EthereumTokenTransfers pallet

[Agusrodri]

What does it do?

This PR introduces the pallet-ethereum-token-transfers and adds it to Dancelight runtime, alongside:

• Benchmarking and weights
• Rust unit and integration tests
• Typescript integration tests

Pallet's structure

The purpose of this pallet is to send the native Starlight token from Starlight to Ethereum. It does this by sending a MintForeignToken command to Ethereum through a specific channel_id (which is also stored in this pallet).

Config types

• Currency: type to manage the internal transfers of native balance.
• OutboundQueue: implementation that takes care of validating and send the message to Ethereum.
• EthereumSystemHandler: Hook that manages the insertion of channel information inside EthereumSystem pallet.
• EthereumSovereignAccount: Sovereign account of Ethereum in Starlight chain. This is the account in which we store and track how much tokens are transferred from Starlight to Ethereum as a whole.
• FeesAccount: the account in which we deposit fees (calculated at the moment of delivering the message).
• TokenLocationReanchored: the Starlight token location seen from the external chain's (Ethereum) point of view. This is the location that should be stored in EthereumSystem pallet prior to transfer the token using the EthereumTokenTransfers pallet.
• TokenIdFromLocation: this is how we convert a Location object to a TokenId, used inside the MintForeignToken command. If the previous TokenLocationReanchored is not found in EthereumSystem, this conversion fails.

Extrinsics

set_token_transfer_channel: only callable by root. Used to specify which channel_id will be used to send the tokens through. It also receives the para_id and agent_id params corresponding to the channel specified.

transfer_native_token: used to perform the actual sending of the tokens, it requires to specify an amount and a recipient, which is a H160 account on the Ethereum side.

Storage

Inside the pallet we group and store the channel information using the ChannelInfo struct:

    pub struct ChannelInfo {
        pub channel_id: ChannelId,
        pub para_id: ParaId,
        pub agent_id: AgentId,
    }

    #[pallet::storage]
    pub type CurrentChannelInfo<T: Config> = StorageValue<_, ChannelInfo, OptionQuery>;

Events

• ChannelInfoSet: information for the channel was set properly.
• NativeTokenTransferred: some native token was successfully transferred to Ethereum.

Errors

• ChannelIdAlreadyExists: the requested ChannelId is already present in this pallet.
• ChannelInfoNotSet: the channel's information has not been set on this pallet yet.
• ParaIdAlreadyExists: the requested ParaId is already present in this pallet.
• AgentIdAlreadyExists: the requested AgentId is already present in this pallet.
• UnknownLocationForToken: conversion from Location to TokenId failed.
• InvalidMessage: the outbound message is invalid prior to send.
• TransferMessageNotSent: the outbound message could not be sent.

[github-actions]

WASM runtime size check:

Compared to target branch

dancebox runtime: 1412 KB (no changes) ✅

flashbox runtime: 824 KB (no changes) ✅

dancelight runtime: 2180 KB (+2180 KB) ⚠️

container chain template simple runtime: 1116 KB (-4300 KB) ✅

container chain template frontier runtime: 1404 KB (-5156 KB) ✅

[github-actions]

Coverage Report

(master)

@@                             Coverage Diff                             @@
##           master   agustin-ethereum-token-transfers-pallet      +/-   ##
===========================================================================
+ Coverage   66.04%                                    66.10%   +0.06%     
+ Files         335                                       339       +4     
+ Lines       58858                                     59175     +317     
===========================================================================
+ Hits        38869                                     39116     +247     
+ Misses      19989                                     20059      +70     

Files Changed	Coverage
/chains/orchestrator-relays/runtime/dancelight/src/bridge_to_ethereum_config.rs	77.27% (+20.13%)	✅
/chains/orchestrator-relays/runtime/dancelight/src/lib.rs	68.63% (+0.02%)	✅

Coverage generated Tue Feb 4 22:49:43 UTC 2025

[tmpolaczyk]

Why?

[Agusrodri]

Because in benchmarks we need to check the message_id value thrown by the NativeTokenTransferred event. If we return the default, we don't need to worry about reading the entropy (which I don't know if it's possible inside benchmarks) to calculate the actual message_id.

I can take another look, but in my opinion we are fine by just returning the default here.