- Added permit() to aToken.

buidler.config.ts

@@ -2,13 +2,13 @@ import {usePlugin, BuidlerConfig} from '@nomiclabs/buidler/config';
 // @ts-ignore
 import {accounts} from './test-wallets.js';
 import {eEthereumNetwork} from './helpers/types';
+import { BUIDLEREVM_CHAINID, COVERAGE_CHAINID } from './helpers/constants';
 
 usePlugin('@nomiclabs/buidler-ethers');
 usePlugin('buidler-typechain');
 usePlugin('solidity-coverage');
 usePlugin('@nomiclabs/buidler-waffle');
 usePlugin('@nomiclabs/buidler-etherscan');
-usePlugin('buidler-gas-reporter');
 
 const DEFAULT_BLOCK_GAS_LIMIT = 10000000;
 const DEFAULT_GAS_PRICE = 10;
@@ -59,6 +59,7 @@ const config: any = {
   networks: {
     coverage: {
       url: 'http://localhost:8555',
+      chainId: COVERAGE_CHAINID,
     },
     kovan: getCommonNetworkConfig(eEthereumNetwork.kovan, 42),
     ropsten: getCommonNetworkConfig(eEthereumNetwork.ropsten, 3),
@@ -68,7 +69,7 @@ const config: any = {
       blockGasLimit: DEFAULT_BLOCK_GAS_LIMIT,
       gas: DEFAULT_BLOCK_GAS_LIMIT,
       gasPrice: 8000000000,
-      chainId: 31337,
+      chainId: BUIDLEREVM_CHAINID,
       throwOnTransactionFailures: true,
       throwOnCallFailures: true,
       accounts: accounts.map(({secretKey, balance}: {secretKey: string; balance: string}) => ({

contracts/tokenization/AToken.sol

@@ -29,9 +29,16 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
 
   mapping(address => uint256) private _scaledRedirectedBalances;
 
+  /// @dev owner => next valid nonce to submit with permit()
+  mapping (address => uint256) public _nonces;
 
   uint256 public constant ATOKEN_REVISION = 0x1;
   
+  bytes32 public DOMAIN_SEPARATOR;
+  bytes public constant EIP712_REVISION = bytes("1");
+  bytes32 internal constant EIP712_DOMAIN = keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
+  bytes32 public constant PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
+
   modifier onlyLendingPool {
     require(msg.sender == address(POOL), Errors.CALLER_MUST_BE_LENDING_POOL);
     _;
@@ -56,6 +63,21 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     string calldata tokenName,
     string calldata tokenSymbol
   ) external virtual initializer {
+    uint256 chainId;
+
+    //solium-disable-next-line
+    assembly {
+        chainId := chainid()
+    }
+    
+    DOMAIN_SEPARATOR = keccak256(abi.encode(
+        EIP712_DOMAIN,
+        keccak256(bytes(tokenName)),
+        keccak256(EIP712_REVISION),
+        chainId,
+        address(this)
+    ));
+
     _setName(tokenName);
     _setSymbol(tokenSymbol);
     _setDecimals(underlyingAssetDecimals);
@@ -187,6 +209,42 @@ contract AToken is VersionedInitializable, ERC20, IAToken {
     return amount;
   }
 
+  /**
+  * @dev implements the permit function as for https://github.com/ethereum/EIPs/blob/8a34d644aacf0f9f8f00815307fd7dd5da07655f/EIPS/eip-2612.md
+  * @param owner the owner of the funds
+  * @param spender the spender
+  * @param value the amount
+  * @param deadline the deadline timestamp, 0 for no deadline
+  * @param v signature param
+  * @param s signature param
+  * @param r signature param
+  */
+  function permit(
+      address owner,
+      address spender,
+      uint256 value,
+      uint256 deadline,
+      uint8 v,
+      bytes32 r,
+      bytes32 s
+  ) external {
+      require(owner != address(0), "INVALID_OWNER");
+      //solium-disable-next-line
+      require(block.timestamp <= deadline, "INVALID_EXPIRATION");
+      uint256 currentValidNonce = _nonces[owner];
+      bytes32 digest = keccak256(
+              abi.encodePacked(
+                  "\x19\x01",
+                  DOMAIN_SEPARATOR,
+                  keccak256(
+                      abi.encode(PERMIT_TYPEHASH, owner, spender, value, currentValidNonce, deadline))
+                  )
+      );
+      require(owner == ecrecover(digest, v, r, s), "INVALID_SIGNATURE");
+      _nonces[owner] = currentValidNonce.add(1);
+      _approve(owner, spender, value);
+  }
+
   function _transfer(
     address from,
     address to,

