lib.rs

// Copyright 2019-2021 Parity Technologies (UK) Ltd.
// This file is part of Parity Bridges Common.

// Parity Bridges Common 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.

// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.

#![cfg_attr(not(feature = "std"), no_std)]

use bp_messages::MessageNonce;
use bp_runtime::{Chain, EncodedOrDecodedCall, StorageMapKeyProvider};
use codec::Compact;
use frame_support::{
	dispatch::DispatchClass,
	parameter_types,
	weights::{
		constants::{BlockExecutionWeight, WEIGHT_PER_SECOND},
		Weight,
	},
	Blake2_128Concat, RuntimeDebug,
};
use frame_system::limits;
use scale_info::TypeInfo;
use sp_core::{storage::StorageKey, Hasher as HasherT};
use sp_runtime::{
	generic,
	traits::{BlakeTwo256, DispatchInfoOf, IdentifyAccount, Verify},
	transaction_validity::TransactionValidityError,
	MultiAddress, MultiSignature, OpaqueExtrinsic,
};
use sp_std::prelude::Vec;

// Re-export's to avoid extra substrate dependencies in chain-specific crates.
pub use frame_support::{weights::constants::ExtrinsicBaseWeight, Parameter};
pub use sp_runtime::{traits::Convert, Perbill};

pub mod parachains;

/// Number of extra bytes (excluding size of storage value itself) of storage proof, built at
/// Polkadot-like chain. This mostly depends on number of entries in the storage trie.
/// Some reserve is reserved to account future chain growth.
///
/// To compute this value, we've synced Kusama chain blocks [0; 6545733] to see if there were
/// any significant changes of the storage proof size (NO):
///
/// - at block 3072 the storage proof size overhead was 579 bytes;
/// - at block 2479616 it was 578 bytes;
/// - at block 4118528 it was 711 bytes;
/// - at block 6540800 it was 779 bytes.
///
/// The number of storage entries at the block 6546170 was 351207 and number of trie nodes in
/// the storage proof was 5 (log(16, 351207) ~ 4.6).
///
/// So the assumption is that the storage proof size overhead won't be larger than 1024 in the
/// nearest future. If it'll ever break this barrier, then we'll need to update this constant
/// at next runtime upgrade.
pub const EXTRA_STORAGE_PROOF_SIZE: u32 = 1024;

/// All Polkadot-like chains allow normal extrinsics to fill block up to 75 percent.
///
/// This is a copy-paste from the Polkadot repo's `polkadot-runtime-common` crate.
const NORMAL_DISPATCH_RATIO: Perbill = Perbill::from_percent(75);

/// All Polkadot-like chains allow 2 seconds of compute with a 6-second average block time.
///
/// This is a copy-paste from the Polkadot repo's `polkadot-runtime-common` crate.
// TODO: https://github.com/paritytech/parity-bridges-common/issues/1543 - remove `set_proof_size`
pub const MAXIMUM_BLOCK_WEIGHT: Weight = WEIGHT_PER_SECOND.set_proof_size(1_000).saturating_mul(2);

/// All Polkadot-like chains assume that an on-initialize consumes 1 percent of the weight on
/// average, hence a single extrinsic will not be allowed to consume more than
/// `AvailableBlockRatio - 1 percent`.
///
/// This is a copy-paste from the Polkadot repo's `polkadot-runtime-common` crate.
pub const AVERAGE_ON_INITIALIZE_RATIO: Perbill = Perbill::from_percent(1);

parameter_types! {
	/// All Polkadot-like chains have maximal block size set to 5MB.
	///
	/// This is a copy-paste from the Polkadot repo's `polkadot-runtime-common` crate.
	pub BlockLength: limits::BlockLength = limits::BlockLength::max_with_normal_ratio(
		5 * 1024 * 1024,
		NORMAL_DISPATCH_RATIO,
	);
	/// All Polkadot-like chains have the same block weights.
	///
	/// This is a copy-paste from the Polkadot repo's `polkadot-runtime-common` crate.
	pub BlockWeights: limits::BlockWeights = limits::BlockWeights::builder()
		.base_block(BlockExecutionWeight::get())
		.for_class(DispatchClass::all(), |weights| {
			weights.base_extrinsic = ExtrinsicBaseWeight::get();
		})
		.for_class(DispatchClass::Normal, |weights| {
			weights.max_total = Some(NORMAL_DISPATCH_RATIO * MAXIMUM_BLOCK_WEIGHT);
		})
		.for_class(DispatchClass::Operational, |weights| {
			weights.max_total = Some(MAXIMUM_BLOCK_WEIGHT);
			// Operational transactions have an extra reserved space, so that they
			// are included even if block reached `MAXIMUM_BLOCK_WEIGHT`.
			weights.reserved = Some(
				MAXIMUM_BLOCK_WEIGHT - NORMAL_DISPATCH_RATIO * MAXIMUM_BLOCK_WEIGHT,
			);
		})
		.avg_block_initialization(AVERAGE_ON_INITIALIZE_RATIO)
		.build_or_panic();
}

