Transaction Hash:
Block:
16462226 at Jan-22-2023 12:05:11 PM +UTC
Transaction Fee:
0.001226509787193851 ETH
$3.57
Gas Used:
77,053 Gas / 15.917742167 Gwei
Emitted Events:
145 |
Erc20SwapAsset.Transfer( from=[Sender] 0x569cdc5b765ba27076f7c68c3f435267b56f4616, to=[Receiver] SwapTokens, value=9928365814202797163 )
|
146 |
Erc20SwapAsset.Approval( owner=[Sender] 0x569cdc5b765ba27076f7c68c3f435267b56f4616, spender=[Receiver] SwapTokens, value=115792089237316195423570985008687907853269984665640564039447655642098926842772 )
|
147 |
MultichainToken.Transfer( from=[Receiver] SwapTokens, to=[Sender] 0x569cdc5b765ba27076f7c68c3f435267b56f4616, value=9928365814202797163 )
|
148 |
SwapTokens.Swapped( sender=[Sender] 0x569cdc5b765ba27076f7c68c3f435267b56f4616, srcAmount=9928365814202797163, dstAmount=9928365814202797163 )
|
Account State Difference:
Address | Before | After | State Difference | ||
---|---|---|---|---|---|
0x569cDc5B...7B56F4616 |
1.847067726657101167 Eth
Nonce: 489
|
1.845841216869907316 Eth
Nonce: 490
| 0.001226509787193851 | ||
0x65Ef703f...548492df4 | |||||
0xAAB27b15...5c8729bd1
Miner
| (Eden Network: Builder) | 4.664820227150430479 Eth | 4.664935806650430479 Eth | 0.0001155795 | |
0xf99d58e4...91861b4D6 |
Execution Trace
SwapTokens.swap( srcAmount=9928365814202797163 ) => ( dstAmount=9928365814202797163 )
-
Erc20SwapAsset.transferFrom( sender=0x569cDc5B765bA27076f7C68c3f435267B56F4616, recipient=0xaed0472b498548B1354925d222B832b99Bb2EC60, amount=9928365814202797163 ) => ( True )
-
MultichainToken.transfer( recipient=0x569cDc5B765bA27076f7C68c3f435267B56F4616, amount=9928365814202797163 ) => ( True )
swap[SwapTokens (ln:59)]
safeTransferFrom[SwapTokens (ln:61)]
call[TransferHelper (ln:15)]
encodeWithSelector[TransferHelper (ln:15)]
decode[TransferHelper (ln:16)]
safeTransfer[SwapTokens (ln:62)]
call[TransferHelper (ln:9)]
encodeWithSelector[TransferHelper (ln:9)]
decode[TransferHelper (ln:10)]
Swapped[SwapTokens (ln:63)]
File 1 of 3: SwapTokens
File 2 of 3: Erc20SwapAsset
File 3 of 3: MultichainToken
// SPDX-License-Identifier: GPL-3.0-or-later pragma solidity ^0.8.6; // helper methods for interacting with ERC20 tokens library TransferHelper { function safeTransfer(address token, address to, uint value) internal { // bytes4(keccak256(bytes('transfer(address,uint256)'))); (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value)); require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED'); } function safeTransferFrom(address token, address from, address to, uint value) internal { // bytes4(keccak256(bytes('transferFrom(address,address,uint256)'))); (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value)); require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED'); } } contract SwapTokens { address public immutable srcToken; address public immutable dstToken; // eg. if swap rate 1:100 (src:dst), then numeratorOfRate=100, denominatorOfRate=1 // eg. if swap rate 2:3 (src:dst), then numeratorOfRate=3, denominatorOfRate=2 uint256 public immutable numeratorOfRate; uint256 public immutable denominatorOfRate; uint256 public latestWithdrawRequestTime; uint256 public latestWithdrawRequestAmount; uint256 public constant minWithdrawApprovalInterval = 2 days; address public owner; modifier onlyOwner() { require(msg.sender == owner, "only owner"); _; } event Swapped(address indexed sender, uint256 indexed srcAmount, uint256 indexed dstAmount); constructor(address _srcToken, address _dstToken, uint256 _numeratorOfRate, uint256 _denominatorOfRate) { srcToken = _srcToken; dstToken = _dstToken; numeratorOfRate = _numeratorOfRate; denominatorOfRate = _denominatorOfRate; owner = msg.sender; } function transferOwnership(address newOwner) external onlyOwner { require(newOwner != address(0), "the new owner is the zero address"); owner = newOwner; } /// @dev swap with `srcAmount` of `srcToken` to get `dstToken`. /// Returns swap result of `dstAmount` of `dstToken`. /// Requirements: /// - `msg.sender` must have approved at least `srcAmount` `srcToken` to `address(this)`. /// - `address(this)` must have at least `dstAmount` `dstToken`. function swap(uint256 srcAmount) external returns (uint256 dstAmount) { dstAmount = srcAmount * numeratorOfRate / denominatorOfRate; TransferHelper.safeTransferFrom(srcToken, msg.sender, address(this), srcAmount); TransferHelper.safeTransfer(dstToken, msg.sender, dstAmount); emit Swapped(msg.sender, srcAmount, dstAmount); return dstAmount; } function