😎
プロキシパターンでtokenをdeployする
tl;dr
- Solidity で Proxy パターンを使って BEP-20 Token をデプロイする手順の解説です。
なぜ Proxy パターンが必要か
一度 deploy したコントラクトのアドレスは一生固定です。
もし、deloy した後にバグがあったり、仕様を変更したくなった場合、再度 deploy し直す必要があります。（別の address でコントラクトが作られる）
そこで、ユーザーが使うコントラクトを Proxy として、実際のロジックを持つコントラクトを別に作成することで deploy 後でもロジックを差し替えられるようにするのが Proxy パターンです。
- Proxy：みんなが使う固定アドレス。残高や合計供給量などのデータもここに保存される。
- Implementation（実装／ロジック）：関数の中身。バージョンアップで差し替え可能。
BEP-20 Token を Proxy パターンで実装する
今回は BSC の BEP-20 Token を Proxy パターンで実装してみます。
一から Contract を書くのは大変なので、公式の Mainnet の実装をコピーしてきます。
contract のコードは explorer で確認できます。
Proxy コントラクト
BEP20UpgradeableProxy
/**
*Submitted for verification at BscScan.com on 2020-09-29
*/
// File: openzeppelin-solidity/contracts/proxy/Proxy.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
* instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
* be specified by overriding the virtual {_implementation} function.
*
* Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
* different contract through the {_delegate} function.
*
* The success and return data of the delegated call will be returned back to the caller of the proxy.
*/
abstract contract Proxy {
/**
* @dev Delegates the current call to `implementation`.
*
* This function does not return to its internall call site, it will return directly to the external caller.
*/
function _delegate(address implementation) internal {
// solhint-disable-next-line no-inline-assembly
assembly {
// Copy msg.data. We take full control of memory in this inline assembly
// block because it will not return to Solidity code. We overwrite the
// Solidity scratch pad at memory position 0.
calldatacopy(0, 0, calldatasize())
// Call the implementation.
// out and outsize are 0 because we don't know the size yet.
let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
// Copy the returned data.
returndatacopy(0, 0, returndatasize())
switch result
// delegatecall returns 0 on error.
case 0 { revert(0, returndatasize()) }
default { return(0, returndatasize()) }
}
}
/**
* @dev This is a virtual function that should be overriden so it returns the address to which the fallback function
* and {_fallback} should delegate.
*/
function _implementation() internal virtual view returns (address);
/**
* @dev Delegates the current call to the address returned by `_implementation()`.
*
* This function does not return to its internall call site, it will return directly to the external caller.
*/
function _fallback() internal {
_beforeFallback();
_delegate(_implementation());
}
/**
* @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
* function in the contract matches the call data.
*/
fallback () payable external {
_fallback();
}
/**
* @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
* is empty.
*/
receive () payable external {
_fallback();
}
/**
* @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
* call, or as part of the Solidity `fallback` or `receive` functions.
*
* If overriden should call `super._beforeFallback()`.
*/
function _beforeFallback() internal virtual {
}
}
// File: openzeppelin-solidity/contracts/utils/Address.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.2;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies in extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return _functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
return _functionCallWithValue(target, data, value, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// File: openzeppelin-solidity/contracts/proxy/UpgradeableProxy.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
* implementation address that can be changed. This address is stored in storage in the location specified by
* https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
* implementation behind the proxy.
*
* Upgradeability is only provided internally through {_upgradeTo}. For an externally upgradeable proxy see
* {TransparentUpgradeableProxy}.
*/
contract UpgradeableProxy is Proxy {
/**
* @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
*
* If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
* function call, and allows initializating the storage of the proxy like a Solidity constructor.
*/
constructor(address _logic, bytes memory _data) public payable {
assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
_setImplementation(_logic);
if(_data.length > 0) {
// solhint-disable-next-line avoid-low-level-calls
(bool success,) = _logic.delegatecall(_data);
require(success);
}
}
/**
* @dev Emitted when the implementation is upgraded.
*/
event Upgraded(address indexed implementation);
/**
* @dev Storage slot with the address of the current implementation.
* This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
* validated in the constructor.
*/
bytes32 private constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
/**
* @dev Returns the current implementation address.
*/
function _implementation() internal override view returns (address impl) {
bytes32 slot = _IMPLEMENTATION_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
impl := sload(slot)
}
}
/**
* @dev Upgrades the proxy to a new implementation.
*
* Emits an {Upgraded} event.
