Staking Precompiles

node/src/chain_spec.rs

@@ -21,6 +21,7 @@
 
 use bip39::{Language, Mnemonic, Seed};
 use cumulus_primitives_core::ParaId;
+use evm::GenesisAccount;
 use log::debug;
 use moonbeam_runtime::{
 	AccountId, Balance, BalancesConfig, CouncilCollectiveConfig, DemocracyConfig, EVMConfig,
@@ -39,7 +40,7 @@ use sp_runtime::{
 	Perbill,
 };
 use std::convert::TryInto;
-use std::{collections::BTreeMap, str::FromStr};
+use std::str::FromStr;
 use tiny_hderive::bip32::ExtendedPrivKey;
 
 /// Helper function to derive `num_accounts` child pairs from mnemonics
@@ -232,6 +233,15 @@ pub fn testnet_genesis(
 	para_id: ParaId,
 	chain_id: u64,
 ) -> GenesisConfig {
+	// This is supposed the be the simplest bytecode to revert without returning any data.
+	// We will pre-deploy it under all of our precompiles to ensure they can be called from
+	// within contracts. TODO We should have a test to ensure this is the right bytecode.
+	// (PUSH1 0x00 PUSH1 0x00 REVERT)
+	let revert_bytecode = vec![0x60, 0x00, 0x60, 0x00, 0xFD];
+	// TODO consider whether this should be imported from moonbeam precompiles
+	let precompile_addresses = vec![1, 2, 3, 4, 5, 6, 7, 8, 1024, 1025, 2048]
+		.into_iter()
+		.map(H160::from_low_u64_be);
 	GenesisConfig {
 		frame_system: SystemConfig {
 			code: WASM_BINARY
@@ -252,7 +262,26 @@ pub fn testnet_genesis(
 		},
 		pallet_ethereum_chain_id: EthereumChainIdConfig { chain_id },
 		pallet_evm: EVMConfig {
-			accounts: BTreeMap::new(),
+			// We need _some_ code inserted at the precompile address so that
+			// the evm will actually call the address.
+			// TODO Cleanly fetch the addresses from
+			// the runtime/moonbeam precompiles and systematically fill them with code
+			// that will revert if it is called by accident (it shouldn't be because
+			// it is shadowed by the precompile).
+			// This one is for the parachain staking precompile wrappers
+			accounts: precompile_addresses
+				.map(|a| {
+					(
+						a,
+						GenesisAccount {
+							nonce: Default::default(),
+							balance: Default::default(),
+							storage: Default::default(),
+							code: revert_bytecode.clone(),
+						},
+					)
+				})
+				.collect(),
 		},
 		pallet_ethereum: EthereumConfig {},
 		pallet_democracy: DemocracyConfig {},

runtime/Cargo.toml

@@ -60,23 +60,21 @@ moonbeam-rpc-primitives-debug = { path = "../primitives/rpc/debug", default-feat
 moonbeam-rpc-primitives-txpool = { path = "../primitives/rpc/txpool", default-features = false }
 
 # Cumulus dependencies
-cumulus-pallet-parachain-system = { git = "https://github.com/paritytech/cumulus",  default-features = false, branch = "rococo-v1" }
-cumulus-primitives-core = { git = "https://github.com/paritytech/cumulus",  default-features = false, branch = "rococo-v1" }
-parachain-info = { git = "https://github.com/paritytech/cumulus",  default-features = false, branch = "rococo-v1" }
+cumulus-pallet-parachain-system = { git = "https://github.com/paritytech/cumulus", default-features = false, branch = "rococo-v1" }
+cumulus-primitives-core = { git = "https://github.com/paritytech/cumulus", default-features = false, branch = "rococo-v1" }
+parachain-info = { git = "https://github.com/paritytech/cumulus", default-features = false, branch = "rococo-v1" }
 
 [dev-dependencies]
-cumulus-test-relay-sproof-builder = { git = "https://github.com/paritytech/cumulus",  default-features = false, branch = "rococo-v1" }
-cumulus-primitives-parachain-inherent = { git = "https://github.com/paritytech/cumulus",  default-features = false, branch = "rococo-v1" }
+cumulus-test-relay-sproof-builder = { git = "https://github.com/paritytech/cumulus", default-features = false, branch = "rococo-v1" }
+cumulus-primitives-parachain-inherent = { git = "https://github.com/paritytech/cumulus", default-features = false, branch = "rococo-v1" }
+evm = { version = "0.26.0", default-features = false, features = ["with-codec"] }
 
 [build-dependencies]
 substrate-wasm-builder = { version = "4.0.0", git = "https://github.com/paritytech/substrate", branch = "rococo-v1" }
 