withdrawRequest(uint256 amount) external onlyOwner { if (amount > 0) { latestWithdrawRequestTime = block.timestamp; latestWithdrawRequestAmount = amount; } else { latestWithdrawRequestTime = 0; latestWithdrawRequestAmount = 0; } } function withdraw() external onlyOwner { require( latestWithdrawRequestTime > 0 && latestWithdrawRequestAmount > 0, "please do withdraw request firstly" ); require( latestWithdrawRequestTime + minWithdrawApprovalInterval < block.timestamp, "the minimum withdraw approval interval is not satisfied" ); uint256 amount = latestWithdrawRequestAmount; latestWithdrawRequestTime = 0; latestWithdrawRequestAmount = 0; TransferHelper.safeTransfer(dstToken, msg.sender, amount); } }
File 2 of 3: Erc20SwapAsset
// SPDX-License-Identifier: MIT // File: @openzeppelin/contracts/GSN/Context.sol pragma solidity ^0.5.0; /* * @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 GSN 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. */ contract Context { // Empty internal constructor, to prevent people from mistakenly deploying // an instance of this contract, which should be used via inheritance. constructor () internal { } // solhint-disable-previous-line no-empty-blocks function _msgSender() internal view returns (address payable) { return msg.sender; } function _msgData() internal view returns (bytes memory) { this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691 return msg.data; } } // File: @openzeppelin/contracts/token/ERC20/IERC20.sol pragma solidity ^0.5.0; /** * @dev Interface of the ERC20 standard as defined in the EIP. Does not include * the optional functions; to access them see {ERC20Detailed}. */ interface IERC20 { /** * @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 `recipient`. * * Returns a boolean value indicating whether the operation succeeded. * * Emits a {Transfer} event. */ function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount) external returns (bool); /** * @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); } // File: @openzeppelin/contracts/math/SafeMath.sol pragma solidity ^0.5.0; /** * @dev Wrappers over Solidity's arithmetic operations with added overflow * checks. * * Arithmetic operations in Solidity wrap on overflow. This can easily result * in bugs, because programmers usually assume that an overflow raises an * error, which is the standard behavior in high level programming languages. * `SafeMath` restores this intuition by reverting the transaction when an * operation overflows. * * Using this library instead of the unchecked operations eliminates an entire * class of bugs, so it's recommended to use it always. */ library SafeMath { /** * @dev Returns the addition of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity's `+` operator. * * Requirements: * - Addition cannot overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; require(c >= a, "SafeMath: addition overflow"); return c; } /** * @dev Returns the subtraction of two unsigned integers, reverting on * overflow (when the result is negative). * * Counterpart to Solidity's `-` operator. * * Requirements: * - Subtraction cannot overflow. */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { return sub(a, b, "SafeMath: subtraction overflow"); } /** * @dev Returns the subtraction of two unsigned integers, reverting with custom message on * overflow (when the result is negative). * * Counterpart to Solidity's `-` operator. * * Requirements: * - Subtraction cannot overflow. * * _Available since v2.4.0._ */ function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) { require(b <= a, errorMessage); uint256 c = a - b; return c; } /** * @dev Returns the multiplication of two unsigned integers, reverting on * overflow. * * Counterpart to Solidity's `*` operator. * * Requirements: * - Multiplication cannot overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b, "SafeMath: multiplication overflow"); return c; } /** * @dev Returns the integer division of two unsigned integers. Reverts on * division by zero. The result is rounded towards zero. * * Counterpart to Solidity's `/` operator. Note: this function uses a * `revert` opcode (which leaves remaining gas untouched) while Solidity * uses an invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { return div(a, b, "SafeMath: division by zero"); } /** * @dev Returns the integer division of two unsigned integers. Reverts with custom message on * division by zero. The result is rounded