From 28ca8cb8c4f0ed414ee5a3ef765455eec4f259d2 Mon Sep 17 00:00:00 2001 From: Branislav Kontur Date: Tue, 12 Dec 2023 16:04:26 +0100 Subject: [PATCH] Ensure xcm versions over bridge (on sending chains) (#2481) ## Summary This pull request proposes a solution for improved control of the versioned XCM flow over the bridge (across different consensus chains) and resolves the situation where the sending chain/consensus has already migrated to a higher XCM version than the receiving chain/consensus. ## Problem/Motivation The current flow over the bridge involves a transfer from AssetHubRococo (AHR) to BridgeHubRococo (BHR) to BridgeHubWestend (BHW) and finally to AssetHubWestend (AHW), beginning with a reserve-backed transfer on AHR. In this process: 1. AHR sends XCM `ExportMessage` through `XcmpQueue`, incorporating XCM version checks using the `WrapVersion` feature, influenced by `pallet_xcm::SupportedVersion` (managed by `pallet_xcm::force_xcm_version` or version discovery). 2. BHR handles the `ExportMessage` instruction, utilizing the latest XCM version. The `HaulBlobExporter` converts the inner XCM to [`VersionedXcm::from`](https://github.com/paritytech/polkadot-sdk/blob/63ac2471aa0210f0ac9903bdd7d8f9351f9a635f/polkadot/xcm/xcm-builder/src/universal_exports.rs#L465-L467), also using the latest XCM version. However, challenges arise: - Incompatibility when BHW uses a different version than BHR. For instance, if BHR migrates to **XCMv4** while BHW remains on **XCMv3**, BHR's `VersionedXcm::from` uses `VersionedXcm::V4` variant, causing encoding issues for BHW. ``` /// Just a simulation of possible error, which could happen on BHW /// (this code is based on actual master without XCMv4) let encoded = hex_literal::hex!("0400"); println!("{:?}", VersionedXcm::<()>::decode(&mut &encoded[..])); Err(Error { cause: None, desc: "Could not decode `VersionedXcm`, variant doesn't exist" }) ``` - Similar compatibility issues exist between AHR and AHW. ## Solution This pull request introduces the following solutions: 1. **New trait `CheckVersion`** - added to the `xcm` module and exposing `pallet_xcm::SupportedVersion`. This enhancement allows checking the actual XCM version for desired destinations outside of the `pallet_xcm` module. 2. **Version Check in `HaulBlobExporter`** uses `CheckVersion` to check known/configured destination versions, ensuring compatibility. For example, in the scenario mentioned, BHR can store the version `3` for BHW. If BHR is on XCMv4, it will attempt to downgrade the message to version `3` instead of using the latest version `4`. 3. **Version Check in `pallet-xcm-bridge-hub-router`** - this check ensures compatibility with the real destination's XCM version, preventing the unnecessary sending of messages to the local bridge hub if versions are incompatible. These additions aim to improve the control and compatibility of XCM flows over the bridge and addressing issues related to version mismatches. ## Possible alternative solution _(More investigation is needed, and at the very least, it should extend to XCMv4/5. If this proves to be a viable option, I can open an RFC for XCM.)._ Add the `XcmVersion` attribute to the `ExportMessage` so that the sending chain can determine, based on what is stored in `pallet_xcm::SupportedVersion`, the version the destination is using. This way, we may not need to handle the version in `HaulBlobExporter`. ``` ExportMessage { network: NetworkId, destination: InteriorMultiLocation, xcm: Xcm<()> destination_xcm_version: Version, // <- new attritbute }, ``` ``` pub trait ExportXcm { fn validate( network: NetworkId, channel: u32, universal_source: &mut Option, destination: &mut Option, message: &mut Option>, destination_xcm_version: Version, , // <- new attritbute ) -> SendResult; ``` ## Future