feat: Disputes

[abarmat]

This PR implements Disputes on a different contract that interacts with the Staking contract.

Spec:
https://www.notion.so/thegraph/Disputes-51960724e8464c119ce4b249c7c1f425

Tasks:

• add disregard dispute
• remove bool return types for some methods
• add all require error texts
• set the staking contract relationship from this contract
• reorganize function and vars according to solidity style guide
• add a function to slash on the staking contract
• have the possiblity to have many slashers for the staking contract
• have the domain hash eip-712 calculated in the constructor
• replace indexing node with indexNode
• move parse of attestation out of the createDispute function
• add zeppelin math lib
• review how the attestation is built and the signatures
• add lint for JS tests
• rewrite tests
  x dispute deposit below what is required
  x two exactly equal disputes should be rejected
  x reject dispute
  x ignore dispute
  x accept dispute
  x dispute manager not allowed to slash

• update specs with latest interface
• reject token transfers to this contract without proper _data format
• review all natspec
• can we use chain.id?
• support for conflicting attestations

[davekay100]

Mostly just small changes, but I was unable to get the tests running. I was getting this error:

Error: web3@1.2.1 detected, incompatible with requirement of web3@1.0.0-beta.37

Any ideas how to get past it?

[abarmat]

I'm pushing some fixes based on the review. I fixed web3 problems by bumping version of openzeppelin/test-helpers library and others.

[davekay100]

The updates look good, I approve, but I see you still have a few unchecked boxes. Up to you if you want to include these in this PR, or we just merge this and go forward

[Zerim]

Is this right? This doesn't quite match up with how I interpret the spec here: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md#definition-of-hashstruct

hashStruct(s : 𝕊) = keccak256(typeHash ‖ encodeData(s)) where typeHash = keccak256(encodeType(typeOf(s)))

[abarmat]

The function that is performing that is this one:

function createAttestationHash(attestation) {
  const attestationTypeHash = web3.utils.sha3(
    'Attestation(IpfsHash requestCID,IpfsHash responseCID,uint256 gasUsed,uint256 responseNumBytes)IpfsHash(bytes32 hash,uint16 hashFunction)',
  )

  // ABI encoded
  return web3.utils.sha3(
    web3.eth.abi.encodeParameters(
      ['bytes32', 'bytes'],
      [attestationTypeHash, attestation],
    ),
  )
}

[Zerim]

Got it, thanks for clarifying 👍