*/
function _upgradeTo(address newImplementation) internal {
_setImplementation(newImplementation);
emit Upgraded(newImplementation);
}
/**
* @dev Stores a new address in the EIP1967 implementation slot.
*/
function _setImplementation(address newImplementation) private {
require(Address.isContract(newImplementation), "UpgradeableProxy: new implementation is not a contract");
bytes32 slot = _IMPLEMENTATION_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
sstore(slot, newImplementation)
}
}
}
// File: openzeppelin-solidity/contracts/proxy/TransparentUpgradeableProxy.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev This contract implements a proxy that is upgradeable by an admin.
*
* To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
* clashing], which can potentially be used in an attack, this contract uses the
* https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
* things that go hand in hand:
*
* 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
* that call matches one of the admin functions exposed by the proxy itself.
* 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
* implementation. If the admin tries to call a function on the implementation it will fail with an error that says
* "admin cannot fallback to proxy target".
*
* These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
* the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
* to sudden errors when trying to call a function from the proxy implementation.
*
* Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
* you should think of the `ProxyAdmin` instance as the real administrative inerface of your proxy.
*/
contract TransparentUpgradeableProxy is UpgradeableProxy {
/**
* @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
* optionally initialized with `_data` as explained in {UpgradeableProxy-constructor}.
*/
constructor(address _logic, address _admin, bytes memory _data) public payable UpgradeableProxy(_logic, _data) {
assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
_setAdmin(_admin);
}
/**
* @dev Emitted when the admin account has changed.
*/
event AdminChanged(address previousAdmin, address newAdmin);
/**
* @dev Storage slot with the admin of the contract.
* This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
* validated in the constructor.
*/
bytes32 private constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
/**
* @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
*/
modifier ifAdmin() {
if (msg.sender == _admin()) {
_;
} else {
_fallback();
}
}
/**
* @dev Returns the current admin.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyAdmin}.
*
* TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
* https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
* `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
*/
function admin() external ifAdmin returns (address) {
return _admin();
}
/**
* @dev Returns the current implementation.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyImplementation}.
*
* TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
* https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
* `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
*/
function implementation() external ifAdmin returns (address) {
return _implementation();
}
/**
* @dev Changes the admin of the proxy.
*
* Emits an {AdminChanged} event.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.
*/
function changeAdmin(address newAdmin) external ifAdmin {
require(newAdmin != address(0), "TransparentUpgradeableProxy: new admin is the zero address");
emit AdminChanged(_admin(), newAdmin);
_setAdmin(newAdmin);
}
/**
* @dev Upgrade the implementation of the proxy.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-upgrade}.
*/
function upgradeTo(address newImplementation) external ifAdmin {
_upgradeTo(newImplementation);
}
/**
* @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
* by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
* proxied contract.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-upgradeAndCall}.
*/
function upgradeToAndCall(address newImplementation, bytes calldata data) external payable ifAdmin {
_upgradeTo(newImplementation);
// solhint-disable-next-line avoid-low-level-calls
(bool success,) = newImplementation.delegatecall(data);
require(success);
}
/**
* @dev Returns the current admin.
*/
function _admin() internal view returns (address adm) {
bytes32 slot = _ADMIN_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
adm := sload(slot)
}
}
/**
* @dev Stores a new address in the EIP1967 admin slot.
*/
function _setAdmin(address newAdmin) private {
bytes32 slot = _ADMIN_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
sstore(slot, newAdmin)
}
}
/**
* @dev Makes sure the admin cannot access the fallback function. See {Proxy-_beforeFallback}.
*/
function _beforeFallback() internal override virtual {
require(msg.sender != _admin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
super._beforeFallback();
}
}
// File: contracts/BEP20UpgradeableProxy.sol
pragma solidity ^0.6.0;
contract BEP20UpgradeableProxy is TransparentUpgradeableProxy {
constructor(address logic, address admin, bytes memory data) TransparentUpgradeableProxy(logic, admin, data) public {
}
}
Implementation コントラクト
BEP20TokenImplementation
/**
*Submitted for verification at BscScan.com on 2020-09-29
*/
// File: contracts/IBEP20.sol
pragma solidity ^0.6.0;
interface IBEP20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the token decimals.
*/
function decimals() external view returns (uint8);
/**
* @dev Returns the token symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the token name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the bep token owner.
*/
function getOwner() external view returns (address);
/**
* @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-solidity/contracts/GSN/Context.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/*
* @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.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// File: openzeppelin-solidity/contracts/math/SafeMath.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @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.
