ERC7399 Flash Lender Wrappers

This repository contains contracts that work as ERC7399 entry points for popular flash lenders.

How Do These Wrappers Work

sequenceDiagram
  title ERC3156Wrapper
    Borrower->>Wrapper: ERC7399.flash(to,token,amt,data,callback)
    Wrapper->>Lender: lender specific flashLoan call
    Lender-->>Wrapper: transfer loan amount
    Lender->>Wrapper: lender specific callback()
    Wrapper -->>Wrapper: bridgeToCallback()
    Wrapper-->>Borrower: transfer loan amount
    Wrapper->>Borrower: callback()
    Borrower -> Borrower: Borrower does stuff
    Borrower -->> Wrapper: transfer loan amount + fee †
    Borrower ->> Wrapper: callback return
    Wrapper --> Wrapper: approves token repayment to lender †
    Wrapper -->> Lender: lender calls transferFrom(wrapper, amount + fee) †

† For the BalancerWrapper and Uniswap v3 the borrower transfers the repayment to the lender and the wrapper skips the repayment approval.

Deployments

Disclaimer: The gas costs are calculated for calling flashLoan on each wrapper for an arbitrarily chosen token and loan amount. Gas refunds are not taken into account and might be significant in some cases. Calling the underlying flash lender directly may have larger gas savings in some instances than others. Requesting loans for different tokens or amounts might have different gas costs. For AMMs the fees often vary according to pool parameters and state.

Gnosis Safe Wrapper

The Gnosis Safe Wrapper is intended for individual users to flash lend their own assets held in a Gnosis Safe and earn a fee. To enable it, from your own Gnosis Safe, execute a transaction bundle to enable the GnosisSafeWrapperFactory and set the fees for individual assets.

safe.enableModule(gnosisSafeWrapperFactory);
gnosisSafeWrapperFactory.lend(asset, fee);
...

or an override to lend all assets in the safe:

safe.enableModule(gnosisSafeWrapperFactory);
gnosisSafeWrapperFactory.lendAll(fee);
...

The fee parameter can be zero for free flash loans. To disable lending, execute from your safe the following command:

gnosisSafeWrapperFactory.disableLend(asset);
...

If you set a lending override, you can disable it to go back to individual asset configuration:

gnosisSafeWrapperFactory.disableLendAll();
...

Gnosis Safe Wrapper

The Gnosis Safe Wrapper is intended for individual users to flash lend their own assets held in a Gnosis Safe and earn a fee. To enable it, from your own Gnosis Safe, execute a transaction bundle to enable the GnosisSafeWrapperFactory and set the fees for individual assets.

safe.enableModule(gnosisSafeWrapperFactory);
gnosisSafeWrapperFactory.lend(asset, fee);
...

or an override to lend all assets in the safe:

safe.enableModule(gnosisSafeWrapperFactory);
gnosisSafeWrapperFactory.lendAll(fee);
...

The fee parameter can be zero for free flash loans. To disable lending, execute from your safe the following command:

gnosisSafeWrapperFactory.disableLend(asset);
...

If you set a lending override, you can disable it to go back to individual asset configuration:

gnosisSafeWrapperFactory.disableLendAll();
...

Flash Loans

For detail on executing flash loans, please refer to the ERC7399 EIP.

Safety

This is experimental software and is provided on an "as is" and "as available" basis.

While care has been taken during development, and most contracts have seen significant use, we do not give any warranties and will not be liable for any loss incurred through any use of this codebase.

Using This Repository

This is a list of the most frequently needed commands.

Build

Build the contracts:

$ forge build

Clean

Delete the build artifacts and cache directories:

$ forge clean

Compile

Compile the contracts:

$ forge build

Coverage

Get a test coverage report:

$ forge coverage

Deploy

Deploy to Anvil:

$ forge script script/Deploy.s.sol --broadcast --fork-url http://localhost:8545

For this script to work, you need to have a MNEMONIC environment variable set to a valid BIP39 mnemonic.

For instructions on how to deploy to a testnet or mainnet, check out the Solidity Scripting tutorial.

Format

Format the contracts:

$ forge fmt

Gas Usage

Get a gas report:

$ forge test --gas-report

Lint

Lint the contracts:

$ pnpm lint

Test

Run the tests:

$ forge test

Notes

1. Foundry uses git submodules to manage dependencies. For detailed instructions on working with dependencies, please refer to the guide in the book
2. You don't have to create a .env file, but filling in the environment variables may be useful when debugging and testing against a fork.

License

This project is licensed under MIT.