// TODO [#78] may need to be updated after https://github.com/paritytech/parity-bridges-common/issues/78
/// Maximal number of messages in single delivery transaction.
pub const MAX_MESSAGES_IN_DELIVERY_TRANSACTION: MessageNonce = 128;

/// Maximal number of bytes, included in the signed Polkadot-like transaction apart from the encoded
/// call itself.
///
/// Can be computed by subtracting encoded call size from raw transaction size.
pub const TX_EXTRA_BYTES: u32 = 256;

/// Re-export `time_units` to make usage easier.
pub use time_units::*;

/// Human readable time units defined in terms of number of blocks.
pub mod time_units {
	use super::BlockNumber;

	pub const MILLISECS_PER_BLOCK: u64 = 6000;
	pub const SLOT_DURATION: u64 = MILLISECS_PER_BLOCK;

	pub const MINUTES: BlockNumber = 60_000 / (MILLISECS_PER_BLOCK as BlockNumber);
	pub const HOURS: BlockNumber = MINUTES * 60;
	pub const DAYS: BlockNumber = HOURS * 24;
}

/// Block number type used in Polkadot-like chains.
pub type BlockNumber = u32;

/// Hash type used in Polkadot-like chains.
pub type Hash = <BlakeTwo256 as HasherT>::Out;

/// Account Index (a.k.a. nonce).
pub type Index = u32;

/// Hashing type.
pub type Hashing = BlakeTwo256;

/// The type of object that can produce hashes on Polkadot-like chains.
pub type Hasher = BlakeTwo256;

/// The header type used by Polkadot-like chains.
pub type Header = generic::Header<BlockNumber, Hasher>;

/// Signature type used by Polkadot-like chains.
pub type Signature = MultiSignature;

/// Public key of account on Polkadot-like chains.
pub type AccountPublic = <Signature as Verify>::Signer;

/// Id of account on Polkadot-like chains.
pub type AccountId = <AccountPublic as IdentifyAccount>::AccountId;

/// Address of account on Polkadot-like chains.
pub type AccountAddress = MultiAddress<AccountId, ()>;

/// Index of a transaction on the Polkadot-like chains.
pub type Nonce = u32;

/// Block type of Polkadot-like chains.
pub type Block = generic::Block<Header, OpaqueExtrinsic>;

/// Polkadot-like block signed with a Justification.
pub type SignedBlock = generic::SignedBlock<Block>;

/// The balance of an account on Polkadot-like chain.
pub type Balance = u128;

/// Unchecked Extrinsic type.
pub type UncheckedExtrinsic<Call> = generic::UncheckedExtrinsic<
	AccountAddress,
	EncodedOrDecodedCall<Call>,
	Signature,
	SignedExtensions,
>;

/// Account address, used by the Polkadot-like chain.
pub type Address = MultiAddress<AccountId, ()>;

/// A type of the data encoded as part of the transaction.
pub type SignedExtra =
	((), (), (), (), sp_runtime::generic::Era, Compact<Nonce>, (), Compact<Balance>);

/// Parameters which are part of the payload used to produce transaction signature,
/// but don't end up in the transaction itself (i.e. inherent part of the runtime).
pub type AdditionalSigned = ((), u32, u32, Hash, Hash, (), (), ());

