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Governor.sol
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Governor.sol
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// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (governance/Governor.sol)
pragma solidity ^0.8.0;
import "../utils/cryptography/ECDSA.sol";
import "../utils/cryptography/draft-EIP712.sol";
import "../utils/introspection/ERC165.sol";
import "../utils/math/SafeCast.sol";
import "../utils/structs/DoubleEndedQueue.sol";
import "../utils/Address.sol";
import "../utils/Context.sol";
import "../utils/Timers.sol";
import "./IGovernor.sol";
/**
* @dev Core of the governance system, designed to be extended though various modules.
*
* This contract is abstract and requires several function to be implemented in various modules:
*
* - A counting module must implement {quorum}, {_quorumReached}, {_voteSucceeded} and {_countVote}
* - A voting module must implement {_getVotes}
* - Additionanly, the {votingPeriod} must also be implemented
*
* _Available since v4.3._
*/
abstract contract Governor is Context, ERC165, EIP712, IGovernor {
using DoubleEndedQueue for DoubleEndedQueue.Bytes32Deque;
using SafeCast for uint256;
using Timers for Timers.BlockNumber;
bytes32 public constant BALLOT_TYPEHASH = keccak256("Ballot(uint256 proposalId,uint8 support)");
bytes32 public constant EXTENDED_BALLOT_TYPEHASH =
keccak256("ExtendedBallot(uint256 proposalId,uint8 support,string reason,bytes params)");
struct ProposalCore {
Timers.BlockNumber voteStart;
Timers.BlockNumber voteEnd;
bool executed;
bool canceled;
}
string private _name;
mapping(uint256 => ProposalCore) private _proposals;
// This queue keeps track of the governor operating on itself. Calls to functions protected by the
// {onlyGovernance} modifier needs to be whitelisted in this queue. Whitelisting is set in {_beforeExecute},
// consummed by the {onlyGovernance} modifier and eventually reset in {_afterExecute}. This ensures that the
// execution of {onlyGovernance} protected calls can only be achieved through successful proposals.
DoubleEndedQueue.Bytes32Deque private _governanceCall;
/**
* @dev Restricts a function so it can only be executed through governance proposals. For example, governance
* parameter setters in {GovernorSettings} are protected using this modifier.
*
* The governance executing address may be different from the Governor's own address, for example it could be a
* timelock. This can be customized by modules by overriding {_executor}. The executor is only able to invoke these
* functions during the execution of the governor's {execute} function, and not under any other circumstances. Thus,
* for example, additional timelock proposers are not able to change governance parameters without going through the
* governance protocol (since v4.6).
*/
modifier onlyGovernance() {
require(_msgSender() == _executor(), "Governor: onlyGovernance");
if (_executor() != address(this)) {
bytes32 msgDataHash = keccak256(_msgData());
// loop until poping the expected operation - throw if deque is empty (operation not authorized)
while (_governanceCall.popFront() != msgDataHash) {}
}
_;
}
/**
* @dev Sets the value for {name} and {version}
*/
constructor(string memory name_) EIP712(name_, version()) {
_name = name_;
}
/**
* @dev Function to receive ETH that will be handled by the governor (disabled if executor is a third party contract)
*/
receive() external payable virtual {
require(_executor() == address(this));
}
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC165) returns (bool) {
// In addition to the current interfaceId, also support previous version of the interfaceId that did not
// include the castVoteWithReasonAndParams() function as standard
return
interfaceId ==
(type(IGovernor).interfaceId ^
this.castVoteWithReasonAndParams.selector ^
this.castVoteWithReasonAndParamsBySig.selector ^
this.getVotesWithParams.selector) ||
interfaceId == type(IGovernor).interfaceId ||
super.supportsInterface(interfaceId);
}
/**
* @dev See {IGovernor-name}.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev See {IGovernor-version}.
*/
function version() public view virtual override returns (string memory) {
return "1";
}
/**
* @dev See {IGovernor-hashProposal}.