towards zero. * * Counterpart to Solidity's `/` operator. Note: this function uses a * `revert` opcode (which leaves remaining gas untouched) while Solidity * uses an invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. * * _Available since v2.4.0._ */ function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0, errorMessage); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), * Reverts when dividing by zero. * * Counterpart to Solidity's `%` operator. This function uses a `revert` * opcode (which leaves remaining gas untouched) while Solidity uses an * invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { return mod(a, b, "SafeMath: modulo by zero"); } /** * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), * Reverts with custom message when dividing by zero. * * Counterpart to Solidity's `%` operator. This function uses a `revert` * opcode (which leaves remaining gas untouched) while Solidity uses an * invalid opcode to revert (consuming all remaining gas). * * Requirements: * - The divisor cannot be zero. * * _Available since v2.4.0._ */ function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) { require(b != 0, errorMessage); return a % b; } } // File: @openzeppelin/contracts/token/ERC20/ERC20.sol pragma solidity ^0.5.0; /** * @dev Implementation of the {IERC20} interface. * * This implementation is agnostic to the way tokens are created. This means * that a supply mechanism has to be added in a derived contract using {_mint}. * For a generic mechanism see {ERC20Mintable}. * * TIP: For a detailed writeup see our guide * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How * to implement supply mechanisms]. * * We have followed general OpenZeppelin guidelines: functions revert instead * of returning `false` on failure. This behavior is nonetheless conventional * and does not conflict with the expectations of ERC20 applications. * * Additionally, an {Approval} event is emitted on calls to {transferFrom}. * This allows applications to reconstruct the allowance for all accounts just * by listening to said events. Other implementations of the EIP may not emit * these events, as it isn't required by the specification. * * Finally, the non-standard {decreaseAllowance} and {increaseAllowance} * functions have been added to mitigate the well-known issues around setting * allowances. See {IERC20-approve}. */ contract ERC20 is Context, IERC20 { using SafeMath for uint256; mapping (address => uint256) private _balances; mapping (address => mapping (address => uint256)) private _allowances; uint256 private _totalSupply; /** * @dev See {IERC20-totalSupply}. */ function totalSupply() public view returns (uint256) { return _totalSupply; } /** * @dev See {IERC20-balanceOf}. */ function balanceOf(address account) public view returns (uint256) { return _balances[account]; } /** * @dev See {IERC20-transfer}. * * Requirements: * * - `recipient` cannot be the zero address. * - the caller must have a balance of at least `amount`. */ function transfer(address recipient, uint256 amount) public returns (bool) { _transfer(_msgSender(), recipient, amount); return true; } /** * @dev See {IERC20-allowance}. */ function allowance(address owner, address spender) public view returns (uint256) { return _allowances[owner][spender]; } /** * @dev See {IERC20-approve}. * * Requirements: * * - `spender` cannot be the zero address. */ function approve(address spender, uint256 amount) public returns (bool) { _approve(_msgSender(), spender, amount); return true; } /** * @dev See {IERC20-transferFrom}. * * Emits an {Approval} event indicating the updated allowance. This is not * required by the EIP. See the note at the beginning of {ERC20}; * * Requirements: * - `sender` and `recipient` cannot be the zero address. * - `sender` must have a balance of at least `amount`. * - the caller must have allowance for `sender`'s tokens of at least * `amount`. */ function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) { _transfer(sender, recipient, amount); _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance")); return true; } /** * @dev Atomically increases the allowance granted to `spender` by the caller. * * This is an alternative to {approve} that can be used as a mitigation for * problems described in {IERC20-approve}. * * Emits an {Approval} event indicating the updated allowance. * * Requirements: * * - `spender` cannot be the zero address. */ function increaseAllowance(address