tornado-governance/contracts/v2-vault-and-gas/gas/GovernanceGasUpgrade.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;
pragma experimental ABIEncoderV2;

import { GovernanceVaultUpgrade } from "../vault/GovernanceVaultUpgrade.sol";
import { GasCompensator } from "./GasCompensator.sol";
import { Math } from "@openzeppelin/contracts/math/Math.sol";

/**
 * @notice This contract should upgrade governance to be able to compensate gas for certain actions.
 *         These actions are set to castVote, castDelegatedVote in this contract.
 * */
contract GovernanceGasUpgrade is GovernanceVaultUpgrade, GasCompensator {
  /**
   * @notice constructor
   * @param _gasCompLogic gas compensation vault address
   * @param _userVault tornado vault address
   * */
  constructor(address _gasCompLogic, address _userVault)
    public
    GovernanceVaultUpgrade(_userVault)
    GasCompensator(_gasCompLogic)
  {}

  /// @notice check that msg.sender is multisig
  modifier onlyMultisig() {
    require(msg.sender == returnMultisigAddress(), "only multisig");
    _;
  }

  /**
   * @notice receive ether function, does nothing but receive ether
   * */
  receive() external payable {}

  /**
   * @notice function to add a certain amount of ether for gas compensations
   * @dev send ether is used in the logic as we don't expect multisig to make a reentrancy attack on governance
   * @param gasCompensationsLimit the amount of gas to be compensated
   * */
  function setGasCompensations(uint256 gasCompensationsLimit) external virtual override onlyMultisig {
    require(payable(address(gasCompensationVault)).send(Math.min(gasCompensationsLimit, address(this).balance)));
  }

  /**
   * @notice function to withdraw funds from the gas compensator
   * @dev send ether is used in the logic as we don't expect multisig to make a reentrancy attack on governance
   * @param amount the amount of ether to withdraw
   * */
  function withdrawFromHelper(uint256 amount) external virtual override onlyMultisig {
    gasCompensationVault.withdrawToGovernance(amount);
  }

  /**
  * @notice function to cast callers votes on a proposal
  * @dev IMPORTANT: This function uses the gasCompensation modifier.
  *                 as such this function can trigger a payable fallback.
                    It is not possible to vote without revert more than once,
		    without hasAccountVoted being true, eliminating gas refunds in this case.
		    Gas compensation is also using the low level send(), forwarding 23000 gas 
		    as to disallow further logic execution above that threshold.
  * @param proposalId id of proposal account is voting on
  * @param support true if yes false if no
  * */
  function castVote(uint256 proposalId, bool support)
    external
    virtual
    override
    gasCompensation(
      msg.sender,
      !hasAccountVoted(proposalId, msg.sender) && !checkIfQuorumReached(proposalId),
      (msg.sender == tx.origin ? 21e3 : 0)
    )
  {
    _castVote(msg.sender, proposalId, support);
  }

  /**
   * @notice function to cast callers votes and votes delegated to the caller
   * @param from array of addresses that should have delegated to voter
   * @param proposalId id of proposal account is voting on
   * @param support true if yes false if no
   * */
  function castDelegatedVote(
    address[] memory from,
    uint256 proposalId,
    bool support
  ) external virtual override {
    require(from.length > 0, "Can not be empty");
    _castDelegatedVote(from, proposalId, support, !hasAccountVoted(proposalId, msg.sender) && !checkIfQuorumReached(proposalId));
  }

  /// @notice checker for success on deployment
  /// @return returns precise version of governance
  function version() external pure virtual override returns (string memory) {
    return "2.lottery-and-gas-upgrade";
  }

  /**
   * @notice function to check if quorum has been reached on a given proposal
   * @param proposalId id of proposal
   * @return true if quorum has been reached
   * */
  function checkIfQuorumReached(uint256 proposalId) public view returns (bool) {
    return (proposals[proposalId].forVotes + proposals[proposalId].againstVotes >= QUORUM_VOTES);
  }

  /**
   * @notice function to check if account has voted on a proposal
   * @param proposalId id of proposal account should have voted on
   * @param account address of the account
   * @return true if acc has voted
   * */
  function hasAccountVoted(uint256 proposalId, address account) public view returns (bool) {
    return proposals[proposalId].receipts[account].hasVoted;
  }

  /**
   * @notice function to retrieve the multisig address
   * @dev reasoning: if multisig changes we need governance to approve the next multisig address,
   *                 so simply inherit in a governance upgrade from this function and set the new address
   * @return the multisig address
   * */
  function returnMultisigAddress() public pure virtual returns (address) {
    return 0xb04E030140b30C27bcdfaafFFA98C57d80eDa7B4;
  }

  /**
   * @notice This should handle the logic of the external function
   * @dev IMPORTANT: This function uses the gasCompensation modifier.
   *                 as such this function can trigger a payable fallback.
   *                 It is not possible to vote without revert more than once,
   *        	     without hasAccountVoted being true, eliminating gas refunds in this case.
   *      	     Gas compensation is also using the low level send(), forwarding 23000 gas
   *   		     as to disallow further logic execution above that threshold.
   * @param from array of addresses that should have delegated to voter
   * @param proposalId id of proposal account is voting on
   * @param support true if yes false if no
   * @param gasCompensated true if gas should be compensated (given all internal checks pass)
   * */
  function _castDelegatedVote(
    address[] memory from,
    uint256 proposalId,
    bool support,
    bool gasCompensated
  ) internal gasCompensation(msg.sender, gasCompensated, (msg.sender == tx.origin ? 21e3 : 0)) {
    for (uint256 i = 0; i < from.length; i++) {
      address delegator = from[i];
      require(delegatedTo[delegator] == msg.sender || delegator == msg.sender, "Governance: not authorized");
      require(!gasCompensated || !hasAccountVoted(proposalId, delegator), "Governance: voted already");
      _castVote(delegator, proposalId, support);
    }
  }
}