Include EIP-5267 discovery in EIP-712

contracts/interfaces/ERC5267.sol

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+interface ERC5267 {
+    /**
+     * @dev MAY be emitted to signal that the domain could have changed.
+     */
+    event EIP712DomainChanged();
+
+    /**
+     * @dev returns the fields and values that describe the domain separator used by this contract for EIP-712
+     * signature.
+     */
+    function eip712Domain()
+        external
+        view
+        returns (
+            bytes1 fields,
+            string memory name,
+            string memory version,
+            uint256 chainId,
+            address verifyingContract,
+            bytes32 salt,
+            uint256[] memory extensions
+        );
+}

contracts/utils/cryptography/EIP712.sol

@@ -4,6 +4,7 @@
 pragma solidity ^0.8.0;
 
 import "./ECDSA.sol";
+import "../../interfaces/ERC5267.sol";
 
 /**
  * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
@@ -24,17 +25,21 @@ import "./ECDSA.sol";
  *
  * _Available since v3.4._
  */
-abstract contract EIP712 {
+abstract contract EIP712 is ERC5267 {
     /* solhint-disable var-name-mixedcase */
     // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
     // invalidate the cached domain separator if the chain id changes.
     bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
     uint256 private immutable _CACHED_CHAIN_ID;
     address private immutable _CACHED_THIS;
 
+    string private _NAME;
+    string private _VERSION;
+
     bytes32 private immutable _HASHED_NAME;
     bytes32 private immutable _HASHED_VERSION;
-    bytes32 private immutable _TYPE_HASH;
+    bytes32 private immutable _TYPE_HASH =
+        keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
 
     /* solhint-enable var-name-mixedcase */
 
@@ -53,15 +58,13 @@ abstract contract EIP712 {
     constructor(string memory name, string memory version) {
         bytes32 hashedName = keccak256(bytes(name));
         bytes32 hashedVersion = keccak256(bytes(version));
-        bytes32 typeHash = keccak256(
-            "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
-        );
+        _NAME = name;
+        _VERSION = version;
         _HASHED_NAME = hashedName;
         _HASHED_VERSION = hashedVersion;
         _CACHED_CHAIN_ID = block.chainid;
-        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
+        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(_TYPE_HASH, hashedName, hashedVersion);
         _CACHED_THIS = address(this);
-        _TYPE_HASH = typeHash;
     }
 
     /**
@@ -101,4 +104,33 @@ abstract contract EIP712 {
     function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
         return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
     }
+
+    /**
+     * @dev See {EIP-5267}.
+     */
+    function eip712Domain()
+        public
+        view
+        virtual
+        override
+        returns (
+            bytes1 fields,
+            string memory name,
+            string memory version,
+            uint256 chainId,
+            address verifyingContract,
+            bytes32 salt,
+            uint256[] memory extensions
+        )
+    {
+        return (
+            hex"0f", // 01111
+            _NAME,
+            _VERSION,
+            block.chainid,
+            address(this),
+            bytes32(0),
+            new uint256[](0)
+        );
+    }
 }

test/governance/Governor.test.js

@@ -4,7 +4,7 @@ const ethSigUtil = require('eth-sig-util');
 const Wallet = require('ethereumjs-wallet').default;
 const { fromRpcSig } = require('ethereumjs-util');
 const Enums = require('../helpers/enums');
-const { EIP712Domain } = require('../helpers/eip712');
+const { getDomain, domainType } = require('../helpers/eip712');
 const { GovernorHelper } = require('../helpers/governance');
 
 const { shouldSupportInterfaces } = require('../utils/introspection/SupportsInterface.behavior');
@@ -20,7 +20,7 @@ contract('Governor', function (accounts) {
   const empty = web3.utils.toChecksumAddress(web3.utils.randomHex(20));
 
   const name = 'OZ-Governor';
-  const version = '1';
+  // const version = '1';
   const tokenName = 'MockToken';
   const tokenSymbol = 'MTKN';
   const tokenSupply = web3.utils.toWei('100');
@@ -148,24 +148,22 @@ contract('Governor', function (accounts) {
     const voterBySig = Wallet.generate();
     const voterBySigAddress = web3.utils.toChecksumAddress(voterBySig.getAddressString());
 