helpers/constants.ts

@@ -8,12 +8,16 @@ import {
   IReserveParams,
   tEthereumAddress,
   iBasicDistributionParams,
+  eEthereumNetwork,
 } from './types';
 import BigNumber from 'bignumber.js';
-import {getParamPerPool} from './contracts-helpers';
+import {getParamPerPool, getParamPerNetwork} from './contracts-helpers';
 
 export const TEST_SNAPSHOT_ID = '0x1';
 
+export const BUIDLEREVM_CHAINID = 31337;
+export const COVERAGE_CHAINID = 1337;
+
 // ----------------
 // MATH
 // ----------------
@@ -531,3 +535,18 @@ export const getFeeDistributionParamsCommon = (
     percentages,
   };
 };
+
+export const getATokenDomainSeparatorPerNetwork = (
+  network: eEthereumNetwork
+): tEthereumAddress =>
+  getParamPerNetwork<tEthereumAddress>(
+    {
+      [eEthereumNetwork.coverage]: "0x95b73a72c6ecf4ccbbba5178800023260bad8e75cdccdb8e4827a2977a37c820",
+      [eEthereumNetwork.buidlerevm]:
+        "0x76cbbf8aa4b11a7c207dd79ccf8c394f59475301598c9a083f8258b4fafcfa86",
+      [eEthereumNetwork.kovan]: "",
+      [eEthereumNetwork.ropsten]: "",
+      [eEthereumNetwork.main]: "",
+    },
+    network
+  );

helpers/contracts-helpers.ts

@@ -32,6 +32,8 @@ import {Ierc20Detailed} from '../types/Ierc20Detailed';
 import {StableDebtToken} from '../types/StableDebtToken';
 import {VariableDebtToken} from '../types/VariableDebtToken';
 import {MockSwapAdapter} from '../types/MockSwapAdapter';
+import { signTypedData_v4, TypedData } from "eth-sig-util";
+import { fromRpcSig, ECDSASignature } from "ethereumjs-util";
 
 export const registerContractInJsonDb = async (contractId: string, contractInstance: Contract) => {
   const currentNetwork = BRE.network.name;
@@ -431,10 +433,14 @@ const linkBytecode = (artifact: Artifact, libraries: any) => {
 };
 
 export const getParamPerNetwork = <T>(
-  {kovan, ropsten, main}: iParamsPerNetwork<T>,
+  {kovan, ropsten, main, buidlerevm, coverage}: iParamsPerNetwork<T>,
   network: eEthereumNetwork
 ) => {
   switch (network) {
+    case eEthereumNetwork.coverage:
+      return coverage;
+    case eEthereumNetwork.buidlerevm:
+      return buidlerevm;
     case eEthereumNetwork.kovan:
       return kovan;
     case eEthereumNetwork.ropsten:
@@ -471,3 +477,59 @@ export const convertToCurrencyUnits = async (tokenAddress: string, amount: strin
   const amountInCurrencyUnits = new BigNumber(amount).div(currencyUnit);
   return amountInCurrencyUnits.toFixed();
 };
+
+export const buildPermitParams = (
+  chainId: number,
+  token: tEthereumAddress,
+  revision: string,
+  tokenName: string,
+  owner: tEthereumAddress,
+  spender: tEthereumAddress,
+  nonce: number,
+  deadline: string,
+  value: tStringTokenSmallUnits
+) => ({
+  types: {
+    EIP712Domain: [
+      { name: "name", type: "string" },
+      { name: "version", type: "string" },
+      { name: "chainId", type: "uint256" },
+      { name: "verifyingContract", type: "address" },
+    ],
+    Permit: [
+      { name: "owner", type: "address" },
+      { name: "spender", type: "address" },
+      { name: "value", type: "uint256" },
+      { name: "nonce", type: "uint256" },
+      { name: "deadline", type: "uint256" },
+    ],
+  },
+  primaryType: "Permit" as const,
+  domain: {
+    name: tokenName,
+    version: revision,
+    chainId: chainId,
+    verifyingContract: token,
+  },
+  message: {
+    owner,
+    spender,
+    value,
+    nonce,
+    deadline,
+  },
+});
+
+
+export const getSignatureFromTypedData = (
+  privateKey: string,
+  typedData: any // TODO: should be TypedData, from eth-sig-utils, but TS doesn't accept it
+): ECDSASignature => {
+  const signature = signTypedData_v4(
+    Buffer.from(privateKey.substring(2, 66), "hex"),
+    {
+      data: typedData,
+    }
+  );
+  return fromRpcSig(signature);
+};