/// A simplified version of signed extensions meant for producing signed transactions
/// and signed payload in the client code.
#[derive(codec::Encode, codec::Decode, PartialEq, Eq, Clone, RuntimeDebug, TypeInfo)]
pub struct SignedExtensions {
	encode_payload: SignedExtra,
	// It may be set to `None` if extensions are decoded. We are never reconstructing transactions
	// (and it makes no sense to do that) => decoded version of `SignedExtensions` is only used to
	// read fields of `encode_payload`. And when resigning transaction, we're reconstructing
	// `SignedExtensions` from the scratch.
	#[codec(skip)]
	additional_signed: Option<AdditionalSigned>,
}

impl SignedExtensions {
	pub fn new(
		spec_version: u32,
		transaction_version: u32,
		era: bp_runtime::TransactionEraOf<PolkadotLike>,
		genesis_hash: Hash,
		nonce: Nonce,
		tip: Balance,
	) -> Self {
		Self {
			encode_payload: (
				(),              // non-zero sender
				(),              // spec version
				(),              // tx version
				(),              // genesis
				era.frame_era(), // era
				nonce.into(),    // nonce (compact encoding)
				(),              // Check weight
				tip.into(),      // transaction payment / tip (compact encoding)
			),
			additional_signed: Some((
				(),
				spec_version,
				transaction_version,
				genesis_hash,
				era.signed_payload(genesis_hash),
				(),
				(),
				(),
			)),
		}
	}
}

impl SignedExtensions {
	/// Return signer nonce, used to craft transaction.
	pub fn nonce(&self) -> Nonce {
		self.encode_payload.5.into()
	}

	/// Return transaction tip.
	pub fn tip(&self) -> Balance {
		self.encode_payload.7.into()
	}
}

impl sp_runtime::traits::SignedExtension for SignedExtensions {
	const IDENTIFIER: &'static str = "Not needed.";

	type AccountId = AccountId;
	type Call = ();
	type AdditionalSigned = AdditionalSigned;
	type Pre = ();

	fn additional_signed(
		&self,
	) -> Result<Self::AdditionalSigned, frame_support::unsigned::TransactionValidityError> {
		// we shall not ever see this error in relay, because we are never signing decoded
		// transactions. Instead we're constructing and signing new transactions. So the error code
		// is kinda random here
		self.additional_signed
			.ok_or(frame_support::unsigned::TransactionValidityError::Unknown(
				frame_support::unsigned::UnknownTransaction::Custom(0xFF),
			))
	}

	fn pre_dispatch(
		self,
		_who: &Self::AccountId,
		_call: &Self::Call,
		_info: &DispatchInfoOf<Self::Call>,
		_len: usize,
	) -> Result<Self::Pre, TransactionValidityError> {
		Ok(())
	}
}

/// Polkadot-like chain.
#[derive(RuntimeDebug)]
pub struct PolkadotLike;

impl Chain for PolkadotLike {
	type BlockNumber = BlockNumber;
	type Hash = Hash;
	type Hasher = Hasher;
	type Header = Header;

	type AccountId = AccountId;
	type Balance = Balance;
	type Index = Index;
	type Signature = Signature;

	fn max_extrinsic_size() -> u32 {
		*BlockLength::get().max.get(DispatchClass::Normal)
	}

	fn max_extrinsic_weight() -> Weight {
		BlockWeights::get()
			.get(DispatchClass::Normal)
			.max_extrinsic
			.unwrap_or(Weight::MAX)
	}
}

/// Provides a storage key for account data.
///
/// We need to use this approach when we don't have access to the runtime.
/// The equivalent command to invoke in case full `Runtime` is known is this:
/// `let key = frame_system::Account::<Runtime>::storage_map_final_key(&account_id);`
pub struct AccountInfoStorageMapKeyProvider;

impl StorageMapKeyProvider for AccountInfoStorageMapKeyProvider {
	const MAP_NAME: &'static str = "Account";
	type Hasher = Blake2_128Concat;
	type Key = AccountId;
	// This should actually be `AccountInfo`, but we don't use this property in order to decode the
	// data. So we use `Vec<u8>` as if we would work with encoded data.
	type Value = Vec<u8>;
}

impl AccountInfoStorageMapKeyProvider {
	const PALLET_NAME: &'static str = "System";

	pub fn final_key(id: &AccountId) -> StorageKey {
		<Self as StorageMapKeyProvider>::final_key(Self::PALLET_NAME, id)
	}
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn should_generate_storage_key() {
		let acc = [
			1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
			25, 26, 27, 28, 29, 30, 31, 32,
		]
		.into();
		let key = AccountInfoStorageMapKeyProvider::final_key(&acc);
		assert_eq!(hex::encode(key), "26aa394eea5630e07c48ae0c9558cef7b99d880ec681799c0cf30e8886371da92dccd599abfe1920a1cff8a7358231430102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f20");
	}
}