*/
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.
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
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.
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
// File: openzeppelin-solidity/contracts/proxy/Initializable.sol
// SPDX-License-Identifier: MIT
pragma solidity >=0.4.24 <0.7.0;
/**
* @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
* behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
* external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
* function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
*
* TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
* possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
*
* CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
* that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
*/
abstract contract Initializable {
/**
* @dev Indicates that the contract has been initialized.
*/
bool private _initialized;
/**
* @dev Indicates that the contract is in the process of being initialized.
*/
bool private _initializing;
/**
* @dev Modifier to protect an initializer function from being invoked twice.
*/
modifier initializer() {
require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");
bool isTopLevelCall = !_initializing;
if (isTopLevelCall) {
_initializing = true;
_initialized = true;
}
_;
if (isTopLevelCall) {
_initializing = false;
}
}
/// @dev Returns true if and only if the function is running in the constructor
function _isConstructor() private view returns (bool) {
// extcodesize checks the size of the code stored in an address, and
// address returns the current address. Since the code is still not
// deployed when running a constructor, any checks on its code size will
// yield zero, making it an effective way to detect if a contract is
// under construction or not.
address self = address(this);
uint256 cs;
// solhint-disable-next-line no-inline-assembly
assembly { cs := extcodesize(self) }
return cs == 0;
}
}
// File: contracts/BEP20TokenImplementation.sol
pragma solidity ^0.6.0;
contract BEP20TokenImplementation is Context, IBEP20, Initializable {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
uint8 private _decimals;
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
bool private _mintable;
constructor() public {
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(_owner == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev sets initials supply and the owner
*/
function initialize(string memory name, string memory symbol, uint8 decimals, uint256 amount, bool mintable, address owner) public initializer {
_owner = owner;
_name = name;
_symbol = symbol;
_decimals = decimals;
_mintable = mintable;
_mint(owner, amount);
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
/**
* @dev Returns if the token is mintable or not
*/
function mintable() external view returns (bool) {
return _mintable;
}
/**
* @dev Returns the bep token owner.
*/
function getOwner() external override view returns (address) {
return _owner;
}
/**
* @dev Returns the token decimals.
*/
function decimals() external override view returns (uint8) {
return _decimals;
}
/**
* @dev Returns the token symbol.
*/
function symbol() external override view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the token name.
*/
function name() external override view returns (string memory) {
return _name;
}
/**
* @dev See {BEP20-totalSupply}.
*/
function totalSupply() external override view returns (uint256) {
return _totalSupply;
}
/**
* @dev See {BEP20-balanceOf}.
*/
function balanceOf(address account) external override view returns (uint256) {
return _balances[account];
}
/**
* @dev See {BEP20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) external override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {BEP20-allowance}.
*/
function allowance(address owner, address spender) external override view returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {BEP20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) external override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {BEP20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {BEP20};
*
* 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) external override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "BEP20: 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 {BEP20-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 {BEP20-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, "BEP20: decreased allowance below zero"));
return true;
}
/**
* @dev Creates `amount` tokens and assigns them to `msg.sender`, increasing
* the total supply.
*
* Requirements
*
* - `msg.sender` must be the token owner
* - `_mintable` must be true
*/
function mint(uint256 amount) public onlyOwner returns (bool) {
require(_mintable, "this token is not mintable");
_mint(_msgSender(), amount);
return true;
}
/**
* @dev Burn `amount` tokens and decreasing the total supply.
