AA-176: Add ERC-165 "supportsInterface" to the EntryPoint

contracts/core/EntryPoint.sol

@@ -19,7 +19,7 @@ import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
  * Account-Abstraction (EIP-4337) singleton EntryPoint implementation.
  * Only one instance required on each chain.
  */
-contract EntryPoint is IEntryPoint, StakeManager, NonceManager, ReentrancyGuard {
+contract EntryPoint is IEntryPoint, StakeManager, NonceManager, ReentrancyGuard, OpenZeppelin.ERC165 {
 
     using UserOperationLib for UserOperation;
 
@@ -39,6 +39,15 @@ contract EntryPoint is IEntryPoint, StakeManager, NonceManager, ReentrancyGuard
      */
     uint256 public constant SIG_VALIDATION_FAILED = 1;
 
+    /// @inheritdoc OpenZeppelin.IERC165
+    function supportsInterface(bytes4 interfaceId) public view virtual override(OpenZeppelin.ERC165, OpenZeppelin.IERC165) returns (bool) {
+        return interfaceId == (type(IEntryPoint).interfaceId ^ type(IStakeManager).interfaceId ^ type(INonceManager).interfaceId) ||
+            interfaceId == type(IEntryPoint).interfaceId ||
+            interfaceId == type(IStakeManager).interfaceId ||
+            interfaceId == type(INonceManager).interfaceId ||
+            super.supportsInterface(interfaceId);
+    }
+
     /**
      * Compensate the caller's beneficiary address with the collected fees of all UserOperations.
      * @param beneficiary - The address to receive the fees.

contracts/interfaces/IEntryPoint.sol

@@ -9,12 +9,15 @@ pragma solidity ^0.8.12;
 /* solhint-disable no-inline-assembly */
 /* solhint-disable reason-string */
 
+// we also require '@gnosis.pm/safe-contracts' and both libraries have 'IERC165.sol', leading to conflicts
+import "@openzeppelin/contracts/utils/introspection/ERC165.sol" as OpenZeppelin;
+
 import "./UserOperation.sol";
 import "./IStakeManager.sol";
 import "./IAggregator.sol";
 import "./INonceManager.sol";
 
-interface IEntryPoint is IStakeManager, INonceManager {
+interface IEntryPoint is IStakeManager, INonceManager, OpenZeppelin.IERC165 {
     /***
      * An event emitted after each successful request.
      * @param userOpHash    - Unique identifier for the request (hash its entire content, except signature).

reports/gas-checker.txt

@@ -4,36 +4,36 @@
 ╔══════════════════════════╤════════╗
 ║ gas estimate "simple"    │  29014 ║
 ╟──────────────────────────┼────────╢
-║ gas estimate "big tx 5k" │ 125260 ║
+║ gas estimate "big tx 5k" │ 125248 ║
 ╚══════════════════════════╧════════╝
 
 ╔════════════════════════════════╤═══════╤═══════════════╤════════════════╤═════════════════════╗
 ║ handleOps description          │ count │ total gasUsed │ per UserOp gas │ per UserOp overhead ║
 ║                                │       │               │     (delta for │        (compared to ║
 ║                                │       │               │    one UserOp) │     account.exec()) ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple                         │     1 │         81899 │                │                     ║
+║ simple                         │     1 │         81943 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple - diff from previous    │     2 │               │          44186 │               15172 ║
+║ simple - diff from previous    │     2 │               │          44208 │               15194 ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple                         │    10 │        479702 │                │                     ║
+║ simple                         │    10 │        479944 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple - diff from previous    │    11 │               │          44222 │               15208 ║
+║ simple - diff from previous    │    11 │               │          44280 │               15266 ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple paymaster               │     1 │         88182 │                │                     ║
+║ simple paymaster               │     1 │         88202 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple paymaster with diff     │     2 │               │          43175 │               14161 ║
+║ simple paymaster with diff     │     2 │               │          43197 │               14183 ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple paymaster               │    10 │        476938 │                │                     ║
+║ simple paymaster               │    10 │        477132 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ simple paymaster with diff     │    11 │               │          43234 │               14220 ║
+║ simple paymaster with diff     │    11 │               │          43208 │               14194 ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ big tx 5k                      │     1 │        182932 │                │                     ║
+║ big tx 5k                      │     1 │        182976 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ big tx - diff from previous    │     2 │               │         144721 │               19461 ║
+║ big tx - diff from previous    │     2 │               │         144707 │               19459 ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ big tx 5k                      │    10 │       1485370 │                │                     ║
+║ big tx 5k                      │    10 │       1485552 │                │                     ║
 ╟────────────────────────────────┼───────┼───────────────┼────────────────┼─────────────────────╢
-║ big tx - diff from previous    │    11 │               │         144710 │               19450 ║
+║ big tx - diff from previous    │    11 │               │         144744 │               19496 ║
 ╚════════════════════════════════╧═══════╧═══════════════╧════════════════╧═════════════════════╝
 

