以太猫CryptoKitties源码(一)：准备工作
2019-02-22 本文已影响0人
雪飘千里
1、准备工作
-
1、submit3 下载安装
https://www.sublimetext.com/3 -
2、安装Package Control：
- submit3 —> View —> Show Console menu
复制黏贴下面这段代码安装
- submit3 —> View —> Show Console menu
import urllib.request,os,hashlib; h = '6f4c264a24d933ce70df5dedcf1dcaee' + 'ebe013ee18cced0ef93d5f746d80ef60'; pf = 'Package Control.sublime-package'; ipp = sublime.installed_packages_path(); urllib.request.install_opener( urllib.request.build_opener( urllib.request.ProxyHandler()) ); by = urllib.request.urlopen( 'http://packagecontrol.io/' + pf.replace(' ', '%20')).read(); dh = hashlib.sha256(by).hexdigest(); print('Error validating download (got %s instead of %s), please try manual install' % (dh, h)) if dh != h else open(os.path.join( ipp, pf), 'wb' ).write(by)
这段代码在这里，https://packagecontrol.io/installation
- 3、按下Ctrl+Shift+P调出命令面板；输入install，选择Install Package
image.png
- 4、在列表中选择想要的插件，或者输入插件名
"Ethereum",
"EthereumSoliditySnippets",
image.png
- 5、新建cat.sol文件，复制CryptoKitties源码
https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d#code
pragma solidity ^0.4.11;
/**
* @title Ownable
* @dev The Ownable contract has an owner address, and provides basic authorization control
* functions, this simplifies the implementation of "user permissions".
*/
contract Ownable {
address public owner;
/**
* @dev The Ownable constructor sets the original `owner` of the contract to the sender
* account.
*/
function Ownable() {
owner = msg.sender;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
/**
* @dev Allows the current owner to transfer control of the contract to a newOwner.
* @param newOwner The address to transfer ownership to.
*/
function transferOwnership(address newOwner) onlyOwner {
if (newOwner != address(0)) {
owner = newOwner;
}
}
}
/// @title Interface for contracts conforming to ERC-721: Non-Fungible Tokens
/// @author Dieter Shirley <dete@axiomzen.co> (https://github.com/dete)
contract ERC721 {
// Required methods
function totalSupply() public view returns (uint256 total);
function balanceOf(address _owner) public view returns (uint256 balance);
function ownerOf(uint256 _tokenId) external view returns (address owner);
function approve(address _to, uint256 _tokenId) external;
function transfer(address _to, uint256 _tokenId) external;
function transferFrom(address _from, address _to, uint256 _tokenId) external;
// Events
event Transfer(address from, address to, uint256 tokenId);
event Approval(address owner, address approved, uint256 tokenId);
// Optional
// function name() public view returns (string name);
// function symbol() public view returns (string symbol);
// function tokensOfOwner(address _owner) external view returns (uint256[] tokenIds);
// function tokenMetadata(uint256 _tokenId, string _preferredTransport) public view returns (string infoUrl);
// ERC-165 Compatibility (https://github.com/ethereum/EIPs/issues/165)
function supportsInterface(bytes4 _interfaceID) external view returns (bool);
}
// // Auction wrapper functions
// Auction wrapper functions
/// @title SEKRETOOOO
contract GeneScienceInterface {
/// @dev simply a boolean to indicate this is the contract we expect to be
function isGeneScience() public pure returns (bool);
/// @dev given genes of kitten 1 & 2, return a genetic combination - may have a random factor
/// @param genes1 genes of mom
/// @param genes2 genes of sire
/// @return the genes that are supposed to be passed down the child
function mixGenes(uint256 genes1, uint256 genes2, uint256 targetBlock) public returns (uint256);
}
/// @title A facet of KittyCore that manages special access privileges.
/// @author Axiom Zen (https://www.axiomzen.co)
/// @dev See the KittyCore contract documentation to understand how the various contract facets are arranged.
contract KittyAccessControl {
// This facet controls access control for CryptoKitties. There are four roles managed here:
//
// - The CEO: The CEO can reassign other roles and change the addresses of our dependent smart
// contracts. It is also the only role that can unpause the smart contract. It is initially
// set to the address that created the smart contract in the KittyCore constructor.
//
// - The CFO: The CFO can withdraw funds from KittyCore and its auction contracts.
//
// - The COO: The COO can release gen0 kitties to auction, and mint promo cats.
//
// It should be noted that these roles are distinct without overlap in their access abilities, the
// abilities listed for each role above are exhaustive. In particular, while the CEO can assign any
// address to any role, the CEO address itself doesn't have the ability to act in those roles. This
// restriction is intentional so that we aren't tempted to use the CEO address frequently out of
// convenience. The less we use an address, the less likely it is that we somehow compromise the
// account.
/// @dev Emited when contract is upgraded - See README.md for updgrade plan
event ContractUpgrade(address newContract);
// The addresses of the accounts (or contracts) that can execute actions within each roles.
address public ceoAddress;
address public cfoAddress;
address public cooAddress;
// @dev Keeps track whether the contract is paused. When that is true, most actions are blocked
bool public paused = false;
/// @dev Access modifier for CEO-only functionality
modifier onlyCEO() {
require(msg.sender == ceoAddress);
_;
}
/// @dev Access modifier for CFO-only functionality
modifier onlyCFO() {
require(msg.sender == cfoAddress);
_;
}
/// @dev Access modifier for COO-only functionality
modifier onlyCOO() {
require(msg.sender == cooAddress);
_;
}
modifier onlyCLevel() {
require(
msg.sender == cooAddress ||
msg.sender == ceoAddress ||
msg.sender == cfoAddress
);
_;
}
/// @dev Assigns a new address to act as the CEO. Only available to the current CEO.
/// @param _newCEO The address of the new CEO
function setCEO(address _newCEO) external onlyCEO {
require(_newCEO != address(0));
ceoAddress = _newCEO;
}
/// @dev Assigns a new address to act as the CFO. Only available to the current CEO.
/// @param _newCFO The address of the new CFO
function setCFO(address _newCFO) external onlyCEO {
require(_newCFO != address(0));
cfoAddress = _newCFO;
}
/// @dev Assigns a new address to act as the COO. Only available to the current CEO.