*
* The proposal id is produced by hashing the RLC encoded `targets` array, the `values` array, the `calldatas` array
* and the descriptionHash (bytes32 which itself is the keccak256 hash of the description string). This proposal id
* can be produced from the proposal data which is part of the {ProposalCreated} event. It can even be computed in
* advance, before the proposal is submitted.
*
* Note that the chainId and the governor address are not part of the proposal id computation. Consequently, the
* same proposal (with same operation and same description) will have the same id if submitted on multiple governors
* accross multiple networks. This also means that in order to execute the same operation twice (on the same
* governor) the proposer will have to change the description in order to avoid proposal id conflicts.
*/
function hashProposal(
address[] memory targets,
uint256[] memory values,
bytes[] memory calldatas,
bytes32 descriptionHash
) public pure virtual override returns (uint256) {
return uint256(keccak256(abi.encode(targets, values, calldatas, descriptionHash)));
}
/**
* @dev See {IGovernor-state}.
*/
function state(uint256 proposalId) public view virtual override returns (ProposalState) {
ProposalCore storage proposal = _proposals[proposalId];
if (proposal.executed) {
return ProposalState.Executed;
}
if (proposal.canceled) {
return ProposalState.Canceled;
}
uint256 snapshot = proposalSnapshot(proposalId);
if (snapshot == 0) {
revert("Governor: unknown proposal id");
}
if (snapshot >= block.number) {
return ProposalState.Pending;
}
uint256 deadline = proposalDeadline(proposalId);
if (deadline >= block.number) {
return ProposalState.Active;
}
if (_quorumReached(proposalId) && _voteSucceeded(proposalId)) {
return ProposalState.Succeeded;
} else {
return ProposalState.Defeated;
}
}
/**
* @dev See {IGovernor-proposalSnapshot}.
*/
function proposalSnapshot(uint256 proposalId) public view virtual override returns (uint256) {
return _proposals[proposalId].voteStart.getDeadline();
}
/**
* @dev See {IGovernor-proposalDeadline}.
*/
function proposalDeadline(uint256 proposalId) public view virtual override returns (uint256) {
return _proposals[proposalId].voteEnd.getDeadline();
}
/**
* @dev Part of the Governor Bravo's interface: _"The number of votes required in order for a voter to become a proposer"_.
*/
function proposalThreshold() public view virtual returns (uint256) {
return 0;
}
/**
* @dev Amount of votes already cast passes the threshold limit.
*/
function _quorumReached(uint256 proposalId) internal view virtual returns (bool);
/**
* @dev Is the proposal successful or not.
*/
function _voteSucceeded(uint256 proposalId) internal view virtual returns (bool);
/**
* @dev Get the voting weight of `account` at a specific `blockNumber`, for a vote as described by `params`.
*/
function _getVotes(
address account,
uint256 blockNumber,
bytes memory params
) internal view virtual returns (uint256);
/**
* @dev Register a vote with a given support and voting weight.
*
* Note: Support is generic and can represent various things depending on the voting system used.
*/
function _countVote(
uint256 proposalId,
address account,
uint8 support,
uint256 weight,
bytes memory params
) internal virtual;
/**
* @dev Default additional encoded parameters used by castVote methods that don't include them
*
* Note: Should be overriden by specific implementations to use an appropriate value, the
* meaning of the additional params, in the context of that implementation
*/
function _defaultParams() internal view virtual returns (bytes memory) {
return "";
}
/**
* @dev See {IGovernor-propose}.
