bridge_hub_common/

barriers.rs

// 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.

use core::{marker::PhantomData, ops::ControlFlow};
use cumulus_primitives_core::Weight;
use frame_support::traits::{Contains, ProcessMessageError};
use xcm::prelude::{ExportMessage, Instruction, Location, NetworkId};

use xcm_builder::{CreateMatcher, MatchXcm};
use xcm_executor::traits::{DenyExecution, Properties};

/// Deny execution if the message contains instruction `ExportMessage` with
/// a. origin is contained in `FromOrigin` (i.e.`FromOrigin::Contains(origin)`)
/// b. network is contained in `ToGlobalConsensus`, (i.e. `ToGlobalConsensus::contains(network)`)
pub struct DenyExportMessageFrom<FromOrigin, ToGlobalConsensus>(
	PhantomData<(FromOrigin, ToGlobalConsensus)>,
);

impl<FromOrigin, ToGlobalConsensus> DenyExecution
	for DenyExportMessageFrom<FromOrigin, ToGlobalConsensus>
where
	FromOrigin: Contains<Location>,
	ToGlobalConsensus: Contains<NetworkId>,
{
	fn deny_execution<RuntimeCall>(
		origin: &Location,
		message: &mut [Instruction<RuntimeCall>],
		_max_weight: Weight,
		_properties: &mut Properties,
	) -> Result<(), ProcessMessageError> {
		// This barrier only cares about messages with `origin` matching `FromOrigin`.
		if !FromOrigin::contains(origin) {
			return Ok(())
		}
		message.matcher().match_next_inst_while(
			|_| true,
			|inst| match inst {
				ExportMessage { network, .. } if ToGlobalConsensus::contains(network) =>
					Err(ProcessMessageError::Unsupported),
				_ => Ok(ControlFlow::Continue(())),
			},
		)?;
		Ok(())
	}
}