spender, uint256 addedValue) public returns (bool) { _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue)); return true; } /** * @dev Atomically decreases the allowance granted to `spender` by the caller. * * This is an alternative to {approve} that can be used as a mitigation for * problems described in {IERC20-approve}. * * Emits an {Approval} event indicating the updated allowance. * * Requirements: * * - `spender` cannot be the zero address. * - `spender` must have allowance for the caller of at least * `subtractedValue`. */ function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) { _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero")); return true; } /** * @dev Moves tokens `amount` from `sender` to `recipient`. * * This is internal function is equivalent to {transfer}, and can be used to * e.g. implement automatic token fees, slashing mechanisms, etc. * * Emits a {Transfer} event. * * Requirements: * * - `sender` cannot be the zero address. * - `recipient` cannot be the zero address. * - `sender` must have a balance of at least `amount`. */ function _transfer(address sender, address recipient, uint256 amount) internal { require(sender != address(0), "ERC20: transfer from the zero address"); require(recipient != address(0), "ERC20: transfer to the zero address"); _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance"); _balances[recipient] = _balances[recipient].add(amount); emit Transfer(sender, recipient, amount); } /** @dev Creates `amount` tokens and assigns them to `account`, increasing * the total supply. * * Emits a {Transfer} event with `from` set to the zero address. * * Requirements * * - `to` cannot be the zero address. */ function _mint(address account, uint256 amount) internal { require(account != address(0), "ERC20: mint to the zero address"); _totalSupply = _totalSupply.add(amount); _balances[account] = _balances[account].add(amount); emit Transfer(address(0), account, amount); } /** * @dev Destroys `amount` tokens from `account`, reducing the * total supply. * * Emits a {Transfer} event with `to` set to the zero address. * * Requirements * * - `account` cannot be the zero address. * - `account` must have at least `amount` tokens. */ function _burn(address account, uint256 amount) internal { require(account != address(0), "ERC20: burn from the zero address"); _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance"); _totalSupply = _totalSupply.sub(amount); emit Transfer(account, address(0), amount); } /** * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens. * * This is internal function is equivalent to `approve`, and can be used to * e.g. set automatic allowances for certain subsystems, etc. * * Emits an {Approval} event. * * Requirements: * * - `owner` cannot be the zero address. * - `spender` cannot be the zero address. */ function _approve(address owner, address spender, uint256 amount) internal { require(owner != address(0), "ERC20: approve from the zero address"); require(spender != address(0), "ERC20: approve to the zero address"); _allowances[owner][spender] = amount; emit Approval(owner, spender, amount); } /** * @dev Destroys `amount` tokens from `account`.`amount` is then deducted * from the caller's allowance. * * See {_burn} and {_approve}. */ function _burnFrom(address account, uint256 amount) internal { _burn(account, amount); _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance")); } } // File: @openzeppelin/contracts/token/ERC20/ERC20Detailed.sol pragma solidity ^0.5.0; /** * @dev Optional functions from the ERC20 standard. */ contract ERC20Detailed is IERC20 { string private _name; string private _symbol; uint8 private _decimals; /** * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of * these values are immutable: they can only be set once during * construction. */ constructor (string memory name, string memory symbol, uint8 decimals) public { _name = name; _symbol = symbol; _decimals = decimals; } /** * @dev Returns the name of the token. */ function name() public view returns (string memory) { return _name; } /** * @dev Returns the symbol of the token, usually a shorter version of the * name. */ function symbol() public view returns (string memory) { return _symbol; } /** * @dev Returns the number of decimals used to get its user representation. * For example, if `decimals` equals `2`, a balance of `505` tokens should * be displayed to a user as `5,05` (`505 / 10 ** 2`). * * Tokens usually opt