Looping

This is a mulitasset ERC4626 supporting lend and borrow. A leverage strat is executed / unwound upon deposit / withdraw. This is WIP and still exploitable, coverage about 50%, and ERC4626 compatibility is only partially satisfied. It has been deployed to arb:0xca2b23d3cb0c22a745fd8c7a1049f7d199783ae1

deposit

Assume existing debt and collateral of ETH value L and A. Denote px = pxB / pxQ the price of base/quote in USD using IAAVEOracle.getPrice. Quote is WETH.

Upon Deposit assets quote asset (WETH):

• flashloan flashLoanAmt
• swap amountToSwap = assets + flashLoanAmt to base; swap returns amountCalculated base asset (WstETH)
• amountCalculated > minAmountsOuts = (assets + flashLoanAmt) / px / ( 1 + slippage ).
• lend amountCalculated and borrow ltv * minAmountsOuts * px (note: borrow a little less than lent so health increases a bit and dust accrues in aBase)
• refund flashLoanAmt
• do not call super.deposit, but _mint the right amount based on refreshed LoanInfo. We need: flashLoanAmt = ltv * minAmountsOuts * px = alpha * (assets + flashLoanAmt) So: flashLoanAmt = assets * alpha / 1-alpha, where alpha = ltv / ( 1 + slippage )

balances trajectory (0 slippage):

step quote base dQuote aBase deposit assets 0 0 0 flashLoan amountToSwap swap 0 minAmountsOut 0 0 lend 0 0 0 minAmountsOut borrow flashLoanAmt 0 flashLoanAmt minAmountsOut replayFlash 0 0 flashLoanAmt minAmountsOut

withdraw

Upon withdraw shares of the vault, we want to achieve: new totalCollateral = totalCollateral * (1-shares/totalSupply).

• flashloan quote flashLoanAmt
• repay quote amountToRepay = flashLoanAmt
• un-supply base withdrawAmt = totalCollateral * shareBps / 10000. For this to be allowed we need new debt = max_ltv * new collateral, which solves to flashLoanAmt = max(0, totalDebt - max_ltv * (totalCollateral-withdrawAmt)). Please note this is max_ltv allowed by the vault, more efficient than ltv used.
• swap amountToSwap = withdrawAmt to quote; swap returns amountCalculated base asset (WETH).
• amountCalculated > minAmountsOuts = withdrawAmt * px / ( 1 + slippage ).
• repay flashloan
• refresh loanInfo and return quote balance.
• do not call super.withdraw, but _burn.

balances trajectory (for sharesBps = 10000, 0 slippage). amountToSwap = totalCollateral * shareBps:

step quote base dQuote aBase start 0 0 0 0 flashLoan flashLoanAmt 0 0 0 repay 0 0 -flashLoanAmt 0 un-supply 0 amountToSwap 0 -amountToSwap swap minAmountsOuts 0 0 0 replayFlash minAmountsOuts-flashLoanAmt0 0 0