Transaction Hash:
Block:
19538740 at Mar-29-2024 09:22:35 AM +UTC
Transaction Fee:
0.001188388889529464 ETH
$3.72
Gas Used:
46,136 Gas / 25.758385849 Gwei
Emitted Events:
327 |
WrappedCK.Approval( owner=[Sender] 0xda3239782a6d8493b6cc7a30816df93ac9bbec76, spender=0x00000000...43aC78BA3, value=115000000000000000000 )
|
Account State Difference:
Address | Before | After | State Difference | ||
---|---|---|---|---|---|
0x09fE5f02...B04128075 | |||||
0x4838B106...B0BAD5f97
Miner
| (Titan Builder) | 5.951016589646980939 Eth | 5.951017626400455555 Eth | 0.000001036753474616 | |
0xda323978...AC9bBEC76 |
0.094035448811799584 Eth
Nonce: 485
|
0.09284705992227012 Eth
Nonce: 486
| 0.001188388889529464 |
Execution Trace
WrappedCK.approve( spender=0x000000000022D473030F116dDEE9F6B43aC78BA3, value=115000000000000000000 ) => ( True )
approve[ERC20 (ln:157)]
Approval[ERC20 (ln:161)]
pragma solidity ^0.5.8; /** * @title ERC20 interface * @dev see https://github.com/ethereum/EIPs/issues/20 */ interface IERC20 { function transfer(address to, uint256 value) external returns (bool); function approve(address spender, uint256 value) external returns (bool); function transferFrom(address from, address to, uint256 value) external returns (bool); function totalSupply() external view returns (uint256); function balanceOf(address who) external view returns (uint256); function allowance(address owner, address spender) external view returns (uint256); event Transfer(address indexed from, address indexed to, uint256 value); event Approval(address indexed owner, address indexed spender, uint256 value); } /** * @title SafeMath * @dev Unsigned math operations with safety checks that revert on error */ library SafeMath { /** * @dev Multiplies two unsigned integers, reverts on 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-solidity/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b); return c; } /** * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend). */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { require(b <= a); uint256 c = a - b; return c; } /** * @dev Adds two unsigned integers, reverts on overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; require(c >= a); return c; } /** * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo), * reverts when dividing by zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { require(b != 0); return a % b; } } /** * @title Standard ERC20 token * * @dev Implementation of the basic standard token. * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md * Originally based on code by FirstBlood: * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol * * This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for * all accounts just by listening to said events. Note that this isn't required by the specification, and other * compliant implementations may not do it. */ contract ERC20 is IERC20 { using SafeMath for uint256; mapping (address => uint256) private _balances; mapping (address => mapping (address => uint256)) private _allowed; uint256 private _totalSupply; /** * @dev Total number of tokens in existence */ function totalSupply() public view returns (uint256) { return _totalSupply; } /** * @dev Gets the balance of the specified address. * @param owner The address to query the balance of. * @return An uint256 representing the amount owned by the passed address. */ function balanceOf(address owner) public view returns (uint256) { return _balances[owner]; } /** * @dev Function to check the amount of tokens that an owner allowed to a spender. * @param owner address The address which owns the funds. * @param spender address The address which will spend the funds. * @return A uint256 specifying the amount of tokens still available for the spender. */ function allowance(address owner, address spender) public view returns (uint256) { return _allowed[owner][spender]; } /** * @dev Transfer token for a specified address * @param to The address to transfer to. * @param value The amount to be transferred. */ function transfer(address to, uint256 value) public returns (bool) { _transfer(msg.sender, to, value); return true; } /** * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender. * 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 * @param spender The address which will spend the funds. * @param value The amount of tokens to be spent. */ function approve(address spender, uint256 value) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = value; emit Approval(msg.sender, spender, value); return true; } /** * @dev Transfer tokens from one address to another. * Note that while this function emits an Approval event, this is not required as per the specification, * and other compliant implementations may not emit the event. * @param from address The address which you want to