*/
function burn(uint256 amount) public returns (bool) {
_burn(_msgSender(), amount);
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), "BEP20: transfer from the zero address");
require(recipient != address(0), "BEP20: transfer to the zero address");
_balances[sender] = _balances[sender].sub(amount, "BEP20: 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), "BEP20: 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), "BEP20: burn from the zero address");
_balances[account] = _balances[account].sub(amount, "BEP20: 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), "BEP20: approve from the zero address");
require(spender != address(0), "BEP20: 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, "BEP20: burn amount exceeds allowance"));
}
}
deploy 手順は次のようになります。
- Contract を deploy するためのアカウントを用意（ex. Metamask）
- 実装コントラクト（BEP20TokenImplementation）をデプロイ。
- deploy された実装コントラクトの initialize を実行
- 初期期されたデータで Proxy をデプロイ（BEP20UpgradeableProxy）
deploy
必要なライブラリは以下です。
今回はhardhatとethersを使います。
hardhat.config で環境変数を使用するのでdotenvも追加します。
{
//省略
"scripts": {
"compile": "hardhat compile",
"clean": "hardhat clean",
"test": "hardhat test",
"format": "biome format --write",
"lint": "biome lint --write",
"check": "biome check --write",
"deploy": "hardhat run scripts/deploy.ts --network bsctest"
},
"devDependencies": {
"@biomejs/biome": "2.2.3",
"@nomicfoundation/hardhat-toolbox": "^3.0.0",
"@types/node": "^20.11.19",
"dotenv": "^17.2.2",
"hardhat": "^2.22.5",
"ts-node": "^10.9.2",
"typescript": "^5.4.0"
},
"dependencies": {
"ethers": "^6.13.2"
}
}
hardhat.config.ts
import 'dotenv/config';
import type { HardhatUserConfig } from 'hardhat/config';
import '@nomicfoundation/hardhat-toolbox';
const PRIVATE_KEY = process.env.PRIVATE_KEY || '';
const BSCTEST_RPC_URL = process.env.BSC_TESTNET_RPC_URL || '';
const config: HardhatUserConfig = {
defaultNetwork: 'hardhat',
solidity: {
version: '0.6.12',
settings: {
optimizer: { enabled: true, runs: 200 },
},
},
networks: {
bsctest: {
url: BSCTEST_RPC_URL,
chainId: 97,
accounts: [PRIVATE_KEY],
gasPrice: 3000000000, // 3 gwei (低めに設定)
gas: 6000000,
},
},
etherscan: {
apiKey: {
bsc: process.env.BSCSCAN_API_KEY || '',
bscTestnet: process.env.BSCSCAN_API_KEY || '',
},
customChains: [
{
network: 'bscTestnet',
chainId: 97,
urls: {
apiURL: 'https://api-testnet.bscscan.com/api',
browserURL: 'https://testnet.bscscan.com',
},
},
],
},
typechain: {
outDir: 'typechain-types',
target: 'ethers-v6',
},
paths: {
sources: './contracts',
tests: './test',
cache: './cache',
artifacts: './artifacts',
},
};
export default config;
token 情報をまず定義します。
今回は BEP20 の USDC なので以下のように定義します。
const [deployer] = await ethers.getSigners();
const tokenConfig: TokenConfig = {
name: 'USD Coin',
symbol: 'USDC',
decimals: 18,
initialSupply: ethers.parseUnits('1000000', 18), // 100万
mintable: true,
owner: deployer.address,
};
次に実装コントラクトをデプロイします。
const provider = ethers.provider;
const bal = await provider.getBalance(deployer.address);
const BEP20TokenImplementation = await ethers.getContractFactory(
'BEP20TokenImplementation'
);
const deployTx = await BEP20TokenImplementation.getDeployTransaction();
const estimatedGas = await provider.estimateGas(deployTx);
const feeData = await ethers.provider.getFeeData();
const price = feeData.gasPrice ?? feeData.maxFeePerGas ?? 0n;
const estimatedCost = estimatedGas * price;
const currentBalance = await provider.getBalance(deployer.address);
if (currentBalance < estimatedCost) {
throw new Error(
`残高不足: 必要 ${ethers.formatEther(
estimatedCost
)} BNB, 現在 ${ethers.formatEther(currentBalance)} BNB`
);
}
const implementation = await BEP20TokenImplementation.deploy();
await implementation.waitForDeployment();
const implementationAddress = await implementation.getAddress();
console.log('implementationAddress:', implementationAddress);
これで実行コントラクトが deploy されるので、initialize を実行して初期化します。
const initializeData = implementation.interface.encodeFunctionData(
'initialize',
[
tokenConfig.name,
tokenConfig.symbol,
tokenConfig.decimals,
tokenConfig.initialSupply,
tokenConfig.mintable,
tokenConfig.owner,
]
);
次はこの初期化されたデータを元に Proxy をデプロイします。
const proxyAdmin = deployer.address;
const BEP20UpgradeableProxy = await ethers.getContractFactory(
'BEP20UpgradeableProxy'
);
const proxy = await BEP20UpgradeableProxy.deploy(
implementationAddress, // 実装コントラクト
proxyAdmin, // 管理者
initializeData // 初期化データ
);
await proxy.waitForDeployment();
const proxyAddress = await proxy.getAddress();
console.log('proxyAddress:', proxyAddress);
npm run deployで deploy が完了したら、explorer で確認してみましょう。
explorere で確認できたら正常に deploy されています。
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