Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../system/HSystemChecker.sol";
import "../../common/IChildToken.sol";
contract MilkChild is ERC20, IChildToken, HSystemChecker {
bytes32 public constant DEPOSITOR_ROLE = keccak256("DEPOSITOR_ROLE");
bool public _adminCanMint = true;
bool public _canMintMilk = false;
address public _burnHolderAddress;
constructor(
string memory name,
string memory symbol,
address systemCheckerContractAddress
) ERC20(name, symbol) HSystemChecker(systemCheckerContractAddress) {}
/// @notice called when token is deposited on root chain
/// @dev Should be callable only by ChildChainManager
/// Should handle deposit by minting the required amount for user
/// Make sure minting is done only by this function
/// @param user user address for whom deposit is being done
/// @param depositData abi encoded amount
function deposit(address user, bytes calldata depositData) external override onlyRole(DEPOSITOR_ROLE) {
uint256 amount = abi.decode(depositData, (uint256));
_mint(user, amount);
}
/// @notice called when user wants to withdraw tokens back to root chain
/// @dev Should burn user's tokens. This transaction will be verified when exiting on root chain
/// @dev external with no role to allow users requesting withdraw of token when not part of game
/// @dev _burn() handles quantity check
/// @param amount amount of tokens to withdraw
function withdraw(uint256 amount) external {
_burn(_msgSender(), amount);
}
/* TREASURY ROLES **/
// Special role specifically for the treasury. This allows us to create a special relationship between
// the treasury and Milk contract. Never know when you might need it :)
/// @notice called when user wants to withdraw tokens back to root chain
/// @dev Should burn user's tokens. This transaction will be verified when exiting on root chain
/// @dev User requests withdrawal and game system handles it so we have to stipulate the users address
/// @dev Strictly speaking a logged in user has given us permission to do this, but its polite to ask :)
/// @dev _burn() handles quantity check
/// @param owner address of user withdrawing tokens
/// @param amount amount of tokens to withdraw
function gameWithdraw(address owner, uint256 amount) external onlyRole(TREASURY_ROLE) isUser(owner) {
_burn(owner, amount);
}
/// @notice Allow the system to manage Milk within itself
/// @dev _transfer() handles amount check
/// @param sender Address to transfer from
/// @param recipient Address to transfer to
/// @param amount Amount of Gold to send - wei
function gameTransferFrom(
address sender,
address recipient,
uint256 amount
) external onlyRole(TREASURY_ROLE) isUser(sender) {
_transfer(sender, recipient, amount);
}
/// @notice Allows system to burn tokens
/// @dev _burn handles the amount checking
/// @dev to prevent double milking :p we have to transfer token before burning it
/// @dev Due to the way PoS bridge works we have to use a _burnHolderAddress that we control
/// @dev on the Ethereum side. Contract will work but wallet is more versatile.
/// @param owner Holder address to burn tokens of
/// @param amount Amount of tokens to burn
function gameBurn(address owner, uint256 amount) external onlyRole(TREASURY_ROLE) isUser(owner) {
_transfer(owner, _burnHolderAddress, amount);
_burn(_burnHolderAddress, amount);
}
/// @notice Mint a user some gold
/// @dev Only activate users should ever be minted Gold
/// @dev Reserved for game generation of Gold via quests/battles/etc...
/// @param to Address to mint to
/// @param amount Amount of Gold to send - wei
function gameMint(address to, uint256 amount) external onlyRole(TREASURY_ROLE) isUser(to) {
require(_canMintMilk, "MILK: MILK minting is disabled");
_mint(to, amount);
}
/* MASTER ROLES **/
// For ease of use and security we separate TREASURY_ROLE from MASTER_ROLES
/// @notice Mint that MILK
/// @dev Designed for minting of initial token allocations
/// @param account user for whom tokens are being minted
/// @param amount amount of token to mint in wei
function mint(address account, uint256 amount) public onlyRole(MASTER_ROLE) {
require(_adminCanMint, "MILK: Admin cant mint");
_mint(account, amount);
}
/// @notice Method to lock admin minting
/// @dev Only use once you are 100% sure minting is done
function lockAdminMinting() external onlyRole(MASTER_ROLE) {
_adminCanMint = false;
}
/// @notice Method to enable MILK minting for the game
/// @dev Only use when you are 100% sure users can start earning MILK
function allowMilkMinting() external onlyRole(MASTER_ROLE) {
_canMintMilk = true;
}
/// @notice Method to enable MILK minting for the game
/// @dev Only use when you are 100% sure users can start earning MILK
function setBurnHolderAddress(address burnHolderAddress) external onlyRole(MASTER_ROLE) {
require(burnHolderAddress != address(0), "MILK: Cant be zero address");
_burnHolderAddress = burnHolderAddress;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";
/**
* @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 {}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./ISystemChecker.sol";
import "./RolesAndKeys.sol";
contract HSystemChecker is RolesAndKeys {
ISystemChecker _systemChecker;
address public _systemCheckerContractAddress;
constructor(address systemCheckerContractAddress) {
_systemCheckerContractAddress = systemCheckerContractAddress;
_systemChecker = ISystemChecker(systemCheckerContractAddress);
}
/// @notice Check if an address is a registered user or not
/// @dev Triggers a require in systemChecker
modifier isUser(address user) {
_systemChecker.isUser(user);
_;
}
/// @notice Check that the msg.sender has the desired role
/// @dev Triggers a require in systemChecker
modifier onlyRole(bytes32 role) {
require(_systemChecker.hasRole(role, _msgSender()), "SC: Invalid transaction source");
_;
}
/// @notice Push new address for the SystemChecker Contract
/// @param systemCheckerContractAddress - address of the System Checker
function setSystemCheckerContractAddress(address systemCheckerContractAddress) external onlyRole(ADMIN_ROLE) {
_systemCheckerContractAddress = systemCheckerContractAddress;
_systemChecker = ISystemChecker(systemCheckerContractAddress);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
interface IChildToken {
function deposit(address user, bytes calldata depositData) external;
}
// SPDX-License-Identifier: MIT
// 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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
/**
* @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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
interface ISystemChecker {
function createNewRole(bytes32 role) external;
function hasRole(bytes32 role, address account) external returns (bool);
function hasPermission(bytes32 role, address account) external;
function isUser(address user) external;
function getSafeAddress(bytes32 key) external returns (address);
function grantRole(bytes32 role, address account) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import '@openzeppelin/contracts/utils/Context.sol';
abstract contract RolesAndKeys is Context {
// ROLES
bytes32 constant MASTER_ROLE = keccak256("MASTER_ROLE");
bytes32 constant ADMIN_ROLE = keccak256("ADMIN_ROLE");
bytes32 constant GAME_ROLE = keccak256("GAME_ROLE");
bytes32 constant CONTRACT_ROLE = keccak256("CONTRACT_ROLE");
bytes32 constant TREASURY_ROLE = keccak256("TREASURY_ROLE");
// KEYS
bytes32 constant MARKETPLACE_KEY_BYTES = keccak256("MARKETPLACE");
bytes32 constant SYSTEM_KEY_BYTES = keccak256("SYSTEM");
bytes32 constant QUEST_KEY_BYTES = keccak256("QUEST");
bytes32 constant BATTLE_KEY_BYTES = keccak256("BATTLE");
bytes32 constant HOUSE_KEY_BYTES = keccak256("HOUSE");
bytes32 constant QUEST_GUILD_KEY_BYTES = keccak256("QUEST_GUILD");
// COMMON
bytes32 constant public PET_BYTES = 0x5065740000000000000000000000000000000000000000000000000000000000;
}