Update ERC-4337: validate using handleOps()

ERCS/erc-4337.md

@@ -243,7 +243,7 @@ In the execution loop, the `handleOps` call must perform the following steps for
 
 ![](../assets/eip-4337/bundle-seq.svg)
 
-Before accepting a `UserOperation`, bundlers should use an RPC method to locally call the `simulateValidation` function on the `EntryPoint`, to verify that the signature is correct and the `UserOperation` actually pays fees; see the [Simulation section below](#useroperation-simulation) for details.
+Before accepting a `UserOperation`, bundlers should use an RPC method to locally call the `handleOps` function on the `EntryPoint`, to verify that the signature is correct and the `UserOperation` actually pays fees; see the [Simulation section below](#useroperation-simulation) for details.
 A node/bundler SHOULD drop (not add to the mempool) a `UserOperation` that fails the validation
 
 
@@ -382,57 +382,24 @@ Intuitively, the aim of the simulation is to ensure the onchain validation code
 
 #### Simulation Specification:
 
-To simulate a `UserOperation` validation, the bundler makes a view call to `simulateValidation(userOp)`.
+To simulate a `UserOperation` validation, the bundler makes a view call to the `handleOps()` method with the UserOperation to check.
 
-The `EntryPoint` itself does not implement the simulation methods. Instead, when making the simulation view call,
-The bundler MAY provide the alternate `EntryPointSimulations` code, which extends the `EntryPoint` with the simulation methods.
+Simulation should run only on the validation section of the account and paymaster, and is not required for the UserOperations's execution.
+A bundler MAY add second "always failed" `UserOperation` to the bundle, so that the simulation will 
+end as soon as the first UserOperation's validation complete.
 
-The simulation core methods:
-
-```solidity
-
-struct ValidationResult {
-    ReturnInfo returnInfo;
-    StakeInfo senderInfo;
-    StakeInfo factoryInfo;
-    StakeInfo paymasterInfo;
-    AggregatorStakeInfo aggregatorInfo;
-}
-
-function simulateValidation(PackedUserOperation calldata userOp)
-external returns (ValidationResult memory);
-
-struct ReturnInfo {
-    uint256 preOpGas;
-    uint256 prefund;
-    uint256 accountValidationData;
-    uint256 paymasterValidationData;
-    bytes paymasterContext;
-}
-
-struct StakeInfo {
-  uint256 stake;
-  uint256 unstakeDelaySec;
-}
-
-```
-
-The `AggregatorStakeInfo` structure is further defined in [ERC-7766](./eip-7766.md).
-
-This method returns `ValidationResult` or revert on validation failure.
-The node MUST drop the `UserOperation` if the simulation fails (either by revert or by "signature failure")
+The bundler MUST drop the `UserOperation` if the simulation reverts
 
 The simulated call performs the full validation, by calling:
 
 1. If `initCode` is present, create the account.
 2. `account.validateUserOp`.
 3. if specified a paymaster: `paymaster.validatePaymasterUserOp`.
 
-The simulateValidation should validate the return value (validationData) returned by the account's `validateUserOp` and paymaster's `validatePaymasterUserOp`.
-The paymaster MUST return either `SIG_VALIDATION_SUCCESS` (`0`) for success or `SIG_VALIDATION_FAILED` (`1`) for signature verification failure.
-Either return value may contain a "validAfter" and "validUntil" timestamps, which is the time-range that this `UserOperation` is valid on-chain.
-A node MAY drop a `UserOperation` if it expires too soon (e.g. wouldn't make it to the next block) by either the account or paymaster.
-If the `ValidationResult` includes `sigFail`, the bundler MUST drop the `UserOperation`.
+Either account or paymaster may return a time-range (validAfter/validUntil). 
+The `UserOperation` MUST be valid at the current time to be considered valid (that is, validAfter<=block.timestamp)
+A bundler MAY drop a `UserOperation` if it expires too soon (e.g. wouldn't make it to the next block) by either the account or paymaster.
+To decode the returned time-ranges, the bundler should run the validation using tracing, to decode the return value from the `validateUserOp` and `validatePaymasterUserOp` methods.
 
 To prevent DoS attacks on bundlers, they must make sure the validation methods above pass the validation rules, which constrain their usage of opcodes and storage.
 For the complete procedure see [ERC-7562](./eip-7562.md)