simulate-l2-ownership-transfer.md

Simulating an L2 Deposit Transaction Before Execution

The following steps describe how to simulate an L2 deposit transaction prior to L1 task execution. The TransferL2PAOFromL1.sol transfers the ownership of a L2PAO from a current aliased L1 address to a new aliased L1 address. This template executes an L1 transaction, which is later forwarded to the L2 by the op-node. To gain additional confidence that the L2 deposit transaction works as expected, we manually simulate it and record the results in the task’s VALIDATION.md file.

Steps

1. Simulate the task that uses the TransferL2PAOFromL1.sol template.

2. In the terminal output, copy the Tenderly link and open it in your browser.

3. In Tenderly, open the Events tab and look for the TransactionDeposited event.

     {
         "from": "0x7e6c183f538abb8572f5cd17109c617b994d6944",
         "to": "0x4200000000000000000000000000000000000018",
         "version": "0",
         "opaqueData": "0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000030d4000f2fde38b0000000000000000000000006b1bae59d09fccbddb6c6cceb07b7279367c4e3b"
     }

4. Using the data in the TransactionDeposited event, create a new Tenderly simulation by opening the Simulator and filling in the form using the fields below. Set gas price and value to 0. The from address and gas will be derived from the event data and filled in step 9.

5. Insert the to address (0x4200000000000000000000000000000000000018) as the destination address and select the correct L2 network.

6. Next, we need to create the calldata from the opaqueData field in the TransactionDeposited event. This is going to go into the Enter raw input data field. We know this particular transaction is a transferOwnership call to the ProxyAdmin contract. We can identify the start of the relevant calldata by extracting the function selector:

   cast sig "transferOwnership(address)"
   # returns: 0xf2fde38b

   Now that we know the function selector, we can extract the calldata from the opaqueData field and run the following cast command:

   cast calldata-decode "transferOwnership(address)" 0xf2fde38b0000000000000000000000006b1bae59d09fccbddb6c6cceb07b7279367c4e3b
   # returns: 0x6B1BAE59D09fCcbdDB6C6cceb07B7279367C4E3b

   We must put 0xf2fde38b0000000000000000000000006b1bae59d09fccbddb6c6cceb07b7279367c4e3b in the Enter raw input data field.

7. Double-check that the address returned from the cast calldata-decode step matches the aliased new L1 ProxyAdmin owner (L1PAO) for the target chain. In this case, the L1PAO is 0x5a0Aae59D09fccBdDb6C6CcEB07B7279367C3d2A. Confirm this by manually unaliasing the address using chisel.

   > uint160 constant offset = uint160(0x1111000000000000000000000000000000001111)
   > function undoL1ToL2Alias(address l2Address) internal pure returns (address l1Address) {
       unchecked {
           l1Address = address(uint160(l2Address) - offset);
       }
   }
   > undoL1ToL2Alias(0x6B1BAE59D09fCcbdDB6C6cceb07B7279367C4E3b)
   # returns: 0x5a0Aae59D09fccBdDb6C6CcEB07B7279367C3d2A

8. Next we need to fill out the Transaction Parameters section on the right of the UI. Specifically, fill out the From address and Gas fields. The From address should be the aliased old L1PAO address obtained as the from field in the TransactionDeposited event (i.e. 0x6B1BAE59D09fCcbdDB6C6cceb07B7279367C4E3b). The Gas field should be set to 200000. You can get this number by further parsing the opaque data and extracting the gas limit.

   cast --to-dec 0x30d40
   # returns: 200000

   

9. Click Simulate Transaction and you should see the transaction succeed.

10. Finally, check the State tab and ensure the state changes are as expected. Specifically, confirm that the ProxyAdmin contract reflects the new, expected owner.