send tokens from * @param to address The address which you want to transfer to * @param value uint256 the amount of tokens to be transferred */ function transferFrom(address from, address to, uint256 value) public returns (bool) { _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value); _transfer(from, to, value); emit Approval(from, msg.sender, _allowed[from][msg.sender]); return true; } /** * @dev Increase the amount of tokens that an owner allowed to a spender. * approve should be called when allowed_[_spender] == 0. To increment * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * Emits an Approval event. * @param spender The address which will spend the funds. * @param addedValue The amount of tokens to increase the allowance by. */ function increaseAllowance(address spender, uint256 addedValue) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = _allowed[msg.sender][spender].add(addedValue); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; } /** * @dev Decrease the amount of tokens that an owner allowed to a spender. * approve should be called when allowed_[_spender] == 0. To decrement * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * Emits an Approval event. * @param spender The address which will spend the funds. * @param subtractedValue The amount of tokens to decrease the allowance by. */ function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) { require(spender != address(0)); _allowed[msg.sender][spender] = _allowed[msg.sender][spender].sub(subtractedValue); emit Approval(msg.sender, spender, _allowed[msg.sender][spender]); return true; } /** * @dev Transfer token for a specified addresses * @param from The address to transfer from. * @param to The address to transfer to. * @param value The amount to be transferred. */ function _transfer(address from, address to, uint256 value) internal { require(to != address(0)); _balances[from] = _balances[from].sub(value); _balances[to] = _balances[to].add(value); emit Transfer(from, to, value); } /** * @dev Internal function that mints an amount of the token and assigns it to * an account. This encapsulates the modification of balances such that the * proper events are emitted. * @param account The account that will receive the created tokens. * @param value The amount that will be created. */ function _mint(address account, uint256 value) internal { require(account != address(0)); _totalSupply = _totalSupply.add(value); _balances[account] = _balances[account].add(value); emit Transfer(address(0), account, value); } /** * @dev Internal function that burns an amount of the token of a given * account. * @param account The account whose tokens will be burnt. * @param value The amount that will be burnt. */ function _burn(address account, uint256 value) internal { require(account != address(0)); _totalSupply = _totalSupply.sub(value); _balances[account] = _balances[account].sub(value); emit Transfer(account, address(0), value); } /** * @dev Internal function that burns an amount of the token of a given * account, deducting from the sender's allowance for said account. Uses the * internal burn function. * Emits an Approval event (reflecting the reduced allowance). * @param account The account whose tokens will be burnt. * @param value The amount that will be burnt. */ function _burnFrom(address account, uint256 value) internal { _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value); _burn(account, value); emit Approval(account, msg.sender, _allowed[account][msg.sender]); } } /** * @title Helps contracts guard against reentrancy attacks. * @author Remco Bloemen <remco@2π.com>, Eenae <[email protected]> * @dev If you mark a function `nonReentrant`, you should also * mark it `external`. */ contract ReentrancyGuard { /// @dev counter to allow mutex lock with only one SSTORE operation uint256 private _guardCounter; constructor() public { // The counter starts at one to prevent changing it from zero to a non-zero // value, which is a more expensive operation. _guardCounter = 1; } /** * @dev Prevents a contract from calling itself, directly or indirectly. * Calling a `nonReentrant` function from another `nonReentrant` * function is not supported. It is possible to prevent this from happening * by making the `nonReentrant` function external, and make it call a * `private` function that does the actual work. */ modifier nonReentrant() { _guardCounter += 1; uint256 localCounter = _guardCounter; _; require(localCounter == _guardCounter); } } /// @title Main contract for WrappedCK. This contract converts Cryptokitties between the ERC721 standard and the /// ERC20 standard by locking cryptokitties into the contract and minting 1:1 backed ERC20 tokens, that /// can then be redeemed for cryptokitties when desired. /// @notice When wrapping a