/// @param _newCOO The address of the new COO
function setCOO(address _newCOO) external onlyCEO {
require(_newCOO != address(0));
cooAddress = _newCOO;
}
/*** Pausable functionality adapted from OpenZeppelin ***/
/// @dev Modifier to allow actions only when the contract IS NOT paused
modifier whenNotPaused() {
require(!paused);
_;
}
/// @dev Modifier to allow actions only when the contract IS paused
modifier whenPaused {
require(paused);
_;
}
/// @dev Called by any "C-level" role to pause the contract. Used only when
/// a bug or exploit is detected and we need to limit damage.
function pause() external onlyCLevel whenNotPaused {
paused = true;
}
/// @dev Unpauses the smart contract. Can only be called by the CEO, since
/// one reason we may pause the contract is when CFO or COO accounts are
/// compromised.
/// @notice This is public rather than external so it can be called by
/// derived contracts.
function unpause() public onlyCEO whenPaused {
// can't unpause if contract was upgraded
paused = false;
}
}
/// @title Base contract for CryptoKitties. Holds all common structs, events and base variables.
/// @author Axiom Zen (https://www.axiomzen.co)
/// @dev See the KittyCore contract documentation to understand how the various contract facets are arranged.
contract KittyBase is KittyAccessControl {
/*** EVENTS ***/
/// @dev The Birth event is fired whenever a new kitten comes into existence. This obviously
/// includes any time a cat is created through the giveBirth method, but it is also called
/// when a new gen0 cat is created.
event Birth(address owner, uint256 kittyId, uint256 matronId, uint256 sireId, uint256 genes);
/// @dev Transfer event as defined in current draft of ERC721. Emitted every time a kitten
/// ownership is assigned, including births.
event Transfer(address from, address to, uint256 tokenId);
/*** DATA TYPES ***/
/// @dev The main Kitty struct. Every cat in CryptoKitties is represented by a copy
/// of this structure, so great care was taken to ensure that it fits neatly into
/// exactly two 256-bit words. Note that the order of the members in this structure
/// is important because of the byte-packing rules used by Ethereum.
/// Ref: http://solidity.readthedocs.io/en/develop/miscellaneous.html
struct Kitty {
// The Kitty's genetic code is packed into these 256-bits, the format is
// sooper-sekret! A cat's genes never change.
uint256 genes;
// The timestamp from the block when this cat came into existence.
uint64 birthTime;
// The minimum timestamp after which this cat can engage in breeding
// activities again. This same timestamp is used for the pregnancy
// timer (for matrons) as well as the siring cooldown.
uint64 cooldownEndBlock;
// The ID of the parents of this kitty, set to 0 for gen0 cats.
// Note that using 32-bit unsigned integers limits us to a "mere"
// 4 billion cats. This number might seem small until you realize
// that Ethereum currently has a limit of about 500 million
// transactions per year! So, this definitely won't be a problem
// for several years (even as Ethereum learns to scale).
uint32 matronId;
uint32 sireId;
// Set to the ID of the sire cat for matrons that are pregnant,
// zero otherwise. A non-zero value here is how we know a cat
// is pregnant. Used to retrieve the genetic material for the new
// kitten when the birth transpires.
uint32 siringWithId;
// Set to the index in the cooldown array (see below) that represents
// the current cooldown duration for this Kitty. This starts at zero
// for gen0 cats, and is initialized to floor(generation/2) for others.
// Incremented by one for each successful breeding action, regardless
// of whether this cat is acting as matron or sire.
uint16 cooldownIndex;
// The "generation number" of this cat. Cats minted by the CK contract
// for sale are called "gen0" and have a generation number of 0. The
// generation number of all other cats is the larger of the two generation
// numbers of their parents, plus one.
// (i.e. max(matron.generation, sire.generation) + 1)
uint16 generation;
}
/*** CONSTANTS ***/
/// @dev A lookup table indicating the cooldown duration after any successful
/// breeding action, called "pregnancy time" for matrons and "siring cooldown"
/// for sires. Designed such that the cooldown roughly doubles each time a cat
/// is bred, encouraging owners not to just keep breeding the same cat over
/// and over again. Caps out at one week (a cat can breed an unbounded number
/// of times, and the maximum cooldown is always seven days).
uint32[14] public cooldowns = [
uint32(1 minutes),
uint32(2 minutes),
uint32(5 minutes),
uint32(10 minutes),
uint32(30 minutes),
uint32(1 hours),
uint32(2 hours),
uint32(4 hours),
uint32(8 hours),
uint32(16 hours),
uint32(1 days),
uint32(2 days),
uint32(4 days),
uint32(7 days)
];
// An approximation of currently how many seconds are in between blocks.
uint256 public secondsPerBlock = 15;
/*** STORAGE ***/
/// @dev An array containing the Kitty struct for all Kitties in existence. The ID
/// of each cat is actually an index into this array. Note that ID 0 is a negacat,
/// the unKitty, the mythical beast that is the parent of all gen0 cats. A bizarre
/// creature that is both matron and sire... to itself! Has an invalid genetic code.
/// In other words, cat ID 0 is invalid... ;-)
Kitty[] kitties;
/// @dev A mapping from cat IDs to the address that owns them. All cats have
/// some valid owner address, even gen0 cats are created with a non-zero owner.
mapping (uint256 => address) public kittyIndexToOwner;
// @dev A mapping from owner address to count of tokens that address owns.
// Used internally inside balanceOf() to resolve ownership count.
mapping (address => uint256) ownershipTokenCount;
/// @dev A mapping from KittyIDs to an address that has been approved to call
/// transferFrom(). Each Kitty can only have one approved address for transfer
/// at any time. A zero value means no approval is outstanding.
mapping (uint256 => address) public kittyIndexToApproved;
/// @dev A mapping from KittyIDs to an address that has been approved to use
/// this Kitty for siring via breedWith(). Each Kitty can only have one approved
/// address for siring at any time. A zero value means no approval is outstanding.
mapping (uint256 => address) public sireAllowedToAddress;
/// @dev The address of the ClockAuction contract that handles sales of Kitties. This
/// same contract handles both peer-to-peer sales as well as the gen0 sales which are
/// initiated every 15 minutes.
