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Variable interest rate oracle fix #21

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Variable interest rate oracle fix #21

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82 changes: 39 additions & 43 deletions src/oracles/VariableInterestRateOracle.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -176,53 +176,49 @@ contract VariableInterestRateOracle is IOracle, AccessControl, Constants {

uint256 secondsSinceLastUpdate = (block.timestamp -
rateParameters.lastUpdated);
if (secondsSinceLastUpdate > 0) {
// Calculate the total debt
uint128 totalDebt;
DataTypes.Debt memory debt_;
debt_ = cauldron.debt(base.b6(), base.b6());
// Adding the debt borrowing base against itself
totalDebt = totalDebt + debt_.sum;

// Adding the debt borrowing base against other ilks
for (uint256 i = 0; i < rateParameters.ilks.length; i++) {
if (cauldron.ilks(base.b6(), rateParameters.ilks[i])) {
debt_ = cauldron.debt(base.b6(), rateParameters.ilks[i]);
totalDebt = totalDebt + debt_.sum;
}
}

// Calculate utilization rate
// Total debt / Total Liquidity
uint256 utilizationRate = uint256(totalDebt).wdiv(
rateParameters.join.storedBalance()
);

uint256 interestRate;
if (utilizationRate <= rateParameters.optimalUsageRate) {
interestRate =
rateParameters.baseVariableBorrowRate +
(utilizationRate * rateParameters.slope1) /
rateParameters.optimalUsageRate;
} else {
interestRate =
rateParameters.baseVariableBorrowRate +
rateParameters.slope1 +
((utilizationRate - rateParameters.optimalUsageRate) *
rateParameters.slope2) /
(1e18 - rateParameters.optimalUsageRate);
// Calculate the total debt
uint128 totalDebt;
DataTypes.Debt memory debt_;

// Adding the debt borrowing base against other ilks
for (uint256 i = 0; i < rateParameters.ilks.length; i++) {
if (cauldron.ilks(base.b6(), rateParameters.ilks[i])) {
debt_ = cauldron.debt(base.b6(), rateParameters.ilks[i]);
totalDebt = totalDebt + debt_.sum;
}
// Calculate per second rate
interestRate = interestRate / 365 days;
rateParameters.accumulated *= (1e18 + interestRate).wpow(
secondsSinceLastUpdate
);
rateParameters.accumulated /= 1e18;
rateParameters.lastUpdated = block.timestamp;

sources[base.b6()][kind.b6()] = rateParameters;
}

// Calculate utilization rate
// Total debt / Total Liquidity
uint256 utilizationRate = uint256(totalDebt).wdiv(
rateParameters.join.storedBalance()
);

uint256 interestRate;
if (utilizationRate <= rateParameters.optimalUsageRate) {
interestRate =
rateParameters.baseVariableBorrowRate +
(utilizationRate * rateParameters.slope1) /
rateParameters.optimalUsageRate;
} else {
interestRate =
rateParameters.baseVariableBorrowRate +
rateParameters.slope1 +
((utilizationRate - rateParameters.optimalUsageRate) *
rateParameters.slope2) /
(1e18 - rateParameters.optimalUsageRate);
}
// Calculate per second rate
interestRate = interestRate / 365 days;
rateParameters.accumulated *= (1e18 + interestRate).wpow(
secondsSinceLastUpdate
);
rateParameters.accumulated /= 1e18;
rateParameters.lastUpdated = block.timestamp;

sources[base.b6()][kind.b6()] = rateParameters;

accumulated = rateParameters.accumulated;
require(accumulated > 0, "Accumulated rate is zero");
updateTime = block.timestamp;
Expand Down
20 changes: 0 additions & 20 deletions src/variable/VRLadle.sol
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Expand Up @@ -297,26 +297,6 @@ contract VRLadle is UUPSUpgradeable, AccessControl() {

// ---- Asset and debt management ----

/// @dev Move collateral and debt between vaults.
function stir(
bytes12 from,
bytes12 to,
uint128 ink,
uint128 art
) external payable {
if (ink > 0)
require(
cauldron.vaults(from).owner == msg.sender,
"Only origin vault owner"
);
if (art > 0)
require(
cauldron.vaults(to).owner == msg.sender,
"Only destination vault owner"
);
cauldron.stir(from, to, ink, art);
}

/// @dev Add collateral and borrow from vault, pull assets from and push borrowed asset to user
/// Or, repay to vault and remove collateral, pull borrowed asset from and push assets to user
/// Borrow only before maturity.
Expand Down
71 changes: 1 addition & 70 deletions src/variable/VYToken.sol
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Original file line number Diff line number Diff line change
@@ -1,8 +1,6 @@
// SPDX-License-Identifier: BUSL-1.1
pragma solidity >=0.8.13;

import "erc3156/contracts/interfaces/IERC3156FlashBorrower.sol";
import "erc3156/contracts/interfaces/IERC3156FlashLender.sol";
import "@yield-protocol/utils-v2/src/token/ERC20Permit.sol";
import "@yield-protocol/utils-v2/src/token/SafeERC20Namer.sol";
import "@yield-protocol/utils-v2/src/access/AccessControl.sol";
Expand All @@ -13,19 +11,14 @@ import "../interfaces/IOracle.sol";
import "../constants/Constants.sol";
import { UUPSUpgradeable } from "@openzeppelin/contracts/proxy/utils/UUPSUpgradeable.sol";

contract VYToken is IERC3156FlashLender, UUPSUpgradeable, AccessControl, ERC20Permit, Constants {
contract VYToken is UUPSUpgradeable, AccessControl, ERC20Permit, Constants {
using Math for uint256;
using Cast for uint256;

event FlashFeeFactorSet(uint256 indexed fee);
event Redeemed(address indexed holder, address indexed receiver, uint256 principalAmount, uint256 underlyingAmount);

bool public initialized;

bytes32 internal constant FLASH_LOAN_RETURN = keccak256("ERC3156FlashBorrower.onFlashLoan");
uint256 constant FLASH_LOANS_DISABLED = type(uint256).max;
uint256 public flashFeeFactor = FLASH_LOANS_DISABLED; // Fee on flash loans, as a percentage in fixed point with 18 decimals. Flash loans disabled by default by overflow from `flashFee`.

