feat: supports EIP-712 and EIP-1271 signatures to claim airdrop

[smol-ninja]

Sorry for the massive PR @andreivladbrg. It was very complicated than I thought, both writing source code and then testing it. Now its ready for your review. I will recommend to read the PR description first.

This should be merged after the following PR:

• feat: creates user with private key and adds ERC-1271 wallet mock evm-utils#31

---

Changelog

Source code

• Closes Claim to third-party address using signatures (EIP-712 and EIP-1272) #95
• Adds missing view to read only functions
• Adds SignatureHash library to keep signature hashes. This is a better approach as it keeps the campaign related constants separate from the signature related constants.

Tests

• Generates users.recipient using createUserAndKey function as we need private key to create signatures.
• DRY'ifies some sections in Base test contract and Integration base contract
• Adds getIndexInMerkleTree and getMerkleProof functions replacing hardcoded use of INDEX1 and index1Proof to avoid manual errors
• I only added important tests for claimViaSig and ignored what is already being thoroughly tested through claim and claimTo. This is also why I didn't write fuzz tests for it.
• Refactors users type. See Types.sol for details.

Some notes

• Foundry currently does not support EIP-712 hashing (refer to Cheatcode: EIP712 canonical hashing foundry-rs/foundry#4818), so its only possible to generate off-chain. I thought of writing TS code to do it but then since that foundry PR is going to get merged soon, we can do hash verification using Foundry cheatcode itself.
• tests/utils/Utilities.sol contain signature utilities but note that it uses solidity whereas the correct approach is to use eth_signTypedData_v4 so its not being tested. I will wait for foundry to release the new cheatcode for that. Nevertheless, using approach below, I have verified that signature are correctly generated.

To generate EIP-712 signature, run the following in your browser:

Load your address:

const address = (await ethereum.request({ method: 'eth_requestAccounts' }))[0];

Define "TypedData":

const typedData = {
  types: {
    EIP712Domain: [
      { name: "name", type: "string" },
      { name: "chainId", type: "uint256" },
      { name: "verifyingContract", type: "address" },
    ],
    Claim: [
      { name: "index", type: "uint256" },
      { name: "recipient", type: "address" },
      { name: "to", type: "address" },
      { name: "amount", type: "uint128" },
    ],
  },
  domain: {
    name: "Sablier Airdrops Protocol",
    chainId: 1, // Chain on which the contract is deployed
    verifyingContract: "0x03cdcCF81765783bE8c15886d0931C816c3A6BC7", // The address of the campaign
  },
  primaryType: "Claim",
  message: {
    index: 2, // The index of the signer in the Merkle tree
    recipient: "0x39EF0Bbb69b81a9EB148530946E94C69012a29C2", // The address of the airdrop recipient
    to: "0xEAF39695973254D21c8956037c0BAf5FdDA92eC6", // The address where recipient wants to transfer the tokens
    amount: "1000000000000000000000" // The amount of tokens allocated to the recipient
  },
}

Call "eth_signTypedData_v4":

ethereum.request({
  method: "eth_signTypedData_v4",
  params: [
    address,
    JSON.stringify(typedData)
  ]
})
.then(signature => {
  console.log("Signature:", signature);
})
.catch(err => {
  console.error(err);
});

It will then show you something like this:

Once you sign it, it will then display the signature in the console.

Some reference:

• chore(forge): cheat eip712 struct hash foundry-rs/foundry#10626
• feat(forge): cheatcode eip712 foundry-rs/foundry#10570
• feat(forge): eip712 cheatcodes + forge cmd (eip712 + bind-json) with solar foundry-rs/foundry#10510