@waku/vote-sdk-contracts

wakuconnect-voting-sdk/contracts

WakuConnect Proposal Contracts.

Voting Contract

The Voting Contract is a smart contract that enables the storage of proposals, from creation to vote result.

Lifecycle of proposal:

1. Initialize proposal,
2. Proposal is open, votes are accepted,
3. Voting time ends, votes are no longer accepted, result is final.

Types

The main types used in the contract are:

• Proposal

  Holds information about the proposal

  Fields

  // block at which the proposal was created
  uint256 startBlock;
  // timestamp in seconds after which new votes won't be accepted
  // when casting votes endAt is compared to block.timestamp
  uint256 endAt;
  // proposal title
  string title;
  // proposal description
  string description;
  // total number of votes in favour of the proposal, this may be weighted
  uint256 totalVotesFor;
  // total number of votes against the proposal, this may be weighted
  uint256 totalVotesAgainst;
  // list of addresses that already voted
  address[] voters;

• Vote

  Holds the information for one vote

  Fields

  // address of the voter
  address voter;
  // encoded proposalId and type
  // first bit this field is a vote type:
  // 1 is a vote for
  // 0 is a vote against
  // rest of this field is a roomId shifted one bit to 
  // the left
  uint256 proposalIdAndType;
  // amount of token used to vote
  uint256 tokenAmount;
  //signature of vote
  bytes32 r;
  bytes32 vs;

Constants and variables

• token contract address of the token used for vote verification. It is assigned at contract creation. Only holders of this token can vote.

• voteDuration Length of duration during which proposals can be vote on, in seconds. It is assigned at contract creation.

• EIP712DOMAIN_TYPEHASH Constant holding type hash of EIP712 domain as per EIP712 specification.

• VOTE_TYPEHASH Constant holding type hash of Vote as per EIP712 specification.

• DOMAIN_SEPARATOR Variable holding hash of domain separator according to EIP712 spec. It is assigned at smart contract creation.

• voted Holds whether a given address has voted to a given proposal. It is a mapping of proposal id to mapping of addresses to booleans which indicates whether the given address has voted.

• proposals Array that holds all proposals. The id for a proposal is the index in this array.

Signing with EIP712

EIP712 MUST be used to sign votes. The structure of typed data for a vote message is as follows:

{
  types: {
      EIP712Domain: [
          { name: 'name', type: 'string' },
          { name: 'version', type: 'string' },
          { name: 'chainId', type: 'uint256' },
          { name: 'verifyingContract', type: 'address' },
      ],
      Vote: [
        { name: 'proposalIdAndType', type: 'uint256' },
        { name: 'tokenAmount', type: 'uint256' },
        { name: 'voter', type: 'address' },
      ],
  },
  primaryType: 'Vote',
  domain: {
      name: 'Voting Contract',
      version: '1',
      chainId: chainId,
      verifyingContract: contract.address,
  },
  message: {
      voter: voterAddress,
      tokenAmount: tokenAmount,
      proposalIdAndType: proposalIdAndType
  }
}

For more information about EIP-712 go to docs

Functions

• constructor(IERC20 _address) Assigns _address to token and generates DOMAIN_SEPARATOR

• getProposals() Returns proposals

• getProposalsLength() Returns the length of the proposals array

• getLastNProposals(uint256 amount) Returns the N last proposals

• getProposalFromId(uint256 id) Gets proposal from given id

• getOpenProposals() Returns proposals for which proposal.endAt > block.timestamp which means the proposals are still accepting votes. Since proposalDuration is set at contract creation and never changed, proposal.endAt is never decreasing with increasing index of votingRoom. Therefore, it is enough to check from proposal.length up to first element which endAt < block.timestamp

• listVotersForProposal(uint256 proposalId) Returns a list of voters for a given proposal. Reverts if there are no proposal for the given proposalId.

• initializeProposal(string calldata title, string calldata description, uint256 creatorVoteForAmount) Creates a new proposal with the vote of the proposal creator. First checks if the creator voter has enough tokens to set vote for. Then creates a new proposal. startBlock is set as current block number. endAt is set a current block timestamp plus votingDuration. title is set as argument title. description is set as argument description. creatorVoteForAmount is set as argument voteAmount. Mapping voted of new proposal id of msg.sender is set to true to reflect that message sender has voted on this voting room with creatorVoteForAmount. votingRooms are appended with newVotingRoom and voters in this new appended element are appended with message sender. After proposal creation, ProposalStarted is emitted.

• verify(Vote calldata vote, bytes32 r, bytes32 vs) Function used to verify that vote was signed by vote.voter as per EIP712 specification. See docs for more info.

• castVote(Vote calldata vote, uint256 proposalId) Cast a single vote. Updates totalVotes amount of proposal with index corresponding to proposalId.

  If voting first bit of vote.proposalIdAndType is 1 that means that vote is for and vote.tokenAmount is added to votingRooms[roomId].totalVotesFor, otherwise if vote.proposalIdAndType is 0 vote.tokenAmount is added to votingRooms[roomId].totalVotesAgainst.

  After that add new address to room voters and updates mapping voted accordingly.

• castVotes(Vote[] calldata votes) Function used to cast votes on a single proposas. Function accepts an array of votes of type Vote.

  All votes are looped through and verified that votes are:

  • properly signed
  • voter has enough tokens to vote
  • proposal exists
  • proposal hasn't been closed

  Vote verification is as follows:

  First proposalId is decoded from vote.proposalIdAndType which means shifting it to the right once.

  Then it is verified that the proposal with given proposalId exists and isn't closed, otherwise, function reverts.

  Then it is checked that vote.voter didn't vote in this vote room before if he did function goes to another voter (IDEA: emit alreadyVoted ?).

  After that it is verified that vote has been signed by vote.voter.

  Last check is whether vote.voter has enough tokens to vote.

  If all checks passed, the vote is cast with castVote and VoteCast is emitted.