Flashloan with NFTs
A proof of concept project to show how do a flashloan with NFTs. Loosely based on EIP-3156
Design Requirements
- The owner of the NFT effectively keeps their NFT in their wallet at all times
- The owner can set and is paid a premium when anyone uses their NFT
- Premiums are settled in ether
- A borrower can temporary move a token to their wallet
Interfaces
IERC721FlashLoanFacilitator.sol
interface IERC721FlashLoanFacilitator {
/**
* @dev Receive a flash loan. Must return the borrowed token before returning.
* @param _tokenContract The addresses of the ERC721 contract to loan
* @param _tokenId The NFT token id to loan
* @param _owner The original owner of the token
* @param _premium The additional amount of tokens to repay.
* @param _params Variadic packed params to pass to the receiver as extra information
* @return True if the execution was successful
*/
function executeOperation(
address _tokenContract,
uint256 _tokenId,
address _owner,
uint256 _premium,
bytes calldata _params
) external returns (bool);
}
IERC721FlashLoan.sol
interface IERC721FlashLoan {
/**
* @dev The premium to be charged to loan the NFT.
* @param _tokenContract The addresses of the ERC721 contract to loan
* @param _tokenId The NFT token id to loan
* @return The amount of ether needed to complete the flashloan
*/
function getPremiumForToken(
address _tokenContract,
uint256 _tokenId
) external view returns (uint256);
/**
* @dev Allows the msg.sender access to an approved NFT through a smartcontract within one transaction,
* @param _facilitatorAddress The address of the contract implementing the IERC721FlashLoanFacilitator interface
* @param _tokenContract The addresses of the ERC721 contract to loan
* @param _tokenId The NFT token id to loan
* @param _params Variadic packed params to pass to the receiver as extra information
**/
function flashLoan( address _facilitatorContract, address _tokenContract, uint256 _tokenId, bytes calldata _params) external payable;
}
Workflow
Setup
- Deploy the flashloan contract like FlashLoanNFT.sol
For the NFT lender
- NFT lender calls the NFT contract's
setApprovalForAll({flashloan_contract_address}, true)
- NFT lender calls the flashloan contract's
approveForFlashLoans
method and sets a premium for each NFT he/she wants to enable for flashloan.
For the NFT borrower
- Deploy a facilitator contract like NFTWithRedeemableFlashLoanFacilitator
- Call NFT contract's
setApprovalForAll({facilitators_contract_address}, true)
- Call the flashloan contract's
flashloan
method with the necessary premium - Profit!
Installing
npm install
Testing
npm test
Deloying the FlashLoanNFT contract
npx hardhat deploy