_COUNT: u32 = 1_256;
 /// reserve here.
 pub const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 2;
 
-/// Approximate average header size in `votes_ancestries` field of justification on Polkadot-like
+/// Average header size in `votes_ancestries` field of justification on Polkadot-like
+/// chains.
+///
+/// See [`bp-header-chain::ChainWithGrandpa`] for more details.
+///
+/// This value comes from recent (February, 2023) Kusama headers. Average is `336` there, but let's
+/// have some reserve and make it 1024.
+pub const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 1024;
+
+/// Worst-case header size in `votes_ancestries` field of justification on Polkadot-like
 /// chains.
 ///
 /// See [`bp-header-chain::ChainWithGrandpa`] for more details.
@@ -82,7 +91,7 @@ pub const REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY: u32 = 2;
 /// non-mandatory headers has size `40kb` (they contain the BABE epoch descriptor with all
 /// authorities - just like our mandatory header). Since we assume `2` headers in justification
 /// votes ancestry, let's set average header to `40kb / 2`.
-pub const AVERAGE_HEADER_SIZE_IN_JUSTIFICATION: u32 = 20 * 1024;
+pub const WORST_HEADER_SIZE_IN_JUSTIFICATION: u32 = 20 * 1024;
 
 /// Approximate maximal header size on Polkadot-like chains.
 ///