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Governor.sol
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Governor.sol
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// SPDX-License-Identifier: MIT
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/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 SafeCast for uint256;
using Timers for Timers.BlockNumber;
bytes32 public constant BALLOT_TYPEHASH = keccak256("Ballot(uint256 proposalId,uint8 support)");
struct ProposalCore {
Timers.BlockNumber voteStart;
Timers.BlockNumber voteEnd;
bool executed;
bool canceled;
}
string private _name;
mapping(uint256 => ProposalCore) private _proposals;
/**
* @dev Restrict access to governor executing address. Some module might override the _executor function to make
* sure this modifier is consistant with the execution model.
*/
modifier onlyGovernance() {
require(_msgSender() == _executor(), "Governor: onlyGovernance");
_;
}
/**
* @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) {
return 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 memory proposal = _proposals[proposalId];
if (proposal.executed) {
return ProposalState.Executed;
} else if (proposal.canceled) {
return ProposalState.Canceled;
} else if (proposal.voteStart.getDeadline() >= block.number) {
return ProposalState.Pending;
} else if (proposal.voteEnd.getDeadline() >= block.number) {
return ProposalState.Active;
} else if (proposal.voteEnd.isExpired()) {
return
_quorumReached(proposalId) && _voteSucceeded(proposalId)
? ProposalState.Succeeded
: ProposalState.Defeated;
} else {
revert("Governor: unknown proposal id");
}
}
/**
* @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 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
) internal virtual;
/**
* @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(msg.sender, 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);
_execute(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 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-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-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 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
) 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());
_countVote(proposalId, account, support, weight);
emit VoteCast(account, proposalId, support, weight, reason);
return weight;
}
/**
* @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);
}
}