for a value of 18, imitating the relationship between * Ether and Wei. * * NOTE: This information is only used for _display_ purposes: it in * no way affects any of the arithmetic of the contract, including * {IERC20-balanceOf} and {IERC20-transfer}. */ function decimals() public view returns (uint8) { return _decimals; } } // File: internal/Erc20SwapAsset.sol pragma solidity ^0.5.0; contract Erc20SwapAsset is ERC20, ERC20Detailed { event LogChangeDCRMOwner(address indexed oldOwner, address indexed newOwner, uint indexed effectiveHeight); event LogSwapin(bytes32 indexed txhash, address indexed account, uint amount); event LogSwapout(address indexed account, address indexed bindaddr, uint amount); address private _oldOwner; address private _newOwner; uint256 private _newOwnerEffectiveHeight; modifier onlyOwner() { require(msg.sender == owner(), "only owner"); _; } constructor(string memory name, string memory symbol, uint8 decimals) public ERC20Detailed(name, symbol, decimals) { _newOwner = msg.sender; _newOwnerEffectiveHeight = block.number; } function owner() public view returns (address) { if (block.number >= _newOwnerEffectiveHeight) { return _newOwner; } return _oldOwner; } function changeDCRMOwner(address newOwner) public onlyOwner returns (bool) { require(newOwner != address(0), "new owner is the zero address"); _oldOwner = owner(); _newOwner = newOwner; _newOwnerEffectiveHeight = block.number + 13300; emit LogChangeDCRMOwner(_oldOwner, _newOwner, _newOwnerEffectiveHeight); return true; } function Swapin(bytes32 txhash, address account, uint256 amount) public onlyOwner returns (bool) { _mint(account, amount); emit LogSwapin(txhash, account, amount); return true; } function Swapout(uint256 amount, address bindaddr) public returns (bool) { require(bindaddr != address(0), "bind address is the zero address"); _burn(_msgSender(), amount); emit LogSwapout(_msgSender(), bindaddr, amount); return true; } }
File 3 of 3: MultichainToken
// SPDX-License-Identifier: GPL-3.0-or-later // Sources flattened with hardhat v2.8.0 https://hardhat.org // File @openzeppelin/contracts/token/ERC20/[email protected] // OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol) pragma solidity ^0.8.0; /** * @dev Interface of the ERC20 standard as defined in the EIP. */ interface IERC20 { /** * @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 `recipient`. * * Returns a boolean value indicating whether the operation succeeded. * * Emits a {Transfer} event. */ function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount ) external returns (bool); /** * @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); } // File @openzeppelin/contracts/token/ERC20/extensions/[email protected] // OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol) pragma solidity ^0.8.0; /** * @dev Interface for the optional metadata functions from the ERC20 standard. * * _Available since v4.1._ */ interface IERC20Metadata is IERC20 { /** * @dev Returns the name of the token. */ function name() external view returns (string memory); /** * @dev Returns the symbol of the token. */ function symbol() external view returns (string memory); /** * @dev Returns the decimals places of the token. */ function decimals() external view returns (uint8); } // File @openzeppelin/contracts/utils/[email protected] // 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; } } // File @openzeppelin/contracts/token/ERC20/[email protected] // OpenZeppelin Contracts v4.4.1 (token/ERC20/ERC20.sol) pragma solidity ^0.8.0; /** * @dev Implementation of the {IERC20} interface. * * This implementation is agnostic to the way tokens are created. This means * that a supply mechanism has to be added in a derived contract using {_mint}. * For a generic mechanism see {ERC20PresetMinterPauser}. * * TIP: For a detailed writeup see our guide * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How * to implement supply mechanisms]. * * We have followed general OpenZeppelin Contracts guidelines: functions revert * instead returning `false` on failure. This behavior is nonetheless * conventional and does not conflict with the expectations of ERC20 * applications. * * Additionally, an {Approval} event is emitted on calls to {transferFrom}. * This allows applications to reconstruct the allowance for all accounts just * by listening to said events. Other implementations of the EIP may not emit * these events, as it isn't required by the