// This file is part of Substrate.
// Copyright (C) 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.
//! Supporting pallet for the statement store.
//!
//! - [`Pallet`]
//!
//! ## Overview
//!
//! The Statement pallet provides means to create and validate statements for the statement store.
//!
//! For each statement validation function calculates the following three values based on the
//! statement author balance:
//! `max_count`: Maximum number of statements allowed for the author (signer) of this statement.
//! `max_size`: Maximum total size of statements allowed for the author (signer) of this statement.
//!
//! This pallet also contains an offchain worker that turns on-chain statement events into
//! statements. These statements are placed in the store and propagated over the network.
#![cfg_attr(not(feature = "std"), no_std)]
use frame_support::{
pallet_prelude::*,
sp_runtime::{traits::CheckedDiv, SaturatedConversion},
traits::fungible::Inspect,
};
use frame_system::pallet_prelude::*;
use sp_statement_store::{
runtime_api::{InvalidStatement, StatementSource, ValidStatement},
Proof, SignatureVerificationResult, Statement,
};
#[cfg(test)]
// We do not declare all features used by `construct_runtime`
#[allow(unexpected_cfgs)]
mod mock;
#[cfg(test)]
mod tests;
pub use pallet::*;
const LOG_TARGET: &str = "runtime::statement";
#[frame_support::pallet]
pub mod pallet {
use super::*;
pub type BalanceOf<T> =
<<T as Config>::Currency as Inspect<<T as frame_system::Config>::AccountId>>::Balance;
pub type AccountIdOf<T> = <T as frame_system::Config>::AccountId;
#[pallet::config]
pub trait Config: frame_system::Config
where
<Self as frame_system::Config>::AccountId: From<sp_statement_store::AccountId>,
{
/// The overarching event type.
type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
/// The currency which is used to calculate account limits.
type Currency: Inspect<Self::AccountId>;
/// Min balance for priority statements.
#[pallet::constant]
type StatementCost: Get<BalanceOf<Self>>;
/// Cost of data byte used for priority calculation.
#[pallet::constant]
type ByteCost: Get<BalanceOf<Self>>;
/// Minimum number of statements allowed per account.
#[pallet::constant]
type MinAllowedStatements: Get<u32>;
/// Maximum number of statements allowed per account.
#[pallet::constant]
type MaxAllowedStatements: Get<u32>;
/// Minimum data bytes allowed per account.
#[pallet::constant]
type MinAllowedBytes: Get<u32>;
/// Maximum data bytes allowed per account.
#[pallet::constant]
type MaxAllowedBytes: Get<u32>;
}
#[pallet::pallet]
pub struct Pallet<T>(core::marker::PhantomData<T>);
#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T: Config>
where
<T as frame_system::Config>::AccountId: From<sp_statement_store::AccountId>,
{
/// A new statement is submitted
NewStatement { account: T::AccountId, statement: Statement },
}
#[pallet::hooks]
impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T>
where
<T as frame_system::Config>::AccountId: From<sp_statement_store::AccountId>,
sp_statement_store::AccountId: From<<T as frame_system::Config>::AccountId>,
<T as frame_system::Config>::RuntimeEvent: From<pallet::Event<T>>,
<T as frame_system::Config>::RuntimeEvent: TryInto<pallet::Event<T>>,
sp_statement_store::BlockHash: From<<T as frame_system::Config>::Hash>,
{
fn offchain_worker(now: BlockNumberFor<T>) {
log::trace!(target: LOG_TARGET, "Collecting statements at #{:?}", now);
Pallet::<T>::collect_statements();
}
}
}
impl<T: Config> Pallet<T>
where
<T as frame_system::Config>::AccountId: From<sp_statement_store::AccountId>,
sp_statement_store::AccountId: From<<T as frame_system::Config>::AccountId>,
<T as frame_system::Config>::RuntimeEvent: From<pallet::Event<T>>,
<T as frame_system::Config>::RuntimeEvent: TryInto<pallet::Event<T>>,
sp_statement_store::BlockHash: From<<T as frame_system::Config>::Hash>,
{
/// Validate a statement against current state. This is supposed to be called by the statement
/// store on the host side.
pub fn validate_statement(
_source: StatementSource,
mut statement: Statement,
) -> Result<ValidStatement, InvalidStatement> {
sp_io::init_tracing();
log::debug!(target: LOG_TARGET, "Validating statement {:?}", statement);
let account: T::AccountId = match statement.proof() {
Some(Proof::OnChain { who, block_hash, event_index }) => {
if frame_system::Pallet::<T>::parent_hash().as_ref() != block_hash.as_slice() {
log::debug!(target: LOG_TARGET, "Bad block hash.");
return Err(InvalidStatement::BadProof)
}
let account: T::AccountId = (*who).into();
match frame_system::Pallet::<T>::event_no_consensus(*event_index as usize) {
Some(e) => {
statement.remove_proof();
if let Ok(Event::NewStatement { account: a, statement: s }) = e.try_into() {
if a != account || s != statement {
log::debug!(target: LOG_TARGET, "Event data mismatch");
return Err(InvalidStatement::BadProof)
}
} else {
log::debug!(target: LOG_TARGET, "Event type mismatch");
return Err(InvalidStatement::BadProof)
}
},
_ => {
log::debug!(target: LOG_TARGET, "Bad event index");
return Err(InvalidStatement::BadProof)
},
}
account
},
_ => match statement.verify_signature() {
SignatureVerificationResult::Valid(account) => account.into(),
SignatureVerificationResult::Invalid => {
log::debug!(target: LOG_TARGET, "Bad statement signature.");
return Err(InvalidStatement::BadProof)
},
SignatureVerificationResult::NoSignature => {
log::debug!(target: LOG_TARGET, "Missing statement signature.");
return Err(InvalidStatement::NoProof)
},
},
};
let statement_cost = T::StatementCost::get();
let byte_cost = T::ByteCost::get();
let balance = <T::Currency as Inspect<AccountIdOf<T>>>::balance(&account);
let min_allowed_statements = T::MinAllowedStatements::get();
let max_allowed_statements = T::MaxAllowedStatements::get();
let min_allowed_bytes = T::MinAllowedBytes::get();
let max_allowed_bytes = T::MaxAllowedBytes::get();
let max_count = balance
.checked_div(&statement_cost)
.unwrap_or_default()
.saturated_into::<u32>()
.clamp(min_allowed_statements, max_allowed_statements);
let max_size = balance
.checked_div(&byte_cost)
.unwrap_or_default()
.saturated_into::<u32>()
.clamp(min_allowed_bytes, max_allowed_bytes);
Ok(ValidStatement { max_count, max_size })
}
/// Submit a statement event. The statement will be picked up by the offchain worker and
/// broadcast to the network.
pub fn submit_statement(account: T::AccountId, statement: Statement) {
Self::deposit_event(Event::NewStatement { account, statement });
}
fn collect_statements() {
// Find `NewStatement` events and submit them to the store
for (index, event) in frame_system::Pallet::<T>::read_events_no_consensus().enumerate() {
if let Ok(Event::<T>::NewStatement { account, mut statement }) = event.event.try_into()
{
if statement.proof().is_none() {
let proof = Proof::OnChain {
who: account.into(),
block_hash: frame_system::Pallet::<T>::parent_hash().into(),
event_index: index as u64,
};
statement.set_proof(proof);
}
sp_statement_store::runtime_api::statement_store::submit_statement(statement);
}
}
}
}