Merge upstream openzeppelin-contracts into upstream-patched

CHANGELOG.md

@@ -6,6 +6,8 @@
  * `ERC777`: make reception acquirement optional in `_mint`. ([#2552](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2552))
  * `ERC20Permit`: add a `_useNonce` to enable further usage of ERC712 signatures. ([#2565](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2565))
  * `ERC20FlashMint`: add an implementation of the ERC3156 extension for flash-minting ERC20 tokens. ([#2543](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2543))
+ * `SignatureChecker`: add a signature verification library that supports both EOA and ERC1271 compliant contracts as signers. ([#2532](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2532))
+ * `Multicall`: add abstract contract with `multicall(bytes[] calldata data)` function to bundle multiple calls together ([#2608](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2608))
 
 ## 4.0.0 (2021-03-23)
 

contracts/interfaces/IERC1271.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+/**
+ * @dev Interface of the ERC1271 standard signature validation method for
+ * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
+ */
+interface IERC1271 {
+  /**
+   * @dev Should return whether the signature provided is valid for the provided data
+   * @param hash      Hash of the data to be signed
+   * @param signature Signature byte array associated with _data
+   */
+  function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);
+}

contracts/mocks/ERC1271WalletMock.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../access/Ownable.sol";
+import "../interfaces/IERC1271.sol";
+import "../utils/cryptography/ECDSA.sol";
+
+contract ERC1271WalletMock is Ownable, IERC1271 {
+    constructor(address originalOwner) {
+        transferOwnership(originalOwner);
+    }
+
+    function isValidSignature(bytes32 hash, bytes memory signature) public view override returns (bytes4 magicValue) {
+        return ECDSA.recover(hash, signature) == owner() ? this.isValidSignature.selector : bytes4(0);
+    }
+}

contracts/mocks/MulticallTest.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./MulticallTokenMock.sol";
+
+contract MulticallTest {
+    function testReturnValues(MulticallTokenMock multicallToken, address[] calldata recipients, uint256[] calldata amounts) external {
+        bytes[] memory calls = new bytes[](recipients.length);
+        for (uint i = 0; i < recipients.length; i++) {
+            calls[i] = abi.encodeWithSignature("transfer(address,uint256)", recipients[i], amounts[i]);
+        }
+
+        bytes[] memory results = multicallToken.multicall(calls);
+        for (uint i = 0; i < results.length; i++) {
+            require(abi.decode(results[i], (bool)));
+        }
+    }
+}

contracts/mocks/MulticallTokenMock.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../utils/Multicall.sol";
+import "./ERC20Mock.sol";
+
+contract MulticallTokenMock is ERC20Mock, Multicall {
+    constructor (uint256 initialBalance) ERC20Mock("MulticallToken", "BCT", msg.sender, initialBalance) {}
+}

contracts/mocks/SignatureCheckerMock.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "../utils/cryptography/SignatureChecker.sol";
+
+contract SignatureCheckerMock {
+    using SignatureChecker for address;
+
+    function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature) public view returns (bool) {
+        return signer.isValidSignatureNow(hash, signature);
+    }
+}

contracts/utils/Multicall.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./Address.sol";
+
+/**
+ * @dev Provides a function to batch together multiple calls in a single external call.
+ */
+abstract contract Multicall {
+    /**
+    * @dev Receives and executes a batch of function calls on this contract.
+    */
+    function multicall(bytes[] calldata data) external returns (bytes[] memory results) {
+        results = new bytes[](data.length);
+        for (uint i = 0; i < data.length; i++) {
+            results[i] = Address.functionDelegateCall(address(this), data[i]);
+        }
+        return results;
+    }
+}

contracts/utils/README.adoc

@@ -6,6 +6,7 @@ NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/
 Miscellaneous contracts and libraries containing utility functions you can use to improve security, work with new data types, or safely use low-level primitives.
 
 The {Address}, {Arrays} and {Strings} libraries provide more operations related to these native data types, while {SafeCast} adds ways to safely convert between the different signed and unsigned numeric types.
+{Multicall} provides a function to batch together multiple calls in a single external call.
 