specification. * * Finally, the non-standard {decreaseAllowance} and {increaseAllowance} * functions have been added to mitigate the well-known issues around setting * allowances. See {IERC20-approve}. */ contract ERC20 is Context, IERC20, IERC20Metadata { mapping(address => uint256) private _balances; mapping(address => mapping(address => uint256)) private _allowances; uint256 private _totalSupply; string private _name; string private _symbol; /** * @dev Sets the values for {name} and {symbol}. * * The default value of {decimals} is 18. To select a different value for * {decimals} you should overload it. * * All two of these values are immutable: they can only be set once during * construction. */ constructor(string memory name_, string memory symbol_) { _name = name_; _symbol = symbol_; } /** * @dev Returns the name of the token. */ function name() public view virtual override returns (string memory) { return _name; } /** * @dev Returns the symbol of the token, usually a shorter version of the * name. */ function symbol() public view virtual override returns (string memory) { return _symbol; } /** * @dev Returns the number of decimals used to get its user representation. * For example, if `decimals` equals `2`, a balance of `505` tokens should * be displayed to a user as `5.05` (`505 / 10 ** 2`). * * Tokens usually opt for a value of 18, imitating the relationship between * Ether and Wei. This is the value {ERC20} uses, unless this function is * overridden; * * NOTE: This information is only used for _display_ purposes: it in * no way affects any of the arithmetic of the contract, including * {IERC20-balanceOf} and {IERC20-transfer}. */ function decimals() public view virtual override returns (uint8) { return 18; } /** * @dev See {IERC20-totalSupply}. */ function totalSupply() public view virtual override returns (uint256) { return _totalSupply; } /** * @dev See {IERC20-balanceOf}. */ function balanceOf(address account) public view virtual override returns (uint256) { return _balances[account]; } /** * @dev See {IERC20-transfer}. * * Requirements: * * - `recipient` cannot be the zero address. * - the caller must have a balance of at least `amount`. */ function transfer(address recipient, uint256 amount) public virtual override returns (bool) { _transfer(_msgSender(), recipient, amount); return true; } /** * @dev See {IERC20-allowance}. */ function allowance(address owner, address spender) public view virtual override returns (uint256) { return _allowances[owner][spender]; } /** * @dev See {IERC20-approve}. * * Requirements: * * - `spender` cannot be the zero address. */ function approve(address spender, uint256 amount) public virtual override returns (bool) { _approve(_msgSender(), spender, amount); return true; } /** * @dev See {IERC20-transferFrom}. * * Emits an {Approval} event indicating the updated allowance. This is not * required by the EIP. See the note at the beginning of {ERC20}. * * Requirements: * * - `sender` and `recipient` cannot be the zero address. * - `sender` must have a balance of at least `amount`. * - the caller must have allowance for ``sender``'s tokens of at least * `amount`. */ function transferFrom( address sender, address recipient, uint256 amount ) public virtual override returns (bool) { _transfer(sender, recipient, amount); uint256 currentAllowance = _allowances[sender][_msgSender()]; require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance"); unchecked { _approve(sender, _msgSender(), currentAllowance - amount); } return true; } /** * @dev Atomically increases the allowance granted to `spender` by the caller. * * This is an alternative to {approve} that can be used as a mitigation for * problems described in {IERC20-approve}. * * Emits an {Approval} event indicating the updated allowance. * * Requirements: * * - `spender` cannot be the zero address. */ function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) { _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue); return true; } /** * @dev Atomically decreases the allowance granted to `spender` by the caller. * * This is an alternative to {approve} that can be used as a mitigation for * problems described in {IERC20-approve}. * * Emits an {Approval} event indicating the updated allowance. * * Requirements: * * - `spender` cannot be the zero address. * - `spender` must have allowance for the caller of at least * `subtractedValue`. */ function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) { uint256 