Check that the validation code matches the parachain code (#3433)

This introduces a check to ensure that the parachain code matches the
validation code stored in the relay chain state. If not, it will print a
warning. This should be mainly useful for parachain builders to make
sure they have setup everything correctly.

cumulus/client/relay-chain-rpc-interface/src/lib.rs

@@ -19,7 +19,7 @@ use core::time::Duration;
 use cumulus_primitives_core::{
 	relay_chain::{
 		CommittedCandidateReceipt, Hash as RelayHash, Header as RelayHeader, InboundHrmpMessage,
-		OccupiedCoreAssumption, SessionIndex, ValidatorId,
+		OccupiedCoreAssumption, SessionIndex, ValidationCodeHash, ValidatorId,
 	},
 	InboundDownwardMessage, ParaId, PersistedValidationData,
 };
@@ -110,6 +110,17 @@ impl RelayChainInterface for RelayChainRpcInterface {
 			.await
 	}
 
+	async fn validation_code_hash(
+		&self,
+		hash: RelayHash,
+		para_id: ParaId,
+		occupied_core_assumption: OccupiedCoreAssumption,
+	) -> RelayChainResult<Option<ValidationCodeHash>> {
+		self.rpc_client
+			.validation_code_hash(hash, para_id, occupied_core_assumption)
+			.await
+	}
+
 	async fn candidate_pending_availability(
 		&self,
 		hash: RelayHash,

cumulus/client/relay-chain-rpc-interface/src/rpc_client.rs

@@ -647,6 +647,20 @@ impl RelayChainRpcClient {
 			.await
 	}
 
+	pub async fn validation_code_hash(
+		&self,
+		at: RelayHash,
+		para_id: ParaId,
+		occupied_core_assumption: OccupiedCoreAssumption,
+	) -> Result<Option<ValidationCodeHash>, RelayChainError> {
+		self.call_remote_runtime_function(
+			"ParachainHost_validation_code_hash",
+			at,
+			Some((para_id, occupied_core_assumption)),
+		)
+		.await
+	}
+
 	fn send_register_message_to_worker(
 		&self,
 		message: RpcDispatcherMessage,