Directions This PR does not fix version discovery over bridge, further investigation will be conducted here: https://github.com/paritytech/polkadot-sdk/issues/2417. ## TODO - [x] `pallet_xcm` mock for tests uses hard-coded XCM version `2` - change to 3 or lastest? - [x] fix `pallet-xcm-bridge-hub-router` - [x] fix HaulBlobExporter with version determination [here](https://github.com/paritytech/polkadot-sdk/blob/2183669d05f9b510f979a0cc3c7847707bacba2e/polkadot/xcm/xcm-builder/src/universal_exports.rs#L465) - [x] add unit-tests to the runtimes - [x] run benchmarks for `ExportMessage` - [x] extend local run scripts about `force_xcm_version(dest, version)` - [ ] when merged, prepare governance calls for Rococo/Westend - [ ] add PRDoc Part of: https://github.com/paritytech/parity-bridges-common/issues/2719 --------- Co-authored-by: command-bot <> --- pallet-xcm/src/lib.rs | 8 +- pallet-xcm/src/mock.rs | 13 +++- pallet-xcm/src/tests/mod.rs | 73 ++++++++++++++++++- src/lib.rs | 20 ++++- .../src/tests/bridging/local_para_para.rs | 9 ++- .../src/tests/bridging/local_relay_relay.rs | 9 ++- xcm-builder/src/tests/bridging/mod.rs | 1 + .../tests/bridging/paid_remote_relay_relay.rs | 3 +- .../src/tests/bridging/remote_para_para.rs | 3 +- .../bridging/remote_para_para_via_relay.rs | 3 +- .../src/tests/bridging/remote_relay_relay.rs | 3 +- xcm-builder/src/universal_exports.rs | 68 +++++++++++++---- 12 files changed, 186 insertions(+), 27 deletions(-) diff --git a/pallet-xcm/src/lib.rs b/pallet-xcm/src/lib.rs index ab4403f6c..2848527f1 100644 --- a/pallet-xcm/src/lib.rs +++ b/pallet-xcm/src/lib.rs @@ -2591,7 +2591,7 @@ impl WrapVersion for Pallet { dest: &MultiLocation, xcm: impl Into>, ) -> Result, ()> { - SupportedVersion::::get(XCM_VERSION, LatestVersionedMultiLocation(dest)) + Self::get_version_for(dest) .or_else(|| { Self::note_unknown_version(dest); SafeXcmVersion::::get() @@ -2608,6 +2608,12 @@ impl WrapVersion for Pallet { } } +impl GetVersion for Pallet { + fn get_version_for(dest: &MultiLocation) -> Option { + SupportedVersion::::get(XCM_VERSION, LatestVersionedMultiLocation(dest)) + } +} + impl VersionChangeNotifier for Pallet { /// Start notifying `location` should the XCM version of this chain change. /// diff --git a/pallet-xcm/src/mock.rs b/pallet-xcm/src/mock.rs index e7f5870c9..2443d3a9c 100644 --- a/pallet-xcm/src/mock.rs +++ b/pallet-xcm/src/mock.rs @@ -655,6 +655,17 @@ pub(crate) fn buy_limited_execution( pub(crate) fn new_test_ext_with_balances( balances: Vec<(AccountId, Balance)>, +) -> sp_io::TestExternalities { + new_test_ext_with_balances_and_xcm_version( + balances, + // By default set actual latest XCM version + Some(XCM_VERSION), + ) +} + +pub(crate) fn new_test_ext_with_balances_and_xcm_version( + balances: Vec<(AccountId, Balance)>, + safe_xcm_version: Option, ) -> sp_io::TestExternalities { let mut t = frame_system::GenesisConfig::::default().build_storage().unwrap(); @@ -662,7 +673,7 @@ pub(crate) fn new_test_ext_with_balances( .assimilate_storage(&mut t) .unwrap(); - pallet_xcm::GenesisConfig:: { safe_xcm_version: Some(2), ..Default::default() } + pallet_xcm::GenesisConfig:: { safe_xcm_version, ..Default::default() } .assimilate_storage(&mut t) .unwrap(); diff --git a/pallet-xcm/src/tests/mod.rs b/pallet-xcm/src/tests/mod.rs index 5829eb6ed..e7a6fdc9d 100644 --- a/pallet-xcm/src/tests/mod.rs +++ b/pallet-xcm/src/tests/mod.rs @@ -774,12 +774,13 @@ fn subscription_side_upgrades_work_without_notify() { #[test] fn subscriber_side_subscription_works() { - new_test_ext_with_balances(vec![]).execute_with(|| { + new_test_ext_with_balances_and_xcm_version(vec![], Some(XCM_VERSION)).execute_with(|| { let remote: MultiLocation = Parachain(1000).into(); assert_ok!(XcmPallet::force_subscribe_version_notify( RuntimeOrigin::root(), Box::new(remote.into()), )); + assert_eq!