currentAllowance = _allowances[_msgSender()][spender]; require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero"); unchecked { _approve(_msgSender(), spender, currentAllowance - subtractedValue); } return true; } /** * @dev Moves `amount` of tokens from `sender` to `recipient`. * * This internal function is equivalent to {transfer}, and can be used to * e.g. implement automatic token fees, slashing mechanisms, etc. * * Emits a {Transfer} event. * * Requirements: * * - `sender` cannot be the zero address. * - `recipient` cannot be the zero address. * - `sender` must have a balance of at least `amount`. */ function _transfer( address sender, address recipient, uint256 amount ) internal virtual { require(sender != address(0), "ERC20: transfer from the zero address"); require(recipient != address(0), "ERC20: transfer to the zero address"); _beforeTokenTransfer(sender, recipient, amount); uint256 senderBalance = _balances[sender]; require(senderBalance >= amount, "ERC20: transfer amount exceeds balance"); unchecked { _balances[sender] = senderBalance - amount; } _balances[recipient] += amount; emit Transfer(sender, recipient, amount); _afterTokenTransfer(sender, recipient, amount); } /** @dev Creates `amount` tokens and assigns them to `account`, increasing * the total supply. * * Emits a {Transfer} event with `from` set to the zero address. * * Requirements: * * - `account` cannot be the zero address. */ function _mint(address account, uint256 amount) internal virtual { require(account != address(0), "ERC20: mint to the zero address"); _beforeTokenTransfer(address(0), account, amount); _totalSupply += amount; _balances[account] += amount; emit Transfer(address(0), account, amount); _afterTokenTransfer(address(0), account, amount); } /** * @dev Destroys `amount` tokens from `account`, reducing the * total supply. * * Emits a {Transfer} event with `to` set to the zero address. * * Requirements: * * - `account` cannot be the zero address. * - `account` must have at least `amount` tokens. */ function _burn(address account, uint256 amount) internal virtual { require(account != address(0), "ERC20: burn from the zero address"); _beforeTokenTransfer(account, address(0), amount); uint256 accountBalance = _balances[account]; require(accountBalance >= amount, "ERC20: burn amount exceeds balance"); unchecked { _balances[account] = accountBalance - amount; } _totalSupply -= amount; emit Transfer(account, address(0), amount); _afterTokenTransfer(account, address(0), amount); } /** * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens. * * This internal function is equivalent to `approve`, and can be used to * e.g. set automatic allowances for certain subsystems, etc. * * Emits an {Approval} event. * * Requirements: * * - `owner` cannot be the zero address. * - `spender` cannot be the zero address. */ function _approve( address owner, address spender, uint256 amount ) internal virtual { require(owner != address(0), "ERC20: approve from the zero address"); require(spender != address(0), "ERC20: approve to the zero address"); _allowances[owner][spender] = amount; emit Approval(owner, spender, amount); } /** * @dev Hook that is called before any transfer of tokens. This includes * minting and burning. * * Calling conditions: * * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens * will be transferred to `to`. * - when `from` is zero, `amount` tokens will be minted for `to`. * - when `to` is zero, `amount` of ``from``'s tokens will be burned. * - `from` and `to` are never both zero. * * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks]. */ function _beforeTokenTransfer( address from, address to, uint256 amount ) internal virtual {} /** * @dev Hook that is called after any transfer of tokens. This includes * minting and burning. * * Calling conditions: * * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens * has been transferred to `to`. * - when `from` is zero, `amount` tokens have been minted for `to`. * - when `to` is zero, `amount` of ``from``'s tokens have been burned. * - `from` and `to` are never both zero. * * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks]. */ function _afterTokenTransfer( address from, address to, uint256 amount ) internal virtual {} } // File internal/MultichainToken.sol pragma solidity ^0.8.6; contract MultichainToken is ERC20 { constructor() ERC20("Multichain", "MULTI") { _mint(msg.sender, 1e8 * 10**uint(decimals())); } }