 [features]
-# By default, we build the parachain runtime
 default = [
-	"std"
-	# parachain-only dependencies can't be conditionally included here.
-	# Default feature dependencies must not be optional (aparently)
+	"std",
 ]
 std = [
 	"parity-scale-codec/std",
@@ -125,12 +123,10 @@ std = [
 
 # Will be enabled by the `wasm-builder` when building the runtime for WASM.
 runtime-wasm = [
-	# "cumulus-upward-message/runtime-wasm",
+	# "cumulus-upward-message/runtime-wasm",	
 ]
 
 # A feature that should be enabled when the runtime should be build for on-chain
 # deployment. This will disable stuff that shouldn't be part of the on-chain wasm
 # to make it smaller like logging for example.
-on-chain-release-build = [
-   "sp-api/disable-logging",
-]
+on-chain-release-build = ["sp-api/disable-logging"]

runtime/precompiles/Cargo.toml

@@ -16,15 +16,21 @@ frame-support = { git = "https://github.com/paritytech/substrate", branch = "roc
 evm = { version = "0.26.0", default-features = false, features = ["with-codec"] }
 sp-std = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "rococo-v1" }
 sp-core = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "rococo-v1" }
+sp-io = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "rococo-v1" }
 pallet-evm = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
 pallet-evm-precompile-bn128 = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
 pallet-evm-precompile-dispatch = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
 pallet-evm-precompile-modexp = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
 pallet-evm-precompile-simple = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
 pallet-evm-precompile-sha3fips = { git = "https://github.com/purestake/frontier", default-features = false, branch = "notlesh-moonbeam-v0.7" }
+parachain-staking = { path = "../../pallets/parachain-staking", default-features = false }
+frame-system = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "rococo-v1" }
+
+[dev-dependencies]
+hex = "0.4"
 
 [features]
-default = [ "std" ]
+default = ["std"]
 std = [
 	"codec/std",
 	"frame-support/std",
@@ -36,5 +42,7 @@ std = [
 	"pallet-evm-precompile-dispatch/std",
 	"pallet-evm-precompile-modexp/std",
 	"pallet-evm-precompile-simple/std",
+	"parachain-staking/std",
+	"frame-system/std",
 	"pallet-evm-precompile-sha3fips/std",
 ]

runtime/precompiles/src/StakingInterface.sol

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity >=0.8.0;
+
+/// The interface through which solidity contracts will interact with Parachain Staking
+/// We follow this same interface including four-byte function selectors, in the precompile that
+/// wraps the pallet
+interface ParachainStaking {
+    // First some simple accessors
+
+    /// Check whether the specified address is currently a staking nominator
+    function is_nominator(address nominator) external view returns (bool);
+
+    /// Check whether the specified addess is currently a collator candidate
+    function is_candidate(address collator) external view returns (bool);
+
+    /// Get the minimum nomination amount
+    function min_nomination() external view returns (uint256);
+
+    // Now the dispatchables
+
+    /// Join the set of collator candidates
+    function join_candidates(uint256 amount) external;
+
+    /// Request to leave the set of candidates. If successful, the account is immediately
+    /// removed from the candidate pool to prevent selection as a collator, but unbonding is
+    /// executed with a delay of `BondDuration` rounds.
+    function leave_candidates() external;
+
+    /// Temporarily leave the set of collator candidates without unbonding
+    function go_offline() external;
+
+    /// Rejoin the set of collator candidates if previously had called `go_offline`
+    function go_online() external;
+
+    /// Bond more for collator candidates
+    function candidate_bond_more(uint256 more) external;
+
+    /// Bond less for collator candidates
+    function candidate_bond_less(uint256 less) external;
+
+    /// If caller is not a nominator, then join the set of nominators
+    /// If caller is a nominator, then makes nomination to change their nomination state
+    function nominate(address collator, uint256 amount) external;
+
+    /// Leave the set of nominators and, by implication, revoke all ongoing nominations
+    function leave_nominators() external;
+
+    /// Revoke an existing nomination
+    function revoke_nomination(address collator) external;
+
+    /// Bond more for nominators with respect to a specific collator candidate
+    function nominator_bond_more(address candidate, uint256 more) external;
+
+    /// Bond less for nominators with respect to a specific nominator candidate
+    function nominator_bond_less(address candidate, uint256 less) external;
+}
+
+// These are the selectors generated by remix following this advice
+// https://ethereum.stackexchange.com/a/73405/9963
+// Eventually we will probably want a better way of generating these and copying them to Rust
+// {
+// 	"289b6ba7": "candidate_bond_less(uint256)",
+// 	"c57bd3a8": "candidate_bond_more(uint256)",
+// 	"767e0450": "go_offline()",
+// 	"d2f73ceb": "go_online()",
+// 	"8545c833": "is_candidate(address)",
+// 	"8e5080e7": "is_nominator(address)",
+// 	"ad76ed5a": "join_candidates(uint256)",
+// 	"b7694219": "leave_candidates()",
+// 	"e8d68a37": "leave_nominators()",
+// 	"c9f593b2": "min_nomination()",
+// 	"82f2c8df": "nominate(address,uint256)",
+// 	"f6a52569": "nominator_bond_less(address,uint256)",
+// 	"971d44c8": "nominator_bond_more(address,uint256)",
+// 	"4b65c34b": "revoke_nomination(address)"
+// }

