Contract Name:
SwapWorkflow
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;
import {IERC20} from "@openzeppelin-5.0.1/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@openzeppelin-5.0.1/contracts/token/ERC20/utils/SafeERC20.sol";
import {Address} from "@openzeppelin-5.0.1/contracts/utils/Address.sol";
/**
* @title SwapWorkflow
* @notice Implements a token swap functionality using Ox AP.
*/
contract SwapWorkflow {
using SafeERC20 for IERC20;
using Address for address;
/// @notice The address of the 0x exchange proxy through which swaps are executed.
address public immutable exchangeProxy;
/// @notice An event that is emitted after a successful token swap.
event SwapExecuted(address indexed tokenIn, uint256 amountIn, address indexed tokenOut, uint256 amountOut);
/// @notice An error that is thrown if the output amount of the swap is less than the minimum specified.
error AmountOutTooLow(uint256 amountOut, uint256 minAmountOut);
/**
* @dev Initializes the contract by setting the exchange proxy address.
* @param _exchangeProxy The address of the exchange proxy to be used for token swaps.
*/
constructor(address _exchangeProxy) {
exchangeProxy = _exchangeProxy;
}
/**
* @notice Executes a token swap via the 0x protocol using provided swap calldata.
* @dev Increases allowance, invokes the swap, and verifies the output. The `swapCallData` should contain all
* necessary data for executing a swap on 0x. It does not verify if the parameters match the `swapCallData`.
* Set the slippage at the "quote," as it is relative to the market price of the asset..
* The `takerAddress` must be set to the access point's address in the quote to enable RFQ liquidity.
* Both `allowanceTarget` and `to` are always set to the 0x exchange proxy.
* For more details, visit: https://0x.org/docs/0x-swap-api/api-references/get-swap-v1-quote
* @param tokenIn The token being swapped.
* @param amountIn The amount of `tokenIn` being swapped.
* @param tokenOut The token expected to be received from the swap.
* @param swapCallData The calldata to be sent to the exchange proxy to execute the swap.
* @return amountOut The actual amount of `tokenOut` received from the swap.
*/
function fillQuote(IERC20 tokenIn, uint256 amountIn, IERC20 tokenOut, bytes calldata swapCallData)
external
returns (uint256 amountOut)
{
// Increase the allowance for the exchangeProxy to handle `amountIn` of `tokenIn`
tokenIn.safeIncreaseAllowance(exchangeProxy, amountIn);
// Store the `tokenOut` balance of this contract before the swap is executed.
uint256 balanceBeforeSwap = tokenOut.balanceOf(address(this));
// Perform the swap call to the exchange proxy.
exchangeProxy.functionCall(swapCallData);
// Calculate the output amount by subtracting the pre-swap balance from the post-swap balance.
amountOut = tokenOut.balanceOf(address(this)) - balanceBeforeSwap;
// Emit an event to log the successful swap.
emit SwapExecuted(address(tokenIn), amountIn, address(tokenOut), amountOut);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.20;
/**
* @dev Interface of the ERC-20 standard as defined in the ERC.
*/
interface IERC20 {
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
/**
* @dev Returns the value of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the value of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves a `value` amount of tokens from the caller's account to `to`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address to, uint256 value) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets a `value` amount of tokens as the allowance of `spender` over the
* caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 value) external returns (bool);
/**
* @dev Moves a `value` amount of tokens from `from` to `to` using the
* allowance mechanism. `value` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(address from, address to, uint256 value) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/utils/SafeERC20.sol)
pragma solidity ^0.8.20;
import {IERC20} from "../IERC20.sol";
import {IERC1363} from "../../../interfaces/IERC1363.sol";
import {Address} from "../../../utils/Address.sol";
/**
* @title SafeERC20
* @dev Wrappers around ERC-20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
using Address for address;
/**
* @dev An operation with an ERC-20 token failed.
*/
error SafeERC20FailedOperation(address token);
/**
* @dev Indicates a failed `decreaseAllowance` request.
*/
error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);
/**
* @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
* non-reverting calls are assumed to be successful.
*/
function safeTransfer(IERC20 token, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
}
/**
* @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
* calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
*/
function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
}
/**
* @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
* non-reverting calls are assumed to be successful.
*/
function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
uint256 oldAllowance = token.allowance(address(this), spender);
forceApprove(token, spender, oldAllowance + value);
}
/**
* @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
* value, non-reverting calls are assumed to be successful.
*/
function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
unchecked {
uint256 currentAllowance = token.allowance(address(this), spender);
if (currentAllowance < requestedDecrease) {
revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
}
forceApprove(token, spender, currentAllowance - requestedDecrease);
}
}
/**
* @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
* non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
* to be set to zero before setting it to a non-zero value, such as USDT.
*/
function forceApprove(IERC20 token, address spender, uint256 value) internal {
bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));
if (!_callOptionalReturnBool(token, approvalCall)) {
_callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
_callOptionalReturn(token, approvalCall);
}
}
/**
* @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
* code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
* targeting contracts.
*
* Reverts if the returned value is other than `true`.
*/
function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
if (to.code.length == 0) {
safeTransfer(token, to, value);
} else if (!token.transferAndCall(to, value, data)) {
revert SafeERC20FailedOperation(address(token));
}
}
/**
* @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
* has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
* targeting contracts.
*
* Reverts if the returned value is other than `true`.
