MMR: move RPC code from frame/ to client/ (#12805)

* mmr: move MMR RPC from frame/ to client/

Signed-off-by: Adrian Catangiu <adrian@parity.io>

* client/mmr: adjust logging levels to avoid spam

* cargo fmt

* remove unused imports

Signed-off-by: Adrian Catangiu <adrian@parity.io>

substrate/client/merkle-mountain-range/rpc/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "mmr-rpc"
+version = "4.0.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "Apache-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Node-specific RPC methods for interaction with Merkle Mountain Range pallet."
+publish = false
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.0.0" }
+jsonrpsee = { version = "0.15.1", features = ["server", "macros"] }
+serde = { version = "1.0.136", features = ["derive"] }
+sp-api = { version = "4.0.0-dev", path = "../../../primitives/api" }
+sp-blockchain = { version = "4.0.0-dev", path = "../../../primitives/blockchain" }
+sp-core = { version = "7.0.0", path = "../../../primitives/core" }
+sp-mmr-primitives = { version = "4.0.0-dev", path = "../../../primitives/merkle-mountain-range" }
+sp-runtime = { version = "7.0.0", path = "../../../primitives/runtime" }
+anyhow = "1"
+
+[dev-dependencies]
+serde_json = "1.0.85"

substrate/client/merkle-mountain-range/rpc/src/lib.rs

@@ -0,0 +1,361 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2021-2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#![warn(missing_docs)]
+#![warn(unused_crate_dependencies)]
+
+//! Node-specific RPC methods for interaction with Merkle Mountain Range pallet.
+
+use std::{marker::PhantomData, sync::Arc};
+
+use codec::{Codec, Decode, Encode};
+use jsonrpsee::{
+	core::{async_trait, RpcResult},
+	proc_macros::rpc,
+	types::error::{CallError, ErrorObject},
+};
+use serde::{Deserialize, Serialize};
+
+use sp_api::{NumberFor, ProvideRuntimeApi};
+use sp_blockchain::HeaderBackend;
+use sp_core::Bytes;
+use sp_mmr_primitives::{Error as MmrError, Proof};
+use sp_runtime::{generic::BlockId, traits::Block as BlockT};
+
+pub use sp_mmr_primitives::MmrApi as MmrRuntimeApi;
+
+const RUNTIME_ERROR: i32 = 8000;
+const MMR_ERROR: i32 = 8010;
+
+/// Retrieved MMR leaves and their proof.
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct LeavesProof<BlockHash> {
+	/// Block hash the proof was generated for.
+	pub block_hash: BlockHash,
+	/// SCALE-encoded vector of `LeafData`.
+	pub leaves: Bytes,
+	/// SCALE-encoded proof data. See [sp_mmr_primitives::Proof].
+	pub proof: Bytes,
+}
+
+impl<BlockHash> LeavesProof<BlockHash> {
+	/// Create new `LeavesProof` from a given vector of `Leaf` and a
+	/// [sp_mmr_primitives::Proof].
+	pub fn new<Leaf, MmrHash>(
+		block_hash: BlockHash,
+		leaves: Vec<Leaf>,
+		proof: Proof<MmrHash>,
+	) -> Self
+	where
+		Leaf: Encode,
+		MmrHash: Encode,
+	{
+		Self { block_hash, leaves: Bytes(leaves.encode()), proof: Bytes(proof.encode()) }
+	}
+}
+
+/// MMR RPC methods.
+#[rpc(client, server)]
+pub trait MmrApi<BlockHash, BlockNumber, MmrHash> {
+	/// Get the MMR root hash for the current best block.
+	#[method(name = "mmr_root")]
+	fn mmr_root(&self, at: Option<BlockHash>) -> RpcResult<MmrHash>;
+
+	/// Generate an MMR proof for the given `block_numbers`.
+	///
+	/// This method calls into a runtime with MMR pallet included and attempts to generate
+	/// an MMR proof for the set of blocks that have the given `block_numbers` with the MMR root at
+	/// `best_known_block_number`. `best_known_block_number` must be larger than all the
+	/// `block_numbers` for the function to succeed.
+	///
+	/// Optionally via `at`, a block hash at which the runtime should be queried can be specified.
+	/// Optionally via `best_known_block_number`, the proof can be generated using the MMR's state
+	/// at a specific best block. Note that if `best_known_block_number` is provided, then also
+	/// specifying the block hash via `at` isn't super-useful here, unless you're generating proof
+	/// using non-finalized blocks where there are several competing forks. That's because MMR state
+	/// will be fixed to the state with `best_known_block_number`, which already points to
+	/// some historical block.
+	///
