From 8ce691dcc163c4ca3fe90a33f87c8821d1a73412 Mon Sep 17 00:00:00 2001
From: Liu-Cheng Xu <xuliuchengxlc@gmail.com>
Date: Sun, 6 Mar 2022 19:59:51 +0800
Subject: [PATCH] Add `verify_execution_proof` to ProofProvider

---
 client/api/src/call_executor.rs            | 14 ++++++++
 client/api/src/proof_provider.rs           | 12 +++++++
 client/service/src/client/call_executor.rs | 41 ++++++++++++++++++++++
 client/service/src/client/client.rs        | 13 +++++++
 4 files changed, 80 insertions(+)

diff --git a/client/api/src/call_executor.rs b/client/api/src/call_executor.rs
index 15088a573600d..c3973fedd7184 100644
--- a/client/api/src/call_executor.rs
+++ b/client/api/src/call_executor.rs
@@ -107,4 +107,18 @@ pub trait CallExecutor<B: BlockT>: RuntimeVersionOf {
 		call_data: &[u8],
 		overlay: Option<sp_api::OverlayedChanges>,
 	) -> Result<(Vec<u8>, StorageProof), sp_blockchain::Error>;
+
+	/// Verify the execution of the given `method`.
+	///
+	/// No changes are made.
+	fn verify_execution<'a>(
+		&'a self,
+		root: sp_core::H256,
+		proof: StorageProof,
+		at: &'a BlockId<B>,
+		method: &'a str,
+		call_data: &'a [u8],
+		overlay: sp_api::OverlayedChanges,
+		runtime_code: Option<sp_core::traits::RuntimeCode<'a>>,
+	) -> Result<Vec<u8>, sp_blockchain::Error>;
 }
diff --git a/client/api/src/proof_provider.rs b/client/api/src/proof_provider.rs
index 4fe145edcd575..4d2e8627266f3 100644
--- a/client/api/src/proof_provider.rs
+++ b/client/api/src/proof_provider.rs
@@ -52,6 +52,18 @@ pub trait ProofProvider<Block: BlockT> {
 		overlay: Option<sp_api::OverlayedChanges>,
 	) -> sp_blockchain::Result<(Vec<u8>, StorageProof)>;
 
+	/// Verify the execution proof produced by [`execution_proof`].
+	fn verify_execution_proof<'a>(
+		&'a self,
+		root: sp_core::H256,
+		proof: StorageProof,
+		id: &'a BlockId<Block>,
+		method: &'a str,
+		call_data: &'a [u8],
+		overlay: sp_api::OverlayedChanges,
+		runtime_code: Option<sp_core::traits::RuntimeCode<'a>>,
+	) -> sp_blockchain::Result<Vec<u8>>;
+
 	/// Given a `BlockId` iterate over all storage values starting at `start_keys`.
 	/// Last `start_keys` element contains last accessed key value.
 	/// With multiple `start_keys`, first `start_keys` element is
diff --git a/client/service/src/client/call_executor.rs b/client/service/src/client/call_executor.rs
index 1dc513176f966..5addc1d23a5a2 100644
--- a/client/service/src/client/call_executor.rs
+++ b/client/service/src/client/call_executor.rs
@@ -318,6 +318,47 @@ where
 		)
 		.map_err(Into::into)
 	}
+
+	fn verify_execution<'a>(
+		&self,
+		root: sp_core::H256,
+		proof: StorageProof,
+		at: &'a BlockId<Block>,
+		method: &'a str,
+		call_data: &'a [u8],
+		overlay: sp_api::OverlayedChanges,
+		maybe_runtime_code: Option<RuntimeCode<'a>>,
+	) -> sp_blockchain::Result<Vec<u8>> {
+		let state = self.backend.state_at(*at)?;
+
+		let trie_backend = state.as_trie_backend().ok_or_else(|| {
+			Box::new(sp_state_machine::ExecutionError::UnableToGenerateProof)
+				as Box<dyn sp_state_machine::Error>
+		})?;
+
+		let state_runtime_code = sp_state_machine::backend::BackendRuntimeCode::new(trie_backend);
+		let runtime_code = state_runtime_code.runtime_code().map_err(sp_blockchain::Error::RuntimeCode)?;
+		let runtime_code = self.check_override(runtime_code, at)?;
+
+		// TODO: unwrap_or_else and then fix the lifetime issue.
+		let runtime_code = match maybe_runtime_code {
+			Some(runtime_code) => runtime_code,
+			None => runtime_code
+		};
+
+		let mut overlay = overlay;
+		sp_state_machine::execution_proof_check::<sp_runtime::traits::BlakeTwo256, _, _>(
+			root,
+			proof,
+			&mut overlay,
+			&self.executor,
+			self.spawn_handle.clone(),
+			method,
+			call_data,
+			&runtime_code,
+		)
+		.map_err(Into::into)
+	}
 }
 
 impl<B, E, Block> RuntimeVersionOf for LocalCallExecutor<Block, B, E>
diff --git a/client/service/src/client/client.rs b/client/service/src/client/client.rs
index e312d14f34d44..bb68cf46395d8 100644
--- a/client/service/src/client/client.rs
+++ b/client/service/src/client/client.rs
@@ -1172,6 +1172,19 @@ where
 		self.executor.prove_execution(id, method, call_data, overlay)
 	}
 
+	fn verify_execution_proof<'a>(
+		&self,
+		root: sp_core::H256,
+		proof: StorageProof,
+		id: &'a BlockId<Block>,
+		method: &'a str,
+		call_data: &'a [u8],
+		overlay: sp_api::OverlayedChanges,
+		runtime_code: Option<sp_core::traits::RuntimeCode<'a>>
+	) -> sp_blockchain::Result<Vec<u8>> {
+		self.executor.verify_execution(root, proof, id, method, call_data, overlay, runtime_code)
+	}
+
 	fn read_proof_collection(
 		&self,
 		id: &BlockId<Block>,