aave-protocol-v2/contracts/adapters/BaseParaSwapAdapter.sol

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// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import {SafeMath} from '../dependencies/openzeppelin/contracts/SafeMath.sol';
import {IERC20} from '../dependencies/openzeppelin/contracts/IERC20.sol';
import {IERC20Detailed} from '../dependencies/openzeppelin/contracts/IERC20Detailed.sol';
import {SafeERC20} from '../dependencies/openzeppelin/contracts/SafeERC20.sol';
import {Ownable} from '../dependencies/openzeppelin/contracts/Ownable.sol';
import {ILendingPoolAddressesProvider} from '../interfaces/ILendingPoolAddressesProvider.sol';
import {DataTypes} from '../protocol/libraries/types/DataTypes.sol';
import {IPriceOracleGetter} from '../interfaces/IPriceOracleGetter.sol';
import {IERC20WithPermit} from '../interfaces/IERC20WithPermit.sol';
import {FlashLoanReceiverBase} from '../flashloan/base/FlashLoanReceiverBase.sol';
/**
* @title BaseParaSwapAdapter
* @notice Utility functions for adapters using ParaSwap
* @author Jason Raymond Bell
*/
abstract contract BaseParaSwapAdapter is FlashLoanReceiverBase, Ownable {
using SafeMath for uint256;
using SafeERC20 for IERC20;
using SafeERC20 for IERC20Detailed;
using SafeERC20 for IERC20WithPermit;
struct PermitSignature {
uint256 amount;
uint256 deadline;
uint8 v;
bytes32 r;
bytes32 s;
}
// Max slippage percent allowed
uint256 public constant MAX_SLIPPAGE_PERCENT = 3000; // 30%
IPriceOracleGetter public immutable ORACLE;
event Swapped(address indexed fromAsset, address indexed toAsset, uint256 fromAmount, uint256 receivedAmount);
constructor(
ILendingPoolAddressesProvider addressesProvider
) public FlashLoanReceiverBase(addressesProvider) {
ORACLE = IPriceOracleGetter(addressesProvider.getPriceOracle());
}
/**
* @dev Get the price of the asset from the oracle denominated in eth
* @param asset address
* @return eth price for the asset
*/
function _getPrice(address asset) internal view returns (uint256) {
return ORACLE.getAssetPrice(asset);
}
/**
* @dev Get the decimals of an asset
* @return number of decimals of the asset
*/
function _getDecimals(IERC20Detailed asset) internal view returns (uint8) {
uint8 decimals = asset.decimals();
// Ensure 10**decimals won't overflow a uint256
require(decimals <= 77, 'TOO_MANY_DECIMALS_ON_TOKEN');
return decimals;
}
/**
* @dev Get the aToken associated to the asset
* @return address of the aToken
*/
function _getReserveData(address asset) internal view returns (DataTypes.ReserveData memory) {
return LENDING_POOL.getReserveData(asset);
}
/**
* @dev Pull the ATokens from the user
* @param reserve address of the asset
* @param reserveAToken address of the aToken of the reserve
* @param user address
* @param amount of tokens to be transferred to the contract
* @param permitSignature struct containing the permit signature
*/
function _pullATokenAndWithdraw(
address reserve,
IERC20WithPermit reserveAToken,
address user,
uint256 amount,
PermitSignature memory permitSignature
) internal {
// If deadline is set to zero, assume there is no signature for permit
if (permitSignature.deadline != 0) {
reserveAToken.permit(
user,
address(this),
permitSignature.amount,
permitSignature.deadline,
permitSignature.v,
permitSignature.r,
permitSignature.s
);
}
// transfer from user to adapter
reserveAToken.safeTransferFrom(user, address(this), amount);
// withdraw reserve
require(
LENDING_POOL.withdraw(reserve, amount, address(this)) == amount,
'UNEXPECTED_AMOUNT_WITHDRAWN'
);
}
/**
* @dev Emergency rescue for token stucked on this contract, as failsafe mechanism
* - Funds should never remain in this contract more time than during transactions
* - Only callable by the owner
*/
function rescueTokens(IERC20 token) external onlyOwner {
token.safeTransfer(owner(), token.balanceOf(address(this)));
}
}