+	/// Returns the (full) leaves and a proof for these leaves (compact encoding, i.e. hash of
+	/// the leaves). Both parameters are SCALE-encoded.
+	/// The order of entries in the `leaves` field of the returned struct
+	/// is the same as the order of the entries in `block_numbers` supplied
+	#[method(name = "mmr_generateProof")]
+	fn generate_proof(
+		&self,
+		block_numbers: Vec<BlockNumber>,
+		best_known_block_number: Option<BlockNumber>,
+		at: Option<BlockHash>,
+	) -> RpcResult<LeavesProof<BlockHash>>;
+
+	/// Verify an MMR `proof`.
+	///
+	/// This method calls into a runtime with MMR pallet included and attempts to verify
+	/// an MMR proof.
+	///
+	/// Returns `true` if the proof is valid, else returns the verification error.
+	#[method(name = "mmr_verifyProof")]
+	fn verify_proof(&self, proof: LeavesProof<BlockHash>) -> RpcResult<bool>;
+
+	/// Verify an MMR `proof` statelessly given an `mmr_root`.
+	///
+	/// This method calls into a runtime with MMR pallet included and attempts to verify
+	/// an MMR proof against a provided MMR root.
+	///
+	/// Returns `true` if the proof is valid, else returns the verification error.
+	#[method(name = "mmr_verifyProofStateless")]
+	fn verify_proof_stateless(
+		&self,
+		mmr_root: MmrHash,
+		proof: LeavesProof<BlockHash>,
+	) -> RpcResult<bool>;
+}
+
+/// MMR RPC methods.
+pub struct Mmr<Client, Block> {
+	client: Arc<Client>,
+	_marker: PhantomData<Block>,
+}
+
+impl<C, B> Mmr<C, B> {
+	/// Create new `Mmr` with the given reference to the client.
+	pub fn new(client: Arc<C>) -> Self {
+		Self { client, _marker: Default::default() }
+	}
+}
+
+#[async_trait]
+impl<Client, Block, MmrHash> MmrApiServer<<Block as BlockT>::Hash, NumberFor<Block>, MmrHash>
+	for Mmr<Client, (Block, MmrHash)>
+where
+	Block: BlockT,
+	Client: Send + Sync + 'static + ProvideRuntimeApi<Block> + HeaderBackend<Block>,
+	Client::Api: MmrRuntimeApi<Block, MmrHash, NumberFor<Block>>,
+	MmrHash: Codec + Send + Sync + 'static,
+{
+	fn mmr_root(&self, at: Option<<Block as BlockT>::Hash>) -> RpcResult<MmrHash> {
+		let block_hash = at.unwrap_or_else(||
+			// If the block hash is not supplied assume the best block.
+			self.client.info().best_hash);
+		let api = self.client.runtime_api();
+		let mmr_root = api
+			.mmr_root(&BlockId::Hash(block_hash))
+			.map_err(runtime_error_into_rpc_error)?
+			.map_err(mmr_error_into_rpc_error)?;
+		Ok(mmr_root)
+	}
+
+	fn generate_proof(
+		&self,
+		block_numbers: Vec<NumberFor<Block>>,
+		best_known_block_number: Option<NumberFor<Block>>,
+		at: Option<<Block as BlockT>::Hash>,
+	) -> RpcResult<LeavesProof<<Block as BlockT>::Hash>> {
+		let api = self.client.runtime_api();
+		let block_hash = at.unwrap_or_else(||
+			// If the block hash is not supplied assume the best block.
+			self.client.info().best_hash);
+
+		let (leaves, proof) = api
+			.generate_proof_with_context(
+				&BlockId::hash(block_hash),
+				sp_core::ExecutionContext::OffchainCall(None),
+				block_numbers,
+				best_known_block_number,
+			)
+			.map_err(runtime_error_into_rpc_error)?
+			.map_err(mmr_error_into_rpc_error)?;
+
+		Ok(LeavesProof::new(block_hash, leaves, proof))
+	}
+
+	fn verify_proof(&self, proof: LeavesProof<<Block as BlockT>::Hash>) -> RpcResult<bool> {
+		let api = self.client.runtime_api();
+
+		let leaves = Decode::decode(&mut &proof.leaves.0[..])
+			.map_err(|e| CallError::InvalidParams(anyhow::Error::new(e)))?;
+
+		let decoded_proof = Decode::decode(&mut &proof.proof.0[..])
+			.map_err(|e| CallError::InvalidParams(anyhow::Error::new(e)))?;
+
+		api.verify_proof_with_context(
+			&BlockId::hash(proof.block_hash),
+			sp_core::ExecutionContext::OffchainCall(None),
+			leaves,
+			decoded_proof,
+		)
+		.map_err(runtime_error_into_rpc_error)?
+		.map_err(mmr_error_into_rpc_error)?;
+
+		Ok(true)
+	}
+
+	fn verify_proof_stateless(
+		&self,
+		mmr_root: MmrHash,
+		proof: LeavesProof<<Block as BlockT>::Hash>,
+	) -> RpcResult<bool> {
+		let api = self.client.runtime_api();
+
+		let leaves = Decode::decode(&mut &proof.leaves.0[..])
+			.map_err(|e| CallError::InvalidParams(anyhow::Error::new(e)))?;
+
+		let decoded_proof = Decode::decode(&mut &proof.proof.0[..])