*/
function transferFromAndCallRelaxed(
IERC1363 token,
address from,
address to,
uint256 value,
bytes memory data
) internal {
if (to.code.length == 0) {
safeTransferFrom(token, from, to, value);
} else if (!token.transferFromAndCall(from, to, value, data)) {
revert SafeERC20FailedOperation(address(token));
}
}
/**
* @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
* code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
* targeting contracts.
*
* NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
* Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
* once without retrying, and relies on the returned value to be true.
*
* Reverts if the returned value is other than `true`.
*/
function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
if (to.code.length == 0) {
forceApprove(token, to, value);
} else if (!token.approveAndCall(to, value, data)) {
revert SafeERC20FailedOperation(address(token));
}
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data);
if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
revert SafeERC20FailedOperation(address(token));
}
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*
* This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
*/
function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
// and not revert is the subcall reverts.
(bool success, bytes memory returndata) = address(token).call(data);
return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Address.sol)
pragma solidity ^0.8.20;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev The ETH balance of the account is not enough to perform the operation.
*/
error AddressInsufficientBalance(address account);
/**
* @dev There's no code at `target` (it is not a contract).
*/
error AddressEmptyCode(address target);
/**
* @dev A call to an address target failed. The target may have reverted.
*/
error FailedInnerCall();
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
if (address(this).balance < amount) {
revert AddressInsufficientBalance(address(this));
}
(bool success, ) = recipient.call{value: amount}("");
if (!success) {
revert FailedInnerCall();
}
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason or custom error, it is bubbled
* up by this function (like regular Solidity function calls). However, if
* the call reverted with no returned reason, this function reverts with a
* {FailedInnerCall} error.
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
if (address(this).balance < value) {
revert AddressInsufficientBalance(address(this));
}
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResultFromTarget(target, success, returndata);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResultFromTarget(target, success, returndata);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResultFromTarget(target, success, returndata);
}
/**
* @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
* was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
* unsuccessful call.
*/
function verifyCallResultFromTarget(
address target,
bool success,
bytes memory returndata
) internal view returns (bytes memory) {
if (!success) {
_revert(returndata);
} else {
// only check if target is a contract if the call was successful and the return data is empty
// otherwise we already know that it was a contract
if (returndata.length == 0 && target.code.length == 0) {
revert AddressEmptyCode(target);
}
return returndata;
}
}
/**
* @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
* revert reason or with a default {FailedInnerCall} error.
*/
function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
if (!success) {
_revert(returndata);
} else {
return returndata;
}
}
/**
* @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
*/
function _revert(bytes memory returndata) private pure {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
/// @solidity memory-safe-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert FailedInnerCall();
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC1363.sol)
pragma solidity ^0.8.20;
import {IERC20} from "./IERC20.sol";
import {IERC165} from "./IERC165.sol";
/**
* @title IERC1363
* @dev Interface of the ERC-1363 standard as defined in the https://eips.ethereum.org/EIPS/eip-1363[ERC-1363].
*
* Defines an extension interface for ERC-20 tokens that supports executing code on a recipient contract
* after `transfer` or `transferFrom`, or code on a spender contract after `approve`, in a single transaction.
*/
interface IERC1363 is IERC20, IERC165 {
/*
* Note: the ERC-165 identifier for this interface is 0xb0202a11.
* 0xb0202a11 ===
* bytes4(keccak256('transferAndCall(address,uint256)')) ^
* bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
* bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
* bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)')) ^
* bytes4(keccak256('approveAndCall(address,uint256)')) ^
* bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
*/
/**
* @dev Moves a `value` amount of tokens from the caller's account to `to`
* and then calls {IERC1363Receiver-onTransferReceived} on `to`.
* @param to The address which you want to transfer to.
* @param value The amount of tokens to be transferred.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function transferAndCall(address to, uint256 value) external returns (bool);
/**
* @dev Moves a `value` amount of tokens from the caller's account to `to`
* and then calls {IERC1363Receiver-onTransferReceived} on `to`.
* @param to The address which you want to transfer to.
* @param value The amount of tokens to be transferred.
* @param data Additional data with no specified format, sent in call to `to`.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function transferAndCall(address to, uint256 value, bytes calldata data) external returns (bool);
/**
* @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
* and then calls {IERC1363Receiver-onTransferReceived} on `to`.
* @param from The address which you want to send tokens from.
* @param to The address which you want to transfer to.
* @param value The amount of tokens to be transferred.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function transferFromAndCall(address from, address to, uint256 value) external returns (bool);
/**
* @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
* and then calls {IERC1363Receiver-onTransferReceived} on `to`.
* @param from The address which you want to send tokens from.
* @param to The address which you want to transfer to.
* @param value The amount of tokens to be transferred.
* @param data Additional data with no specified format, sent in call to `to`.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function transferFromAndCall(address from, address to, uint256 value, bytes calldata data) external returns (bool);
/**
* @dev Sets a `value` amount of tokens as the allowance of `spender` over the
* caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function approveAndCall(address spender, uint256 value) external returns (bool);
/**
* @dev Sets a `value` amount of tokens as the allowance of `spender` over the
* caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
* @param data Additional data with no specified format, sent in call to `spender`.
* @return A boolean value indicating whether the operation succeeded unless throwing.
*/
function approveAndCall(address spender, uint256 value, bytes calldata data) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC20.sol)
pragma solidity ^0.8.20;
import {IERC20} from "../token/ERC20/IERC20.sol";
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC165.sol)
pragma solidity ^0.8.20;
import {IERC165} from "../utils/introspection/IERC165.sol";
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/introspection/IERC165.sol)
pragma solidity ^0.8.20;
/**
* @dev Interface of the ERC-165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[ERC].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[ERC section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}