Contract Name:
UniswapV2LikeExchange
Contract Source Code:
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (proxy/utils/Initializable.sol)
pragma solidity ^0.8.2;
import "../../utils/Address.sol";
/**
* @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
* behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
* external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
* function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
*
* The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
* reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
* case an upgrade adds a module that needs to be initialized.
*
* For example:
*
* [.hljs-theme-light.nopadding]
* ```
* contract MyToken is ERC20Upgradeable {
* function initialize() initializer public {
* __ERC20_init("MyToken", "MTK");
* }
* }
* contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
* function initializeV2() reinitializer(2) public {
* __ERC20Permit_init("MyToken");
* }
* }
* ```
*
* TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
* possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
*
* CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
* that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
*
* [CAUTION]
* ====
* Avoid leaving a contract uninitialized.
*
* An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
* contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
* the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
*
* [.hljs-theme-light.nopadding]
* ```
* /// @custom:oz-upgrades-unsafe-allow constructor
* constructor() {
* _disableInitializers();
* }
* ```
* ====
*/
abstract contract Initializable {
/**
* @dev Indicates that the contract has been initialized.
* @custom:oz-retyped-from bool
*/
uint8 private _initialized;
/**
* @dev Indicates that the contract is in the process of being initialized.
*/
bool private _initializing;
/**
* @dev Triggered when the contract has been initialized or reinitialized.
*/
event Initialized(uint8 version);
/**
* @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
* `onlyInitializing` functions can be used to initialize parent contracts. Equivalent to `reinitializer(1)`.
*/
modifier initializer() {
bool isTopLevelCall = _setInitializedVersion(1);
if (isTopLevelCall) {
_initializing = true;
}
_;
if (isTopLevelCall) {
_initializing = false;
emit Initialized(1);
}
}
/**
* @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
* contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
* used to initialize parent contracts.
*
* `initializer` is equivalent to `reinitializer(1)`, so a reinitializer may be used after the original
* initialization step. This is essential to configure modules that are added through upgrades and that require
* initialization.
*
* Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
* a contract, executing them in the right order is up to the developer or operator.
*/
modifier reinitializer(uint8 version) {
bool isTopLevelCall = _setInitializedVersion(version);
if (isTopLevelCall) {
_initializing = true;
}
_;
if (isTopLevelCall) {
_initializing = false;
emit Initialized(version);
}
}
/**
* @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
* {initializer} and {reinitializer} modifiers, directly or indirectly.
*/
modifier onlyInitializing() {
require(_initializing, "Initializable: contract is not initializing");
_;
}
/**
* @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
* Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
* to any version. It is recommended to use this to lock implementation contracts that are designed to be called
* through proxies.
*/
function _disableInitializers() internal virtual {
_setInitializedVersion(type(uint8).max);
}
function _setInitializedVersion(uint8 version) private returns (bool) {
// If the contract is initializing we ignore whether _initialized is set in order to support multiple
// inheritance patterns, but we only do this in the context of a constructor, and for the lowest level
// of initializers, because in other contexts the contract may have been reentered.
if (_initializing) {
require(
version == 1 && !Address.isContract(address(this)),
"Initializable: contract is already initialized"
);
return false;
} else {
require(_initialized < version, "Initializable: contract is already initialized");
_initialized = version;
return true;
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
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 amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` 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 amount) 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 `amount` 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 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `from` to `to` using the
* allowance mechanism. `amount` 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 amount
) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
import "../../../utils/Address.sol";
/**
* @title SafeERC20
* @dev Wrappers around ERC20 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;
function safeTransfer(
IERC20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IERC20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
/**
* @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, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)
pragma solidity ^0.8.1;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*
* [IMPORTANT]
* ====
* You shouldn't rely on `isContract` to protect against flash loan attacks!
*
* Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
* like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
* constructor.
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize/address.code.length, which returns 0
// for contracts in construction, since the code is only stored at the end
// of the constructor execution.
return account.code.length > 0;
}
/**
* @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://diligence.consensys.net/posts/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/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @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, it is bubbled up by this
* function (like regular Solidity function calls).
