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Branislav Kontur 575b8f8d15 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<InteriorMultiLocation>,
		destination: &mut Option<InteriorMultiLocation>,
		message: &mut Option<Xcm<()>>,
                destination_xcm_version: Version, , // <- new attritbute
	) -> SendResult<Self::Ticket>;
```

## 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 <>

2023-12-12 17:04:26 +02:00

bridge-hub-rococo

Ensure xcm versions over bridge (on sending chains) (#2481 )

2023-12-12 17:04:26 +02:00

bridge-hub-westend

Ensure xcm versions over bridge (on sending chains) (#2481 )

2023-12-12 17:04:26 +02:00

docs

BridgeHubKusama - initial setup - (chain_spec + basic runtime without any bridging pallets) (#1764 )

2022-12-02 14:06:39 +01:00

test-utils

Ensure xcm versions over bridge (on sending chains) (#2481 )

2023-12-12 17:04:26 +02:00

README.md

[testnet] Remove Wococo stuff from BridgeHubRococo/AssetHubRococo (#2300 )

2023-11-15 17:40:07 +02:00

README.md

Bridge-hub Parachains

Bridge-hub Parachains

BridgeHub(s) are system parachains that will house trustless bridges from the local ecosystem to others. The current trustless bridges planned for the BridgeHub(s) are:

BridgeHubPolkadot system parachain:
1. Polkadot <-> Kusama bridge
2. Polkadot <-> Ethereum bridge (Snowbridge)
BridgeHubKusama system parachain:
1. Kusama <-> Polkadot bridge
2. Kusama <-> Ethereum bridge The high-level responsibilities of each bridge living on BridgeHub:
sync finality proofs between relay chains (or equivalent)
sync finality proofs between BridgeHub parachains
pass (XCM) messages between different BridgeHub parachains

Requirements for local run/testing

# Prepare empty directory for testing
mkdir -p ~/local_bridge_testing/bin
mkdir -p ~/local_bridge_testing/logs

---
# 1. Install zombienet
Go to: https://github.com/paritytech/zombienet/releases
Copy the apropriate binary (zombienet-linux) from the latest release to ~/local_bridge_testing/bin


---
# 2. Build polkadot binary

We need polkadot binary with "fast-runtime" feature:

cd <polkadot-sdk-git-repo-dir>
cargo build --release --features fast-runtime --bin polkadot
cp target/release/polkadot ~/local_bridge_testing/bin/polkadot

cargo build --release --features fast-runtime --bin polkadot-prepare-worker
cp target/release/polkadot-prepare-worker ~/local_bridge_testing/bin/polkadot-prepare-worker

cargo build --release --features fast-runtime --bin polkadot-execute-worker
cp target/release/polkadot-execute-worker ~/local_bridge_testing/bin/polkadot-execute-worker


---
# 3. Build substrate-relay binary
git clone https://github.com/paritytech/parity-bridges-common.git
cd parity-bridges-common

# checkout desired branch or use master:
# git checkout -b master --track origin/master
# `polkadot-staging` (recommended) is stabilized and compatible for Cumulus releases
# `master` is latest development
git checkout -b polkadot-staging --track origin/polkadot-staging

cargo build --release -p substrate-relay
cp target/release/substrate-relay ~/local_bridge_testing/bin/substrate-relay


---
# 4. Build cumulus polkadot-parachain binary
cd <polkadot-sdk-git-repo-dir>

cargo build --release -p polkadot-parachain-bin
cp target/release/polkadot-parachain ~/local_bridge_testing/bin/polkadot-parachain
cp target/release/polkadot-parachain ~/local_bridge_testing/bin/polkadot-parachain-asset-hub

How to test local Rococo <-> Westend bridge

Run Rococo/Westend chains with zombienet

cd <polkadot-sdk-git-repo-dir>

# Rococo + BridgeHubRococo + AssetHub for Rococo (mirroring Kusama)
POLKADOT_BINARY_PATH=~/local_bridge_testing/bin/polkadot \
POLKADOT_PARACHAIN_BINARY_PATH=~/local_bridge_testing/bin/polkadot-parachain \
POLKADOT_PARACHAIN_BINARY_PATH_FOR_ASSET_HUB_ROCOCO=~/local_bridge_testing/bin/polkadot-parachain-asset-hub \
	~/local_bridge_testing/bin/zombienet-linux --provider native spawn ./cumulus/zombienet/bridge-hubs/bridge_hub_rococo_local_network.toml

cd <polkadot-sdk-git-repo-dir>

# Westend + BridgeHubWestend + AssetHub for Westend (mirroring Polkadot)
POLKADOT_BINARY_PATH=~/local_bridge_testing/bin/polkadot \
POLKADOT_PARACHAIN_BINARY_PATH=~/local_bridge_testing/bin/polkadot-parachain \
