Contract Source Code:
File 1 of 1 : Gravity
// Sources flattened with hardhat v2.6.4 https://hardhat.org
// File @openzeppelin/contracts/token/ERC20/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// File @openzeppelin/contracts/utils/[email protected]
pragma solidity ^0.8.0;
/**
* @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 on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
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");
(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");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
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
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// File @openzeppelin/contracts/token/ERC20/utils/[email protected]
pragma solidity ^0.8.0;
/**
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
using Address for address;
function safeTransfer(
IERC20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IERC20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// File @openzeppelin/contracts/security/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor() {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// File @openzeppelin/contracts/utils/cryptography/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
*
* These functions can be used to verify that a message was signed by the holder
* of the private keys of a given address.
*/
library ECDSA {
enum RecoverError {
NoError,
InvalidSignature,
InvalidSignatureLength,
InvalidSignatureS,
InvalidSignatureV
}
function _throwError(RecoverError error) private pure {
if (error == RecoverError.NoError) {
return; // no error: do nothing
} else if (error == RecoverError.InvalidSignature) {
revert("ECDSA: invalid signature");
} else if (error == RecoverError.InvalidSignatureLength) {
revert("ECDSA: invalid signature length");
} else if (error == RecoverError.InvalidSignatureS) {
revert("ECDSA: invalid signature 's' value");
} else if (error == RecoverError.InvalidSignatureV) {
revert("ECDSA: invalid signature 'v' value");
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature` or error string. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*
* Documentation for signature generation:
* - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
* - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
// Check the signature length
// - case 65: r,s,v signature (standard)
// - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
if (signature.length == 65) {
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return tryRecover(hash, v, r, s);
} else if (signature.length == 64) {
bytes32 r;
bytes32 vs;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
vs := mload(add(signature, 0x40))
}
return tryRecover(hash, r, vs);
} else {
return (address(0), RecoverError.InvalidSignatureLength);
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature`. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, signature);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
*
* See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
*
* _Available since v4.3._
*/
function tryRecover(
bytes32 hash,
bytes32 r,
bytes32 vs
) internal pure returns (address, RecoverError) {
bytes32 s;
uint8 v;
assembly {
s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
v := add(shr(255, vs), 27)
}
return tryRecover(hash, v, r, s);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
*
* _Available since v4.2._
*/
function recover(
bytes32 hash,
bytes32 r,
bytes32 vs
) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, r, vs);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `v`,
* `r` and `s` signature fields separately.
*
* _Available since v4.3._
*/
function tryRecover(
bytes32 hash,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address, RecoverError) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
return (address(0), RecoverError.InvalidSignatureS);
}
if (v != 27 && v != 28) {
return (address(0), RecoverError.InvalidSignatureV);
}
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(hash, v, r, s);
if (signer == address(0)) {
return (address(0), RecoverError.InvalidSignature);
}
return (signer, RecoverError.NoError);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `v`,
* `r` and `s` signature fields separately.
*/
function recover(
bytes32 hash,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, v, r, s);
_throwError(error);
return recovered;
}
/**
* @dev Returns an Ethereum Signed Message, created from a `hash`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
// 32 is the length in bytes of hash,
// enforced by the type signature above
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
}
/**
* @dev Returns an Ethereum Signed Typed Data, created from a
* `domainSeparator` and a `structHash`. This produces hash corresponding
* to the one signed with the
* https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
* JSON-RPC method as part of EIP-712.
*
* See {recover}.
*/
function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
}
}
// File @openzeppelin/contracts/token/ERC20/extensions/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
* _Available since v4.1._
*/
interface IERC20Metadata is IERC20 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the decimals places of the token.
*/
function decimals() external view returns (uint8);
}
// File @openzeppelin/contracts/utils/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// File @openzeppelin/contracts/token/ERC20/[email protected]
pragma solidity ^0.8.0;
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead returning `false` on failure. This behavior is nonetheless
* conventional and does not conflict with the expectations of ERC20
* applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
/**
* @dev Sets the values for {name} and {symbol}.
*
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overridden;
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view virtual override returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* Requirements:
*
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
uint256 currentAllowance = _allowances[sender][_msgSender()];
require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
unchecked {
_approve(sender, _msgSender(), currentAllowance - amount);
}
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
uint256 currentAllowance = _allowances[_msgSender()][spender];
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(_msgSender(), spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `sender` to `recipient`.