SaleClockAuction public saleAuction;
/// @dev The address of a custom ClockAuction subclassed contract that handles siring
/// auctions. Needs to be separate from saleAuction because the actions taken on success
/// after a sales and siring auction are quite different.
SiringClockAuction public siringAuction;
/// @dev Assigns ownership of a specific Kitty to an address.
function _transfer(address _from, address _to, uint256 _tokenId) internal {
// Since the number of kittens is capped to 2^32 we can't overflow this
ownershipTokenCount[_to]++;
// transfer ownership
kittyIndexToOwner[_tokenId] = _to;
// When creating new kittens _from is 0x0, but we can't account that address.
if (_from != address(0)) {
ownershipTokenCount[_from]--;
// once the kitten is transferred also clear sire allowances
delete sireAllowedToAddress[_tokenId];
// clear any previously approved ownership exchange
delete kittyIndexToApproved[_tokenId];
}
// Emit the transfer event.
Transfer(_from, _to, _tokenId);
}
/// @dev An internal method that creates a new kitty and stores it. This
/// method doesn't do any checking and should only be called when the
/// input data is known to be valid. Will generate both a Birth event
/// and a Transfer event.
/// @param _matronId The kitty ID of the matron of this cat (zero for gen0)
/// @param _sireId The kitty ID of the sire of this cat (zero for gen0)
/// @param _generation The generation number of this cat, must be computed by caller.
/// @param _genes The kitty's genetic code.
/// @param _owner The inital owner of this cat, must be non-zero (except for the unKitty, ID 0)
function _createKitty(
uint256 _matronId,
uint256 _sireId,
uint256 _generation,
uint256 _genes,
address _owner
)
internal
returns (uint)
{
// These requires are not strictly necessary, our calling code should make
// sure that these conditions are never broken. However! _createKitty() is already
// an expensive call (for storage), and it doesn't hurt to be especially careful
// to ensure our data structures are always valid.
require(_matronId == uint256(uint32(_matronId)));
require(_sireId == uint256(uint32(_sireId)));
require(_generation == uint256(uint16(_generation)));
// New kitty starts with the same cooldown as parent gen/2
uint16 cooldownIndex = uint16(_generation / 2);
if (cooldownIndex > 13) {
cooldownIndex = 13;
}
Kitty memory _kitty = Kitty({
genes: _genes,
birthTime: uint64(now),
cooldownEndBlock: 0,
matronId: uint32(_matronId),
sireId: uint32(_sireId),
siringWithId: 0,
cooldownIndex: cooldownIndex,
generation: uint16(_generation)
});
uint256 newKittenId = kitties.push(_kitty) - 1;
// It's probably never going to happen, 4 billion cats is A LOT, but
// let's just be 100% sure we never let this happen.
require(newKittenId == uint256(uint32(newKittenId)));
// emit the birth event
Birth(
_owner,
newKittenId,
uint256(_kitty.matronId),
uint256(_kitty.sireId),
_kitty.genes
);
// This will assign ownership, and also emit the Transfer event as
// per ERC721 draft
_transfer(0, _owner, newKittenId);
return newKittenId;
}
// Any C-level can fix how many seconds per blocks are currently observed.
function setSecondsPerBlock(uint256 secs) external onlyCLevel {
require(secs < cooldowns[0]);
secondsPerBlock = secs;
}
}
function getMetadata(uint256 _tokenId, string) public view returns (bytes32[4] buffer, uint256 count) {
if (_tokenId == 1) {
buffer[0] = "Hello World! :D";
count = 15;
} else if (_tokenId == 2) {
buffer[0] = "I would definitely choose a medi";
buffer[1] = "um length string.";
count = 49;
} else if (_tokenId == 3) {
buffer[0] = "Lorem ipsum dolor sit amet, mi e";
buffer[1] = "st accumsan dapibus augue lorem,";
buffer[2] = " tristique vestibulum id, libero";
buffer[3] = " suscipit varius sapien aliquam.";
count = 128;
}
}
}
contract KittyOwnership is KittyBase, ERC721 {
/// @notice Name and symbol of the non fungible token, as defined in ERC721.
string public constant name = "CryptoKitties";
string public constant symbol = "CK";
// The contract that will return kitty metadata
ERC721Metadata public erc721Metadata;
bytes4 constant InterfaceSignature_ERC165 =
bytes4(keccak256('supportsInterface(bytes4)'));
bytes4 constant InterfaceSignature_ERC721 =
bytes4(keccak256('name()')) ^
bytes4(keccak256('symbol()')) ^
bytes4(keccak256('totalSupply()')) ^
bytes4(keccak256('balanceOf(address)')) ^
bytes4(keccak256('ownerOf(uint256)')) ^
bytes4(keccak256('approve(address,uint256)')) ^
bytes4(keccak256('transfer(address,uint256)')) ^
bytes4(keccak256('transferFrom(address,address,uint256)')) ^
bytes4(keccak256('tokensOfOwner(address)')) ^
bytes4(keccak256('tokenMetadata(uint256,string)'));
function supportsInterface(bytes4 _interfaceID) external view returns (bool)
{
// DEBUG ONLY
//require((InterfaceSignature_ERC165 == 0x01ffc9a7) && (InterfaceSignature_ERC721 == 0x9a20483d));
return ((_interfaceID == InterfaceSignature_ERC165) || (_interfaceID == InterfaceSignature_ERC721));
}
/// @dev Set the address of the sibling contract that tracks metadata.
/// CEO only.
function setMetadataAddress(address _contractAddress) public onlyCEO {
erc721Metadata = ERC721Metadata(_contractAddress);
}
function _owns(address _claimant, uint256 _tokenId) internal view returns (bool) {
return kittyIndexToOwner[_tokenId] == _claimant;
}
function _approvedFor(address _claimant, uint256 _tokenId) internal view returns (bool) {
return kittyIndexToApproved[_tokenId] == _claimant;
}
function _approve(uint256 _tokenId, address _approved) internal {
kittyIndexToApproved[_tokenId] = _approved;
}
function balanceOf(address _owner) public view returns (uint256 count) {
return ownershipTokenCount[_owner];
}
function transfer(
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Safety check to prevent against an unexpected 0x0 default.
require(_to != address(0));
// Disallow transfers to this contract to prevent accidental misuse.