+			.map_err(|e| CallError::InvalidParams(anyhow::Error::new(e)))?;
+
+		api.verify_proof_stateless(
+			&BlockId::hash(proof.block_hash),
+			mmr_root,
+			leaves,
+			decoded_proof,
+		)
+		.map_err(runtime_error_into_rpc_error)?
+		.map_err(mmr_error_into_rpc_error)?;
+
+		Ok(true)
+	}
+}
+
+/// Converts an mmr-specific error into a [`CallError`].
+fn mmr_error_into_rpc_error(err: MmrError) -> CallError {
+	let error_code = MMR_ERROR +
+		match err {
+			MmrError::LeafNotFound => 1,
+			MmrError::GenerateProof => 2,
+			MmrError::Verify => 3,
+			MmrError::InvalidNumericOp => 4,
+			MmrError::InvalidBestKnownBlock => 5,
+			_ => 0,
+		};
+
+	CallError::Custom(ErrorObject::owned(error_code, err.to_string(), Some(format!("{:?}", err))))
+}
+
+/// Converts a runtime trap into a [`CallError`].
+fn runtime_error_into_rpc_error(err: impl std::fmt::Debug) -> CallError {
+	CallError::Custom(ErrorObject::owned(
+		RUNTIME_ERROR,
+		"Runtime trapped",
+		Some(format!("{:?}", err)),
+	))
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use sp_core::H256;
+
+	#[test]
+	fn should_serialize_leaf_proof() {
+		// given
+		let leaf = vec![1_u8, 2, 3, 4];
+		let proof = Proof {
+			leaf_indices: vec![1],
+			leaf_count: 9,
+			items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
+		};
+
+		let leaf_proof = LeavesProof::new(H256::repeat_byte(0), vec![leaf], proof);
+
+		// when
+		let actual = serde_json::to_string(&leaf_proof).unwrap();
+
+		// then
+		assert_eq!(
+			actual,
+			r#"{"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000","leaves":"0x041001020304","proof":"0x04010000000000000009000000000000000801010101010101010101010101010101010101010101010101010101010101010202020202020202020202020202020202020202020202020202020202020202"}"#
+		);
+	}
+
+	#[test]
+	fn should_serialize_leaves_proof() {
+		// given
+		let leaf_a = vec![1_u8, 2, 3, 4];
+		let leaf_b = vec![2_u8, 2, 3, 4];
+		let proof = Proof {
+			leaf_indices: vec![1, 2],
+			leaf_count: 9,
+			items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
+		};
+
+		let leaf_proof = LeavesProof::new(H256::repeat_byte(0), vec![leaf_a, leaf_b], proof);
+
+		// when
+		let actual = serde_json::to_string(&leaf_proof).unwrap();
+
+		// then
+		assert_eq!(
+			actual,
+			r#"{"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000","leaves":"0x0810010203041002020304","proof":"0x080100000000000000020000000000000009000000000000000801010101010101010101010101010101010101010101010101010101010101010202020202020202020202020202020202020202020202020202020202020202"}"#
+		);
+	}
+
+	#[test]
+	fn should_deserialize_leaf_proof() {
+		// given
+		let expected = LeavesProof {
+			block_hash: H256::repeat_byte(0),
+			leaves: Bytes(vec![vec![1_u8, 2, 3, 4]].encode()),
+			proof: Bytes(
+				Proof {
+					leaf_indices: vec![1],
+					leaf_count: 9,
+					items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
+				}
+				.encode(),
+			),
+		};
+
+		// when
+		let actual: LeavesProof<H256> = serde_json::from_str(r#"{
+			"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000",
+			"leaves":"0x041001020304",
+			"proof":"0x04010000000000000009000000000000000801010101010101010101010101010101010101010101010101010101010101010202020202020202020202020202020202020202020202020202020202020202"
+		}"#).unwrap();
+
+		// then
+		assert_eq!(actual, expected);
+	}
+
+	#[test]
+	fn should_deserialize_leaves_proof() {
+		// given
+		let expected = LeavesProof {
+			block_hash: H256::repeat_byte(0),
+			leaves: Bytes(vec![vec![1_u8, 2, 3, 4], vec![2_u8, 2, 3, 4]].encode()),
+			proof: Bytes(
+				Proof {
+					leaf_indices: vec![1, 2],
+					leaf_count: 9,
+					items: vec![H256::repeat_byte(1), H256::repeat_byte(2)],
+				}
+				.encode(),
+			),
+		};
+
+		// when
+		let actual: LeavesProof<H256> = serde_json::from_str(r#"{
+			"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000",
+			"leaves":"0x0810010203041002020304",
+			"proof":"0x080100000000000000020000000000000009000000000000000801010101010101010101010101010101010101010101010101010101010101010202020202020202020202020202020202020202020202020202020202020202"
+		}"#).unwrap();
+
+		// then
+		assert_eq!(actual, expected);
+	}
+}