*
* 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.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @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`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// 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
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
pragma solidity >=0.5.0;
interface IUniswapV2Factory {
event PairCreated(address indexed token0, address indexed token1, address pair, uint);
function feeTo() external view returns (address);
function feeToSetter() external view returns (address);
function getPair(address tokenA, address tokenB) external view returns (address pair);
function allPairs(uint) external view returns (address pair);
function allPairsLength() external view returns (uint);
function createPair(address tokenA, address tokenB) external returns (address pair);
function setFeeTo(address) external;
function setFeeToSetter(address) external;
}
pragma solidity >=0.5.0;
interface IUniswapV2Pair {
event Approval(address indexed owner, address indexed spender, uint value);
event Transfer(address indexed from, address indexed to, uint value);
function name() external pure returns (string memory);
function symbol() external pure returns (string memory);
function decimals() external pure returns (uint8);
function totalSupply() external view returns (uint);
function balanceOf(address owner) external view returns (uint);
function allowance(address owner, address spender) external view returns (uint);
function approve(address spender, uint value) external returns (bool);
function transfer(address to, uint value) external returns (bool);
function transferFrom(address from, address to, uint value) external returns (bool);
function DOMAIN_SEPARATOR() external view returns (bytes32);
function PERMIT_TYPEHASH() external pure returns (bytes32);
function nonces(address owner) external view returns (uint);
function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
event Mint(address indexed sender, uint amount0, uint amount1);
event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
event Swap(
address indexed sender,
uint amount0In,
uint amount1In,
uint amount0Out,
uint amount1Out,
address indexed to
);
event Sync(uint112 reserve0, uint112 reserve1);
function MINIMUM_LIQUIDITY() external pure returns (uint);
function factory() external view returns (address);
function token0() external view returns (address);
function token1() external view returns (address);
function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
function price0CumulativeLast() external view returns (uint);
function price1CumulativeLast() external view returns (uint);
function kLast() external view returns (uint);
function mint(address to) external returns (uint liquidity);
function burn(address to) external returns (uint amount0, uint amount1);
function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
function skim(address to) external;
function sync() external;
function initialize(address, address) external;
}
// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.7.0;
/// @title Optimized overflow and underflow safe math operations
/// @notice Contains methods for doing math operations that revert on overflow or underflow for minimal gas cost
library LowGasSafeMath {
/// @notice Returns x + y, reverts if sum overflows uint256
/// @param x The augend
/// @param y The addend
/// @return z The sum of x and y
function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
require((z = x + y) >= x);
}
/// @notice Returns x - y, reverts if underflows
/// @param x The minuend
/// @param y The subtrahend
/// @return z The difference of x and y
function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
require((z = x - y) <= x);
}
/// @notice Returns x * y, reverts if overflows
/// @param x The multiplicand
/// @param y The multiplier
/// @return z The product of x and y
function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
require(x == 0 || (z = x * y) / x == y);
}
/// @notice Returns x + y, reverts if overflows or underflows
/// @param x The augend
/// @param y The addend
/// @return z The sum of x and y
function add(int256 x, int256 y) internal pure returns (int256 z) {
require((z = x + y) >= x == (y >= 0));
}
/// @notice Returns x - y, reverts if overflows or underflows
/// @param x The minuend
/// @param y The subtrahend
/// @return z The difference of x and y
function sub(int256 x, int256 y) internal pure returns (int256 z) {
require((z = x - y) <= x == (y >= 0));
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/proxy/utils/Initializable.sol";
import "../interfaces/IGovernable.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (governor) that can be granted exclusive access to
* specific functions.
*
* By default, the governor account will be the one that deploys the contract. This
* can later be changed with {transferGovernorship}.
*
*/
abstract contract Governable is IGovernable, Context, Initializable {
address public governor;
address private proposedGovernor;
event UpdatedGovernor(address indexed previousGovernor, address indexed proposedGovernor);
/**
* @dev Initializes the contract setting the deployer as the initial governor.