IOracle public immutable oracle; // Oracle for the savings rate.
IJoin public immutable join; // Source of redemption funds.
address public immutable underlying;
Expand Down Expand Up @@ -56,7 +49,6 @@ contract VYToken is IERC3156FlashLender, UUPSUpgradeable, AccessControl, ERC20Pe
initialized = true; // On an uninitialized contract, no governance functions can be executed, because no one has permission to do so
_grantRole(ROOT, root_); // Grant ROOT
_setRoleAdmin(LOCK, LOCK); // Create the LOCK role by setting itself as its own admin, creating an independent role tree
flashFeeFactor = FLASH_LOANS_DISABLED; // Flash loans disabled by default
name = name_;
symbol = symbol_;
decimals = decimals_;
Expand All @@ -65,12 +57,6 @@ contract VYToken is IERC3156FlashLender, UUPSUpgradeable, AccessControl, ERC20Pe
/// @dev Allow to set a new implementation
function _authorizeUpgrade(address newImplementation) internal override auth {}

/// @dev Set the flash loan fee factor
function setFlashFeeFactor(uint256 flashFeeFactor_) external auth {
flashFeeFactor = flashFeeFactor_;
emit FlashFeeFactorSet(flashFeeFactor_);
}

///@dev Converts the amount of the principal to the underlying
function convertToUnderlying(uint256 principalAmount) external returns (uint256 underlyingAmount) {
return _convertToUnderlying(principalAmount);
Expand Down Expand Up @@ -196,59 +182,4 @@ contract VYToken is IERC3156FlashLender, UUPSUpgradeable, AccessControl, ERC20Pe
}
}
}

/**
* @dev From ERC-3156. The amount of currency available to be lended.
* @param token The loan currency. It must be a VYToken contract.
* @return The amount of `token` that can be borrowed.
*/
function maxFlashLoan(address token) external view returns (uint256) {
return token == address(this) ? type(uint256).max - _totalSupply : 0;
}

/**
* @dev From ERC-3156. The fee to be charged for a given loan.
* @param token The loan currency. It must be the asset.
* @param principalAmount The amount of tokens lent.
* @return The amount of `token` to be charged for the loan, on top of the returned principal.
*/
function flashFee(address token, uint256 principalAmount) external view returns (uint256) {
require(token == address(this), "Unsupported currency");
return _flashFee(principalAmount);
}

/**
* @dev The fee to be charged for a given loan.
* @param principalAmount The amount of tokens lent.
* @return The amount of `token` to be charged for the loan, on top of the returned principal.
*/
function _flashFee(uint256 principalAmount) internal view returns (uint256) {
return principalAmount.wmul(flashFeeFactor);
}

/**
* @dev From ERC-3156. Loan `amount` vyDai to `receiver`, which needs to return them plus fee to this contract within the same transaction.
* Note that if the initiator and the borrower are the same address, no approval is needed for this contract to take the principal + fee from the borrower.
* If the borrower transfers the principal + fee to this contract, they will be burnt here instead of pulled from the borrower.
* @param receiver The contract receiving the tokens, needs to implement the `onFlashLoan(address user, uint256 amount, uint256 fee, bytes calldata)` interface.
* @param token The loan currency. Must be a vyDai contract.
* @param principalAmount The amount of tokens lent.
* @param data A data parameter to be passed on to the `receiver` for any custom use.
*/
function flashLoan(
IERC3156FlashBorrower receiver,
address token,
uint256 principalAmount,
bytes memory data
) external returns (bool) {
require(token == address(this), "Unsupported currency");
_mint(address(receiver), principalAmount);
uint128 fee = _flashFee(principalAmount).u128();
require(
receiver.onFlashLoan(msg.sender, token, principalAmount, fee, data) == FLASH_LOAN_RETURN,
"Non-compliant borrower"
);
_burn(address(receiver), principalAmount + fee);
return true;
}
}
13 changes: 1 addition & 12 deletions test/FixtureStates.sol
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Expand Up @@ -159,20 +159,9 @@ abstract contract VYTokenZeroState is ZeroState {
timelock = address(1);
vyToken.grantRole(VYToken.mint.selector, address(this));
vyToken.grantRole(VYToken.deposit.selector, address(this));
vyToken.grantRole(VYToken.setFlashFeeFactor.selector, address(this));

borrower = new FlashBorrower(vyToken);
unit = uint128(10 ** ERC20Mock(address(vyToken)).decimals());
deal(address(vyToken), address(this), unit);
deal(address(vyToken.underlying()), address(this), unit);
}
}

abstract contract FlashLoanEnabledState is VYTokenZeroState {
event Transfer(address indexed src, address indexed dst, uint256 wad);

function setUp() public override {
super.setUp();
vyToken.setFlashFeeFactor(0);
}
}
}
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