SparkLend Conduit

GitHub - marsfoundation/spark-conduits: Conduits for the Spark Protocol.GitHub

Overview

The SparkLend Conduit is a conduit contract designed to be used within the Sky Allocation System. It implements the IAllocatorConduit interface, so it will be able to work within the constraints on the Allocation System design. There is one contract in this repo:

SparkLendConduit: Facilitates the movement of funds between the Sky Allocation System and the SparkLend instance.

ℹ️ In later iterations of this code's development, it is expected for other SparkLend Conduits to be developed to support multichain deployments.

Roles/Permissions

1. wards: The wards mapping tracks the administrative permissions on this contract. Admin can upgrade the contract and set key storage values.

2. operator: The operator performs actions on behalf of a given ilk (SubDAO identifier in the Maker Allocation System). The operator can deposit, withdraw, request funds, and cancel fund requests in the Conduit. Onboarding and offboarding of operator actors is done by Maker admin in the core system.

Admin Configuration

1. roles: The roles contract to perform operator authentication.

2. registry: Returns the buffer contract for a given ilk (source of funds).

Functionality

deposit

The deposit function is used to move funds from a given ilk's buffer into the Conduit. From the Conduit, the funds are used to supply in the SparkLend Pool. The result is that:

1. Funds are moved from the buffer to SparkLend's aToken for that asset.

2. aTokens are minted and sent to the Conduit.

3. The Conduit state to track the ilk's portion of the aTokens in the Conduit is increased.

withdraw

The withdraw function is used to withdraw funds from the SparkLend Pool into the Conduit. From the Conduit, the funds are sent to the ilk's buffer. The result is that:

1. Funds are moved from SparkLend's aToken for that asset to the buffer.

2. The Conduit's aTokens corresponding to the underlying asset withdrawn are burned.

3. The Conduit state to track the ilk's portion of the aTokens in the Conduit is reduced.

Invariants

$totalShares[asset] = \sum_{n=0}^{numIlks}{shares[asset][ilk]}$

$getTotalDeposits(asset) = \sum_{n=0}^{numIlks}{getDeposits(asset, ilk)}$

$totalRequestedShares[asset] = \sum_{n=0}^{numIlks}{requestedShares[asset][ilk]}$

$totalShares[asset] \le aToken.scaledBalanceOf(conduit)$

$getTotalDeposits(asset) \le aToken.balanceOf(conduit)$

ℹ️ The last two invariants are not strict equalities because of A) the potential for a permissionless transfer of the aToken into the conduit and/or B) the rounding behaviour difference (round on SparkLend vs round-down on SparkLend Conduit).

Upgradeability

Since the SparkLend Conduit will likely require maintenance as its desired usage evolves, it will be an upgradeable contract, using upgradeable-proxy for upgradeable logic. This is a non-transparent proxy contract that gives upgrade rights to the PauseProxy.

Technical Assumptions

As with most MakerDAO contracts, non standard token implementations are assumed to not be supported. As examples, this includes tokens that:

• Do not have a decimals field or have more than 18 decimals.

• Do not revert and instead rely on a return value.

• Implement fee on transfer.

• Include rebasing logic.

• Implement callbacks/hooks.

Testing

To run the tests, do the following:

forge test