Introduce code_substitute (paritytech#8898)

This introduces a new field `code_substitute` into the chain spec. This
can be used to substitute the on-chain wasm starting from a given block
until there is another wasm on chain (determined through the
`spec_version`). This can be used to fix broken on chain wasm runtimes.

bin/node/testing/src/client.rs

@@ -32,7 +32,7 @@ pub type Backend = sc_client_db::Backend<node_primitives::Block>;
 /// Test client type.
 pub type Client = client::Client<
 	Backend,
-	client::LocalCallExecutor<Backend, Executor>,
+	client::LocalCallExecutor<node_primitives::Block, Backend, Executor>,
 	node_primitives::Block,
 	node_runtime::RuntimeApi,
 >;
@@ -63,7 +63,7 @@ pub trait TestClientBuilderExt: Sized {
 
 impl TestClientBuilderExt for substrate_test_client::TestClientBuilder<
 	node_primitives::Block,
-	client::LocalCallExecutor<Backend, Executor>,
+	client::LocalCallExecutor<node_primitives::Block, Backend, Executor>,
 	Backend,
 	GenesisParameters,
 > {

client/chain-spec/src/chain_spec.rs

@@ -21,7 +21,7 @@
 
 use std::{borrow::Cow, fs::File, path::PathBuf, sync::Arc, collections::HashMap};
 use serde::{Serialize, Deserialize};
-use sp_core::storage::{StorageKey, StorageData, ChildInfo, Storage, StorageChild};
+use sp_core::{storage::{StorageKey, StorageData, ChildInfo, Storage, StorageChild}, Bytes};
 use sp_runtime::BuildStorage;
 use serde_json as json;
 use crate::{RuntimeGenesis, ChainType, extension::GetExtension, Properties};
@@ -160,6 +160,12 @@ struct ClientSpec<E> {
 	#[serde(skip_serializing)]
 	genesis: serde::de::IgnoredAny,
 	light_sync_state: Option<SerializableLightSyncState>,
+	/// Mapping from `block_hash` to `wasm_code`.
+	///
+	/// The given `wasm_code` will be used to substitute the on-chain wasm code from the given
+	/// block hash onwards.
+	#[serde(default)]
+	code_substitutes: HashMap<String, Bytes>,
 }
 
 /// A type denoting empty extensions.
@@ -249,6 +255,7 @@ impl<G, E> ChainSpec<G, E> {
 			consensus_engine: (),
 			genesis: Default::default(),
 			light_sync_state: None,
+			code_substitutes: HashMap::new(),
 		};
 
 		ChainSpec {
@@ -395,6 +402,10 @@ where
 	fn set_light_sync_state(&mut self, light_sync_state: SerializableLightSyncState) {
 		ChainSpec::set_light_sync_state(self, light_sync_state)
 	}
+
+	fn code_substitutes(&self) -> std::collections::HashMap<String, Vec<u8>> {
+		self.client_spec.code_substitutes.iter().map(|(h, c)| (h.clone(), c.0.clone())).collect()
+	}
 }
 
 /// Hardcoded infomation that allows light clients to sync quickly.

client/chain-spec/src/lib.rs

@@ -161,6 +161,8 @@ pub trait ChainSpec: BuildStorage + Send + Sync {
 	fn set_storage(&mut self, storage: Storage);
 	/// Hardcode infomation to allow light clients to sync quickly into the chain spec.
 	fn set_light_sync_state(&mut self, light_sync_state: SerializableLightSyncState);
+	/// Returns code substitutes that should be used for the on chain wasm.
+	fn code_substitutes(&self) -> std::collections::HashMap<String, Vec<u8>>;
 }
 
 impl std::fmt::Debug for dyn ChainSpec {

client/service/src/builder.rs

@@ -50,7 +50,7 @@ use sp_runtime::traits::{
 };
 use sp_api::{ProvideRuntimeApi, CallApiAt};
 use sc_executor::{NativeExecutor, NativeExecutionDispatch, RuntimeInfo};
-use std::sync::Arc;
+use std::{sync::Arc, str::FromStr};
 use wasm_timer::SystemTime;
 use sc_telemetry::{
 	telemetry,
@@ -150,6 +150,7 @@ pub type TFullBackend<TBl> = sc_client_db::Backend<TBl>;
 
