[xcm] Extend haul_blob with Channel + include NetworkId to channel id (origin/(network, destination))

xcm/xcm-builder/src/tests/bridging/mod.rs

@@ -21,7 +21,7 @@ use crate::{universal_exports::*, WithTopicSource};
 use frame_support::{parameter_types, traits::Get};
 use std::{cell::RefCell, marker::PhantomData};
 use xcm_executor::{
-	traits::{export_xcm, validate_export},
+	traits::{export_xcm, validate_export, Channel},
 	XcmExecutor,
 };
 use SendError::*;
@@ -112,7 +112,7 @@ impl<D: DispatchBlob> TestBridge<D> {
 	}
 }
 impl<D: DispatchBlob> HaulBlob for TestBridge<D> {
-	fn haul_blob(blob: Vec<u8>) -> Result<(), HaulBlobError> {
+	fn haul_blob(blob: Vec<u8>, _channel: Channel) -> Result<(), HaulBlobError> {
 		BRIDGE_TRAFFIC.with(|t| t.borrow_mut().push(blob));
 		Ok(())
 	}

xcm/xcm-builder/src/tests/origins.rs

@@ -94,7 +94,7 @@ fn export_message_should_work() {
 	let uni_src = (ByGenesis([0; 32]), Parachain(42), Parachain(1)).into();
 	assert_eq!(
 		exported_xcm(),
-		vec![(Polkadot, 403611790, uni_src, Here, expected_message, expected_hash)]
+		vec![(Polkadot, 470110423, uni_src, Here, expected_message, expected_hash)]
 	);
 }
 

xcm/xcm-builder/src/universal_exports.rs

@@ -20,7 +20,7 @@ use frame_support::{ensure, traits::Get};
 use parity_scale_codec::{Decode, Encode};
 use sp_std::{convert::TryInto, marker::PhantomData, prelude::*};
 use xcm::prelude::*;
-use xcm_executor::traits::{validate_export, ExportXcm};
+use xcm_executor::traits::{validate_export, Channel, ExportXcm};
 use SendError::*;
 
 /// Returns the network ID and consensus location within that network of the remote
@@ -295,7 +295,7 @@ pub trait DispatchBlob {
 
 pub trait HaulBlob {
 	/// Sends a blob over some point-to-point link. This will generally be implemented by a bridge.
-	fn haul_blob(blob: Vec<u8>) -> Result<(), HaulBlobError>;
+	fn haul_blob(blob: Vec<u8>, channel: Channel) -> Result<(), HaulBlobError>;
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -365,15 +365,15 @@ pub struct HaulBlobExporter<Bridge, BridgedNetwork, Price>(
 impl<Bridge: HaulBlob, BridgedNetwork: Get<NetworkId>, Price: Get<MultiAssets>> ExportXcm
 	for HaulBlobExporter<Bridge, BridgedNetwork, Price>
 {
-	type Ticket = (Vec<u8>, XcmHash);
+	type Ticket = (Vec<u8>, XcmHash, Channel);
 
 	fn validate(
 		network: NetworkId,
-		_channel: u32,
+		channel: Channel,
 		universal_source: &mut Option<InteriorMultiLocation>,
 		destination: &mut Option<InteriorMultiLocation>,
 		message: &mut Option<Xcm<()>>,
-	) -> Result<((Vec<u8>, XcmHash), MultiAssets), SendError> {
+	) -> Result<(Self::Ticket, MultiAssets), SendError> {
 		let bridged_network = BridgedNetwork::get();
 		ensure!(&network == &bridged_network, SendError::NotApplicable);
 		// We don't/can't use the `channel` for this adapter.
@@ -402,11 +402,11 @@ impl<Bridge: HaulBlob, BridgedNetwork: Get<NetworkId>, Price: Get<MultiAssets>>
 		let message = VersionedXcm::from(message);
 		let id = maybe_id.unwrap_or_else(|| message.using_encoded(sp_io::hashing::blake2_256));
 		let blob = BridgeMessage { universal_dest, message }.encode();
-		Ok(((blob, id), Price::get()))
+		Ok(((blob, id, channel), Price::get()))
 	}
 
-	fn deliver((blob, id): (Vec<u8>, XcmHash)) -> Result<XcmHash, SendError> {
-		Bridge::haul_blob(blob)?;
+	fn deliver((blob, id, channel): Self::Ticket) -> Result<XcmHash, SendError> {
+		Bridge::haul_blob(blob, channel)?;
 		Ok(id)
 	}
 }

xcm/xcm-executor/src/lib.rs

@@ -21,18 +21,17 @@ use frame_support::{
 	ensure,
 	traits::{Contains, ContainsPair, Get, PalletsInfoAccess},
 };
-use parity_scale_codec::{Decode, Encode};
+use parity_scale_codec::Encode;
 use sp_core::defer;
-use sp_io::hashing::blake2_128;
 use sp_std::{marker::PhantomData, prelude::*};
 use sp_weights::Weight;
 use xcm::latest::prelude::*;
 
 pub mod traits;
 use traits::{
-	validate_export, AssetExchange, AssetLock, CallDispatcher, ClaimAssets, ConvertOrigin,
-	DropAssets, Enact, ExportXcm, FeeManager, FeeReason, OnResponse, Properties, ShouldExecute,
-	TransactAsset, VersionChangeNotifier, WeightBounds, WeightTrader,
+	channel_from_params, validate_export, AssetExchange, AssetLock, CallDispatcher, ClaimAssets,
+	ConvertOrigin, DropAssets, Enact, ExportXcm, FeeManager, FeeReason, OnResponse, Properties,
+	ShouldExecute, TransactAsset, VersionChangeNotifier, WeightBounds, WeightTrader,
 };
 