 For new data types:
 
@@ -36,6 +37,8 @@ Finally, {Create2} contains all necessary utilities to safely use the https://bl
 
 {{ECDSA}}
 
+{{SignatureChecker}}
+
 {{MerkleProof}}
 
 {{EIP712}}
@@ -92,3 +95,5 @@ Note that, in all cases, accounts simply _declare_ their interfaces, but they ar
 {{Counters}}
 
 {{Strings}}
+
+{{Multicall}}

contracts/utils/cryptography/SignatureChecker.sol

+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./ECDSA.sol";
+import "../Address.sol";
+import "../../interfaces/IERC1271.sol";
+
+/**
+ * @dev Signature verification helper: Provide a single mechanism to verify both private-key (EOA) ECDSA signature and
+ * ERC1271 contract sigantures. Using this instead of ECDSA.recover in your contract will make them compatible with
+ * smart contract wallets such as Argent and Gnosis.
+ *
+ * Note: unlike ECDSA signatures, contract signature's are revocable, and the outcome of this function can thus change
+ * through time. It could return true at block N and false at block N+1 (or the opposite).
+ */
+library SignatureChecker {
+    function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature) internal view returns (bool) {
+        if (Address.isContract(signer)) {
+            try IERC1271(signer).isValidSignature(hash, signature) returns (bytes4 magicValue) {
+                return magicValue == IERC1271(signer).isValidSignature.selector;
+            } catch {
+                return false;
+            }
+        } else {
+            return ECDSA.recover(hash, signature) == signer;
+        }
+    }
+}

docs/modules/ROOT/pages/utilities.adoc

@@ -99,3 +99,41 @@ Want to check if an address is a contract? Use xref:api:utils.adoc#Address[`Addr
 
 Want to keep track of some numbers that increment by 1 every time you want another one? Check out xref:api:utils.adoc#Counters[`Counters`]. This is useful for lots of things, like creating incremental identifiers, as shown on the xref:erc721.adoc[ERC721 guide].
 
+=== Multicall
+
+The `Multicall` abstract contract comes with a `multicall` function that bundles together multiple calls in a single external call. With it, external accounts may perform atomic operations comprising several function calls. This is not only useful for EOAs to make multiple calls in a single transaction, it's also a way to revert a previous call if a later one fails.
+
+Consider this dummy contract:
+
+[source,solidity]
+----
+// contracts/Box.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/utils/Multicall.sol";
+
+contract Box is Multicall {
+    function foo() public {
+        ...
+    }
+
+    function bar() public {
+        ...
+    }
+}
+----
+
+This is how to call the `multicall` function using Truffle, allowing `foo` and `bar` to be called in a single transaction:
+[source,javascript]
+----
+// scripts/foobar.js
+
+const Box = artifacts.require('Box');
+const instance = await Box.new();
+
+await instance.multicall([
+    instance.contract.methods.foo().encodeABI(),
+    instance.contract.methods.bar().encodeABI()
+]);
+----