*
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(
address sender,
address recipient,
uint256 amount
) internal virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(sender, recipient, amount);
uint256 senderBalance = _balances[sender];
require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[sender] = senderBalance - amount;
}
_balances[recipient] += amount;
emit Transfer(sender, recipient, amount);
_afterTokenTransfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
_balances[account] += amount;
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
}
_totalSupply -= amount;
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(
address owner,
address spender,
uint256 amount
) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
// File contracts/CosmosToken.sol
pragma solidity 0.8.10;
contract CosmosERC20 is ERC20 {
uint256 MAX_UINT = 2**256 - 1;
uint8 private cosmosDecimals;
address private gravityAddress;
// This override ensures we return the proper number of decimals
// for the cosmos token
function decimals() public view virtual override returns (uint8) {
return cosmosDecimals;
}
// This is not an accurate total supply. Instead this is the total supply
// of the given cosmos asset on Ethereum at this moment in time. Keeping
// a totally accurate supply would require constant updates from the Cosmos
// side, while in theory this could be piggy-backed on some existing bridge
// operation it's a lot of complextiy to add so we chose to forgoe it.
function totalSupply() public view virtual override returns (uint256) {
return MAX_UINT - balanceOf(gravityAddress);
}
constructor(
address _gravityAddress,
string memory _name,
string memory _symbol,
uint8 _decimals
) ERC20(_name, _symbol) {
cosmosDecimals = _decimals;
gravityAddress = _gravityAddress;
_mint(_gravityAddress, MAX_UINT);
}
}
// File contracts/Gravity.sol
//SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.10;
error InvalidSignature();
error InvalidValsetNonce(uint256 newNonce, uint256 currentNonce);
error InvalidBatchNonce(uint256 newNonce, uint256 currentNonce);
error InvalidLogicCallNonce(uint256 newNonce, uint256 currentNonce);
error InvalidLogicCallTransfers();
error InvalidLogicCallFees();
error InvalidSendToCosmos();
error IncorrectCheckpoint();
error MalformedNewValidatorSet();
error MalformedCurrentValidatorSet();
error MalformedBatch();
error InsufficientPower(uint256 cumulativePower, uint256 powerThreshold);
error BatchTimedOut();
error LogicCallTimedOut();
// This is being used purely to avoid stack too deep errors
struct LogicCallArgs {
// Transfers out to the logic contract
uint256[] transferAmounts;
address[] transferTokenContracts;
// The fees (transferred to msg.sender)
uint256[] feeAmounts;
address[] feeTokenContracts;
// The arbitrary logic call
address logicContractAddress;
bytes payload;
// Invalidation metadata
uint256 timeOut;
bytes32 invalidationId;
uint256 invalidationNonce;
}
// This is used purely to avoid stack too deep errors
// represents everything about a given validator set
struct ValsetArgs {
// the validators in this set, represented by an Ethereum address
address[] validators;
// the powers of the given validators in the same order as above
uint256[] powers;
// the nonce of this validator set
uint256 valsetNonce;
// the reward amount denominated in the below reward token, can be
// set to zero
uint256 rewardAmount;
// the reward token, should be set to the zero address if not being used
address rewardToken;
}
// This represents a validator signature
struct Signature {
uint8 v;
bytes32 r;
bytes32 s;
}
contract Gravity is ReentrancyGuard {
using SafeERC20 for IERC20;
// The number of 'votes' required to execute a valset
// update or batch execution, set to 2/3 of 2^32
uint256 constant constant_powerThreshold = 2863311530;
// These are updated often
bytes32 public state_lastValsetCheckpoint;
mapping(address => uint256) public state_lastBatchNonces;
mapping(bytes32 => uint256) public state_invalidationMapping;
uint256 public state_lastValsetNonce = 0;
// event nonce zero is reserved by the Cosmos module as a special
// value indicating that no events have yet been submitted
uint256 public state_lastEventNonce = 1;
// This is set once at initialization
bytes32 public immutable state_gravityId;
// TransactionBatchExecutedEvent and SendToCosmosEvent both include the field _eventNonce.
// This is incremented every time one of these events is emitted. It is checked by the
// Cosmos module to ensure that all events are received in order, and that none are lost.