helpers/types.ts

@@ -5,6 +5,7 @@ export enum eEthereumNetwork {
   kovan = 'kovan',
   ropsten = 'ropsten',
   main = 'main',
+  coverage = 'coverage'
 }
 
 export enum AavePools {
@@ -251,6 +252,8 @@ export interface IMarketRates {
 }
 
 export interface iParamsPerNetwork<T> {
+  [eEthereumNetwork.coverage]: T;
+  [eEthereumNetwork.buidlerevm]: T;
   [eEthereumNetwork.kovan]: T;
   [eEthereumNetwork.ropsten]: T;
   [eEthereumNetwork.main]: T;

package.json

@@ -16,6 +16,7 @@
     "test-repay-with-collateral": "buidler test test/__setup.spec.ts test/repay-with-collateral.spec.ts",
     "test-liquidate-with-collateral": "buidler test test/__setup.spec.ts test/flash-liquidation-with-collateral.spec.ts",
     "test-flash": "buidler test test/__setup.spec.ts test/flashloan.spec.ts",
+    "test-permit": "buidler test test/__setup.spec.ts test/atoken-permit.spec.ts",
     "dev:coverage": "buidler coverage --network coverage",
     "dev:deployment": "buidler dev-deployment",
     "dev:deployExample": "buidler deploy-Example",
@@ -58,7 +59,9 @@
     "tslint-config-prettier": "^1.18.0",
     "tslint-plugin-prettier": "^2.3.0",
     "typechain": "2.0.0",
-    "typescript": "3.9.3"
+    "typescript": "3.9.3",
+    "eth-sig-util": "2.5.3",
+    "ethereumjs-util": "7.0.2"
   },
   "husky": {
     "hooks": {