 mod assets;
@@ -834,11 +833,7 @@ impl<Config: config::Config> XcmExecutor<Config> {
 				let universal_source = Config::UniversalLocation::get()
 					.within_global(origin)
 					.map_err(|()| XcmError::Unanchored)?;
-				let hash = (self.origin_ref(), &destination).using_encoded(blake2_128);
-				let channel = u32::decode(&mut hash.as_ref()).unwrap_or(0);
-				// Hash identifies the lane on the exporter which we use. We use the pairwise
-				// combination of the origin and destination to ensure origin/destination pairs will
-				// generally have their own lanes.
+				let channel = channel_from_params(self.origin_ref(), &network, &destination);
 				let (ticket, fee) = validate_export::<Config::MessageExporter>(
 					network,
 					channel,

xcm/xcm-executor/src/traits/export.rs

@@ -16,6 +16,24 @@
 
 use xcm::latest::prelude::*;
 
+/// An identifier for a channel.
+pub type Channel = u32;
+
+/// Generates channel identifier for `origin/(network, destination)` combination to ensure using separated lanes.
+pub fn channel_from_params(
+	origin_ref: Option<&MultiLocation>,
+	network: &NetworkId,
+	destination: &InteriorMultiLocation,
+) -> Channel {
+	use parity_scale_codec::{Decode, Encode};
+	// Hash identifies the lane on the exporter which we use. We use the pairwise
+	// combination of the origin and (network, destination) to ensure origin/(network, destination) pairs will
+	// generally have their own lanes.
+	let hash = (origin_ref, (network, destination)).using_encoded(sp_io::hashing::blake2_256);
+	let channel = u32::decode(&mut hash.as_ref()).unwrap_or(0);
+	channel
+}
+
 /// Utility for delivering a message to a system under a different (non-local) consensus with a
 /// spoofed origin. This essentially defines the behaviour of the `ExportMessage` XCM instruction.
 ///
@@ -50,7 +68,7 @@ pub trait ExportXcm {
 	/// early without trying alternative means of delivery.
 	fn validate(
 		network: NetworkId,
-		channel: u32,
+		channel: Channel,
 		universal_source: &mut Option<InteriorMultiLocation>,
 		destination: &mut Option<InteriorMultiLocation>,
 		message: &mut Option<Xcm<()>>,
@@ -70,7 +88,7 @@ impl ExportXcm for Tuple {
 
 	fn validate(
 		network: NetworkId,
-		channel: u32,
+		channel: Channel,
 		universal_source: &mut Option<InteriorMultiLocation>,
 		destination: &mut Option<InteriorMultiLocation>,
 		message: &mut Option<Xcm<()>>,
@@ -111,7 +129,7 @@ impl ExportXcm for Tuple {
 /// both in `Some` before passing them as as mutable references into `T::send_xcm`.
 pub fn validate_export<T: ExportXcm>(
 	network: NetworkId,
-	channel: u32,
+	channel: Channel,
 	universal_source: InteriorMultiLocation,
 	dest: InteriorMultiLocation,
 	msg: Xcm<()>,
@@ -129,7 +147,7 @@ pub fn validate_export<T: ExportXcm>(
 /// before actually doing the delivery.
 pub fn export_xcm<T: ExportXcm>(
 	network: NetworkId,
-	channel: u32,
+	channel: Channel,
 	universal_source: InteriorMultiLocation,
 	dest: InteriorMultiLocation,
 	msg: Xcm<()>,
@@ -144,3 +162,39 @@ pub fn export_xcm<T: ExportXcm>(
 	let hash = T::deliver(ticket)?;
 	Ok((hash, price))
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use std::collections::HashSet;
+
+	#[test]
+	fn channel_from_params_works() {
+		let params: Vec<(Option<MultiLocation>, &NetworkId, &InteriorMultiLocation)> = vec![
+			// different interior
+			(None, &ByGenesis([0; 32]), &X1(Parachain(1234))),
+			(None, &ByGenesis([0; 32]), &X1(Parachain(1235))),
+			// different networkId
+			(None, &ByGenesis([0; 32]), &X1(Parachain(1236))),
+			(None, &ByGenesis([1; 32]), &X1(Parachain(1236))),
+			// different origin
+			(None, &ByGenesis([0; 32]), &X1(Parachain(1237))),
+			(Some(MultiLocation::here()), &ByGenesis([0; 32]), &X1(Parachain(1237))),
+			(Some(MultiLocation::parent()), &ByGenesis([0; 32]), &X1(Parachain(1237))),
+		];
+
+		// check unique
+		let channels: HashSet<Channel> =
+			HashSet::from_iter(params.iter().map(|(origin, network, interior)| {
+				channel_from_params(origin.as_ref(), network, interior)
+			}));
+		assert_eq!(params.len(), channels.len());
+
+		// check not random
+		assert_eq!(
+			channel_from_params(None, &ByGenesis([0; 32]), &X1(Parachain(1234))),
+			channel_from_params(None, &ByGenesis([0; 32]), &X1(Parachain(1234)))
+		);
+		assert_eq!(channel_from_params(Some(&Parachain(1).into()), &Polkadot, &Here), 470110423);
+	}
+}

xcm/xcm-executor/src/traits/mod.rs

@@ -25,7 +25,7 @@ pub use asset_lock::{AssetLock, Enact, LockError};
 mod asset_exchange;
 pub use asset_exchange::AssetExchange;
 mod export;
-pub use export::{export_xcm, validate_export, ExportXcm};
+pub use export::{channel_from_params, export_xcm, validate_export, Channel, ExportXcm};
 mod fee_manager;
 pub use fee_manager::{FeeManager, FeeReason};
 mod filter_asset_location;