 /// Full client call executor type.
 pub type TFullCallExecutor<TBl, TExecDisp> = crate::client::LocalCallExecutor<
+	TBl,
 	sc_client_db::Backend<TBl>,
 	NativeExecutor<TExecDisp>,
 >;
@@ -172,6 +173,7 @@ pub type TLightCallExecutor<TBl, TExecDisp> = sc_light::GenesisCallExecutor<
 		HashFor<TBl>
 	>,
 	crate::client::LocalCallExecutor<
+		TBl,
 		sc_light::Backend<
 			sc_client_db::light::LightStorage<TBl>,
 			HashFor<TBl>
@@ -206,7 +208,7 @@ pub type TLightClientWithBackend<TBl, TRtApi, TExecDisp, TBackend> = Client<
 	TBackend,
 	sc_light::GenesisCallExecutor<
 		TBackend,
-		crate::client::LocalCallExecutor<TBackend, NativeExecutor<TExecDisp>>,
+		crate::client::LocalCallExecutor<TBl, TBackend, NativeExecutor<TExecDisp>>,
 	>,
 	TBl,
 	TRtApi,
@@ -295,6 +297,7 @@ pub fn new_full_client<TBl, TRtApi, TExecDisp>(
 ) -> Result<TFullClient<TBl, TRtApi, TExecDisp>, Error> where
 	TBl: BlockT,
 	TExecDisp: NativeExecutionDispatch + 'static,
+	TBl::Hash: FromStr,
 {
 	new_full_parts(config, telemetry).map(|parts| parts.0)
 }
@@ -303,9 +306,10 @@ pub fn new_full_client<TBl, TRtApi, TExecDisp>(
 pub fn new_full_parts<TBl, TRtApi, TExecDisp>(
 	config: &Configuration,
 	telemetry: Option<TelemetryHandle>,
-) -> Result<TFullParts<TBl, TRtApi, TExecDisp>,	Error> where
+) -> Result<TFullParts<TBl, TRtApi, TExecDisp>, Error> where
 	TBl: BlockT,
 	TExecDisp: NativeExecutionDispatch + 'static,
+	TBl::Hash: FromStr,
 {
 	let keystore_container = KeystoreContainer::new(&config.keystore)?;
 
@@ -349,6 +353,16 @@ pub fn new_full_parts<TBl, TRtApi, TExecDisp>(
 			sc_offchain::OffchainDb::factory_from_backend(&*backend),
 		);
 
+		let wasm_runtime_substitutes = config.chain_spec.code_substitutes().into_iter().map(|(h, c)| {
+			let hash = TBl::Hash::from_str(&h)
+				.map_err(|_|
+					 Error::Application(Box::from(
+						format!("Failed to parse `{}` as block hash for code substitutes.", h)
+					))
+				)?;
+			Ok((hash, c))
+		}).collect::<Result<std::collections::HashMap<_, _>, Error>>()?;
+
 		let client = new_client(
 			backend.clone(),
 			executor,
@@ -363,6 +377,7 @@ pub fn new_full_parts<TBl, TRtApi, TExecDisp>(
 				offchain_worker_enabled : config.offchain_worker.enabled,
 				offchain_indexing_api: config.offchain_worker.indexing_enabled,
 				wasm_runtime_overrides: config.wasm_runtime_overrides.clone(),
+				wasm_runtime_substitutes,
 			},
 		)?;
 
@@ -453,11 +468,11 @@ pub fn new_client<E, Block, RA>(
 	spawn_handle: Box<dyn SpawnNamed>,
 	prometheus_registry: Option<Registry>,
 	telemetry: Option<TelemetryHandle>,
-	config: ClientConfig,
+	config: ClientConfig<Block>,
 ) -> Result<
 	crate::client::Client<
 		Backend<Block>,
-		crate::client::LocalCallExecutor<Backend<Block>, E>,
+		crate::client::LocalCallExecutor<Block, Backend<Block>, E>,
 		Block,
 		RA,
 	>,

client/service/src/client/call_executor.rs

@@ -32,47 +32,56 @@ use sp_core::{
 };
 use sp_api::{ProofRecorder, InitializeBlock, StorageTransactionCache};
 use sc_client_api::{backend, call_executor::CallExecutor};
-use super::{client::ClientConfig, wasm_override::WasmOverride};
+use super::{client::ClientConfig, wasm_override::WasmOverride, wasm_substitutes::WasmSubstitutes};
 
 /// Call executor that executes methods locally, querying all required
 /// data from local backend.
-pub struct LocalCallExecutor<B, E> {
+pub struct LocalCallExecutor<Block: BlockT, B, E> {
 	backend: Arc<B>,
 	executor: E,
 	wasm_override: Option<WasmOverride<E>>,
+	wasm_substitutes: WasmSubstitutes<Block, E, B>,
 	spawn_handle: Box<dyn SpawnNamed>,
-	client_config: ClientConfig,
+	client_config: ClientConfig<Block>,
 }
 
