Setup permissionless lanes for AssetHubs - heads/state-roots store

Cargo.toml

@@ -16,6 +16,7 @@ members = [
 	"bridges/modules/grandpa",
 	"bridges/modules/messages",
 	"bridges/modules/parachains",
+	"bridges/modules/proof-root-store",
 	"bridges/modules/relayers",
 	"bridges/modules/xcm-bridge",
 	"bridges/modules/xcm-bridge-hub",
@@ -26,6 +27,7 @@ members = [
 	"bridges/primitives/messages",
 	"bridges/primitives/parachains",
 	"bridges/primitives/polkadot-core",
+	"bridges/primitives/proof-root-store",
 	"bridges/primitives/relayers",
 	"bridges/primitives/runtime",
 	"bridges/primitives/test-utils",
@@ -685,6 +687,7 @@ bp-messages = { path = "bridges/primitives/messages", default-features = false }
 bp-parachains = { path = "bridges/primitives/parachains", default-features = false }
 bp-polkadot-bulletin = { path = "bridges/chains/chain-polkadot-bulletin", default-features = false }
 bp-polkadot-core = { path = "bridges/primitives/polkadot-core", default-features = false }
+bp-proof-root-store = { path = "bridges/primitives/proof-root-store", default-features = false }
 bp-relayers = { path = "bridges/primitives/relayers", default-features = false }
 bp-rococo = { path = "polkadot/runtime/rococo/bridge-primitives", default-features = false }
 bp-runtime = { path = "bridges/primitives/runtime", default-features = false }
@@ -955,6 +958,7 @@ pallet-bounties = { path = "substrate/frame/bounties", default-features = false
 pallet-bridge-grandpa = { path = "bridges/modules/grandpa", default-features = false }
 pallet-bridge-messages = { path = "bridges/modules/messages", default-features = false }
 pallet-bridge-parachains = { path = "bridges/modules/parachains", default-features = false }
+pallet-bridge-proof-root-store = { path = "bridges/modules/proof-root-store", default-features = false }
 pallet-bridge-relayers = { path = "bridges/modules/relayers", default-features = false }
 pallet-broker = { path = "substrate/frame/broker", default-features = false }
 pallet-child-bounties = { path = "substrate/frame/child-bounties", default-features = false }

bridges/modules/proof-root-store/Cargo.toml

@@ -0,0 +1,43 @@
+[package]
+name = "pallet-bridge-proof-root-store"
+version = "0.1.0"
+description = "Module that allows bridged relay chains to exchange information on their parachains' heads."
+authors.workspace = true
+edition.workspace = true
+homepage.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+codec = { features = ["derive"], workspace = true }
+frame-benchmarking = { optional = true, workspace = true }
+frame-support = { workspace = true }
+frame-system = { workspace = true }
+scale-info = { features = ["derive"], workspace = true }
+
+[dev-dependencies]
+bp-proof-root-store = { workspace = true }
+sp-io = { workspace = true }
+
+[features]
+default = ["std"]
+runtime-benchmarks = [
+	"frame-benchmarking",
+	"frame-benchmarking/runtime-benchmarks",
+	"frame-support/runtime-benchmarks",
+	"frame-system/runtime-benchmarks",
+]
+std = [
+	"codec/std",
+	"frame-benchmarking?/std",
+	"frame-support/std",
+	"frame-system/std",
+	"scale-info/std",
+]
+try-runtime = [
+	"frame-support/try-runtime",
+	"frame-system/try-runtime",
+]