cryptokitty, you get a generic WCK token. Since the WCK token is generic, it has no /// no information about what cryptokitty you submitted, so you will most likely not receive the same kitty /// back when redeeming the token unless you specify that kitty's ID. The token only entitles you to receive /// *a* cryptokitty in return, not necessarily the *same* cryptokitty in return. A different user can submit /// their own WCK tokens to the contract and withdraw the kitty that you originally deposited. WCK tokens have /// no information about which kitty was originally deposited to mint WCK - this is due to the very nature of /// the ERC20 standard being fungible, and the ERC721 standard being nonfungible. contract WrappedCK is ERC20, ReentrancyGuard { // OpenZeppelin's SafeMath library is used for all arithmetic operations to avoid overflows/underflows. using SafeMath for uint256; /* ****** */ /* EVENTS */ /* ****** */ /// @dev This event is fired when a user deposits cryptokitties into the contract in exchange /// for an equal number of WCK ERC20 tokens. /// @param kittyId The cryptokitty id of the kitty that was deposited into the contract. event DepositKittyAndMintToken( uint256 kittyId ); /// @dev This event is fired when a user deposits WCK ERC20 tokens into the contract in exchange /// for an equal number of locked cryptokitties. /// @param kittyId The cryptokitty id of the kitty that was withdrawn from the contract. event BurnTokenAndWithdrawKitty( uint256 kittyId ); /* ******* */ /* STORAGE */ /* ******* */ /// @dev An Array containing all of the cryptokitties that are locked in the contract, backing /// WCK ERC20 tokens 1:1 /// @notice Some of the kitties in this array were indeed deposited to the contract, but they /// are no longer held by the contract. This is because withdrawSpecificKitty() allows a /// user to withdraw a kitty "out of order". Since it would be prohibitively expensive to /// shift the entire array once we've withdrawn a single element, we instead maintain this /// mapping to determine whether an element is still contained in the contract or not. uint256[] private depositedKittiesArray; /// @dev A mapping keeping track of which kittyIDs are currently contained within the contract. /// @notice We cannot rely on depositedKittiesArray as the source of truth as to which cats are /// deposited in the contract. This is because burnTokensAndWithdrawKitties() allows a user to /// withdraw a kitty "out of order" of the order that they are stored in the array. Since it /// would be prohibitively expensive to shift the entire array once we've withdrawn a single /// element, we instead maintain this mapping to determine whether an element is still contained /// in the contract or not. mapping (uint256 => bool) private kittyIsDepositedInContract; /* ********* */ /* CONSTANTS */ /* ********* */ /// @dev The metadata details about the "Wrapped CryptoKitties" WCK ERC20 token. uint8 constant public decimals = 18; string constant public name = "Wrapped CryptoKitties"; string constant public symbol = "WCK"; /// @dev The address of official CryptoKitties contract that stores the metadata about each cat. /// @notice The owner is not capable of changing the address of the CryptoKitties Core contract /// once the contract has been deployed. address public kittyCoreAddress = 0x06012c8cf97BEaD5deAe237070F9587f8E7A266d; KittyCore kittyCore; /* ********* */ /* FUNCTIONS */ /* ********* */ /// @notice Allows a user to lock cryptokitties in the contract in exchange for an equal number /// of WCK ERC20 tokens. /// @param _kittyIds The ids of the cryptokitties that will be locked into the contract. /// @notice The user must first call approve() in the Cryptokitties Core contract on each kitty /// that thye wish to deposit before calling depositKittiesAndMintTokens(). There is no danger /// of this contract overreaching its approval, since the CryptoKitties Core contract's approve() /// function only approves this contract for a single Cryptokitty. Calling approve() allows this /// contract to transfer the specified kitty in the depositKittiesAndMintTokens() function. function depositKittiesAndMintTokens(uint256[] calldata _kittyIds) external nonReentrant { require(_kittyIds.length > 0, 'you must submit an array with at least one element'); for(uint i = 0; i < _kittyIds.length; i++){ uint256 kittyToDeposit = _kittyIds[i]; require(msg.sender == kittyCore.ownerOf(kittyToDeposit), 'you do not own this cat'); require(kittyCore.kittyIndexToApproved(kittyToDeposit) == address(this), 'you must approve() this contract to give it permission to withdraw this cat before you can deposit a cat'); kittyCore.transferFrom(msg.sender, address(this), kittyToDeposit); _pushKitty(kittyToDeposit); emit