(XcmPallet::get_version_for(&remote), None); take_sent_xcm(); // Assume subscription target is working ok. @@ -798,6 +799,7 @@ fn subscriber_side_subscription_works() { let r = XcmExecutor::::execute_xcm(remote, message, hash, weight); assert_eq!(r, Outcome::Complete(weight)); assert_eq!(take_sent_xcm(), vec![]); + assert_eq!(XcmPallet::get_version_for(&remote), Some(1)); // This message cannot be sent to a v2 remote. let v2_msg = xcm::v2::Xcm::<()>(vec![xcm::v2::Instruction::Trap(0)]); @@ -815,6 +817,8 @@ fn subscriber_side_subscription_works() { let hash = fake_message_hash(&message); let r = XcmExecutor::::execute_xcm(remote, message, hash, weight); assert_eq!(r, Outcome::Complete(weight)); + assert_eq!(take_sent_xcm(), vec![]); + assert_eq!(XcmPallet::get_version_for(&remote), Some(2)); // This message can now be sent to remote as it's v2. assert_eq!( @@ -827,7 +831,7 @@ fn subscriber_side_subscription_works() { /// We should auto-subscribe when we don't know the remote's version. #[test] fn auto_subscription_works() { - new_test_ext_with_balances(vec![]).execute_with(|| { + new_test_ext_with_balances_and_xcm_version(vec![], None).execute_with(|| { let remote_v2: MultiLocation = Parachain(1000).into(); let remote_v3: MultiLocation = Parachain(1001).into(); @@ -995,3 +999,68 @@ fn subscription_side_upgrades_work_with_multistage_notify() { ); }); } + +#[test] +fn get_and_wrap_version_works() { + new_test_ext_with_balances_and_xcm_version(vec![], None).execute_with(|| { + let remote_a: MultiLocation = Parachain(1000).into(); + let remote_b: MultiLocation = Parachain(1001).into(); + let remote_c: MultiLocation = Parachain(1002).into(); + + // no `safe_xcm_version` version at `GenesisConfig` + assert_eq!(XcmPallet::get_version_for(&remote_a), None); + assert_eq!(XcmPallet::get_version_for(&remote_b), None); + assert_eq!(XcmPallet::get_version_for(&remote_c), None); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![]); + + // set default XCM version (a.k.a. `safe_xcm_version`) + assert_ok!(XcmPallet::force_default_xcm_version(RuntimeOrigin::root(), Some(1))); + assert_eq!(XcmPallet::get_version_for(&remote_a), None); + assert_eq!(XcmPallet::get_version_for(&remote_b), None); + assert_eq!(XcmPallet::get_version_for(&remote_c), None); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![]); + + // set XCM version only for `remote_a` + assert_ok!(XcmPallet::force_xcm_version( + RuntimeOrigin::root(), + Box::new(remote_a), + XCM_VERSION + )); + assert_eq!(XcmPallet::get_version_for(&remote_a), Some(XCM_VERSION)); + assert_eq!(XcmPallet::get_version_for(&remote_b), None); + assert_eq!(XcmPallet::get_version_for(&remote_c), None); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![]); + + let xcm = Xcm::<()>::default(); + + // wrap version - works because remote_a has `XCM_VERSION` + assert_eq!( + XcmPallet::wrap_version(&remote_a, xcm.clone()), + Ok(VersionedXcm::from(xcm.clone())) + ); + // does not work because remote_b has unknown version and default is set to 1, and + // `XCM_VERSION` cannot be wrapped to the `1` + assert_eq!(XcmPallet::wrap_version(&remote_b, xcm.clone()), Err(())); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![(remote_b.into(), 1)]); + + // set default to the `XCM_VERSION` + assert_ok!(XcmPallet::force_default_xcm_version(RuntimeOrigin::root(), Some(XCM_VERSION))); + assert_eq!(XcmPallet::get_version_for(&remote_b), None); + assert_eq!(XcmPallet::get_version_for(&remote_c), None); + + // now works, because default is `XCM_VERSION` + assert_eq!( + XcmPallet::wrap_version(&remote_b, xcm.clone()), + Ok(VersionedXcm::from(xcm.clone())) + ); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![(remote_b.into(), 2)]); + + // change remote_c to `1` + assert_ok!