//
// ValsetUpdatedEvent does not include the field _eventNonce because it is never submitted to the Cosmos
// module. It is purely for the use of relayers to allow them to successfully submit batches.
event TransactionBatchExecutedEvent(
uint256 indexed _batchNonce,
address indexed _token,
uint256 _eventNonce
);
event SendToCosmosEvent(
address indexed _tokenContract,
address indexed _sender,
string _destination,
uint256 _amount,
uint256 _eventNonce
);
event ERC20DeployedEvent(
// FYI: Can't index on a string without doing a bunch of weird stuff
string _cosmosDenom,
address indexed _tokenContract,
string _name,
string _symbol,
uint8 _decimals,
uint256 _eventNonce
);
event ValsetUpdatedEvent(
uint256 indexed _newValsetNonce,
uint256 _eventNonce,
uint256 _rewardAmount,
address _rewardToken,
address[] _validators,
uint256[] _powers
);
event LogicCallEvent(
bytes32 _invalidationId,
uint256 _invalidationNonce,
bytes _returnData,
uint256 _eventNonce
);
// TEST FIXTURES
// These are here to make it easier to measure gas usage. They should be removed before production
function testMakeCheckpoint(ValsetArgs calldata _valsetArgs, bytes32 _gravityId) external pure {
makeCheckpoint(_valsetArgs, _gravityId);
}
function testCheckValidatorSignatures(
ValsetArgs calldata _currentValset,
Signature[] calldata _sigs,
bytes32 _theHash,
uint256 _powerThreshold
) external pure {
checkValidatorSignatures(_currentValset, _sigs, _theHash, _powerThreshold);
}
// END TEST FIXTURES
function lastBatchNonce(address _erc20Address) external view returns (uint256) {
return state_lastBatchNonces[_erc20Address];
}
function lastLogicCallNonce(bytes32 _invalidation_id) external view returns (uint256) {
return state_invalidationMapping[_invalidation_id];
}
// Utility function to verify geth style signatures
function verifySig(
address _signer,
bytes32 _theHash,
Signature calldata _sig
) private pure returns (bool) {
bytes32 messageDigest = keccak256(
abi.encodePacked("\x19Ethereum Signed Message:\n32", _theHash)
);
return _signer == ECDSA.recover(messageDigest, _sig.v, _sig.r, _sig.s);
}
// Utility function to determine that a validator set and signatures are well formed
function validateValset(ValsetArgs calldata _valset, Signature[] calldata _sigs) private pure {
// Check that current validators, powers, and signatures (v,r,s) set is well-formed
if (
_valset.validators.length != _valset.powers.length ||
_valset.validators.length != _sigs.length
) {
revert MalformedCurrentValidatorSet();
}
}
// Make a new checkpoint from the supplied validator set
// A checkpoint is a hash of all relevant information about the valset. This is stored by the contract,
// instead of storing the information directly. This saves on storage and gas.
// The format of the checkpoint is:
// h(gravityId, "checkpoint", valsetNonce, validators[], powers[])
// Where h is the keccak256 hash function.
// The validator powers must be decreasing or equal. This is important for checking the signatures on the
// next valset, since it allows the caller to stop verifying signatures once a quorum of signatures have been verified.
function makeCheckpoint(ValsetArgs memory _valsetArgs, bytes32 _gravityId)
private
pure
returns (bytes32)
{
// bytes32 encoding of the string "checkpoint"
bytes32 methodName = 0x636865636b706f696e7400000000000000000000000000000000000000000000;
bytes32 checkpoint = keccak256(
abi.encode(
_gravityId,
methodName,
_valsetArgs.valsetNonce,
_valsetArgs.validators,
_valsetArgs.powers,
_valsetArgs.rewardAmount,
_valsetArgs.rewardToken
)
);
return checkpoint;
}
function checkValidatorSignatures(
// The current validator set and their powers
ValsetArgs calldata _currentValset,
// The current validator's signatures
Signature[] calldata _sigs,
// This is what we are checking they have signed
bytes32 _theHash,
uint256 _powerThreshold
) private pure {
uint256 cumulativePower = 0;
for (uint256 i = 0; i < _currentValset.validators.length; i++) {
// If v is set to 0, this signifies that it was not possible to get a signature from this validator and we skip evaluation
// (In a valid signature, it is either 27 or 28)
if (_sigs[i].v != 0) {
// Check that the current validator has signed off on the hash
if (!verifySig(_currentValset.validators[i], _theHash, _sigs[i])) {
revert InvalidSignature();
}
// Sum up cumulative power
cumulativePower = cumulativePower + _currentValset.powers[i];
// Break early to avoid wasting gas
if (cumulativePower > _powerThreshold) {
break;
}
}
}
// Check that there was enough power
if (cumulativePower <= _powerThreshold) {
revert InsufficientPower(cumulativePower, _powerThreshold);
}
// Success
}
// This updates the valset by checking that the validators in the current valset have signed off on the
// new valset. The signatures supplied are the signatures of the current valset over the checkpoint hash
// generated from the new valset.