-impl<B, E> LocalCallExecutor<B, E>
+impl<Block: BlockT, B, E> LocalCallExecutor<Block, B, E>
 where
-	E: CodeExecutor + RuntimeInfo + Clone + 'static
+	E: CodeExecutor + RuntimeInfo + Clone + 'static,
+	B: backend::Backend<Block>,
 {
 	/// Creates new instance of local call executor.
 	pub fn new(
 		backend: Arc<B>,
 		executor: E,
 		spawn_handle: Box<dyn SpawnNamed>,
-		client_config: ClientConfig,
+		client_config: ClientConfig<Block>,
 	) -> sp_blockchain::Result<Self> {
 		let wasm_override = client_config.wasm_runtime_overrides
 			.as_ref()
 			.map(|p| WasmOverride::new(p.clone(), executor.clone()))
 			.transpose()?;
 
+		let wasm_substitutes = WasmSubstitutes::new(
+			client_config.wasm_runtime_substitutes.clone(),
+			executor.clone(),
+			backend.clone(),
+		)?;
+
 		Ok(LocalCallExecutor {
 			backend,
 			executor,
 			wasm_override,
 			spawn_handle,
 			client_config,
+			wasm_substitutes,
 		})
 	}
 
 	/// Check if local runtime code overrides are enabled and one is available
 	/// for the given `BlockId`. If yes, return it; otherwise return the same
 	/// `RuntimeCode` instance that was passed.
-	fn check_override<'a, Block>(
+	fn check_override<'a>(
 		&'a self,
 		onchain_code: RuntimeCode<'a>,
 		id: &BlockId<Block>,
@@ -81,16 +90,16 @@ where
 		Block: BlockT,
 		B: backend::Backend<Block>,
 	{
+		let spec = self.runtime_version(id)?.spec_version;
 		let code = if let Some(d) = self.wasm_override
 			.as_ref()
-			.map::<sp_blockchain::Result<Option<RuntimeCode>>, _>(|o| {
-				let spec = self.runtime_version(id)?.spec_version;
-				Ok(o.get(&spec, onchain_code.heap_pages))
-			})
-			.transpose()?
+			.map(|o| o.get(&spec, onchain_code.heap_pages))
 			.flatten() {
 			log::debug!(target: "wasm_overrides", "using WASM override for block {}", id);
 			d
+		} else if let Some(s) = self.wasm_substitutes.get(spec, onchain_code.heap_pages, id) {
+			log::debug!(target: "wasm_substitutes", "Using WASM substitute for block {:?}", id);
+			s
 		} else {
 			log::debug!(
 				target: "wasm_overrides",
@@ -104,19 +113,20 @@ where
 	}
 }
 
-impl<B, E> Clone for LocalCallExecutor<B, E> where E: Clone {
+impl<Block: BlockT, B, E> Clone for LocalCallExecutor<Block, B, E> where E: Clone {
 	fn clone(&self) -> Self {
 		LocalCallExecutor {
 			backend: self.backend.clone(),
 			executor: self.executor.clone(),
 			wasm_override: self.wasm_override.clone(),
 			spawn_handle: self.spawn_handle.clone(),
 			client_config: self.client_config.clone(),
+			wasm_substitutes: self.wasm_substitutes.clone(),
 		}
 	}
 }
 
-impl<B, E, Block> CallExecutor<Block> for LocalCallExecutor<B, E>
+impl<B, E, Block> CallExecutor<Block> for LocalCallExecutor<Block, B, E>
 where
 	B: backend::Backend<Block>,
 	E: CodeExecutor + RuntimeInfo + Clone + 'static,
@@ -314,7 +324,7 @@ where
 	}
 }
 
-impl<B, E, Block> sp_version::GetRuntimeVersion<Block> for LocalCallExecutor<B, E>
+impl<Block, B, E> sp_version::GetRuntimeVersion<Block> for LocalCallExecutor<Block, B, E>
 	where
 		B: backend::Backend<Block>,
 		E: CodeExecutor + RuntimeInfo + Clone + 'static,
@@ -357,11 +367,7 @@ mod tests {
 
 		// wasm_runtime_overrides is `None` here because we construct the
 		// LocalCallExecutor directly later on
-		let client_config = ClientConfig {
-			offchain_worker_enabled: false,
-			offchain_indexing_api: false,
-			wasm_runtime_overrides: None,
-		};
+		let client_config = ClientConfig::default();
 