// The contract should never own any kitties (except very briefly
// after a gen0 cat is created and before it goes on auction).
require(_to != address(this));
// Disallow transfers to the auction contracts to prevent accidental
// misuse. Auction contracts should only take ownership of kitties
// through the allow + transferFrom flow.
require(_to != address(saleAuction));
require(_to != address(siringAuction));
// You can only send your own cat.
require(_owns(msg.sender, _tokenId));
// Reassign ownership, clear pending approvals, emit Transfer event.
_transfer(msg.sender, _to, _tokenId);
}
/// @dev Required for ERC-721 compliance.
function approve(
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Only an owner can grant transfer approval.
require(_owns(msg.sender, _tokenId));
// Register the approval (replacing any previous approval).
_approve(_tokenId, _to);
// Emit approval event.
Approval(msg.sender, _to, _tokenId);
}
function transferFrom(
address _from,
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Safety check to prevent against an unexpected 0x0 default.
require(_to != address(0));
// Disallow transfers to this contract to prevent accidental misuse.
// The contract should never own any kitties (except very briefly
// after a gen0 cat is created and before it goes on auction).
require(_to != address(this));
// Check for approval and valid ownership
require(_approvedFor(msg.sender, _tokenId));
require(_owns(_from, _tokenId));
// Reassign ownership (also clears pending approvals and emits Transfer event).
_transfer(_from, _to, _tokenId);
}
/// @notice Returns the total number of Kitties currently in existence.
/// @dev Required for ERC-721 compliance.
function totalSupply() public view returns (uint) {
return kitties.length - 1;
}
/// @notice Returns the address currently assigned ownership of a given Kitty.
/// @dev Required for ERC-721 compliance.
function ownerOf(uint256 _tokenId)
external
view
returns (address owner)
{
owner = kittyIndexToOwner[_tokenId];
require(owner != address(0));
}
function tokensOfOwner(address _owner) external view returns(uint256[] ownerTokens) {
uint256 tokenCount = balanceOf(_owner);
if (tokenCount == 0) {
// Return an empty array
return new uint256[](0);
} else {
uint256[] memory result = new uint256[](tokenCount);
uint256 totalCats = totalSupply();
uint256 resultIndex = 0;
// We count on the fact that all cats have IDs starting at 1 and increasing
// sequentially up to the totalCat count.
uint256 catId;
for (catId = 1; catId <= totalCats; catId++) {
if (kittyIndexToOwner[catId] == _owner) {
result[resultIndex] = catId;
resultIndex++;
}
}
return result;
}
}
function _memcpy(uint _dest, uint _src, uint _len) private view {
// Copy word-length chunks while possible
for(; _len >= 32; _len -= 32) {
assembly {
mstore(_dest, mload(_src))
}
_dest += 32;
_src += 32;
}
// Copy remaining bytes
uint256 mask = 256 ** (32 - _len) - 1;
assembly {
let srcpart := and(mload(_src), not(mask))
let destpart := and(mload(_dest), mask)
mstore(_dest, or(destpart, srcpart))
}
}
function _toString(bytes32[4] _rawBytes, uint256 _stringLength) private view returns (string) {
var outputString = new string(_stringLength);
uint256 outputPtr;
uint256 bytesPtr;
assembly {
outputPtr := add(outputString, 32)
bytesPtr := _rawBytes
}
_memcpy(outputPtr, bytesPtr, _stringLength);
return outputString;
}
/// @notice Returns a URI pointing to a metadata package for this token conforming to
/// ERC-721 (https://github.com/ethereum/EIPs/issues/721)
/// @param _tokenId The ID number of the Kitty whose metadata should be returned.
function tokenMetadata(uint256 _tokenId, string _preferredTransport) external view returns (string infoUrl) {
require(erc721Metadata != address(0));
bytes32[4] memory buffer;
uint256 count;
(buffer, count) = erc721Metadata.getMetadata(_tokenId, _preferredTransport);
return _toString(buffer, count);
}
}
contract KittyBreeding is KittyOwnership {
/// @dev The Pregnant event is fired when two cats successfully breed and the pregnancy
/// timer begins for the matron.
event Pregnant(address owner, uint256 matronId, uint256 sireId, uint256 cooldownEndBlock);
/// @notice The minimum payment required to use breedWithAuto(). This fee goes towards
/// the gas cost paid by whatever calls giveBirth(), and can be dynamically updated by
/// the COO role as the gas price changes.
uint256 public autoBirthFee = 2 finney;
// Keeps track of number of pregnant kitties.
uint256 public pregnantKitties;
/// @dev The address of the sibling contract that is used to implement the sooper-sekret
/// genetic combination algorithm.
GeneScienceInterface public geneScience;
function setGeneScienceAddress(address _address) external onlyCEO {
GeneScienceInterface candidateContract = GeneScienceInterface(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isGeneScience());
// Set the new contract address
geneScience = candidateContract;
}
function _isReadyToBreed(Kitty _kit) internal view returns (bool) {
// In addition to checking the cooldownEndBlock, we also need to check to see if
// the cat has a pending birth; there can be some period of time between the end
// of the pregnacy timer and the birth event.
return (_kit.siringWithId == 0) && (_kit.cooldownEndBlock <= uint64(block.number));
}
function _isSiringPermitted(uint256 _sireId, uint256 _matronId) internal view returns (bool) {
address matronOwner = kittyIndexToOwner[_matronId];
address sireOwner = kittyIndexToOwner[_sireId];
// Siring is okay if they have same owner, or if the matron's owner was given
// permission to breed with this sire.
return (matronOwner == sireOwner || sireAllowedToAddress[_sireId] == matronOwner);
}
function _triggerCooldown(Kitty storage _kitten) internal {
// Compute an estimation of the cooldown time in blocks (based on current cooldownIndex).