*/
constructor() {
address msgSender = _msgSender();
governor = msgSender;
emit UpdatedGovernor(address(0), msgSender);
}
/**
* @dev If inheriting child is using proxy then child contract can use
* __Governable_init() function to initialization this contract
*/
// solhint-disable-next-line func-name-mixedcase
function __Governable_init() internal initializer {
address msgSender = _msgSender();
governor = msgSender;
emit UpdatedGovernor(address(0), msgSender);
}
/**
* @dev Throws if called by any account other than the governor.
*/
modifier onlyGovernor() {
require(governor == _msgSender(), "not-governor");
_;
}
/**
* @dev Transfers governorship of the contract to a new account (`proposedGovernor`).
* Can only be called by the current owner.
*/
function transferGovernorship(address _proposedGovernor) external onlyGovernor {
require(_proposedGovernor != address(0), "proposed-governor-is-zero");
proposedGovernor = _proposedGovernor;
}
/**
* @dev Allows new governor to accept governorship of the contract.
*/
function acceptGovernorship() external {
require(proposedGovernor == _msgSender(), "not-the-proposed-governor");
emit UpdatedGovernor(governor, proposedGovernor);
governor = proposedGovernor;
proposedGovernor = address(0);
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0;
import '@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol';
import '@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol';
import '@uniswap/v3-core/contracts/libraries/LowGasSafeMath.sol';
/**
* This is copied from Uniswap's V2SwapRouter.sol deployed at 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45
* and licensed under GPL-2.0-or-later.
* Changelog:
* - Removed hardcoded initCodeHash and taking as param so that we can support multiple UniswapV2Like exchanges
* - Added function getAmountsOut()
*/
library UniswapV2Library {
using LowGasSafeMath for uint256;
// returns sorted token addresses, used to handle return values from pairs sorted in this order
function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
require(tokenA != tokenB);
(token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
require(token0 != address(0));
}
// calculates the CREATE2 address for a pair without making any external calls
function pairFor(address factory, bytes32 initCodeHash, address tokenA, address tokenB) internal pure returns (address pair) {
(address token0, address token1) = sortTokens(tokenA, tokenB);
pair = address(uint160
(uint256(keccak256(abi.encodePacked(
hex'ff',
factory,
keccak256(abi.encodePacked(token0, token1)),
initCodeHash
)))));
}
// fetches and sorts the reserves for a pair
function getReserves(
address factory,
bytes32 initCodeHash,
address tokenA,
address tokenB
) internal view returns (uint256 reserveA, uint256 reserveB) {
(address token0, ) = sortTokens(tokenA, tokenB);
(uint256 reserve0, uint256 reserve1, ) = IUniswapV2Pair(pairFor(factory, initCodeHash, tokenA, tokenB)).getReserves();
(reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
}
// given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
function getAmountOut(
uint256 amountIn,
uint256 reserveIn,
uint256 reserveOut
) internal pure returns (uint256 amountOut) {
require(amountIn > 0, 'INSUFFICIENT_INPUT_AMOUNT');
require(reserveIn > 0 && reserveOut > 0);
uint256 amountInWithFee = amountIn.mul(997);
uint256 numerator = amountInWithFee.mul(reserveOut);
uint256 denominator = reserveIn.mul(1000).add(amountInWithFee);
amountOut = numerator / denominator;
}
// given an output amount of an asset and pair reserves, returns a required input amount of the other asset
function getAmountIn(
uint256 amountOut,
uint256 reserveIn,
uint256 reserveOut
) internal pure returns (uint256 amountIn) {
require(amountOut > 0, 'INSUFFICIENT_OUTPUT_AMOUNT');
require(reserveIn > 0 && reserveOut > 0);
uint256 numerator = reserveIn.mul(amountOut).mul(1000);
uint256 denominator = reserveOut.sub(amountOut).mul(997);
amountIn = (numerator / denominator).add(1);
}
// performs chained getAmountOut calculations on any number of pairs
function getAmountsOut(
address factory,
bytes32 initCodeHash,
uint amountIn,
address[] memory path
) internal view returns (uint[] memory amounts) {
require(path.length >= 2);
amounts = new uint[](path.length);
amounts[0] = amountIn;
for (uint i; i < path.length - 1; i++) {
(uint reserveIn, uint reserveOut) = getReserves(factory, initCodeHash, path[i], path[i + 1]);
amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
}
}
// performs chained getAmountIn calculations on any number of pairs
function getAmountsIn(
address factory,
bytes32 initCodeHash,
uint256 amountOut,
address[] memory path
) internal view returns (uint256[] memory amounts) {
require(path.length >= 2);
amounts = new uint256[](path.length);
amounts[amounts.length - 1] = amountOut;
for (uint256 i = path.length - 1; i > 0; i--) {
(uint256 reserveIn, uint256 reserveOut) = getReserves(factory,initCodeHash, path[i - 1], path[i]);
amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
/**
* @notice Governable interface
*/
interface IGovernable {
function governor() external view returns (address _governor);
function transferGovernorship(address _proposedGovernor) external;
}
// SPDX-License-Identifier: MIT
pragma solidity <=0.8.9;
/**
* @notice Exchange interface
*/
interface IExchange {
/**
* @notice Get *spot* quote
* It will return the swap amount based on the current reserves of the given path (i.e. spot price)
* @dev It shouldn't be used as oracle!!!