substrate/client/merkle-mountain-range/src/lib.rs

@@ -44,7 +44,7 @@ pub mod test_utils;
 use std::{marker::PhantomData, sync::Arc};
 
 use futures::StreamExt;
-use log::{debug, error, trace, warn};
+use log::{error, trace, warn};
 
 use sc_client_api::{Backend, BlockchainEvents, FinalityNotifications};
 use sc_offchain::OffchainDb;
@@ -110,13 +110,16 @@ where
 					}
 				},
 				_ => {
-					trace!(target: LOG_TARGET, "Finality notification: {:?}", notification);
-					debug!(target: LOG_TARGET, "Waiting for MMR pallet to become available ...");
+					trace!(
+						target: LOG_TARGET,
+						"Waiting for MMR pallet to become available... (best finalized {:?})",
+						notification.header.number()
+					);
 				},
 			}
 		}
 
-		warn!(
+		error!(
 			target: LOG_TARGET,
 			"Finality notifications stream closed unexpectedly. \
 			Couldn't build the canonicalization engine",

substrate/client/merkle-mountain-range/src/offchain_mmr.rs

@@ -66,7 +66,7 @@ where
 		match self.client.header_metadata(hash) {
 			Ok(header) => Some(header),
 			_ => {
-				error!(
+				debug!(
 					target: LOG_TARGET,
 					"Block {} not found. Couldn't {} associated branch.", hash, action
 				);
@@ -168,7 +168,7 @@ where
 					canon_key
 				);
 			} else {
-				error!(
+				debug!(
 					target: LOG_TARGET,
 					"Couldn't canonicalize elem at pos {} using temp key {:?}", pos, temp_key
 				);