src/Utils.ts

@@ -0,0 +1,17 @@
+import { Interface, JsonFragment } from '@ethersproject/abi'
+
+export function getERC165InterfaceID (abi: JsonFragment[]): string {
+  let interfaceId =
+    abi
+      .filter(it => it.type === 'function' && it.name != null)
+      .map(it => {
+        const iface = new Interface([it])
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        return iface.getSighash(it.name!)
+      })
+      .filter(it => it !== '0x01ffc9a7') // remove the IERC165 method itself
+      .map((x) => parseInt(x, 16))
+      .reduce((x, y) => x ^ y)
+  interfaceId = interfaceId > 0 ? interfaceId : 0xFFFFFFFF + interfaceId + 1
+  return '0x' + interfaceId.toString(16).padStart(8, '0')
+}

test/entrypoint.test.ts

@@ -21,6 +21,10 @@ import {
   TestSignatureAggregator__factory,
   MaliciousAccount__factory,
   TestWarmColdAccount__factory,
+  IEntryPoint__factory,
+  SimpleAccountFactory__factory,
+  IStakeManager__factory,
+  INonceManager__factory,
   TestPaymasterRevertCustomError__factory
 } from '../typechain'
 import {
@@ -53,6 +57,7 @@ import { arrayify, defaultAbiCoder, hexConcat, hexZeroPad, parseEther } from 'et
 import { debugTransaction } from './debugTx'
 import { BytesLike } from '@ethersproject/bytes'
 import { toChecksumAddress } from 'ethereumjs-util'
+import { getERC165InterfaceID } from '../src/Utils'
 
 describe('EntryPoint', function () {
   let entryPoint: EntryPoint
@@ -1362,4 +1367,42 @@ describe('EntryPoint', function () {
       })
     })
   })
+
+  describe('ERC-165', function () {
+    it('should return true for EntryPoint interface IDs', async function () {
+      const epInterface = IEntryPoint__factory.createInterface()
+      const smInterface = IStakeManager__factory.createInterface()
+      const nmInterface = INonceManager__factory.createInterface()
+      // note: manually generating "pure", solidity-like "type(IEntryPoint).interfaceId" without inherited methods
+      const epPureInterfaceID = getERC165InterfaceID([
+        ...epInterface.fragments.filter(it => [
+          'handleOps',
+          'handleAggregatedOps',
+          'getUserOpHash',
+          'getSenderAddress',
+          'simulateValidation',
+          'simulateHandleOp'
+        ].includes(it.name))
+      ])
+      const epInterfaceID = getERC165InterfaceID([...epInterface.fragments])
+      const smInterfaceID = getERC165InterfaceID([...smInterface.fragments])
+      const nmInterfaceID = getERC165InterfaceID([...nmInterface.fragments])
+      const res1 = await entryPoint.supportsInterface(epInterfaceID)
+      const res2 = await entryPoint.supportsInterface(smInterfaceID)
+      const res3 = await entryPoint.supportsInterface(nmInterfaceID)
+      const res4 = await entryPoint.supportsInterface(epPureInterfaceID)
+      expect(res1).to.equal(true)
+      expect(res2).to.equal(true)
+      expect(res3).to.equal(true)
+      expect(res4).to.equal(true)
+    })
+
+    it('should return false for a wrong interface', async function () {
+      const saInterface = SimpleAccountFactory__factory.createInterface()
+      const entryPointInterfaceID = getERC165InterfaceID([...saInterface.fragments])
+      const res = await entryPoint.supportsInterface(entryPointInterfaceID)
+      expect(res)
+        .to.equal(false)
+    })
+  })
 })