rpc: Implement `chainSpec` RPC API (#12261)

* rpc/chain_spec: Add traits for `chainSpec` API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_spec: Implement `chainSpec` RPC methods

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_spec: Add tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* bin/node: Enable `chainSpec` API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_spec: Assume `genesis_hash` as non-empty

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update client/rpc-spec/Cargo.toml

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Update client/rpc-spec/src/lib.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* client/rpc_spec: Rename crate to `rpc_spec_v2`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc-servers: Remove the `version` field from `rpc_methods`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* rpc/chain_spec: Fix copyright years

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

substrate/Cargo.lock

@@ -4836,6 +4836,7 @@ dependencies = [
  "sc-finality-grandpa-rpc",
  "sc-rpc",
  "sc-rpc-api",
+ "sc-rpc-spec-v2",
  "sc-sync-state-rpc",
  "sc-transaction-pool-api",
  "sp-api",
@@ -8774,6 +8775,17 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "sc-rpc-spec-v2"
+version = "0.10.0-dev"
+dependencies = [
+ "hex",
+ "jsonrpsee",
+ "sc-chain-spec",
+ "serde_json",
+ "tokio",
+]
+
 [[package]]
 name = "sc-runtime-test"
 version = "2.0.0"

substrate/Cargo.toml

@@ -55,6 +55,7 @@ members = [
 	"client/rpc",
 	"client/rpc-api",
 	"client/rpc-servers",
+	"client/rpc-spec-v2",
 	"client/service",
 	"client/service/test",
 	"client/state-db",

substrate/bin/node/rpc/Cargo.toml

@@ -26,6 +26,7 @@ sc-finality-grandpa = { version = "0.10.0-dev", path = "../../../client/finality
 sc-finality-grandpa-rpc = { version = "0.10.0-dev", path = "../../../client/finality-grandpa/rpc" }
 sc-rpc = { version = "4.0.0-dev", path = "../../../client/rpc" }
 sc-rpc-api = { version = "0.10.0-dev", path = "../../../client/rpc-api" }
+sc-rpc-spec-v2 = { version = "0.10.0-dev", path = "../../../client/rpc-spec-v2" }
 sc-sync-state-rpc = { version = "0.10.0-dev", path = "../../../client/sync-state-rpc" }
 sc-transaction-pool-api = { version = "4.0.0-dev", path = "../../../client/transaction-pool/api" }
 sp-api = { version = "4.0.0-dev", path = "../../../primitives/api" }

substrate/bin/node/rpc/src/lib.rs

@@ -124,6 +124,7 @@ where
 	use sc_consensus_babe_rpc::{Babe, BabeApiServer};
 	use sc_finality_grandpa_rpc::{Grandpa, GrandpaApiServer};
 	use sc_rpc::dev::{Dev, DevApiServer};
+	use sc_rpc_spec_v2::chain_spec::{ChainSpec, ChainSpecApiServer};
 	use sc_sync_state_rpc::{SyncState, SyncStateApiServer};
 	use substrate_frame_rpc_system::{System, SystemApiServer};
 	use substrate_state_trie_migration_rpc::{StateMigration, StateMigrationApiServer};
@@ -140,6 +141,11 @@ where
 		finality_provider,
 	} = grandpa;
 
+	let chain_name = chain_spec.name().to_string();
+	let genesis_hash = client.block_hash(0).ok().flatten().expect("Genesis block exists; qed");
+	let properties = chain_spec.properties();
+	io.merge(ChainSpec::new(chain_name, genesis_hash, properties).into_rpc())?;
+
 	io.merge(System::new(client.clone(), pool, deny_unsafe).into_rpc())?;
 	// Making synchronous calls in light client freezes the browser currently,
 	// more context: https://github.com/paritytech/substrate/pull/3480

substrate/client/rpc-servers/src/lib.rs

@@ -203,7 +203,6 @@ fn build_rpc_api<M: Send + Sync + 'static>(mut rpc_api: RpcModule<M>) -> RpcModu
 	rpc_api
 		.register_method("rpc_methods", move |_, _| {
 			Ok(serde_json::json!({
-				"version": 1,
 				"methods": available_methods,
 			}))
 		})

substrate/client/rpc-spec-v2/Cargo.toml

+[package]
+name = "sc-rpc-spec-v2"
+version = "0.10.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
+homepage = "https://substrate.io"
+repository = "https://github.com/paritytech/substrate/"
+description = "Substrate RPC interface v2."
+readme = "README.md"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[dependencies]
+jsonrpsee = { version = "0.15.1", features = ["server", "macros"] }
+# Internal chain structures for "chain_spec".
+sc-chain-spec = { version = "4.0.0-dev", path = "../chain-spec" }
+hex = "0.4"
+
+[dev-dependencies]
+serde_json = "1.0"
+tokio = { version = "1.17.0", features = ["macros"] }

substrate/client/rpc-spec-v2/README.md

+Substrate RPC interfaces.
+
+A collection of RPC methods and subscriptions supported by all substrate clients.
+
+License: GPL-3.0-or-later WITH Classpath-exception-2.0
\ No newline at end of file