_kitten.cooldownEndBlock = uint64((cooldowns[_kitten.cooldownIndex]/secondsPerBlock) + block.number);
// Increment the breeding count, clamping it at 13, which is the length of the
// cooldowns array. We could check the array size dynamically, but hard-coding
// this as a constant saves gas. Yay, Solidity!
if (_kitten.cooldownIndex < 13) {
_kitten.cooldownIndex += 1;
}
}
function approveSiring(address _addr, uint256 _sireId)
external
whenNotPaused
{
require(_owns(msg.sender, _sireId));
sireAllowedToAddress[_sireId] = _addr;
}
function setAutoBirthFee(uint256 val) external onlyCOO {
autoBirthFee = val;
}
/// @dev Checks to see if a given Kitty is pregnant and (if so) if the gestation
/// period has passed.
function _isReadyToGiveBirth(Kitty _matron) private view returns (bool) {
return (_matron.siringWithId != 0) && (_matron.cooldownEndBlock <= uint64(block.number));
}
function isReadyToBreed(uint256 _kittyId)
public
view
returns (bool)
{
require(_kittyId > 0);
Kitty storage kit = kitties[_kittyId];
return _isReadyToBreed(kit);
}
/// @dev Checks whether a kitty is currently pregnant.
/// @param _kittyId reference the id of the kitten, any user can inquire about it
function isPregnant(uint256 _kittyId)
public
view
returns (bool)
{
require(_kittyId > 0);
// A kitty is pregnant if and only if this field is set
return kitties[_kittyId].siringWithId != 0;
}
function _isValidMatingPair(
Kitty storage _matron,
uint256 _matronId,
Kitty storage _sire,
uint256 _sireId
)
private
view
returns(bool)
{
// A Kitty can't breed with itself!
if (_matronId == _sireId) {
return false;
}
// Kitties can't breed with their parents.
if (_matron.matronId == _sireId || _matron.sireId == _sireId) {
return false;
}
if (_sire.matronId == _matronId || _sire.sireId == _matronId) {
return false;
}
// We can short circuit the sibling check (below) if either cat is
// gen zero (has a matron ID of zero).
if (_sire.matronId == 0 || _matron.matronId == 0) {
return true;
}
// Kitties can't breed with full or half siblings.
if (_sire.matronId == _matron.matronId || _sire.matronId == _matron.sireId) {
return false;
}
if (_sire.sireId == _matron.matronId || _sire.sireId == _matron.sireId) {
return false;
}
// Everything seems cool! Let's get DTF.
return true;
}
/// @dev Internal check to see if a given sire and matron are a valid mating pair for
/// breeding via auction (i.e. skips ownership and siring approval checks).
function _canBreedWithViaAuction(uint256 _matronId, uint256 _sireId)
internal
view
returns (bool)
{
Kitty storage matron = kitties[_matronId];
Kitty storage sire = kitties[_sireId];
return _isValidMatingPair(matron, _matronId, sire, _sireId);
}
function canBreedWith(uint256 _matronId, uint256 _sireId)
external
view
returns(bool)
{
require(_matronId > 0);
require(_sireId > 0);
Kitty storage matron = kitties[_matronId];
Kitty storage sire = kitties[_sireId];
return _isValidMatingPair(matron, _matronId, sire, _sireId) &&
_isSiringPermitted(_sireId, _matronId);
}
/// @dev Internal utility function to initiate breeding, assumes that all breeding
/// requirements have been checked.
function _breedWith(uint256 _matronId, uint256 _sireId) internal {
// Grab a reference to the Kitties from storage.
Kitty storage sire = kitties[_sireId];
Kitty storage matron = kitties[_matronId];
// Mark the matron as pregnant, keeping track of who the sire is.
matron.siringWithId = uint32(_sireId);
// Trigger the cooldown for both parents.
_triggerCooldown(sire);
_triggerCooldown(matron);
// Clear siring permission for both parents. This may not be strictly necessary
// but it's likely to avoid confusion!
delete sireAllowedToAddress[_matronId];
delete sireAllowedToAddress[_sireId];
// Every time a kitty gets pregnant, counter is incremented.
pregnantKitties++;
// Emit the pregnancy event.
Pregnant(kittyIndexToOwner[_matronId], _matronId, _sireId, matron.cooldownEndBlock);
}
function breedWithAuto(uint256 _matronId, uint256 _sireId)
external
payable
whenNotPaused
{
// Checks for payment.
require(msg.value >= autoBirthFee);
// Caller must own the matron.
require(_owns(msg.sender, _matronId));
require(_isSiringPermitted(_sireId, _matronId));
// Grab a reference to the potential matron
Kitty storage matron = kitties[_matronId];
// Make sure matron isn't pregnant, or in the middle of a siring cooldown
require(_isReadyToBreed(matron));
// Grab a reference to the potential sire
Kitty storage sire = kitties[_sireId];
// Make sure sire isn't pregnant, or in the middle of a siring cooldown
require(_isReadyToBreed(sire));
// Test that these cats are a valid mating pair.
require(_isValidMatingPair(
matron,
_matronId,
sire,
_sireId
));
// All checks passed, kitty gets pregnant!
_breedWith(_matronId, _sireId);
}
function giveBirth(uint256 _matronId)
external
whenNotPaused
returns(uint256)
{
// Grab a reference to the matron in storage.
Kitty storage matron = kitties[_matronId];
// Check that the matron is a valid cat.
require(matron.birthTime != 0);
// Check that the matron is pregnant, and that its time has come!
require(_isReadyToGiveBirth(matron));
// Grab a reference to the sire in storage.
uint256 sireId = matron.siringWithId;
Kitty storage sire = kitties[sireId];
// Determine the higher generation number of the two parents
uint16 parentGen = matron.generation;
if (sire.generation > matron.generation) {
parentGen = sire.generation;
}
// Call the sooper-sekret gene mixing operation.
uint256 childGenes = geneScience.mixGenes(matron.genes, sire.genes, matron.cooldownEndBlock - 1);
// Make the new kitten!
address owner = kittyIndexToOwner[_matronId];
uint256 kittenId = _createKitty(_matronId, matron.siringWithId, parentGen + 1, childGenes, owner);
// Clear the reference to sire from the matron (REQUIRED! Having siringWithId
// set is what marks a matron as being pregnant.)
delete matron.siringWithId;
// Every time a kitty gives birth counter is decremented.
pregnantKitties--;
// Send the balance fee to the person who made birth happen.
msg.sender.send(autoBirthFee);
// return the new kitten's ID
return kittenId;
}
}
contract ClockAuctionBase {
// Represents an auction on an NFT
struct Auction {
// Current owner of NFT
address seller;
// Price (in wei) at beginning of auction
uint128 startingPrice;
// Price (in wei) at end of auction
uint128 endingPrice;
// Duration (in seconds) of auction
uint64 duration;
// Time when auction started
// NOTE: 0 if this auction has been concluded
uint64 startedAt;
}
// Reference to contract tracking NFT ownership
ERC721 public nonFungibleContract;
// Cut owner takes on each auction, measured in basis points (1/100 of a percent).