(XcmPallet::force_xcm_version(RuntimeOrigin::root(), Box::new(remote_c), 1)); + + // does not work because remote_c has `1` and default is `XCM_VERSION` which cannot be + // wrapped to the `1` + assert_eq!(XcmPallet::wrap_version(&remote_c, xcm.clone()), Err(())); + assert_eq!(VersionDiscoveryQueue::::get().into_inner(), vec![(remote_b.into(), 2)]); + }) +} diff --git a/src/lib.rs b/src/lib.rs index d804e4bf7..ddad0b530 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -373,6 +373,12 @@ pub trait WrapVersion { ) -> Result, ()>; } +/// Check and return the `Version` that should be used for the `Xcm` datum for the destination +/// `MultiLocation`, which will interpret it. +pub trait GetVersion { + fn get_version_for(dest: &latest::MultiLocation) -> Option; +} + /// `()` implementation does nothing with the XCM, just sending with whatever version it was /// authored as. impl WrapVersion for () { @@ -395,6 +401,11 @@ impl WrapVersion for AlwaysV2 { Ok(VersionedXcm::::V2(xcm.into().try_into()?)) } } +impl GetVersion for AlwaysV2 { + fn get_version_for(_dest: &latest::MultiLocation) -> Option { + Some(v2::VERSION) + } +} /// `WrapVersion` implementation which attempts to always convert the XCM to version 3 before /// wrapping it. @@ -407,6 +418,11 @@ impl WrapVersion for AlwaysV3 { Ok(VersionedXcm::::V3(xcm.into().try_into()?)) } } +impl GetVersion for AlwaysV3 { + fn get_version_for(_dest: &latest::MultiLocation) -> Option { + Some(v3::VERSION) + } +} /// `WrapVersion` implementation which attempts to always convert the XCM to the latest version /// before wrapping it. @@ -418,8 +434,8 @@ pub type AlwaysLts = AlwaysV3; pub mod prelude { pub use super::{ - latest::prelude::*, AlwaysLatest, AlwaysLts, AlwaysV2, AlwaysV3, IntoVersion, Unsupported, - Version as XcmVersion, VersionedAssetId, VersionedInteriorMultiLocation, + latest::prelude::*, AlwaysLatest, AlwaysLts, AlwaysV2, AlwaysV3, GetVersion, IntoVersion, + Unsupported, Version as XcmVersion, VersionedAssetId, VersionedInteriorMultiLocation, VersionedMultiAsset, VersionedMultiAssets, VersionedMultiLocation, VersionedResponse, VersionedXcm, WrapVersion, }; diff --git a/xcm-builder/src/tests/bridging/local_para_para.rs b/xcm-builder/src/tests/bridging/local_para_para.rs index de08dbee9..b1361cc85 100644 --- a/xcm-builder/src/tests/bridging/local_para_para.rs +++ b/xcm-builder/src/tests/bridging/local_para_para.rs @@ -23,11 +23,16 @@ use super::*; parameter_types! { pub UniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(1)); pub RemoteUniversalLocation: Junctions = X2(GlobalConsensus(Remote::get()), Parachain(1)); + pub RemoteNetwork: MultiLocation = AncestorThen(2, GlobalConsensus(Remote::get())).into(); } type TheBridge = TestBridge>; -type Router = - TestTopic, UniversalLocation>>; +type Router = TestTopic< + UnpaidLocalExporter< + HaulBlobExporter, + UniversalLocation, + >, +>; /// ```nocompile /// local | remote diff --git a/xcm-builder/src/tests/bridging/local_relay_relay.rs b/xcm-builder/src/tests/bridging/local_relay_relay.rs index 8433b6e02..5371abccf 100644 --- a/xcm-builder/src/tests/bridging/local_relay_relay.rs +++ b/xcm-builder/src/tests/bridging/local_relay_relay.rs @@ -23,11 +23,16 @@ use super::*; parameter_types! { pub UniversalLocation: Junctions = X1(GlobalConsensus(Local::get())); pub RemoteUniversalLocation: Junctions = X1(GlobalConsensus(Remote::get())); + pub RemoteNetwork: MultiLocation = AncestorThen(1, GlobalConsensus(Remote::get())).into(); } type TheBridge = TestBridge>; -type Router = - TestTopic, UniversalLocation>>; +type Router = TestTopic< + UnpaidLocalExporter< + HaulBlobExporter, + UniversalLocation, + >, +>; /// ```nocompile /// local | remote diff --git a/xcm-builder/src/tests/bridging/mod.rs b/xcm-builder/src/tests/bridging/mod.rs index 