POLKADOT_PARACHAIN_BINARY_PATH_FOR_ASSET_HUB_WESTEND=~/local_bridge_testing/bin/polkadot-parachain-asset-hub \
	~/local_bridge_testing/bin/zombienet-linux --provider native spawn ./cumulus/zombienet/bridge-hubs/bridge_hub_westend_local_network.toml

Init bridge and run relayer between BridgeHubRococo and BridgeHubWestend

Accounts of BridgeHub parachains:

Bob is pallet owner of all bridge pallets

Run with script

cd <polkadot-sdk-git-repo-dir>

./cumulus/scripts/bridges_rococo_westend.sh run-relay

Check relay-chain headers relaying:

Rococo parachain: - https://polkadot.js.org/apps/?rpc=ws%3A%2F%2F127.0.0.1%3A8943#/chainstate - Pallet: bridgeWestendGrandpa - Keys: bestFinalized()
Westend parachain: - https://polkadot.js.org/apps/?rpc=ws%3A%2F%2F127.0.0.1%3A8945#/chainstate - Pallet: bridgeRococoGrandpa - Keys: bestFinalized()

Check parachain headers relaying:

Rococo parachain: - https://polkadot.js.org/apps/?rpc=ws%3A%2F%2F127.0.0.1%3A8943#/chainstate - Pallet: bridgeWestendParachains - Keys: parasInfo(None)
Westend parachain: - https://polkadot.js.org/apps/?rpc=ws%3A%2F%2F127.0.0.1%3A8945#/chainstate - Pallet: bridgeRococoParachains - Keys: parasInfo(None)

Initialize configuration for transfer asset over bridge (ROCs/WNDs)

This initialization does several things:

creates ForeignAssets for wrappedROCs/wrappedWNDs
drips SA for AssetHubRococo on AssetHubWestend (and vice versa) which holds reserved assets on source chains

cd <polkadot-sdk-git-repo-dir>

./cumulus/scripts/bridges_rococo_westend.sh init-asset-hub-rococo-local
./cumulus/scripts/bridges_rococo_westend.sh init-bridge-hub-rococo-local
./cumulus/scripts/bridges_rococo_westend.sh init-asset-hub-westend-local
./cumulus/scripts/bridges_rococo_westend.sh init-bridge-hub-westend-local

Send messages - transfer asset over bridge (ROCs/WNDs)

Do reserve-backed transfers:

cd <polkadot-sdk-git-repo-dir>

# ROCs from Rococo's Asset Hub to Westend's.
./cumulus/scripts/bridges_rococo_westend.sh reserve-transfer-assets-from-asset-hub-rococo-local

cd <polkadot-sdk-git-repo-dir>

# WNDs from Westend's Asset Hub to Rococo's.
./cumulus/scripts/bridges_rococo_westend.sh reserve-transfer-assets-from-asset-hub-westend-local

open explorers: (see zombienets)
- AssetHubRococo (see events xcmpQueue.XcmpMessageSent, polkadotXcm.Attempted) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:9910#/explorer
- BridgeHubRococo (see bridgeWestendMessages.MessageAccepted) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:8943#/explorer
- BridgeHubWestend (see bridgeRococoMessages.MessagesReceived, xcmpQueue.XcmpMessageSent) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:8945#/explorer
- AssetHubWestend (see foreignAssets.Issued, xcmpQueue.Success) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:9010#/explorer
- BridgeHubRocococ (see bridgeWestendMessages.MessagesDelivered) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:8943#/explorer

Do reserve withdraw transfers: (when previous is finished)

cd <polkadot-sdk-git-repo-dir>

# wrappedWNDs from Rococo's Asset Hub to Westend's.
./cumulus/scripts/bridges_rococo_westend.sh withdraw-reserve-assets-from-asset-hub-rococo-local

cd <polkadot-sdk-git-repo-dir>

# wrappedROCs from Westend's Asset Hub to Rococo's.
./cumulus/scripts/bridges_rococo_westend.sh withdraw-reserve-assets-from-asset-hub-westend-local

Claim relayer's rewards on BridgeHubRococo and BridgeHubWestend

Accounts of BridgeHub parachains:

//Charlie is relayer account on BridgeHubRococo
//Charlie is relayer account on BridgeHubWestend

cd <polkadot-sdk-git-repo-dir>

# Claim rewards on BridgeHubWestend:
./cumulus/scripts/bridges_rococo_westend.sh claim-rewards-bridge-hub-rococo-local

# Claim rewards on BridgeHubWestend:
./cumulus/scripts/bridges_rococo_westend.sh claim-rewards-bridge-hub-westend-local

open explorers: (see zombienets)
- BridgeHubRococo (see 2x bridgeRelayers.RewardPaid) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:8943#/explorer
- BridgeHubWestend (see 2x bridgeRelayers.RewardPaid) https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:8945#/explorer

How to test local BridgeHubKusama/BridgeHubPolkadot

TODO: see # !!! READ HERE above