// Values 0-10,000 map to 0%-100%
uint256 public ownerCut;
// Map from token ID to their corresponding auction.
mapping (uint256 => Auction) tokenIdToAuction;
event AuctionCreated(uint256 tokenId, uint256 startingPrice, uint256 endingPrice, uint256 duration);
event AuctionSuccessful(uint256 tokenId, uint256 totalPrice, address winner);
event AuctionCancelled(uint256 tokenId);
function _owns(address _claimant, uint256 _tokenId) internal view returns (bool) {
return (nonFungibleContract.ownerOf(_tokenId) == _claimant);
}
function _escrow(address _owner, uint256 _tokenId) internal {
// it will throw if transfer fails
nonFungibleContract.transferFrom(_owner, this, _tokenId);
}
function _transfer(address _receiver, uint256 _tokenId) internal {
// it will throw if transfer fails
nonFungibleContract.transfer(_receiver, _tokenId);
}
function _addAuction(uint256 _tokenId, Auction _auction) internal {
// Require that all auctions have a duration of
// at least one minute. (Keeps our math from getting hairy!)
require(_auction.duration >= 1 minutes);
tokenIdToAuction[_tokenId] = _auction;
AuctionCreated(
uint256(_tokenId),
uint256(_auction.startingPrice),
uint256(_auction.endingPrice),
uint256(_auction.duration)
);
}
/// @dev Cancels an auction unconditionally.
function _cancelAuction(uint256 _tokenId, address _seller) internal {
_removeAuction(_tokenId);
_transfer(_seller, _tokenId);
AuctionCancelled(_tokenId);
}
function _bid(uint256 _tokenId, uint256 _bidAmount)
internal
returns (uint256)
{
// Get a reference to the auction struct
Auction storage auction = tokenIdToAuction[_tokenId];
// Explicitly check that this auction is currently live.
// (Because of how Ethereum mappings work, we can't just count
// on the lookup above failing. An invalid _tokenId will just
// return an auction object that is all zeros.)
require(_isOnAuction(auction));
// Check that the bid is greater than or equal to the current price
uint256 price = _currentPrice(auction);
require(_bidAmount >= price);
// Grab a reference to the seller before the auction struct
// gets deleted.
address seller = auction.seller;
// The bid is good! Remove the auction before sending the fees
// to the sender so we can't have a reentrancy attack.
_removeAuction(_tokenId);
// Transfer proceeds to seller (if there are any!)
if (price > 0) {
// Calculate the auctioneer's cut.
// (NOTE: _computeCut() is guaranteed to return a
// value <= price, so this subtraction can't go negative.)
uint256 auctioneerCut = _computeCut(price);
uint256 sellerProceeds = price - auctioneerCut;
seller.transfer(sellerProceeds);
}
uint256 bidExcess = _bidAmount - price;
msg.sender.transfer(bidExcess);
// Tell the world!
AuctionSuccessful(_tokenId, price, msg.sender);
return price;
}
function _removeAuction(uint256 _tokenId) internal {
delete tokenIdToAuction[_tokenId];
}
/// @dev Returns true if the NFT is on auction.
/// @param _auction - Auction to check.
function _isOnAuction(Auction storage _auction) internal view returns (bool) {
return (_auction.startedAt > 0);
}
function _currentPrice(Auction storage _auction)
internal
view
returns (uint256)
{
uint256 secondsPassed = 0;
if (now > _auction.startedAt) {
secondsPassed = now - _auction.startedAt;
}
return _computeCurrentPrice(
_auction.startingPrice,
_auction.endingPrice,
_auction.duration,
secondsPassed
);
}
function _computeCurrentPrice(
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
uint256 _secondsPassed
)
internal
pure
returns (uint256)
{
if (_secondsPassed >= _duration) {
// We've reached the end of the dynamic pricing portion
// of the auction, just return the end price.
return _endingPrice;
} else {
// Starting price can be higher than ending price (and often is!), so
// this delta can be negative.
int256 totalPriceChange = int256(_endingPrice) - int256(_startingPrice);
// This multiplication can't overflow, _secondsPassed will easily fit within
// 64-bits, and totalPriceChange will easily fit within 128-bits, their product
// will always fit within 256-bits.
int256 currentPriceChange = totalPriceChange * int256(_secondsPassed) / int256(_duration);
// currentPriceChange can be negative, but if so, will have a magnitude
// less that _startingPrice. Thus, this result will always end up positive.
int256 currentPrice = int256(_startingPrice) + currentPriceChange;
return uint256(currentPrice);
}
}
/// @dev Computes owner's cut of a sale.
/// @param _price - Sale price of NFT.
function _computeCut(uint256 _price) internal view returns (uint256) {
return _price * ownerCut / 10000;
}
}
contract Pausable is Ownable {
event Pause();
event Unpause();
bool public paused = false;
modifier whenNotPaused() {
require(!paused);
_;
}
modifier whenPaused {
require(paused);
_;
}
function pause() onlyOwner whenNotPaused returns (bool) {
paused = true;
Pause();
return true;
}
function unpause() onlyOwner whenPaused returns (bool) {
paused = false;
Unpause();
return true;
}
}
contract ClockAuction is Pausable, ClockAuctionBase {
bytes4 constant InterfaceSignature_ERC721 = bytes4(0x9a20483d);
function ClockAuction(address _nftAddress, uint256 _cut) public {
require(_cut <= 10000);
ownerCut = _cut;
ERC721 candidateContract = ERC721(_nftAddress);
require(candidateContract.supportsInterface(InterfaceSignature_ERC721));
nonFungibleContract = candidateContract;
}
function withdrawBalance() external {
address nftAddress = address(nonFungibleContract);
require(
msg.sender == owner ||
msg.sender == nftAddress
);
// We are using this boolean method to make sure that even if one fails it will still work
bool res = nftAddress.send(this.balance);
}
function createAuction(
uint256 _tokenId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
address _seller
)
external
whenNotPaused
{
// Sanity check that no inputs overflow how many bits we've allocated
// to store them in the auction struct.