45630dbfc..0c749b66d 100644 --- a/xcm-builder/src/tests/bridging/mod.rs +++ b/xcm-builder/src/tests/bridging/mod.rs @@ -20,6 +20,7 @@ use super::mock::*; use crate::{universal_exports::*, WithTopicSource}; use frame_support::{parameter_types, traits::Get}; use std::{cell::RefCell, marker::PhantomData}; +use xcm::AlwaysLatest; use xcm_executor::{ traits::{export_xcm, validate_export}, XcmExecutor, diff --git a/xcm-builder/src/tests/bridging/paid_remote_relay_relay.rs b/xcm-builder/src/tests/bridging/paid_remote_relay_relay.rs index 23d6eb99a..079eb0175 100644 --- a/xcm-builder/src/tests/bridging/paid_remote_relay_relay.rs +++ b/xcm-builder/src/tests/bridging/paid_remote_relay_relay.rs @@ -30,6 +30,7 @@ parameter_types! { pub UniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(100)); pub RelayUniversalLocation: Junctions = X1(GlobalConsensus(Local::get())); pub RemoteUniversalLocation: Junctions = X1(GlobalConsensus(Remote::get())); + pub RemoteNetwork: MultiLocation = AncestorThen(1, GlobalConsensus(Remote::get())).into(); pub BridgeTable: Vec = vec![ NetworkExportTableItem::new( Remote::get(), @@ -41,7 +42,7 @@ parameter_types! { } type TheBridge = TestBridge>; -type RelayExporter = HaulBlobExporter; +type RelayExporter = HaulBlobExporter; type LocalInnerRouter = ExecutingRouter; type LocalBridgeRouter = SovereignPaidRemoteExporter< NetworkExportTable, diff --git a/xcm-builder/src/tests/bridging/remote_para_para.rs b/xcm-builder/src/tests/bridging/remote_para_para.rs index f11143ab9..fb6c5da3e 100644 --- a/xcm-builder/src/tests/bridging/remote_para_para.rs +++ b/xcm-builder/src/tests/bridging/remote_para_para.rs @@ -24,6 +24,7 @@ parameter_types! { pub UniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(1000)); pub ParaBridgeUniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(1)); pub RemoteParaBridgeUniversalLocation: Junctions = X2(GlobalConsensus(Remote::get()), Parachain(1)); + pub RemoteNetwork: MultiLocation = AncestorThen(2, GlobalConsensus(Remote::get())).into(); pub BridgeTable: Vec = vec![ NetworkExportTableItem::new( Remote::get(), @@ -36,7 +37,7 @@ parameter_types! { type TheBridge = TestBridge< BridgeBlobDispatcher, >; -type RelayExporter = HaulBlobExporter; +type RelayExporter = HaulBlobExporter; type LocalInnerRouter = UnpaidExecutingRouter; type LocalBridgingRouter = diff --git a/xcm-builder/src/tests/bridging/remote_para_para_via_relay.rs b/xcm-builder/src/tests/bridging/remote_para_para_via_relay.rs index 7218e0a04..0b6dc01e2 100644 --- a/xcm-builder/src/tests/bridging/remote_para_para_via_relay.rs +++ b/xcm-builder/src/tests/bridging/remote_para_para_via_relay.rs @@ -24,6 +24,7 @@ parameter_types! { pub UniversalLocation: Junctions = X1(GlobalConsensus(Local::get())); pub ParaBridgeUniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(1)); pub RemoteParaBridgeUniversalLocation: Junctions = X2(GlobalConsensus(Remote::get()), Parachain(1)); + pub RemoteNetwork: MultiLocation = AncestorThen(2, GlobalConsensus(Remote::get())).into(); pub BridgeTable: Vec = vec![ NetworkExportTableItem::new( Remote::get(), @@ -36,7 +37,7 @@ parameter_types! { type TheBridge = TestBridge< BridgeBlobDispatcher, >; -type RelayExporter = HaulBlobExporter; +type RelayExporter = HaulBlobExporter; type LocalInnerRouter = UnpaidExecutingRouter; type LocalBridgingRouter = diff --git a/xcm-builder/src/tests/bridging/remote_relay_relay.rs b/xcm-builder/src/tests/bridging/remote_relay_relay.rs index 45b5efbc4..e33c7b15b 100644 --- a/xcm-builder/src/tests/bridging/remote_relay_relay.rs +++ b/xcm-builder/src/tests/bridging/remote_relay_relay.rs @@ -24,6 +24,7 @@ parameter_types! { pub UniversalLocation: Junctions = X2(GlobalConsensus(Local::get()), Parachain(1000)); pub RelayUniversalLocation: Junctions = X1(GlobalConsensus(Local::get())); pub