tornado-contracts/scripts/testPermitTornado.ts

import path from 'path';
import { readFile } from 'fs/promises';

import { ethers } from 'hardhat';
import {
  BaseContract,
  formatEther,
  MaxUint256,
  parseEther,
  Provider,
  Signature,
  Signer,
  solidityPackedKeccak256,
  TypedDataEncoder,
  TypedDataField,
} from 'ethers';

import * as constants from './constants';
import {
  ERC20,
  ERC20Mock,
  ERC20Mock__factory,
  Permit2Mock__factory,
} from '../typechain-types';

const { permit2Address } = constants;

/**
 * Deploy Deterministic Deployment Proxy and Permit2
 * 
 * https://github.com/Arachnid/deterministic-deployment-proxy
 * https://github.com/Uniswap/permit2
 */
async function deployPermit2() {
  const [owner] = await ethers.getSigners();

  const { provider } = owner;

  const { deterministicProxy, deterministicSigner, deterministicSignerCost } = constants;

  const deterministicSignedTx = await readFile(path.join(__dirname, './deterministicTx.txt'), { encoding: 'utf-8' });

  // Send deployment cost for deterministicProxyDeploy contract
  (await owner.sendTransaction({ to: deterministicSigner, value: parseEther(deterministicSignerCost) })).wait();

  (await provider.broadcastTransaction(deterministicSignedTx)).wait();

  console.log(`Deterministic Deployment Proxy code: ${await provider.getCode(deterministicProxy)}`);

  // Send Permit2 tx
  const data = await readFile(path.join(__dirname, './permit2tx.txt'), { encoding: 'utf-8' });

  (await owner.sendTransaction({ to: deterministicProxy, data })).wait();

  const permit2code = await provider.getCode(permit2Address);

  console.log(`Permit2 code: ${permit2code ? permit2code.slice(0, 20) : ''}`);
}

interface PermitValue {
    spender: string;
    value: bigint;
    nonce?: bigint;
    deadline?: bigint;
}

async function getPermitSignature(Token: ERC20 | ERC20Mock, { spender, value, nonce, deadline }: PermitValue) {
  const signer = Token.runner as (Signer & { address: string });
  const provider = signer.provider as Provider;

  const [name, { chainId }] = await Promise.all([
    Token.name(),
    provider.getNetwork(),
  ]);

  const DOMAIN_SEPARATOR = {
    name,
    version: '1',
    chainId,
    verifyingContract: Token.target as string,
  };

  const PERMIT_TYPE = {
    Permit: [
      { name: 'owner', type: 'address' },
      { name: 'spender', type: 'address' },
      { name: 'value', type: 'uint256' },
      { name: 'nonce', type: 'uint256' },
      { name: 'deadline', type: 'uint256' },
    ],
  };

  return Signature.from(await signer.signTypedData(DOMAIN_SEPARATOR, PERMIT_TYPE, {
    owner: signer.address,
    spender,
    value,
    nonce,
    deadline: deadline || MaxUint256,
  }));
}

/**
 * From @uniswap/permit2-sdk ported for ethers.js v6
 */
interface Witness {
    witnessTypeName: string;
    witnessType: {
        [key: string]: TypedDataField[]
    },
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    witness: any;
}

function bytesToHex(bytes: Uint8Array) {
  return (
    '0x' +
      Array.from(bytes)
        .map((b) => b.toString(16).padStart(2, '0'))
        .join('')
  );
}

function bytesToBN(bytes: Uint8Array) {
  return BigInt(bytesToHex(bytes));
}

function rBigInt(nbytes: number = 31) {
  return bytesToBN(crypto.getRandomValues(new Uint8Array(nbytes)));
}

function rHex(nbytes: number = 31) {
  return bytesToHex(crypto.getRandomValues(new Uint8Array(nbytes)));
}

async function getPermit2Signature(
  Token: BaseContract,
  { spender, value: amount, nonce, deadline }: PermitValue,
  witness?: Witness
) {
  const signer = Token.runner as (Signer & { address: string });
  const provider = signer.provider as Provider;

  const domain = {
    name: 'Permit2',
    chainId: (await provider.getNetwork()).chainId,
    verifyingContract: permit2Address,
  };

