Limit the size of the statement for further gossiping (#9965)

# Description

Limits the size of statements that are further gossiped over the network
to prevent skipping oversized messages. The limit is set to match the
network protocol's max statement notification size (1 MB), accounting
for 1-byte vector length overhead because statements are sent as
`Vec<Statement>`.

## Integration

Affected crates:
- `sc-statement-store`: Now depends on `sc-network-statement` for size
constants
- `sc-network-statement`: `MAX_STATEMENT_NOTIFICATION_SIZE` is now
public

For downstream users:
- Statements larger than 1 MB will now be rejected earlier before the
validation pipeline

---------

Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Bastian Köcher <[email protected]>

Author: 3 people

Cargo.lock

@@ -0,0 +1,9 @@
+title: Limit the size of the statement for further gossiping
+doc:
+- audience: Node Dev
+  description: "Limits the size of statements that are further gossiped over the network to prevent skipping oversized messages. The limit is set to match the network protocol's `MAX_STATEMENT_NOTIFICATION_SIZE` (1 MB), accounting for 1-byte vector length overhead because statements are sent as `Vec<Statement>`."
+crates:
+- name: sc-network-statement
+  bump: minor
+- name: sc-statement-store
+  bump: minor

prdoc/pr_9965.prdoc

@@ -27,7 +27,7 @@ pub(crate) const PROPAGATE_TIMEOUT: time::Duration = time::Duration::from_millis
 pub(crate) const MAX_KNOWN_STATEMENTS: usize = 4 * 1024 * 1024; // * 32 bytes for hash = 128 MB per peer
 
 /// Maximum allowed size for a statement notification.
-pub(crate) const MAX_STATEMENT_NOTIFICATION_SIZE: u64 = 1024 * 1024;
+pub const MAX_STATEMENT_NOTIFICATION_SIZE: u64 = 1024 * 1024;
 
 /// Maximum number of statement validation request we keep at any moment.
 pub(crate) const MAX_PENDING_STATEMENTS: usize = 2 * 1024 * 1024;

substrate/client/network/statement/src/config.rs

@@ -22,6 +22,7 @@ parking_lot = { workspace = true, default-features = true }
 prometheus-endpoint = { workspace = true, default-features = true }
 sc-client-api = { workspace = true, default-features = true }
 sc-keystore = { workspace = true, default-features = true }
+sc-network-statement = { workspace = true, default-features = true }
 sp-api = { workspace = true, default-features = true }
 sp-blockchain = { workspace = true, default-features = true }
 sp-core = { workspace = true, default-features = true }

substrate/client/statement-store/Cargo.toml

@@ -83,6 +83,10 @@ pub const DEFAULT_MAX_TOTAL_STATEMENTS: usize = 4 * 1024 * 1024; // ~4 million
 /// The maximum amount of data the statement store can hold, regardless of the number of
 /// statements from which the data originates.
 pub const DEFAULT_MAX_TOTAL_SIZE: usize = 2 * 1024 * 1024 * 1024; // 2GiB
+/// The maximum size of a single statement in bytes.
+/// Accounts for the 1-byte vector length prefix when statements are gossiped as `Vec<Statement>`.
+pub const MAX_STATEMENT_SIZE: usize =
+	sc_network_statement::config::MAX_STATEMENT_NOTIFICATION_SIZE as usize - 1;
 
 const MAINTENANCE_PERIOD: std::time::Duration = std::time::Duration::from_secs(30);
 
@@ -890,6 +894,18 @@ impl StatementStore for Store {
 	/// Submit a statement to the store. Validates the statement and returns validation result.
 	fn submit(&self, statement: Statement, source: StatementSource) -> SubmitResult {
 		let hash = statement.hash();
+		let encoded_size = statement.encoded_size();
+		if encoded_size > MAX_STATEMENT_SIZE {
+			log::debug!(
+				target: LOG_TARGET,
+				"Statement is too big for propogation: {:?} ({}/{} bytes)",
+				HexDisplay::from(&hash),
+				statement.encoded_size(),
+				MAX_STATEMENT_SIZE
+			);
+			return SubmitResult::Ignored
+		}
+
 		match self.index.read().query(&hash) {
 			IndexQuery::Expired =>
 				if !source.can_be_resubmitted() {
@@ -1079,6 +1095,7 @@ mod tests {
 									Some(a) if a == account(2) => (2, 1000),
 									Some(a) if a == account(3) => (3, 1000),
 									Some(a) if a == account(4) => (4, 1000),
+									Some(a) if a == account(42) => (42, 42 * crate::MAX_STATEMENT_SIZE as u32),
 									_ => (2, 2000),
 								};
 								Ok(ValidStatement{ max_count, max_size })
@@ -1385,6 +1402,28 @@ mod tests {
 		assert_eq!(expected_statements, statements);
 	}
 
+	#[test]
+	fn max_statement_size_for_gossiping() {
+		let (store, _temp) = test_store();
+		store.index.write().options.max_total_size = 42 * crate::MAX_STATEMENT_SIZE;
+
+		assert_eq!(
+			store.submit(
+				statement(42, 1, Some(1), crate::MAX_STATEMENT_SIZE - 500),
+				StatementSource::Local
+			),
+			SubmitResult::New(NetworkPriority::High)
+		);
+
+		assert_eq!(
+			store.submit(
+				statement(42, 2, Some(1), 2 * crate::MAX_STATEMENT_SIZE),
+				StatementSource::Local
+			),
+			SubmitResult::Ignored
+		);
+	}
+
 	#[test]
 	fn expired_statements_are_purged() {
 		use super::DEFAULT_PURGE_AFTER_SEC;