-    const signature = async message => {
-      return fromRpcSig(
-        ethSigUtil.signTypedMessage(voterBySig.getPrivateKey(), {
-          data: {
-            types: {
-              EIP712Domain,
-              Ballot: [
-                { name: 'proposalId', type: 'uint256' },
-                { name: 'support', type: 'uint8' },
-              ],
-            },
-            domain: { name, version, chainId: this.chainId, verifyingContract: this.mock.address },
-            primaryType: 'Ballot',
-            message,
+    const signature = (contract, message) =>
+      getDomain(contract)
+        .then(domain => ({
+          primaryType: 'Ballot',
+          types: {
+            EIP712Domain: domainType(domain),
+            Ballot: [
+              { name: 'proposalId', type: 'uint256' },
+              { name: 'support', type: 'uint8' },
+            ],
           },
-        }),
-      );
-    };
+          domain,
+          message,
+        }))
+        .then(data => ethSigUtil.signTypedMessage(voterBySig.getPrivateKey(), { data }))
+        .then(fromRpcSig);
 
     await this.token.delegate(voterBySigAddress, { from: voter1 });
 

test/governance/extensions/GovernorWithParams.test.js

@@ -4,7 +4,7 @@ const ethSigUtil = require('eth-sig-util');
 const Wallet = require('ethereumjs-wallet').default;
 const { fromRpcSig } = require('ethereumjs-util');
 const Enums = require('../../helpers/enums');
-const { EIP712Domain } = require('../../helpers/eip712');
+const { getDomain, domainType } = require('../../helpers/eip712');
 const { GovernorHelper } = require('../../helpers/governance');
 
 const Token = artifacts.require('$ERC20VotesComp');
@@ -22,7 +22,7 @@ contract('GovernorWithParams', function (accounts) {
   const [owner, proposer, voter1, voter2, voter3, voter4] = accounts;
 
   const name = 'OZ-Governor';
-  const version = '1';
+  // const version = '1';
   const tokenName = 'MockToken';
   const tokenSymbol = 'MTKN';
   const tokenSupply = web3.utils.toWei('100');
@@ -116,26 +116,24 @@ contract('GovernorWithParams', function (accounts) {
     const voterBySig = Wallet.generate();
     const voterBySigAddress = web3.utils.toChecksumAddress(voterBySig.getAddressString());
 
-    const signature = async message => {
-      return fromRpcSig(
-        ethSigUtil.signTypedMessage(voterBySig.getPrivateKey(), {
-          data: {
-            types: {
-              EIP712Domain,
-              ExtendedBallot: [
-                { name: 'proposalId', type: 'uint256' },
-                { name: 'support', type: 'uint8' },
-                { name: 'reason', type: 'string' },
-                { name: 'params', type: 'bytes' },
-              ],
-            },
-            domain: { name, version, chainId: this.chainId, verifyingContract: this.mock.address },
-            primaryType: 'ExtendedBallot',
-            message,
+    const signature = (contract, message) =>
+      getDomain(contract)
+        .then(domain => ({
+          primaryType: 'ExtendedBallot',
+          types: {
+            EIP712Domain: domainType(domain),
+            ExtendedBallot: [
+              { name: 'proposalId', type: 'uint256' },
+              { name: 'support', type: 'uint8' },
+              { name: 'reason', type: 'string' },
+              { name: 'params', type: 'bytes' },
+            ],
           },
-        }),
-      );
-    };
+          domain,
+          message,
+        }))
+        .then(data => ethSigUtil.signTypedMessage(voterBySig.getPrivateKey(), { data }))
+        .then(fromRpcSig);
 
     await this.token.delegate(voterBySigAddress, { from: voter2 });