DYFIRedeemer

Inherits: IDYFIRedeemer, AccessControlEnumerable, ReentrancyGuard, Pausable

This contract can be used to redeem dYFI for YFI for multiple dYFI holders in a single transaction. Any address that holds dYFI can approve this contract to spend their dYFI. Then the caller of massRedeem will provide a list of dYFI holders and their dYFI amounts. By utilizing low-fee flash loans from Balancer, this contract can redeem all dYFI for YFI, and sell the excess YFI for ETH to pay back the flash loan and to reward the caller. The users who approve this contract to spend their dYFI must acknowledge that they will not receive more than the minimum amount of YFI that should be redeemed for their dYFI. The minimum amount of YFI at a given time can be calculated using the minYfiRedeem(uint256 dYfiAmount) function.

State Variables

_REDEMPTION

Address of the redemption contract for dYFI tokens.

address private constant _REDEMPTION = 0x7dC3A74F0684fc026f9163C6D5c3C99fda2cf60a;

_YFI_ETH_PRICE_FEED

Address of the Chainlink YFI/ETH price feed contract.

address private constant _YFI_ETH_PRICE_FEED = 0x3EbEACa272Ce4f60E800f6C5EE678f50D2882fd4;

_FLASH_LOAN_PROVIDER

Address of the Balancer flash loan provider contract.

address private constant _FLASH_LOAN_PROVIDER = 0xBA12222222228d8Ba445958a75a0704d566BF2C8;

_DYFI

Address of the dYFI token contract.

address private constant _DYFI = 0x41252E8691e964f7DE35156B68493bAb6797a275;

_YFI

Address of the YFI token contract.

address private constant _YFI = 0x0bc529c00C6401aEF6D220BE8C6Ea1667F6Ad93e;

_WETH

Address of the WETH token contract.

address private constant _WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;

_ETH_YFI_CURVE_POOL

Address of the Curve ETH/YFI liquidity pool contract.

address private constant _ETH_YFI_CURVE_POOL = 0xC26b89A667578ec7b3f11b2F98d6Fd15C07C54ba;

_MAX_SLIPPAGE

Maximum slippage allowed during redemption, represented as a fraction of 1e18.

uint256 private constant _MAX_SLIPPAGE = 0.05e18;

_DEFAULT_SLIPPAGE

Default slippage used during redemption if no specific slippage is set, represented as a fraction of 1e18.

uint256 private constant _DEFAULT_SLIPPAGE = 0.01e18;

_slippage

The slippage that should be applied to the redemption process

uint256 private _slippage;

Functions

constructor

constructor(address admin) payable;

receive

Allows this contract to receive ETH

receive() external payable;

massRedeem

Redeems dYFI for YFI for multiple dYFI holders in a single transaction. Any extra ETH will be sent to the caller.

This function utilizes flash loans from Balancer to acquire ETH needed to redeem dYFI for YFI. The amount of YFI to distribute is calculated as follows: YFI to distribute = dYFI amount - ETH required for redemption * YFI/ETH price * (1 + slippage) The extra YFI is swapped for ETH and sent to the caller as an extra reward.

function massRedeem(
    address[] calldata dYfiHolders,
    uint256[] calldata dYfiAmounts
)
    external
    nonReentrant
    whenNotPaused;

Parameters

Name	Type	Description
`dYfiHolders`	`address[]`	list of addresses that hold dYFI and have approved this contract to spend their dYFI
`dYfiAmounts`	`uint256[]`	list of dYFI amounts that should be redeemed for YFI from the corresponding dYFI holder

receiveFlashLoan

Called by the flash loan provider to execute a flash loan of WETH.

The unchecked block is used here because overflow is not possible as the loop index i is simply incremented in each iteration. The loop is bounded by dYfiHolders.length, ensuring that i will not exceed the length of the array and overflow. Underflow is not a concern as i is initialized to 0 and only incremented.

function receiveFlashLoan(
    IERC20[] calldata tokens,
    uint256[] calldata amounts,
    uint256[] calldata feeAmounts,
    bytes calldata userData
)
    external;

Parameters

Name	Type	Description
`tokens`	`IERC20[]`	list of token addresses flash loaned.
`amounts`	`uint256[]`	list of amounts flash loaned.
`feeAmounts`	`uint256[]`	list of fee amounts that must be paid back.
`userData`	`bytes`	additional data with no specified format.

setSlippage

Sets the slippage that should be applied to DYFI -> YFI redeems.