test/atoken-permit.spec.ts

@@ -0,0 +1,312 @@
+import {
+  MAX_UINT_AMOUNT,
+  ZERO_ADDRESS,
+  getATokenDomainSeparatorPerNetwork,
+  BUIDLEREVM_CHAINID,
+} from '../helpers/constants';
+import {buildPermitParams, getSignatureFromTypedData} from '../helpers/contracts-helpers';
+import {expect} from 'chai';
+import {ethers} from 'ethers';
+import {eEthereumNetwork} from '../helpers/types';
+import {makeSuite, TestEnv} from './helpers/make-suite';
+import {BRE} from '../helpers/misc-utils';
+import {waitForTx} from './__setup.spec';
+
+const {parseEther} = ethers.utils;
+
+makeSuite('AToken: Permit', (testEnv: TestEnv) => {
+  it('Checks the domain separator', async () => {
+    const DOMAIN_SEPARATOR_ENCODED = getATokenDomainSeparatorPerNetwork(
+      eEthereumNetwork.buidlerevm
+    );
+
+    const {aDai} = testEnv;
+
+    const separator = await aDai.DOMAIN_SEPARATOR();
+
+    expect(separator).to.be.equal(DOMAIN_SEPARATOR_ENCODED, 'Invalid domain separator');
+  });
+
+  it('Get aDAI for tests', async () => {
+    const {dai, deployer, pool} = testEnv;
+
+    await dai.mint(parseEther('20000'));
+    await dai.approve(pool.address, parseEther('20000'));
+    await pool.deposit(dai.address, parseEther('20000'), deployer.address, 0);
+  });
+
+  it('Reverts submitting a permit with 0 expiration', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const tokenName = await aDai.name();
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const expiration = 0;
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = ethers.utils.parseEther('2').toString();
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      tokenName,
+      owner.address,
+      spender.address,
+      nonce,
+      permitAmount,
+      expiration.toFixed()
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    expect((await aDai.allowance(owner.address, spender.address)).toString()).to.be.equal(
+      '0',
+      'INVALID_ALLOWANCE_BEFORE_PERMIT'
+    );
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await expect(
+      aDai
+        .connect(spender.signer)
+        .permit(owner.address, spender.address, permitAmount, expiration, v, r, s)
+    ).to.be.revertedWith('INVALID_EXPIRATION');
+
+    expect((await aDai.allowance(owner.address, spender.address)).toString()).to.be.equal(
+      '0',
+      'INVALID_ALLOWANCE_AFTER_PERMIT'
+    );
+  });
+
+  it('Submits a permit with maximum expiration length', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const deadline = MAX_UINT_AMOUNT;
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = parseEther('2').toString();
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      deadline,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    expect((await aDai.allowance(owner.address, spender.address)).toString()).to.be.equal(
+      '0',
+      'INVALID_ALLOWANCE_BEFORE_PERMIT'
+    );
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await waitForTx(
+      await aDai
+        .connect(spender.signer)
+        .permit(owner.address, spender.address, permitAmount, deadline, v, r, s)
+    );
+
+    expect((await aDai._nonces(owner.address)).toNumber()).to.be.equal(1);
+  });
+
+  it('Cancels the previous permit', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const deadline = MAX_UINT_AMOUNT;
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = '0';
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      deadline,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    expect((await aDai.allowance(owner.address, spender.address)).toString()).to.be.equal(
+      ethers.utils.parseEther('2'),
+      'INVALID_ALLOWANCE_BEFORE_PERMIT'
+    );
+
+    await waitForTx(
+      await aDai
+        .connect(spender.signer)
+        .permit(owner.address, spender.address, permitAmount, deadline, v, r, s)
+    );
+    expect((await aDai.allowance(owner.address, spender.address)).toString()).to.be.equal(
+      permitAmount,
+      'INVALID_ALLOWANCE_AFTER_PERMIT'
+    );
+
+    expect((await aDai._nonces(owner.address)).toNumber()).to.be.equal(2);
+  });
+
+  it('Tries to submit a permit with invalid nonce', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const deadline = MAX_UINT_AMOUNT;
+    const nonce = 1000;
+    const permitAmount = '0';
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      deadline,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await expect(
+      aDai
+        .connect(spender.signer)
+        .permit(owner.address, spender.address, permitAmount, deadline, v, r, s)
+    ).to.be.revertedWith('INVALID_SIGNATURE');
+  });
+
+  it('Tries to submit a permit with invalid expiration (previous to the current block)', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const expiration = '1';
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = '0';
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      expiration,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await expect(
+      aDai
+        .connect(spender.signer)
+        .permit(owner.address, spender.address, expiration, permitAmount, v, r, s)
+    ).to.be.revertedWith('INVALID_EXPIRATION');
+  });
+
+  it('Tries to submit a permit with invalid signature', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const deadline = MAX_UINT_AMOUNT;
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = '0';
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      deadline,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await expect(
+      aDai
+        .connect(spender.signer)
+        .permit(owner.address, ZERO_ADDRESS, permitAmount, deadline, v, r, s)
+    ).to.be.revertedWith('INVALID_SIGNATURE');
+  });
+
+  it('Tries to submit a permit with invalid owner', async () => {
+    const {aDai, deployer, users} = testEnv;
+    const owner = deployer;
+    const spender = users[1];
+
+    const chainId = BRE.network.config.chainId || BUIDLEREVM_CHAINID;
+    const expiration = MAX_UINT_AMOUNT;
+    const nonce = (await aDai._nonces(owner.address)).toNumber();
+    const permitAmount = '0';
+    const msgParams = buildPermitParams(
+      chainId,
+      aDai.address,
+      '1',
+      await aDai.name(),
+      owner.address,
+      spender.address,
+      nonce,
+      expiration,
+      permitAmount
+    );
+
+    const ownerPrivateKey = require('../test-wallets.js').accounts[0].secretKey;
+    if (!ownerPrivateKey) {
+      throw new Error('INVALID_OWNER_PK');
+    }
+
+    const {v, r, s} = getSignatureFromTypedData(ownerPrivateKey, msgParams);
+
+    await expect(
+      aDai
+        .connect(spender.signer)
+        .permit(ZERO_ADDRESS, spender.address, expiration, permitAmount, v, r, s)
+    ).to.be.revertedWith('INVALID_OWNER');
+  });
+});