  const types: {
        [key: string]: TypedDataField[]
    } = !witness
      ? {
        PermitTransferFrom: [
          { name: 'permitted', type: 'TokenPermissions' },
          { name: 'spender', type: 'address' },
          { name: 'nonce', type: 'uint256' },
          { name: 'deadline', type: 'uint256' },
        ],
        TokenPermissions: [
          { name: 'token', type: 'address' },
          { name: 'amount', type: 'uint256' },
        ],
      }
      : {
        PermitWitnessTransferFrom: [
          { name: 'permitted', type: 'TokenPermissions' },
          { name: 'spender', type: 'address' },
          { name: 'nonce', type: 'uint256' },
          { name: 'deadline', type: 'uint256' },
          { name: 'witness', type: witness.witnessTypeName },
        ],
        TokenPermissions: [
          { name: 'token', type: 'address' },
          { name: 'amount', type: 'uint256' },
        ],
        ...witness.witnessType,
      };

  const values: {
        permitted: {
            token: string;
            amount: bigint;
        };
        spender: string;
        nonce: bigint;
        deadline: bigint;
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        witness?: any;
    } = {
      permitted: {
        token: Token.target as string,
        amount,
      },
      spender,
      // Sorted nonce are not required for Permit2
      nonce: nonce || rBigInt(16),
      deadline: deadline || MaxUint256,
    };

  if (witness) {
    values.witness = witness.witness;
  }

  const hash = new TypedDataEncoder(types).hash(values);

  const signature = Signature.from(await signer.signTypedData(domain, types, values));

  return {
    domain,
    types,
    values,
    hash,
    signature,
  };
}

async function test() {
  await deployPermit2();

  const [owner, user] = await ethers.getSigners();

  const DAI = await new ERC20Mock__factory(owner).deploy();

  (await DAI.mint(owner.address, parseEther('1000000'))).wait();

  // Test Permit
  const { v, r, s } = await getPermitSignature(DAI, {
    spender: user.address,
    value: parseEther('1'),
    nonce: 0n,
  });
    
  (await DAI.permit(owner.address, user.address, parseEther('1'), MaxUint256, v, r, s)).wait();

  (await DAI.connect(user).transferFrom(owner.address, user.address, parseEther('1'))).wait();

  console.log(`User balance: ${formatEther(await DAI.balanceOf(user.address))}`);

  // Test Permit2
  {
    const Permit2Mock = await new Permit2Mock__factory(owner).deploy(parseEther('1'), DAI.target);

    const {
      values: {
        nonce,
        deadline,
      },
      signature: {
        serialized,
      },
    } = await getPermit2Signature(DAI, {
      spender: Permit2Mock.target as string,
      value: parseEther('1'),
    });

    // Should approve Permit2 first
    (await DAI.approve(permit2Address, MaxUint256)).wait();

    (await Permit2Mock.permit2Test(owner.address, nonce, deadline, serialized)).wait();

    console.log(`Permit2Mock balance: ${formatEther(await DAI.balanceOf(Permit2Mock.target))}`);
  }

  {
    const Permit2Mock = await new Permit2Mock__factory(owner).deploy(parseEther('1'), DAI.target);

    const commitments = [
      rHex(32),
      rHex(32),
    ];

    const commitmentsHash = solidityPackedKeccak256(['bytes32[]'], [commitments]);

    const {
      values: {
        nonce,
        deadline,
      },
      signature: {
        serialized,
      },
    } = await getPermit2Signature(
      DAI,
      {
        spender: Permit2Mock.target as string,
        value: BigInt(commitments.length) * parseEther('1'),
      },
      {
        witnessTypeName: 'PermitCommitments',
        witnessType: {
          PermitCommitments: [
            { name: 'instance', type: 'address' },
            { name: 'commitmentsHash', type: 'bytes32' },
          ]
        },
        witness: {
          instance: Permit2Mock.target,
          commitmentsHash,
        }
      }
    );

    // Should approve Permit2 first
    (await DAI.approve(permit2Address, MaxUint256)).wait();

    (await Permit2Mock.permit2Commitments(owner.address, commitments, nonce, deadline, serialized)).wait();

    console.log(`Permit2Mock balance: ${formatEther(await DAI.balanceOf(Permit2Mock.target))}`);

    console.log(owner.address);

    console.log(await Permit2Mock.verifiedCommitments(commitments[0]));

    console.log(await Permit2Mock.verifiedCommitments(commitments[1]));
  }
}

test();