substrate/client/rpc-spec-v2/src/chain_spec/api.rs

+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! API trait of the chain spec.
+
+use jsonrpsee::{core::RpcResult, proc_macros::rpc};
+use sc_chain_spec::Properties;
+
+#[rpc(client, server)]
+pub trait ChainSpecApi {
+	/// Get the chain name, as present in the chain specification.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and subject to change in the future.
+	#[method(name = "chainSpec_unstable_chainName")]
+	fn chain_spec_unstable_chain_name(&self) -> RpcResult<String>;
+
+	/// Get the chain's genesis hash.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and subject to change in the future.
+	#[method(name = "chainSpec_unstable_genesisHash")]
+	fn chain_spec_unstable_genesis_hash(&self) -> RpcResult<String>;
+
+	/// Get the properties of the chain, as present in the chain specification.
+	///
+	/// # Note
+	///
+	/// The json whitespaces are not guaranteed to persist.
+	///
+	/// # Unstable
+	///
+	/// This method is unstable and subject to change in the future.
+	#[method(name = "chainSpec_unstable_properties")]
+	fn chain_spec_unstable_properties(&self) -> RpcResult<Properties>;
+}

substrate/client/rpc-spec-v2/src/chain_spec/chain_spec.rs

+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! API implementation for the specification of a chain.
+
+use crate::chain_spec::api::ChainSpecApiServer;
+use jsonrpsee::core::RpcResult;
+use sc_chain_spec::Properties;
+
+/// An API for chain spec RPC calls.
+pub struct ChainSpec {
+	/// The name of the chain.
+	name: String,
+	/// The hexadecimal encoded hash of the genesis block.
+	genesis_hash: String,
+	/// Chain properties.
+	properties: Properties,
+}
+
+impl ChainSpec {
+	/// Creates a new [`ChainSpec`].
+	pub fn new<Hash: AsRef<[u8]>>(
+		name: String,
+		genesis_hash: Hash,
+		properties: Properties,
+	) -> Self {
+		let genesis_hash = format!("0x{}", hex::encode(genesis_hash));
+
+		Self { name, properties, genesis_hash }
+	}
+}
+
+impl ChainSpecApiServer for ChainSpec {
+	fn chain_spec_unstable_chain_name(&self) -> RpcResult<String> {
+		Ok(self.name.clone())
+	}
+
+	fn chain_spec_unstable_genesis_hash(&self) -> RpcResult<String> {
+		Ok(self.genesis_hash.clone())
+	}
+
+	fn chain_spec_unstable_properties(&self) -> RpcResult<Properties> {
+		Ok(self.properties.clone())
+	}
+}

substrate/client/rpc-spec-v2/src/chain_spec/mod.rs

+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! Substrate chain specification API.
+//!
+//! The *chain spec* (short for *chain specification*) allows inspecting the content of
+//! the specification of the chain that a JSON-RPC server is targeting.
+//!
+//! The values returned by the API are guaranteed to never change during the lifetime of the
+//! JSON-RPC server.
+//!
+//! # Note
+//!
+//! Methods are prefixed by `chainSpec`.
+
+#[cfg(test)]
+mod tests;
+
+pub mod api;
+pub mod chain_spec;
+
+pub use api::ChainSpecApiServer;
+pub use chain_spec::ChainSpec;

substrate/client/rpc-spec-v2/src/chain_spec/tests.rs

+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use super::*;
+use jsonrpsee::{types::EmptyParams, RpcModule};
+use sc_chain_spec::Properties;
+
+const CHAIN_NAME: &'static str = "TEST_CHAIN_NAME";
+const CHAIN_GENESIS: [u8; 32] = [0; 32];
+const CHAIN_PROPERTIES: &'static str = r#"{"three": "123", "one": 1, "two": 12}"#;
+
+fn api() -> RpcModule<ChainSpec> {
+	ChainSpec::new(
+		CHAIN_NAME.to_string(),
+		CHAIN_GENESIS,
+		serde_json::from_str(CHAIN_PROPERTIES).unwrap(),
+	)
+	.into_rpc()
+}
+
+#[tokio::test]
+async fn chain_spec_chain_name_works() {
+	let name = api()
+		.call::<_, String>("chainSpec_unstable_chainName", EmptyParams::new())
+		.await
+		.unwrap();
+	assert_eq!(name, CHAIN_NAME);
+}
+
+#[tokio::test]
+async fn chain_spec_genesis_hash_works() {
+	let genesis = api()
+		.call::<_, String>("chainSpec_unstable_genesisHash", EmptyParams::new())
+		.await
+		.unwrap();
+	assert_eq!(genesis, format!("0x{}", hex::encode(CHAIN_GENESIS)));
+}
+
+#[tokio::test]
+async fn chain_spec_properties_works() {
+	let properties = api()
+		.call::<_, Properties>("chainSpec_unstable_properties", EmptyParams::new())
+		.await
+		.unwrap();
+	assert_eq!(properties, serde_json::from_str(CHAIN_PROPERTIES).unwrap());
+}

substrate/client/rpc-spec-v2/src/lib.rs

+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! Substrate JSON-RPC interface v2.
+//!
+//! Specification [document](https://paritytech.github.io/json-rpc-interface-spec/).
+
+#![warn(missing_docs)]
+#![deny(unused_crate_dependencies)]
+
+pub mod chain_spec;