*/
function propose(
address[] memory targets,
uint256[] memory values,
bytes[] memory calldatas,
string memory description
) public virtual override returns (uint256) {
require(
getVotes(_msgSender(), block.number - 1) >= proposalThreshold(),
"GovernorCompatibilityBravo: proposer votes below proposal threshold"
);
uint256 proposalId = hashProposal(targets, values, calldatas, keccak256(bytes(description)));
require(targets.length == values.length, "Governor: invalid proposal length");
require(targets.length == calldatas.length, "Governor: invalid proposal length");
require(targets.length > 0, "Governor: empty proposal");
ProposalCore storage proposal = _proposals[proposalId];
require(proposal.voteStart.isUnset(), "Governor: proposal already exists");
uint64 snapshot = block.number.toUint64() + votingDelay().toUint64();
uint64 deadline = snapshot + votingPeriod().toUint64();
proposal.voteStart.setDeadline(snapshot);
proposal.voteEnd.setDeadline(deadline);
emit ProposalCreated(
proposalId,
_msgSender(),
targets,
values,
new string[](targets.length),
calldatas,
snapshot,
deadline,
description
);
return proposalId;
}
/**
* @dev See {IGovernor-execute}.
*/
function execute(
address[] memory targets,
uint256[] memory values,
bytes[] memory calldatas,
bytes32 descriptionHash
) public payable virtual override returns (uint256) {
uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
ProposalState status = state(proposalId);
require(
status == ProposalState.Succeeded || status == ProposalState.Queued,
"Governor: proposal not successful"
);
_proposals[proposalId].executed = true;
emit ProposalExecuted(proposalId);
_beforeExecute(proposalId, targets, values, calldatas, descriptionHash);
_execute(proposalId, targets, values, calldatas, descriptionHash);
_afterExecute(proposalId, targets, values, calldatas, descriptionHash);
return proposalId;
}
/**
* @dev Internal execution mechanism. Can be overriden to implement different execution mechanism
*/
function _execute(
uint256, /* proposalId */
address[] memory targets,
uint256[] memory values,
bytes[] memory calldatas,
bytes32 /*descriptionHash*/
) internal virtual {
string memory errorMessage = "Governor: call reverted without message";
for (uint256 i = 0; i < targets.length; ++i) {
(bool success, bytes memory returndata) = targets[i].call{value: values[i]}(calldatas[i]);
Address.verifyCallResult(success, returndata, errorMessage);
}
}
/**
* @dev Hook before execution is trigerred.
*/
function _beforeExecute(
uint256, /* proposalId */
address[] memory targets,
uint256[] memory, /* values */
bytes[] memory calldatas,
bytes32 /*descriptionHash*/
) internal virtual {
if (_executor() != address(this)) {
for (uint256 i = 0; i < targets.length; ++i) {
if (targets[i] == address(this)) {
_governanceCall.pushBack(keccak256(calldatas[i]));
}
}
}
}
/**
* @dev Hook after execution is trigerred.
*/
function _afterExecute(
uint256, /* proposalId */
address[] memory, /* targets */
uint256[] memory, /* values */
bytes[] memory, /* calldatas */
bytes32 /*descriptionHash*/
) internal virtual {
if (_executor() != address(this)) {
if (!_governanceCall.empty()) {
_governanceCall.clear();
}
}
}
/**
* @dev Internal cancel mechanism: locks up the proposal timer, preventing it from being re-submitted. Marks it as
* canceled to allow distinguishing it from executed proposals.
*
* Emits a {IGovernor-ProposalCanceled} event.
*/
function _cancel(
address[] memory targets,
uint256[] memory values,
bytes[] memory calldatas,
bytes32 descriptionHash
) internal virtual returns (uint256) {
uint256 proposalId = hashProposal(targets, values, calldatas, descriptionHash);
ProposalState status = state(proposalId);
require(
status != ProposalState.Canceled && status != ProposalState.Expired && status != ProposalState.Executed,
"Governor: proposal not active"
);
_proposals[proposalId].canceled = true;
emit ProposalCanceled(proposalId);
return proposalId;
}
/**
* @dev See {IGovernor-getVotes}.
*/
function getVotes(address account, uint256 blockNumber) public view virtual override returns (uint256) {
return _getVotes(account, blockNumber, _defaultParams());
}
/**
* @dev See {IGovernor-getVotesWithParams}.