DepositKittyAndMintToken(kittyToDeposit); } _mint(msg.sender, (_kittyIds.length).mul(10**18)); } /// @notice Allows a user to burn WCK ERC20 tokens in exchange for an equal number of locked /// cryptokitties. /// @param _kittyIds The IDs of the kitties that the user wishes to withdraw. If the user submits 0 /// as the ID for any kitty, the contract uses the last kitty in the array for that kitty. /// @param _destinationAddresses The addresses that the withdrawn kitties will be sent to (this allows /// anyone to "airdrop" kitties to addresses that they do not own in a single transaction). function burnTokensAndWithdrawKitties(uint256[] calldata _kittyIds, address[] calldata _destinationAddresses) external nonReentrant { require(_kittyIds.length == _destinationAddresses.length, 'you did not provide a destination address for each of the cats you wish to withdraw'); require(_kittyIds.length > 0, 'you must submit an array with at least one element'); uint256 numTokensToBurn = _kittyIds.length; require(balanceOf(msg.sender) >= numTokensToBurn.mul(10**18), 'you do not own enough tokens to withdraw this many ERC721 cats'); _burn(msg.sender, numTokensToBurn.mul(10**18)); for(uint i = 0; i < numTokensToBurn; i++){ uint256 kittyToWithdraw = _kittyIds[i]; if(kittyToWithdraw == 0){ kittyToWithdraw = _popKitty(); } else { require(kittyIsDepositedInContract[kittyToWithdraw] == true, 'this kitty has already been withdrawn'); require(address(this) == kittyCore.ownerOf(kittyToWithdraw), 'the contract does not own this cat'); kittyIsDepositedInContract[kittyToWithdraw] = false; } kittyCore.transfer(_destinationAddresses[i], kittyToWithdraw); emit BurnTokenAndWithdrawKitty(kittyToWithdraw); } } /// @notice Adds a locked cryptokitty to the end of the array /// @param _kittyId The id of the cryptokitty that will be locked into the contract. function _pushKitty(uint256 _kittyId) internal { depositedKittiesArray.push(_kittyId); kittyIsDepositedInContract[_kittyId] = true; } /// @notice Removes an unlocked cryptokitty from the end of the array /// @notice The reason that this function must check if the kittyIsDepositedInContract /// is that the withdrawSpecificKitty() function allows a user to withdraw a kitty /// from the array out of order. /// @return The id of the cryptokitty that will be unlocked from the contract. function _popKitty() internal returns(uint256){ require(depositedKittiesArray.length > 0, 'there are no cats in the array'); uint256 kittyId = depositedKittiesArray[depositedKittiesArray.length - 1]; depositedKittiesArray.length--; while(kittyIsDepositedInContract[kittyId] == false){ kittyId = depositedKittiesArray[depositedKittiesArray.length - 1]; depositedKittiesArray.length--; } kittyIsDepositedInContract[kittyId] = false; return kittyId; } /// @notice Removes any kitties that exist in the array but are no longer held in the /// contract, which happens if the first few kitties have previously been withdrawn /// out of order using the withdrawSpecificKitty() function. /// @notice This function exists to prevent a griefing attack where a malicious attacker /// could call withdrawSpecificKitty() on a large number of kitties at the front of the /// array, causing the while-loop in _popKitty to always run out of gas. /// @param _numSlotsToCheck The number of slots to check in the array. function batchRemoveWithdrawnKittiesFromStorage(uint256 _numSlotsToCheck) external { require(_numSlotsToCheck <= depositedKittiesArray.length, 'you are trying to batch remove more slots than exist in the array'); uint256 arrayIndex = depositedKittiesArray.length; for(uint i = 0; i < _numSlotsToCheck; i++){ arrayIndex = arrayIndex.sub(1); uint256 kittyId = depositedKittiesArray[arrayIndex]; if(kittyIsDepositedInContract[kittyId] == false){ depositedKittiesArray.length--; } else { return; } } } /// @notice The owner is not capable of changing the address of the CryptoKitties Core /// contract once the contract has been deployed. constructor() public { kittyCore = KittyCore(kittyCoreAddress); } /// @dev We leave the fallback function payable in case the current State Rent proposals require /// us to send funds to this contract to keep it alive on mainnet. /// @notice There is no function that allows the contract creator to withdraw any funds sent /// to this contract, so any funds sent directly to the fallback function that are not used for /// State Rent are lost forever. function() external payable {} } /// @title Interface for interacting with the CryptoKitties Core contract created by Dapper Labs Inc. contract KittyCore { function ownerOf(uint256 _tokenId) public view returns (address owner); function transferFrom(address _from, address _to, uint256 _tokenId) external; function transfer(address _to, uint256 _tokenId) external; mapping (uint256 => address) public kittyIndexToApproved; }