// Anyone can call this function, but they must supply valid signatures of constant_powerThreshold of the current valset over
// the new valset.
function updateValset(
// The new version of the validator set
ValsetArgs calldata _newValset,
// The current validators that approve the change
ValsetArgs calldata _currentValset,
// These are arrays of the parts of the current validator's signatures
Signature[] calldata _sigs
) external {
// CHECKS
// Check that the valset nonce is greater than the old one
if (_newValset.valsetNonce <= _currentValset.valsetNonce) {
revert InvalidValsetNonce({
newNonce: _newValset.valsetNonce,
currentNonce: _currentValset.valsetNonce
});
}
// Check that the valset nonce is less than a million nonces forward from the old one
// this makes it difficult for an attacker to lock out the contract by getting a single
// bad validator set through with uint256 max nonce
if (_newValset.valsetNonce > _currentValset.valsetNonce + 1000000) {
revert InvalidValsetNonce({
newNonce: _newValset.valsetNonce,
currentNonce: _currentValset.valsetNonce
});
}
// Check that new validators and powers set is well-formed
if (
_newValset.validators.length != _newValset.powers.length ||
_newValset.validators.length == 0
) {
revert MalformedNewValidatorSet();
}
// Check that current validators, powers, and signatures (v,r,s) set is well-formed
validateValset(_currentValset, _sigs);
// Check cumulative power to ensure the contract has sufficient power to actually
// pass a vote
uint256 cumulativePower = 0;
for (uint256 i = 0; i < _newValset.powers.length; i++) {
cumulativePower = cumulativePower + _newValset.powers[i];
if (cumulativePower > constant_powerThreshold) {
break;
}
}
if (cumulativePower <= constant_powerThreshold) {
revert InsufficientPower({
cumulativePower: cumulativePower,
powerThreshold: constant_powerThreshold
});
}
// Check that the supplied current validator set matches the saved checkpoint
if (makeCheckpoint(_currentValset, state_gravityId) != state_lastValsetCheckpoint) {
revert IncorrectCheckpoint();
}
// Check that enough current validators have signed off on the new validator set
bytes32 newCheckpoint = makeCheckpoint(_newValset, state_gravityId);
checkValidatorSignatures(_currentValset, _sigs, newCheckpoint, constant_powerThreshold);
// ACTIONS
// Stored to be used next time to validate that the valset
// supplied by the caller is correct.
state_lastValsetCheckpoint = newCheckpoint;
// Store new nonce
state_lastValsetNonce = _newValset.valsetNonce;
// Send submission reward to msg.sender if reward token is a valid value
if (_newValset.rewardToken != address(0) && _newValset.rewardAmount != 0) {
IERC20(_newValset.rewardToken).safeTransfer(msg.sender, _newValset.rewardAmount);
}
// LOGS
state_lastEventNonce = state_lastEventNonce + 1;
emit ValsetUpdatedEvent(
_newValset.valsetNonce,
state_lastEventNonce,
_newValset.rewardAmount,
_newValset.rewardToken,
_newValset.validators,
_newValset.powers
);
}
// submitBatch processes a batch of Cosmos -> Ethereum transactions by sending the tokens in the transactions
// to the destination addresses. It is approved by the current Cosmos validator set.
// Anyone can call this function, but they must supply valid signatures of constant_powerThreshold of the current valset over
// the batch.