 		// client is used for the convenience of creating and inserting the genesis block.
 		let _client = substrate_test_runtime_client::client::new_with_backend::<
@@ -383,10 +389,15 @@ mod tests {
 
 		let call_executor = LocalCallExecutor {
 			backend: backend.clone(),
-			executor,
+			executor: executor.clone(),
 			wasm_override: Some(overrides),
 			spawn_handle: Box::new(TaskExecutor::new()),
 			client_config,
+			wasm_substitutes: WasmSubstitutes::new(
+				Default::default(),
+				executor.clone(),
+				backend.clone(),
+			).unwrap(),
 		};
 
 		let check = call_executor.check_override(onchain_code, &BlockId::Number(Default::default()))

client/service/src/client/client.rs

@@ -118,7 +118,7 @@ pub struct Client<B, E, Block, RA> where Block: BlockT {
 	importing_block: RwLock<Option<Block::Hash>>,
 	block_rules: BlockRules<Block>,
 	execution_extensions: ExecutionExtensions<Block>,
-	config: ClientConfig,
+	config: ClientConfig<Block>,
 	telemetry: Option<TelemetryHandle>,
 	_phantom: PhantomData<RA>,
 }
@@ -159,10 +159,10 @@ pub fn new_in_mem<E, Block, S, RA>(
 	prometheus_registry: Option<Registry>,
 	telemetry: Option<TelemetryHandle>,
 	spawn_handle: Box<dyn SpawnNamed>,
-	config: ClientConfig,
+	config: ClientConfig<Block>,
 ) -> sp_blockchain::Result<Client<
 	in_mem::Backend<Block>,
-	LocalCallExecutor<in_mem::Backend<Block>, E>,
+	LocalCallExecutor<Block, in_mem::Backend<Block>, E>,
 	Block,
 	RA
 >> where
@@ -183,14 +183,28 @@ pub fn new_in_mem<E, Block, S, RA>(
 }
 
 /// Relevant client configuration items relevant for the client.
-#[derive(Debug,Clone,Default)]
-pub struct ClientConfig {
+#[derive(Debug, Clone)]
+pub struct ClientConfig<Block: BlockT> {
 	/// Enable the offchain worker db.
 	pub offchain_worker_enabled: bool,
 	/// If true, allows access from the runtime to write into offchain worker db.
 	pub offchain_indexing_api: bool,
 	/// Path where WASM files exist to override the on-chain WASM.
 	pub wasm_runtime_overrides: Option<PathBuf>,
+	/// Map of WASM runtime substitute starting at the child of the given block until the runtime
+	/// version doesn't match anymore.
+	pub wasm_runtime_substitutes: HashMap<Block::Hash, Vec<u8>>,
+}
+
+impl<Block: BlockT> Default for ClientConfig<Block> {
+	fn default() -> Self {
+		Self {
+			offchain_worker_enabled: false,
+			offchain_indexing_api: false,
+			wasm_runtime_overrides: None,
+			wasm_runtime_substitutes: HashMap::new(),
+		}
+	}
 }
 
 /// Create a client with the explicitly provided backend.
@@ -204,8 +218,8 @@ pub fn new_with_backend<B, E, Block, S, RA>(
 	spawn_handle: Box<dyn SpawnNamed>,
 	prometheus_registry: Option<Registry>,
 	telemetry: Option<TelemetryHandle>,
-	config: ClientConfig,
-) -> sp_blockchain::Result<Client<B, LocalCallExecutor<B, E>, Block, RA>>
+	config: ClientConfig<Block>,
+) -> sp_blockchain::Result<Client<B, LocalCallExecutor<Block, B, E>, Block, RA>>
 	where
 		E: CodeExecutor + RuntimeInfo,
 		S: BuildStorage,
@@ -308,7 +322,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		execution_extensions: ExecutionExtensions<Block>,
 		prometheus_registry: Option<Registry>,
 		telemetry: Option<TelemetryHandle>,
-		config: ClientConfig,
+		config: ClientConfig<Block>,
 	) -> sp_blockchain::Result<Self> {
 		if backend.blockchain().header(BlockId::Number(Zero::zero()))?.is_none() {
 			let genesis_storage = build_genesis_storage.build_storage()

client/service/src/client/light.rs

@@ -45,7 +45,7 @@ pub fn new_light<B, S, RA, E>(
 			Backend<S, HashFor<B>>,
 			GenesisCallExecutor<
 				Backend<S, HashFor<B>>,
-				LocalCallExecutor<Backend<S, HashFor<B>>, E>
+				LocalCallExecutor<B, Backend<S, HashFor<B>>, E>
 			>,
 			B,
 			RA

client/service/src/client/mod.rs

@@ -51,6 +51,7 @@ mod call_executor;
 mod client;
 mod block_rules;
 mod wasm_override;
+mod wasm_substitutes;
 
 pub use self::{
 	call_executor::LocalCallExecutor,