RemoteUniversalLocation: Junctions = X1(GlobalConsensus(Remote::get())); + pub RemoteNetwork: MultiLocation = AncestorThen(1, GlobalConsensus(Remote::get())).into(); pub BridgeTable: Vec = vec![ NetworkExportTableItem::new( Remote::get(), @@ -35,7 +36,7 @@ parameter_types! { } type TheBridge = TestBridge>; -type RelayExporter = HaulBlobExporter; +type RelayExporter = HaulBlobExporter; type LocalInnerRouter = UnpaidExecutingRouter; type LocalBridgeRouter = diff --git a/xcm-builder/src/universal_exports.rs b/xcm-builder/src/universal_exports.rs index 8e2cf88b3..4aa6a0ef7 100644 --- a/xcm-builder/src/universal_exports.rs +++ b/xcm-builder/src/universal_exports.rs @@ -422,11 +422,25 @@ impl< } } -pub struct HaulBlobExporter( - PhantomData<(Bridge, BridgedNetwork, Price)>, +pub struct HaulBlobExporter( + PhantomData<(Bridge, BridgedNetwork, DestinationVersion, Price)>, ); -impl, Price: Get> ExportXcm - for HaulBlobExporter +/// `ExportXcm` implementation for `HaulBlobExporter`. +/// +/// # Type Parameters +/// +/// ```text +/// - Bridge: Implements `HaulBlob`. +/// - BridgedNetwork: The relative location of the bridged consensus system with the expected `GlobalConsensus` junction. +/// - DestinationVersion: Implements `GetVersion` for retrieving XCM version for the destination. +/// - Price: potential fees for exporting. +/// ``` +impl< + Bridge: HaulBlob, + BridgedNetwork: Get, + DestinationVersion: GetVersion, + Price: Get, + > ExportXcm for HaulBlobExporter { type Ticket = (Vec, XcmHash); @@ -437,17 +451,35 @@ impl, Price: Get> destination: &mut Option, message: &mut Option>, ) -> Result<((Vec, XcmHash), MultiAssets), SendError> { - let bridged_network = BridgedNetwork::get(); + let (bridged_network, bridged_network_location_parents) = { + let MultiLocation { parents, interior: mut junctions } = BridgedNetwork::get(); + match junctions.take_first() { + Some(GlobalConsensus(network)) => (network, parents), + _ => return Err(SendError::NotApplicable), + } + }; ensure!(&network == &bridged_network, SendError::NotApplicable); // We don't/can't use the `channel` for this adapter. let dest = destination.take().ok_or(SendError::MissingArgument)?; - let universal_dest = match dest.pushed_front_with(GlobalConsensus(bridged_network)) { - Ok(d) => d.into(), - Err((dest, _)) => { - *destination = Some(dest); - return Err(SendError::NotApplicable) - }, - }; + + // Let's resolve the known/supported XCM version for the destination because we don't know + // if it supports the same/latest version. + let (universal_dest, version) = + match dest.pushed_front_with(GlobalConsensus(bridged_network)) { + Ok(d) => { + let version = DestinationVersion::get_version_for(&MultiLocation::from( + AncestorThen(bridged_network_location_parents, d), + )) + .ok_or(SendError::DestinationUnsupported)?; + (d, version) + }, + Err((dest, _)) => { + *destination = Some(dest); + return Err(SendError::NotApplicable) + }, + }; + + // Let's adjust XCM with `UniversalOrigin`, `DescendOrigin` and`SetTopic`. let (local_net, local_sub) = universal_source .take() .ok_or(SendError::MissingArgument)? @@ -462,7 +494,17 @@ impl, Price: Get> if local_sub != Here { message.0.insert(1, DescendOrigin(local_sub)); } - let message = VersionedXcm::from(message); + + // We cannot use the latest `Versioned` because we don't know if the target chain already + // supports the same version. Therefore, we better control the destination version with best + // efforts. + let message = VersionedXcm::from(message) + .into_version(version) + .map_err(|()| SendError::DestinationUnsupported)?; + let universal_dest = VersionedInteriorMultiLocation::from(universal_dest) + .into_version(version) + .map_err(|()| SendError::DestinationUnsupported)?; + 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()))