*/
function getAmountsIn(uint256 _amountOut, bytes memory path_) external returns (uint256 _amountIn);
/**
* @notice Get *spot* quote
* It will return the swap amount based on the current reserves of the given path (i.e. spot price)
* @dev It shouldn't be used as oracle!!!
*/
function getAmountsOut(uint256 amountIn_, bytes memory path_) external returns (uint256 _amountOut);
/**
* @notice Get *spot* quote
* It will return the swap amount based on the current reserves of the best pair/path found (i.e. spot price)
* @dev It shouldn't be used as oracle!!!
*/
function getBestAmountIn(
address tokenIn_,
address tokenOut_,
uint256 amountOut_
) external returns (uint256 _amountIn, bytes memory _path);
/**
* @notice Get *spot* quote
* It will return the swap amount based on the current reserves of the best pair/path found (i.e. spot price)
* @dev It shouldn't be used as oracle!!!
*/
function getBestAmountOut(
address tokenIn_,
address tokenOut_,
uint256 amountIn_
) external returns (uint256 _amountOut, bytes memory _path);
/**
* @notice Perform an exact input swap
* @dev Should transfer `amountIn_` before performing swap
*/
function swapExactInput(
bytes calldata path_,
uint256 amountIn_,
uint256 amountOutMin_,
address outReceiver_
) external returns (uint256 _amountOut);
/**
* @notice Perform an exact output swap
* @dev Should transfer `amountInMax_` before performing swap
* @dev Sends swap remains - if any - to the `inSender_`
*/
function swapExactOutput(
bytes calldata path_,
uint256 amountOut_,
uint256 amountInMax_,
address inSender_,
address outRecipient_
) external returns (uint256 _amountIn);
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "../dependencies/uniswap/libraries/UniswapV2Library.sol";
import "../access/Governable.sol";
import "../interfaces/swapper/IExchange.sol";
/**
* @notice UniswapV2 Like Exchange
*/
contract UniswapV2LikeExchange is IExchange, Governable {
using SafeERC20 for IERC20;
/**
* @notice The WETH-Like token (a.k.a. Native Token)
* @dev I.e. should be the most liquid token that offer best routers among trade pairs
* @dev It's usually the wrapper token of the chain's native coin but it isn't always true
* For instance: On Polygon, the `WETH` is more liquid than `WMATIC` on UniV3 protocol.
*/
address public wethLike;
/**
* @notice The UniswapV2-Like factory contract
*/
address public immutable factory;
bytes32 internal immutable initCodeHash;
/// @notice Emitted when wethLike token is updated
event WethLikeTokenUpdated(address oldWethLike, address newWethLike);
/**
* @dev Doesn't consider router.WETH() as `wethLike` because isn't guaranteed that it's the most liquid token.