runtime/precompiles/src/lib.rs

@@ -16,35 +16,66 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+mod staking;
 use codec::Decode;
 use evm::{Context, ExitError, ExitSucceed};
 use frame_support::dispatch::{Dispatchable, GetDispatchInfo, PostDispatchInfo};
-use pallet_evm::{Config, Precompile, PrecompileSet};
+use pallet_evm::{Precompile, PrecompileSet};
 use pallet_evm_precompile_bn128::{Bn128Add, Bn128Mul, Bn128Pairing};
 use pallet_evm_precompile_dispatch::Dispatch;
 use pallet_evm_precompile_modexp::Modexp;
 use pallet_evm_precompile_sha3fips::Sha3FIPS256;
 use pallet_evm_precompile_simple::{ECRecover, Identity, Ripemd160, Sha256};
 use sp_core::H160;
+use sp_std::convert::TryFrom;
+use sp_std::fmt::Debug;
 use sp_std::{marker::PhantomData, vec::Vec};
+use staking::ParachainStakingWrapper;
 
+use frame_support::traits::Currency;
+type BalanceOf<Runtime> = <<Runtime as parachain_staking::Config>::Currency as Currency<
+	<Runtime as frame_system::Config>::AccountId,
+>>::Balance;
+
+//TODO Maybe we don't need to / shouldn't be generic over the runtime.
+// Pros: Would simplify trait bounds and speed up compile time (maybe not noticeably).
+// Cons: Would proclude using this precompile set in mocked Runtimes.
 /// The PrecompileSet installed in the Moonbeam runtime.
 /// We include the nine Istanbul precompiles
 /// (https://github.com/ethereum/go-ethereum/blob/3c46f557/core/vm/contracts.go#L69)
 /// as well as a special precompile for dispatching Substrate extrinsics
 #[derive(Debug, Clone, Copy)]
 pub struct MoonbeamPrecompiles<R>(PhantomData<R>);
 
+// The idea here is that we won't have to list the addresses in this file and the chain spec.
+// Unfortunately we still have to type it twice in this file.
+impl<R: frame_system::Config> MoonbeamPrecompiles<R>
+where
+	R::AccountId: From<H160>,
+{
+	/// Return all addresses that contain precompiles. This can be used to populate dummy code
+	/// under the precompile, and potentially in the future to prevent using accounts that have
+	/// precompiles at their addresses explicitly using something like SignedExtra.
+	#[allow(dead_code)]
+	fn used_addresses() -> impl Iterator<Item = R::AccountId> {
+		sp_std::vec![1, 2, 3, 4, 5, 6, 7, 8, 1024, 1025, 2048]
+			.into_iter()
+			.map(|x| hash(x).into())
+	}
+}
+
 /// The following distribution has been decided for the precompiles
 /// 0-1023: Ethereum Mainnet Precompiles
 /// 1024-2047 Precompiles that are not in Ethereum Mainnet but are neither Moonbeam specific
-/// 2048-4095 Moonbeam specific prerecompiles
-
+/// 2048-4095 Moonbeam specific precompiles
 impl<R> PrecompileSet for MoonbeamPrecompiles<R>
 where
-	R: Config,
 	R::Call: Dispatchable<PostInfo = PostDispatchInfo> + GetDispatchInfo + Decode,
 	<R::Call as Dispatchable>::Origin: From<Option<R::AccountId>>,
+	R: parachain_staking::Config + pallet_evm::Config,
+	R::AccountId: From<H160>,
+	BalanceOf<R>: TryFrom<sp_core::U256> + Debug,
+	R::Call: From<parachain_staking::Call<R>>,
 {
 	fn execute(
 		address: H160,
@@ -65,6 +96,10 @@ where
 			// Non-Moonbeam specific nor Ethereum precompiles :
 			a if a == hash(1024) => Some(Dispatch::<R>::execute(input, target_gas, context)),
 			a if a == hash(1025) => Some(Sha3FIPS256::execute(input, target_gas, context)),
+			// Moonbeam specific precompiles :
+			a if a == hash(2048) => Some(ParachainStakingWrapper::<R>::execute(
+				input, target_gas, context,
+			)),
 			_ => None,
 		}
 	}