The slippage is applied to the YFI/ETH price. For example, if the slippage is 0.01e18, then the YFI/ETH price will be multiplied by 1.01.

function setSlippage(uint256 slippage_) external onlyRole(DEFAULT_ADMIN_ROLE);

Parameters

Name	Type	Description
`slippage_`	`uint256`	The new slippage to use for YFI swaps.

kill

Kills the contract. Only the admin can call this function.

function kill() external onlyRole(DEFAULT_ADMIN_ROLE);

minYfiRedeem

Returns the minimum amount of YFI that should be redeemed for a given amount of dYFI

function minYfiRedeem(uint256 dYfiAmount) external view returns (uint256);

Parameters

Name	Type	Description
`dYfiAmount`	`uint256`	The amount of dYFI to redeem

Returns

Name	Type	Description
`<none>`	`uint256`	The minimum amount of YFI that should be redeemed for a given amount of dYFI

currentYfiRedeem

Returns the expected amount of YFI that should be redeemed for a given amount of dYFI

function currentYfiRedeem(uint256 dYfiAmount) external view returns (uint256);

Parameters

Name	Type	Description
`dYfiAmount`	`uint256`	The amount of dYFI to redeem

Returns

Name	Type	Description
`<none>`	`uint256`	The expected amount of YFI that should be redeemed for a given amount of dYFI

expectedMassRedeemReward

Calculates the expected amount of ETH the caller will receive for redeeming dYFI for YFI for the given users and amounts.

This assumes flash loan fee of 0.

function expectedMassRedeemReward(uint256 dYfiAmount) external view returns (uint256);

Parameters

Name	Type	Description
`dYfiAmount`	`uint256`	total dYFI amount that should be redeemed for YFI.

Returns

Name	Type	Description
`<none>`	`uint256`	The expected amount of ETH the caller will receive for redeeming dYFI for YFI.

getLatestPrice

Returns the latest YFI/ETH from the Chainlink price feed.

function getLatestPrice() external view returns (uint256);

Returns

Name	Type	Description
`<none>`	`uint256`	The latest ETH per 1 YFI from the Chainlink price feed.

slippage

Get the slippage that should be applied to DYFI -> YFI redeems.

function slippage() external view returns (uint256);

Returns

Name	Type	Description
`<none>`	`uint256`	The slippage in 1e18 precision.

_setSlippage

Internal function to set the slippage that should be applied to DYFI -> YFI redeems.

function _setSlippage(uint256 slippage_) internal;

Parameters

Name	Type	Description
`slippage_`	`uint256`	The new slippage to use for YFI swaps.

_getLatestPrice

Returns ETH per 1 YFI in 1e18 precision

function _getLatestPrice() internal view returns (uint256);

_getEthRequired

Returns the minimum ETH required for redemption in 1e18 precision

function _getEthRequired(uint256 dYfiAmount) internal view returns (uint256);

Events

SlippageSet

Emitted when the slippage is set.

event SlippageSet(uint256 slippage);

Parameters

Name	Type	Description
`slippage`	`uint256`	The new slippage value set for the redemption process.

DYfiRedeemed

Emitted when dYFI is redeemed for YFI.

event DYfiRedeemed(address indexed dYfiHolder, uint256 dYfiAmount, uint256 yfiAmount);

Parameters

Name	Type	Description
`dYfiHolder`	`address`	The address of the dYFI holder whose tokens were redeemed.
`dYfiAmount`	`uint256`	The amount of dYFI that was redeemed.
`yfiAmount`	`uint256`	The amount of YFI received from redeeming the dYFI.

CallerReward

Emitted when a reward is given to the caller of the massRedeem function.

event CallerReward(address indexed caller, uint256 amount);

Parameters

Name	Type	Description
`caller`	`address`	The address of the caller who received the reward.
`amount`	`uint256`	The amount of the reward received.