test/utils/Multicall.test.js

+const { BN, expectRevert } = require('@openzeppelin/test-helpers');
+const MulticallTokenMock = artifacts.require('MulticallTokenMock');
+
+contract('MulticallToken', function (accounts) {
+  const [deployer, alice, bob] = accounts;
+  const amount = 12000;
+
+  beforeEach(async function () {
+    this.multicallToken = await MulticallTokenMock.new(new BN(amount), { from: deployer });
+  });
+
+  it('batches function calls', async function () {
+    expect(await this.multicallToken.balanceOf(alice)).to.be.bignumber.equal(new BN('0'));
+    expect(await this.multicallToken.balanceOf(bob)).to.be.bignumber.equal(new BN('0'));
+
+    await this.multicallToken.multicall([
+      this.multicallToken.contract.methods.transfer(alice, amount / 2).encodeABI(),
+      this.multicallToken.contract.methods.transfer(bob, amount / 3).encodeABI(),
+    ], { from: deployer });
+
+    expect(await this.multicallToken.balanceOf(alice)).to.be.bignumber.equal(new BN(amount / 2));
+    expect(await this.multicallToken.balanceOf(bob)).to.be.bignumber.equal(new BN(amount / 3));
+  });
+
+  it('returns an array with the result of each call', async function () {
+    const MulticallTest = artifacts.require('MulticallTest');
+    const multicallTest = await MulticallTest.new({ from: deployer });
+    await this.multicallToken.transfer(multicallTest.address, amount, { from: deployer });
+    expect(await this.multicallToken.balanceOf(multicallTest.address)).to.be.bignumber.equal(new BN(amount));
+
+    const recipients = [alice, bob];
+    const amounts = [amount / 2, amount / 3].map(n => new BN(n));
+
+    await multicallTest.testReturnValues(this.multicallToken.address, recipients, amounts);
+  });
+
+  it('reverts previous calls', async function () {
+    expect(await this.multicallToken.balanceOf(alice)).to.be.bignumber.equal(new BN('0'));
+
+    const call = this.multicallToken.multicall([
+      this.multicallToken.contract.methods.transfer(alice, amount).encodeABI(),
+      this.multicallToken.contract.methods.transfer(bob, amount).encodeABI(),
+    ], { from: deployer });
+
+    await expectRevert(call, 'ERC20: transfer amount exceeds balance');
+    expect(await this.multicallToken.balanceOf(alice)).to.be.bignumber.equal(new BN('0'));
+  });
+
+  it('bubbles up revert reasons', async function () {
+    const call = this.multicallToken.multicall([
+      this.multicallToken.contract.methods.transfer(alice, amount).encodeABI(),
+      this.multicallToken.contract.methods.transfer(bob, amount).encodeABI(),
+    ], { from: deployer });
+
+    await expectRevert(call, 'ERC20: transfer amount exceeds balance');
+  });
+});

test/utils/cryptography/SignatureChecker.test.js

+const { toEthSignedMessageHash, fixSignature } = require('../../helpers/sign');
+
+const { expect } = require('chai');
+
+const SignatureCheckerMock = artifacts.require('SignatureCheckerMock');
+const ERC1271WalletMock = artifacts.require('ERC1271WalletMock');
+
+const TEST_MESSAGE = web3.utils.sha3('OpenZeppelin');
+const WRONG_MESSAGE = web3.utils.sha3('Nope');
+
+contract('SignatureChecker (ERC1271)', function (accounts) {
+  const [signer, other] = accounts;
+
+  before('deploying', async function () {
+    this.signaturechecker = await SignatureCheckerMock.new();
+    this.wallet = await ERC1271WalletMock.new(signer);
+    this.signature = fixSignature(await web3.eth.sign(TEST_MESSAGE, signer));
+  });
+
+  context('EOA account', function () {
+    it('with matching signer and signature', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        signer,
+        toEthSignedMessageHash(TEST_MESSAGE),
+        this.signature,
+      )).to.equal(true);
+    });
+
+    it('with invalid signer', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        other,
+        toEthSignedMessageHash(TEST_MESSAGE),
+        this.signature,
+      )).to.equal(false);
+    });
+
+    it('with invalid signature', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        signer,
+        toEthSignedMessageHash(WRONG_MESSAGE),
+        this.signature,
+      )).to.equal(false);
+    });
+  });
+
+  context('ERC1271 wallet', function () {
+    it('with matching signer and signature', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        this.wallet.address,
+        toEthSignedMessageHash(TEST_MESSAGE),
+        this.signature,
+      )).to.equal(true);
+    });
+
+    it('with invalid signer', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        this.signaturechecker.address,
+        toEthSignedMessageHash(TEST_MESSAGE),
+        this.signature,
+      )).to.equal(false);
+    });
+
+    it('with invalid signature', async function () {
+      expect(await this.signaturechecker.isValidSignatureNow(
+        this.wallet.address,
+        toEthSignedMessageHash(WRONG_MESSAGE),
+        this.signature,
+      )).to.equal(false);
+    });
+  });
+});