bridges/modules/proof-root-store/src/lib.rs

@@ -0,0 +1,174 @@
+// 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.
+
+//! This pallet provides mechanisms for tracking and updating data related to the state root of an
+//! external chain.
+//!
+//! The `T::Value` type represents state root-related data—for example, a `state_root` or
+//! an entire `HeadData` structure.
+//! The `T::Key` type serves as the identifier in the map where we store `T::Value`.
+//! For example, it could be a `block_hash` or `block_number`.
+//!
+//! Example use cases:
+//! 1. Store a `block_hash` → `state_root` mapping.
+//! 2. Store a `block_number` → `HeadData` mapping.
+//!
+//! Root data is stored in a ring buffer, respecting the `T::RootsToKeep` limit.
+//! When the limit is reached, the oldest entries are removed.
+//!
+//! There are two approaches for storing data:
+//! 1. Send root data between chains using the dedicated extrinsic `fn note_new_roots(...)`.
+//! 2. Implement an adapter (e.g., using the `OnSystemEvent` callback) that triggers
+//!    `pallet_bridge_proof_root_store::Pallet::<T, I>::do_note_new_roots(...)`.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
+
+use alloc::collections::VecDeque;
+
+pub use pallet::*;
+pub mod weights;
+pub use weights::WeightInfo;
+
+#[cfg(feature = "runtime-benchmarks")]
+pub mod benchmarking {
+	// TODO: FAIL-CI
+}
+#[cfg(test)]
+mod mock;
+#[cfg(test)]
+mod tests;
+
+#[frame_support::pallet]
+pub mod pallet {
+	use super::*;
+	use frame_support::pallet_prelude::*;
+	use frame_system::pallet_prelude::*;
+
+	/// Configuration trait for the pallet.
+	#[pallet::config]
+	pub trait Config<I: 'static = ()>: frame_system::Config {
+		/// Weight information for extrinsics in this pallet.
+		type WeightInfo: WeightInfo;
+
+		/// The origin allowed to submit head updates.
+		type SubmitOrigin: EnsureOrigin<Self::RuntimeOrigin>;
+
+		/// The key type used to identify stored values of type `T::Value`.
+		type Key: Parameter + MaxEncodedLen;
+
+		/// The type of the root value.
+		type Value: Parameter + MaxEncodedLen;
+
+		/// Maximum number of roots to retain in storage.
+		/// This setting prevents unbounded growth of the on-chain state.
+		#[pallet::constant]
+		type RootsToKeep: Get<u32>;
+	}
+
+	#[pallet::pallet]
+	pub struct Pallet<T, I = ()>(PhantomData<(T, I)>);
+
+	/// Storage for root-related data, bounded by `RootIndex` and `T::RootsToKeep`.
+	#[pallet::storage]
+	pub type Roots<T: Config<I>, I: 'static = ()> =
+		StorageMap<_, Blake2_128Concat, T::Key, T::Value, OptionQuery>;
+
+	/// Storage tracking the insertion order of roots for `T::RootsToKeep` (implemented as a simple
+	/// ring buffer).
+	#[pallet::storage]
+	#[pallet::unbounded]
+	pub type RootIndex<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, VecDeque<T::Key>, ValueQuery>;
+
+	#[pallet::call(weight(<T as Config<I>>::WeightInfo))]
+	impl<T: Config<I>, I: 'static> Pallet<T, I> {
+		/// Records a new root data.
+		#[pallet::call_index(0)]
+		pub fn note_new_roots(
+			origin: OriginFor<T>,
+			roots: BoundedVec<(T::Key, T::Value), T::RootsToKeep>,
+		) -> DispatchResult {
+			let _ = T::SubmitOrigin::ensure_origin(origin);
+			Self::do_note_new_roots(roots);
+			Ok(())
+		}
+	}
+
+	#[pallet::hooks]
+	impl<T: Config<I>, I: 'static> Hooks<BlockNumberFor<T>> for Pallet<T, I> {
+		#[cfg(feature = "try-runtime")]
+		fn try_state(
+			_n: BlockNumberFor<T>,
+		) -> Result<(), frame_support::sp_runtime::TryRuntimeError> {
+			Self::do_try_state()
+		}
+	}
+
+	#[cfg(any(feature = "try-runtime", test))]
+	impl<T: Config<I>, I: 'static> Pallet<T, I> {
+		/// Ensure the correctness of the state of this pallet.
+		pub fn do_try_state() -> Result<(), frame_support::sp_runtime::TryRuntimeError> {
+			// Check that `RootIndex` is aligned with `Roots`.
+			let index = RootIndex::<T, I>::get();
+			ensure!(
+				index.len() == Roots::<T, I>::iter_keys().count(),
+				"`RootIndex` contains different keys than `Roots`"
+			);
+			for key in index {
+				ensure!(
+					Roots::<T, I>::get(key).is_some(),
+					"`Roots` does not contain key from `RootIndex`!"
+				);
+			}
+
+			Ok(())
+		}
+	}
+
+	impl<T: Config<I>, I: 'static> Pallet<T, I> {
+		/// Stores root values.
+		pub fn do_note_new_roots(roots: BoundedVec<(T::Key, T::Value), T::RootsToKeep>) {
+			// Update `RootIndex` ring buffer.
+			RootIndex::<T, I>::mutate(|index| {
+				// Add all at the end.
+				for (key, value) in roots {
+					if !index.contains(&key) {
+						Roots::<T, I>::insert(key.clone(), value);
+						index.push_back(key);
+					}
+				}
+
+				// Remove from the front up to the `T::RootsToKeep` limit.
+				while index.len() > T::RootsToKeep::get() as usize {
+					if let Some(key) = index.pop_front() {
+						Roots::<T, I>::remove(key);
+					}
+				}
+			});
+		}
+
+		/// Returns the stored value for the given key.
+		pub fn get_root(key: &T::Key) -> Option<T::Value> {
+			Roots::<T, I>::get(key)
+		}
+
+		/// Returns the stored `RootIndex` data.
+		pub fn get_root_index() -> VecDeque<T::Key> {
+			RootIndex::<T, I>::get()
+		}
+	}
+}

bridges/modules/proof-root-store/src/mock.rs

@@ -0,0 +1,56 @@
+// 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.
+
+#![cfg(test)]
+
+use crate as pallet_bridge_proof_root_store;
+use frame_support::{
+	derive_impl,
+	sp_runtime::{traits::ConstU32, BuildStorage},
+};
+use frame_system::EnsureRoot;
+
+type Block = frame_system::mocking::MockBlock<TestRuntime>;
+
+frame_support::construct_runtime! {
+	pub enum TestRuntime {
+		System: frame_system,
+		ProofRootStore: pallet_bridge_proof_root_store,
+	}
+}
+
+#[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
+impl frame_system::Config for TestRuntime {
+	type Block = Block;
+}
+
+impl pallet_bridge_proof_root_store::Config for TestRuntime {
+	type WeightInfo = ();
+	type SubmitOrigin = EnsureRoot<u64>;
+	type Key = u8;
+	type Value = u8;
+	type RootsToKeep = ConstU32<4>;
+}
+
+/// Return test externalities to use in tests.
+pub fn new_test_ext() -> sp_io::TestExternalities {
+	let t = frame_system::GenesisConfig::<TestRuntime>::default().build_storage().unwrap();
+	sp_io::TestExternalities::new(t)
+}
+
+/// Run pallet test.
+pub fn run_test<T>(test: impl FnOnce() -> T) -> T {
+	new_test_ext().execute_with(test)
+}