*/
constructor(
address factory_,
bytes32 initCodeHash_,
address wethLike_
) {
factory = factory_;
initCodeHash = initCodeHash_;
wethLike = wethLike_;
}
/// @inheritdoc IExchange
function getAmountsIn(uint256 amountOut_, bytes memory path_) external view override returns (uint256 _amountIn) {
_amountIn = getAmountsIn(amountOut_, _decodePath(path_));
}
/// @inheritdoc IExchange
function getAmountsOut(uint256 amountIn_, bytes memory path_) external view override returns (uint256 _amountOut) {
_amountOut = getAmountsOut(amountIn_, _decodePath(path_));
}
/**
* @dev getBestAmountIn require a try/catch version of getAmountsIn and try/catch do not work with internal
* library functions, hence wrapped library call in this function so that it can be used in try/catch
*/
function getAmountsIn(uint256 amountOut_, address[] memory path_) public view returns (uint256 _amountIn) {
_amountIn = UniswapV2Library.getAmountsIn(factory, initCodeHash, amountOut_, path_)[0];
}
/**
* @dev getBestAmountOut require a try/catch version of getAmountsOut and try/catch do not work with internal
* library functions, hence wrapped library call in this function so that it can be used in try/catch
*/
function getAmountsOut(uint256 amountIn_, address[] memory path_) public view returns (uint256 _amountOut) {
_amountOut = UniswapV2Library.getAmountsOut(factory, initCodeHash, amountIn_, path_)[path_.length - 1];
}
/// @inheritdoc IExchange
function getBestAmountIn(
address tokenIn_,
address tokenOut_,
uint256 amountOut_
) external returns (uint256 _amountIn, bytes memory _path) {
// 1. Check IN-OUT pair
address[] memory _pathA = new address[](2);
_pathA[0] = tokenIn_;
_pathA[1] = tokenOut_;
uint256 _amountInA = _getAmountsIn(amountOut_, _pathA);
if (tokenIn_ == wethLike || tokenOut_ == wethLike) {
// Returns if one of the token is WETH-Like
require(_amountInA > 0, "no-path-found");
return (_amountInA, _encodePath(_pathA));
}
// 2. Check IN-WETH-OUT path
address[] memory _pathB = new address[](3);
_pathB[0] = tokenIn_;
_pathB[1] = wethLike;
_pathB[2] = tokenOut_;
uint256 _amountInB = _getAmountsIn(amountOut_, _pathB);
// 3. Get best route between paths A and B
require(_amountInA > 0 || _amountInB > 0, "no-path-found");
// Returns A if it's valid and better than B or if B isn't valid
if ((_amountInA > 0 && _amountInA < _amountInB) || _amountInB == 0) {
return (_amountInA, _encodePath(_pathA));
}
return (_amountInB, _encodePath(_pathB));
}
/// @inheritdoc IExchange
function getBestAmountOut(
address tokenIn_,
address tokenOut_,
uint256 amountIn_
) external returns (uint256 _amountOut, bytes memory _path) {
// 1. Check IN-OUT pair
address[] memory _pathA = new address[](2);
_pathA[0] = tokenIn_;
_pathA[1] = tokenOut_;
uint256 _amountOutA = _getAmountsOut(amountIn_, _pathA);
if (tokenIn_ == wethLike || tokenOut_ == wethLike) {
// Returns if one of the token is WETH-Like
require(_amountOutA > 0, "no-path-found");
return (_amountOutA, _encodePath(_pathA));
}
// 2. Check IN-WETH-OUT path
address[] memory _pathB = new address[](3);
_pathB[0] = tokenIn_;
_pathB[1] = wethLike;
_pathB[2] = tokenOut_;
uint256 _amountOutB = _getAmountsOut(amountIn_, _pathB);
// 3. Get best route between paths A and B
require(_amountOutA > 0 || _amountOutB > 0, "no-path-found");
if (_amountOutA > _amountOutB) return (_amountOutA, _encodePath(_pathA));
return (_amountOutB, _encodePath(_pathB));
}
/// @inheritdoc IExchange
function swapExactInput(
bytes calldata path_,
uint256 amountIn_,
uint256 amountOutMin_,
address outReceiver_
) external returns (uint256 _amountOut) {