function submitBatch(
// The validators that approve the batch
ValsetArgs calldata _currentValset,
// These are arrays of the parts of the validators signatures
Signature[] calldata _sigs,
// The batch of transactions
uint256[] calldata _amounts,
address[] calldata _destinations,
uint256[] calldata _fees,
uint256 _batchNonce,
address _tokenContract,
// a block height beyond which this batch is not valid
// used to provide a fee-free timeout
uint256 _batchTimeout
) external nonReentrant {
// CHECKS scoped to reduce stack depth
{
// Check that the batch nonce is higher than the last nonce for this token
if (_batchNonce <= state_lastBatchNonces[_tokenContract]) {
revert InvalidBatchNonce({
newNonce: _batchNonce,
currentNonce: state_lastBatchNonces[_tokenContract]
});
}
// Check that the batch nonce is less than one million nonces forward from the old one
// this makes it difficult for an attacker to lock out the contract by getting a single
// bad batch through with uint256 max nonce
if (_batchNonce > state_lastBatchNonces[_tokenContract] + 1000000) {
revert InvalidBatchNonce({
newNonce: _batchNonce,
currentNonce: state_lastBatchNonces[_tokenContract]
});
}
// Check that the block height is less than the timeout height
if (block.number >= _batchTimeout) {
revert BatchTimedOut();
}
// Check that current validators, powers, and signatures (v,r,s) set is well-formed
validateValset(_currentValset, _sigs);
// Check that the supplied current validator set matches the saved checkpoint
if (makeCheckpoint(_currentValset, state_gravityId) != state_lastValsetCheckpoint) {
revert IncorrectCheckpoint();
}
// Check that the transaction batch is well-formed
if (_amounts.length != _destinations.length || _amounts.length != _fees.length) {
revert MalformedBatch();
}
// Check that enough current validators have signed off on the transaction batch and valset
checkValidatorSignatures(
_currentValset,
_sigs,
// Get hash of the transaction batch and checkpoint
keccak256(
abi.encode(
state_gravityId,
// bytes32 encoding of "transactionBatch"
0x7472616e73616374696f6e426174636800000000000000000000000000000000,
_amounts,
_destinations,
_fees,
_batchNonce,
_tokenContract,
_batchTimeout
)
),
constant_powerThreshold
);
// ACTIONS
// Store batch nonce
state_lastBatchNonces[_tokenContract] = _batchNonce;
{
// Send transaction amounts to destinations
uint256 totalFee;
for (uint256 i = 0; i < _amounts.length; i++) {
IERC20(_tokenContract).safeTransfer(_destinations[i], _amounts[i]);
totalFee = totalFee + _fees[i];
}
// Send transaction fees to msg.sender
IERC20(_tokenContract).safeTransfer(msg.sender, totalFee);
}
}
// LOGS scoped to reduce stack depth
{
state_lastEventNonce = state_lastEventNonce + 1;
emit TransactionBatchExecutedEvent(_batchNonce, _tokenContract, state_lastEventNonce);
}
}
// This makes calls to contracts that execute arbitrary logic
// First, it gives the logic contract some tokens
// Then, it gives msg.senders tokens for fees
// Then, it calls an arbitrary function on the logic contract
// invalidationId and invalidationNonce are used for replay prevention.
// They can be used to implement a per-token nonce by setting the token
// address as the invalidationId and incrementing the nonce each call.
// They can be used for nonce-free replay prevention by using a different invalidationId
// for each call.
function submitLogicCall(
// The validators that approve the call
ValsetArgs calldata _currentValset,
// These are arrays of the parts of the validators signatures
Signature[] calldata _sigs,
LogicCallArgs memory _args
) external nonReentrant {
// CHECKS scoped to reduce stack depth
{
// Check that the call has not timed out
if (block.number >= _args.timeOut) {
revert LogicCallTimedOut();
}
// Check that the invalidation nonce is higher than the last nonce for this invalidation Id
if (state_invalidationMapping[_args.invalidationId] >= _args.invalidationNonce) {
revert InvalidLogicCallNonce({
newNonce: _args.invalidationNonce,
currentNonce: state_invalidationMapping[_args.invalidationId]
});
}
// note the lack of nonce skipping check, it's not needed here since an attacker
// will never be able to fill the invalidationId space, therefore a nonce lockout
// is simply not possible
// Check that current validators, powers, and signatures (v,r,s) set is well-formed
validateValset(_currentValset, _sigs);
// Check that the supplied current validator set matches the saved checkpoint
if (makeCheckpoint(_currentValset, state_gravityId) != state_lastValsetCheckpoint) {
revert IncorrectCheckpoint();
}