*/
function getVotesWithParams(
address account,
uint256 blockNumber,
bytes memory params
) public view virtual override returns (uint256) {
return _getVotes(account, blockNumber, params);
}
/**
* @dev See {IGovernor-castVote}.
*/
function castVote(uint256 proposalId, uint8 support) public virtual override returns (uint256) {
address voter = _msgSender();
return _castVote(proposalId, voter, support, "");
}
/**
* @dev See {IGovernor-castVoteWithReason}.
*/
function castVoteWithReason(
uint256 proposalId,
uint8 support,
string calldata reason
) public virtual override returns (uint256) {
address voter = _msgSender();
return _castVote(proposalId, voter, support, reason);
}
/**
* @dev See {IGovernor-castVoteWithReasonAndParams}.
*/
function castVoteWithReasonAndParams(
uint256 proposalId,
uint8 support,
string calldata reason,
bytes memory params
) public virtual override returns (uint256) {
address voter = _msgSender();
return _castVote(proposalId, voter, support, reason, params);
}
/**
* @dev See {IGovernor-castVoteBySig}.
*/
function castVoteBySig(
uint256 proposalId,
uint8 support,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override returns (uint256) {
address voter = ECDSA.recover(
_hashTypedDataV4(keccak256(abi.encode(BALLOT_TYPEHASH, proposalId, support))),
v,
r,
s
);
return _castVote(proposalId, voter, support, "");
}
/**
* @dev See {IGovernor-castVoteWithReasonAndParamsBySig}.
*/
function castVoteWithReasonAndParamsBySig(
uint256 proposalId,
uint8 support,
string calldata reason,
bytes memory params,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override returns (uint256) {
address voter = ECDSA.recover(
_hashTypedDataV4(
keccak256(
abi.encode(
EXTENDED_BALLOT_TYPEHASH,
proposalId,
support,
keccak256(bytes(reason)),
keccak256(params)
)
)
),
v,
r,
s
);
return _castVote(proposalId, voter, support, reason, params);
}
/**
* @dev Internal vote casting mechanism: Check that the vote is pending, that it has not been cast yet, retrieve
* voting weight using {IGovernor-getVotes} and call the {_countVote} internal function. Uses the _defaultParams().
*
* Emits a {IGovernor-VoteCast} event.
*/
function _castVote(
uint256 proposalId,
address account,
uint8 support,
string memory reason
) internal virtual returns (uint256) {
return _castVote(proposalId, account, support, reason, _defaultParams());
}
/**
* @dev Internal vote casting mechanism: Check that the vote is pending, that it has not been cast yet, retrieve
* voting weight using {IGovernor-getVotes} and call the {_countVote} internal function.
*
* Emits a {IGovernor-VoteCast} event.
*/
function _castVote(
uint256 proposalId,
address account,
uint8 support,
string memory reason,
bytes memory params
) internal virtual returns (uint256) {
ProposalCore storage proposal = _proposals[proposalId];
require(state(proposalId) == ProposalState.Active, "Governor: vote not currently active");
uint256 weight = _getVotes(account, proposal.voteStart.getDeadline(), params);
_countVote(proposalId, account, support, weight, params);
if (params.length == 0) {
emit VoteCast(account, proposalId, support, weight, reason);
} else {
emit VoteCastWithParams(account, proposalId, support, weight, reason, params);
}
return weight;
}
/**
* @dev Relays a transaction or function call to an arbitrary target. In cases where the governance executor
* is some contract other than the governor itself, like when using a timelock, this function can be invoked
* in a governance proposal to recover tokens or Ether that was sent to the governor contract by mistake.
* Note that if the executor is simply the governor itself, use of `relay` is redundant.
*/
function relay(
address target,
uint256 value,
bytes calldata data
) external virtual onlyGovernance {
Address.functionCallWithValue(target, data, value);
}
/**
* @dev Address through which the governor executes action. Will be overloaded by module that execute actions
* through another contract such as a timelock.
*/
function _executor() internal view virtual returns (address) {
return address(this);
}
}