address[] memory _path = _decodePath(path_);
IERC20 _tokenIn = IERC20(_path[0]);
IERC20 _tokenOut = IERC20(_path[_path.length - 1]);
_tokenIn.safeTransfer(UniswapV2Library.pairFor(factory, initCodeHash, _path[0], _path[1]), amountIn_);
uint256 balanceBefore = _tokenOut.balanceOf(outReceiver_);
_swap(_path, outReceiver_);
_amountOut = _tokenOut.balanceOf(outReceiver_) - balanceBefore;
require(_amountOut >= amountOutMin_, "Too little received");
}
/// @inheritdoc IExchange
function swapExactOutput(
bytes calldata path_,
uint256 amountOut_,
uint256 amountInMax_,
address inSender_,
address outRecipient_
) external returns (uint256 _amountIn) {
address[] memory _path = _decodePath(path_);
IERC20 _tokenIn = IERC20(_path[0]);
_amountIn = UniswapV2Library.getAmountsIn(factory, initCodeHash, amountOut_, _path)[0];
require(_amountIn <= amountInMax_, "Too much requested");
_tokenIn.safeTransfer(UniswapV2Library.pairFor(factory, initCodeHash, _path[0], _path[1]), _amountIn);
_swap(_path, outRecipient_);
// If swap end up costly less than _amountInMax then return remaining
uint256 _remainingAmountIn = amountInMax_ - _amountIn;
if (_remainingAmountIn > 0) {
_tokenIn.safeTransfer(inSender_, _remainingAmountIn);
}
}
/// @dev Returns `0` if reverts
function _getAmountsIn(uint256 _amountOut, address[] memory _path) internal view returns (uint256 _amountIn) {
try this.getAmountsIn(_amountOut, _path) returns (uint256 amountIn) {
_amountIn = amountIn;
} catch {}
}
/// @dev Returns `0` if reverts
function _getAmountsOut(uint256 amountIn_, address[] memory path_) internal view returns (uint256 _amountOut) {
try this.getAmountsOut(amountIn_, path_) returns (uint256 amountOut) {
_amountOut = amountOut;
} catch {}
}
/**
* @notice Encode path from `address[]` to `bytes`
*/
function _encodePath(address[] memory path_) private pure returns (bytes memory _path) {
return abi.encode(path_);
}
/**
* @notice Encode path from `bytes` to `address[]`
*/
function _decodePath(bytes memory path_) private pure returns (address[] memory _path) {
return abi.decode(path_, (address[]));
}
/**
* NOTICE:: This function is being used as is from Uniswap's V2SwapRouter.sol deployed
* at 0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45 and licensed under GPL-2.0-or-later.
* - It does supports fee-on-transfer tokens
* - It does requires the initial amount to have already been sent to the first pair
*/
function _swap(address[] memory path, address _to) private {
for (uint256 i; i < path.length - 1; i++) {
(address input, address output) = (path[i], path[i + 1]);
(address token0, ) = UniswapV2Library.sortTokens(input, output);
IUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, initCodeHash, input, output));
uint256 amountInput;
uint256 amountOutput;
// scope to avoid stack too deep errors
{
(uint256 reserve0, uint256 reserve1, ) = pair.getReserves();
(uint256 reserveInput, uint256 reserveOutput) = input == token0
? (reserve0, reserve1)
: (reserve1, reserve0);
amountInput = IERC20(input).balanceOf(address(pair)) - reserveInput;
amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
}
(uint256 amount0Out, uint256 amount1Out) = input == token0
? (uint256(0), amountOutput)
: (amountOutput, uint256(0));
address to = i < path.length - 2
? UniswapV2Library.pairFor(factory, initCodeHash, output, path[i + 2])
: _to;
pair.swap(amount0Out, amount1Out, to, new bytes(0));
}
}
/**
* @notice Update WETH-Like token
*/
function updateWethLikeToken(address wethLike_) external onlyGovernor {
emit WethLikeTokenUpdated(wethLike, wethLike_);
wethLike = wethLike_;
}
}