if (_args.transferAmounts.length != _args.transferTokenContracts.length) {
revert InvalidLogicCallTransfers();
}
if (_args.feeAmounts.length != _args.feeTokenContracts.length) {
revert InvalidLogicCallFees();
}
}
{
bytes32 argsHash = keccak256(
abi.encode(
state_gravityId,
// bytes32 encoding of "logicCall"
0x6c6f67696343616c6c0000000000000000000000000000000000000000000000,
_args.transferAmounts,
_args.transferTokenContracts,
_args.feeAmounts,
_args.feeTokenContracts,
_args.logicContractAddress,
_args.payload,
_args.timeOut,
_args.invalidationId,
_args.invalidationNonce
)
);
// Check that enough current validators have signed off on the transaction batch and valset
checkValidatorSignatures(
_currentValset,
_sigs,
// Get hash of the transaction batch and checkpoint
argsHash,
constant_powerThreshold
);
}
// ACTIONS
// Update invaldiation nonce
state_invalidationMapping[_args.invalidationId] = _args.invalidationNonce;
// Send tokens to the logic contract
for (uint256 i = 0; i < _args.transferAmounts.length; i++) {
IERC20(_args.transferTokenContracts[i]).safeTransfer(
_args.logicContractAddress,
_args.transferAmounts[i]
);
}
// Make call to logic contract
bytes memory returnData = Address.functionCall(_args.logicContractAddress, _args.payload);
// Send fees to msg.sender
for (uint256 i = 0; i < _args.feeAmounts.length; i++) {
IERC20(_args.feeTokenContracts[i]).safeTransfer(msg.sender, _args.feeAmounts[i]);
}
// LOGS scoped to reduce stack depth
{
state_lastEventNonce = state_lastEventNonce + 1;
emit LogicCallEvent(
_args.invalidationId,
_args.invalidationNonce,
returnData,
state_lastEventNonce
);
}
}
function sendToCosmos(
address _tokenContract,
string calldata _destination,
uint256 _amount
) external nonReentrant {
// we snapshot our current balance of this token
uint256 ourStartingBalance = IERC20(_tokenContract).balanceOf(address(this));
// attempt to transfer the user specified amount
IERC20(_tokenContract).safeTransferFrom(msg.sender, address(this), _amount);
// check what this particular ERC20 implementation actually gave us, since it doesn't
// have to be at all related to the _amount
uint256 ourEndingBalance = IERC20(_tokenContract).balanceOf(address(this));
// a very strange ERC20 may trigger this condition, if we didn't have this we would
// underflow, so it's mostly just an error message printer
if (ourEndingBalance <= ourStartingBalance) {
revert InvalidSendToCosmos();
}
state_lastEventNonce = state_lastEventNonce + 1;
// emit to Cosmos the actual amount our balance has changed, rather than the user
// provided amount. This protects against a small set of wonky ERC20 behavior, like
// burning on send but not tokens that for example change every users balance every day.
emit SendToCosmosEvent(
_tokenContract,
msg.sender,
_destination,
ourEndingBalance - ourStartingBalance,
state_lastEventNonce
);
}
function deployERC20(
string calldata _cosmosDenom,
string calldata _name,
string calldata _symbol,
uint8 _decimals
) external {
// Deploy an ERC20 with entire supply granted to Gravity.sol
CosmosERC20 erc20 = new CosmosERC20(address(this), _name, _symbol, _decimals);
// Fire an event to let the Cosmos module know
state_lastEventNonce = state_lastEventNonce + 1;
emit ERC20DeployedEvent(
_cosmosDenom,
address(erc20),
_name,
_symbol,
_decimals,
state_lastEventNonce
);
}
constructor(
// A unique identifier for this gravity instance to use in signatures
bytes32 _gravityId,
// The validator set, not in valset args format since many of it's
// arguments would never be used in this case
address[] memory _validators,
uint256[] memory _powers
) {
// CHECKS
// Check that validators, powers, and signatures (v,r,s) set is well-formed
if (_validators.length != _powers.length || _validators.length == 0) {
revert MalformedCurrentValidatorSet();
}
// Check cumulative power to ensure the contract has sufficient power to actually
// pass a vote
uint256 cumulativePower = 0;
for (uint256 i = 0; i < _powers.length; i++) {
cumulativePower = cumulativePower + _powers[i];
if (cumulativePower > constant_powerThreshold) {
break;
}
}
if (cumulativePower <= constant_powerThreshold) {
revert InsufficientPower({
cumulativePower: cumulativePower,
powerThreshold: constant_powerThreshold
});
}
ValsetArgs memory _valset;
_valset = ValsetArgs(_validators, _powers, 0, 0, address(0));
bytes32 newCheckpoint = makeCheckpoint(_valset, _gravityId);
// ACTIONS
state_gravityId = _gravityId;
state_lastValsetCheckpoint = newCheckpoint;
// LOGS
emit ValsetUpdatedEvent(
state_lastValsetNonce,
state_lastEventNonce,
0,
address(0),
_validators,
_powers
);
}
}