require(_startingPrice == uint256(uint128(_startingPrice)));
require(_endingPrice == uint256(uint128(_endingPrice)));
require(_duration == uint256(uint64(_duration)));
require(_owns(msg.sender, _tokenId));
_escrow(msg.sender, _tokenId);
Auction memory auction = Auction(
_seller,
uint128(_startingPrice),
uint128(_endingPrice),
uint64(_duration),
uint64(now)
);
_addAuction(_tokenId, auction);
}
function bid(uint256 _tokenId)
external
payable
whenNotPaused
{
// _bid will throw if the bid or funds transfer fails
_bid(_tokenId, msg.value);
_transfer(msg.sender, _tokenId);
}
function cancelAuction(uint256 _tokenId)
external
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
address seller = auction.seller;
require(msg.sender == seller);
_cancelAuction(_tokenId, seller);
}
function cancelAuctionWhenPaused(uint256 _tokenId)
whenPaused
onlyOwner
external
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
_cancelAuction(_tokenId, auction.seller);
}
/// @dev Returns auction info for an NFT on auction.
/// @param _tokenId - ID of NFT on auction.
function getAuction(uint256 _tokenId)
external
view
returns
(
address seller,
uint256 startingPrice,
uint256 endingPrice,
uint256 duration,
uint256 startedAt
) {
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
return (
auction.seller,
auction.startingPrice,
auction.endingPrice,
auction.duration,
auction.startedAt
);
}
/// @dev Returns the current price of an auction.
/// @param _tokenId - ID of the token price we are checking.
function getCurrentPrice(uint256 _tokenId)
external
view
returns (uint256)
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
return _currentPrice(auction);
}
}
contract SiringClockAuction is ClockAuction {
// @dev Sanity check that allows us to ensure that we are pointing to the
// right auction in our setSiringAuctionAddress() call.
bool public isSiringClockAuction = true;
// Delegate constructor
function SiringClockAuction(address _nftAddr, uint256 _cut) public
ClockAuction(_nftAddr, _cut) {}
function createAuction(
uint256 _tokenId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
address _seller
)
external
{
// Sanity check that no inputs overflow how many bits we've allocated
// to store them in the auction struct.
require(_startingPrice == uint256(uint128(_startingPrice)));
require(_endingPrice == uint256(uint128(_endingPrice)));
require(_duration == uint256(uint64(_duration)));
require(msg.sender == address(nonFungibleContract));
_escrow(_seller, _tokenId);
Auction memory auction = Auction(
_seller,
uint128(_startingPrice),
uint128(_endingPrice),
uint64(_duration),
uint64(now)
);
_addAuction(_tokenId, auction);
}
function bid(uint256 _tokenId)
external
payable
{
require(msg.sender == address(nonFungibleContract));
address seller = tokenIdToAuction[_tokenId].seller;
// _bid checks that token ID is valid and will throw if bid fails
_bid(_tokenId, msg.value);
// We transfer the kitty back to the seller, the winner will get
// the offspring
_transfer(seller, _tokenId);
}
}
/// @title Clock auction modified for sale of kitties
/// @notice We omit a fallback function to prevent accidental sends to this contract.
contract SaleClockAuction is ClockAuction {
// @dev Sanity check that allows us to ensure that we are pointing to the
// right auction in our setSaleAuctionAddress() call.
bool public isSaleClockAuction = true;
// Tracks last 5 sale price of gen0 kitty sales
uint256 public gen0SaleCount;
uint256[5] public lastGen0SalePrices;
// Delegate constructor
function SaleClockAuction(address _nftAddr, uint256 _cut) public
ClockAuction(_nftAddr, _cut) {}
function createAuction(
uint256 _tokenId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
address _seller
)
external
{
// Sanity check that no inputs overflow how many bits we've allocated
// to store them in the auction struct.
require(_startingPrice == uint256(uint128(_startingPrice)));
require(_endingPrice == uint256(uint128(_endingPrice)));
require(_duration == uint256(uint64(_duration)));
require(msg.sender == address(nonFungibleContract));
_escrow(_seller, _tokenId);
Auction memory auction = Auction(
_seller,
uint128(_startingPrice),
uint128(_endingPrice),
uint64(_duration),
uint64(now)
);
_addAuction(_tokenId, auction);
}
/// @dev Updates lastSalePrice if seller is the nft contract
/// Otherwise, works the same as default bid method.
function bid(uint256 _tokenId)
external
payable
{
// _bid verifies token ID size
address seller = tokenIdToAuction[_tokenId].seller;
uint256 price = _bid(_tokenId, msg.value);
_transfer(msg.sender, _tokenId);
// If not a gen0 auction, exit
if (seller == address(nonFungibleContract)) {
// Track gen0 sale prices
lastGen0SalePrices[gen0SaleCount % 5] = price;
gen0SaleCount++;
}
}
function averageGen0SalePrice() external view returns (uint256) {
uint256 sum = 0;
for (uint256 i = 0; i < 5; i++) {
sum += lastGen0SalePrices[i];
}
return sum / 5;
}
}
contract KittyAuction is KittyBreeding {
function setSaleAuctionAddress(address _address) external onlyCEO {
SaleClockAuction candidateContract = SaleClockAuction(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isSaleClockAuction());
// Set the new contract address
saleAuction = candidateContract;
}
/// @dev Sets the reference to the siring auction.
/// @param _address - Address of siring contract.
function setSiringAuctionAddress(address _address) external onlyCEO {
SiringClockAuction candidateContract = SiringClockAuction(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isSiringClockAuction());
// Set the new contract address
siringAuction = candidateContract;
}
/// @dev Put a kitty up for auction.
/// Does some ownership trickery to create auctions in one tx.
function createSaleAuction(
uint256 _kittyId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration
)
external
whenNotPaused
{
// Auction contract checks input sizes
// If kitty is already on any auction, this will throw
// because it will be owned by the auction contract.
require(_owns(msg.sender, _kittyId));
// Ensure the kitty is not pregnant to prevent the auction
// contract accidentally receiving ownership of the child.
// NOTE: the kitty IS allowed to be in a cooldown.
require(!isPregnant(_kittyId));
_approve(_kittyId, saleAuction);
// Sale auction throws if inputs are invalid and clears
// transfer and sire approval after escrowing the kitty.
saleAuction.createAuction(
_kittyId,
_startingPrice,
_endingPrice,
_duration,
msg.sender
);
}
function createSiringAuction(
uint256 _kittyId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration
)
external
whenNotPaused
{
require(_owns(msg.sender, _kittyId));
require(isReadyToBreed(_kittyId));
_approve(_kittyId, siringAuction);
siringAuction.createAuction(
_kittyId,
_startingPrice,
_endingPrice,
_duration,
msg.sender
);
}
function bidOnSiringAuction(
uint256 _sireId,
uint256 _matronId
)
external
payable
whenNotPaused
{
// Auction contract checks input sizes
require(_owns(msg.sender, _matronId));
require(isReadyToBreed(_matronId));
require(_canBreedWithViaAuction(_matronId, _sireId));
// Define the current price of the auction.
uint256 currentPrice = siringAuction.getCurrentPrice(_sireId);
require(msg.value >= currentPrice + autoBirthFee);
// Siring auction will throw if the bid fails.
siringAuction.bid.value(msg.value - autoBirthFee)(_sireId);
_breedWith(uint32(_matronId), uint32(_sireId));
}
function withdrawAuctionBalances() external onlyCLevel {
saleAuction.withdrawBalance();
siringAuction.withdrawBalance();
}
}
/// @title all functions related to creating kittens
contract KittyMinting is KittyAuction {
// Limits the number of cats the contract owner can ever create.
uint256 public constant PROMO_CREATION_LIMIT = 5000;
uint256 public constant GEN0_CREATION_LIMIT = 45000;
// Constants for gen0 auctions.
uint256 public constant GEN0_STARTING_PRICE = 10 finney;
uint256 public constant GEN0_AUCTION_DURATION = 1 days;
// Counts the number of cats the contract owner has created.
uint256 public promoCreatedCount;
uint256 public gen0CreatedCount;
function createPromoKitty(uint256 _genes, address _owner) external onlyCOO {
address kittyOwner = _owner;
if (kittyOwner == address(0)) {
kittyOwner = cooAddress;
}
require(promoCreatedCount < PROMO_CREATION_LIMIT);
promoCreatedCount++;
_createKitty(0, 0, 0, _genes, kittyOwner);
}
/// @dev Creates a new gen0 kitty with the given genes and
/// creates an auction for it.
function createGen0Auction(uint256 _genes) external onlyCOO {
require(gen0CreatedCount < GEN0_CREATION_LIMIT);
uint256 kittyId = _createKitty(0, 0, 0, _genes, address(this));
_approve(kittyId, saleAuction);
saleAuction.createAuction(
kittyId,
_computeNextGen0Price(),
0,
GEN0_AUCTION_DURATION,
address(this)
);
gen0CreatedCount++;
}
/// @dev Computes the next gen0 auction starting price, given
/// the average of the past 5 prices + 50%.
function _computeNextGen0Price() internal view returns (uint256) {
uint256 avePrice = saleAuction.averageGen0SalePrice();
// Sanity check to ensure we don't overflow arithmetic
require(avePrice == uint256(uint128(avePrice)));
uint256 nextPrice = avePrice + (avePrice / 2);
// We never auction for less than starting price
if (nextPrice < GEN0_STARTING_PRICE) {
nextPrice = GEN0_STARTING_PRICE;
}
return nextPrice;
}
}
contract KittyCore is KittyMinting {
address public newContractAddress;
/// @notice Creates the main CryptoKitties smart contract instance.
function KittyCore() public {
// Starts paused.
paused = true;
// the creator of the contract is the initial CEO
ceoAddress = msg.sender;
// the creator of the contract is also the initial COO
cooAddress = msg.sender;
// start with the mythical kitten 0 - so we don't have generation-0 parent issues
_createKitty(0, 0, 0, uint256(-1), address(0));
}
function setNewAddress(address _v2Address) external onlyCEO whenPaused {
// See README.md for updgrade plan
newContractAddress = _v2Address;
ContractUpgrade(_v2Address);
}
function() external payable {
require(
msg.sender == address(saleAuction) ||
msg.sender == address(siringAuction)
);
}
function getKitty(uint256 _id)
external
view
returns (
bool isGestating,
bool isReady,
uint256 cooldownIndex,
uint256 nextActionAt,
uint256 siringWithId,
uint256 birthTime,
uint256 matronId,
uint256 sireId,
uint256 generation,
uint256 genes
) {
Kitty storage kit = kitties[_id];
// if this variable is 0 then it's not gestating
isGestating = (kit.siringWithId != 0);
isReady = (kit.cooldownEndBlock <= block.number);
cooldownIndex = uint256(kit.cooldownIndex);
nextActionAt = uint256(kit.cooldownEndBlock);
siringWithId = uint256(kit.siringWithId);
birthTime = uint256(kit.birthTime);
matronId = uint256(kit.matronId);
sireId = uint256(kit.sireId);
generation = uint256(kit.generation);
genes = kit.genes;
}
function unpause() public onlyCEO whenPaused {
require(saleAuction != address(0));
require(siringAuction != address(0));
require(geneScience != address(0));
require(newContractAddress == address(0));
// Actually unpause the contract.
super.unpause();
}
// @dev Allows the CFO to capture the balance available to the contract.
function withdrawBalance() external onlyCFO {
uint256 balance = this.balance;
// Subtract all the currently pregnant kittens we have, plus 1 of margin.
uint256 subtractFees = (pregnantKitties + 1) * autoBirthFee;
if (balance > subtractFees) {
cfoAddress.send(balance - subtractFees);
}
}
}
