Contract Verification - Graceful failure on isBeacon check when using blockscout RPC.

[quintessenial]

When verifying a non-beacon contract, the verify plugin will check if the implementation() call fails to determine if it's not a beacon. Unfortunately with a Blockscout eth-rpc the error message is different than the specified list, causing HH to assume there's something wrong with the RPC.

Adding this additional error message check supports the response coming back from eth-rpc found here

[ericglau]

Hi @quintessenial, thanks for the PR and sorry for the late response. However, this doesn't look like the root cause. The plugin is calling the eth_call RPC method on a function name that possibly does not exist on a contract (and it should catch this case), whereas the "Action not found" error occurs when the RPC method itself does not exist.

For example, if you call eth_call on a Blockscout RPC with an address and a non-existent function:

curl https://eth.blockscout.com/api/eth-rpc \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "method": "eth_call", "params": [{"from": null, "to": "0x6b175474e89094c44da98b954eedeac495271d0f", "data": "0xc2985578"}, "latest"], "id": 1}'

the RPC returns:

{"jsonrpc":"2.0","error": {"code":-32000,"data":"0x","message":"execution reverted"},"id": 1}

which should be caught by the plugin.

However, if you call an invalid RPC method such as "eth_invalid":

curl https://eth.blockscout.com/api/eth-rpc \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "method": "eth_invalid", "params": [{"from": null, "to": "0x6b175474e89094c44da98b954eedeac495271d0f", "data": "0xc2985578"}, "latest"], "id": 1}'

then it returns "Action not found":

{"jsonrpc":"2.0","error": "Action not found.","id": 1}

If the issue still occurs, can you please provide the following info:

• Which specific RPC URL are you using?
• Can you use a different RPC provider? If using Blockscout, is there a different Blockscout RPC URL that you can try?
• Please provide the debug logs and other information described in https://forum.openzeppelin.com/t/required-information-when-requesting-support-for-upgrades-plugins/30530

[quintessenial]

Thanks for the response @ericglau

This error was received using the explorer & RPC over at https://evm.taostats.io/ (RPC: https://evm.taostats.io/api/eth-rpc)

It may not be the root cause, but the only workaround I was able to find was temporarily removing the import for openzeppelin-upgrades which then no longer ran the implementation() check while verifying a contract.

[afa7789]

Hey @quintessenial, hope you're doing well!

I reviewed the Elixir link you shared before, so the {:error, "Action not found."} error only occurs when an unknown RPC method is called (when get_action(method) fails) - not from contract execution failures.

In the case you mentioned, a VM exception is the expected behavior when calling non-existent functions on contracts.
If there were any errors in the validation logic, we would be seeing VM reverts - which is what you get with non-beacon contracts:

{"jsonrpc":"2.0","error": {"code":-32603,"data":"0x","message":"VM Exception while processing transaction: revert"},"id": 1}

You can make the curl calls, as Eric mentioned, to verify it.

However, I can still debug this a bit more. I need the following:

• The proxy and implementation contract addresses you deployed
• What type of proxy you are using (e.g. beacon or UUPS or transparent)

Note that our plugin only supports source code verification on Etherscan-based explorers. If you’re using Blockscout, please see this thread on how to verify your proxy and implementation: https://forum.openzeppelin.com/t/how-to-verify-a-contract-on-etherscan-bscscan-polygonscan/14225

If you’d like us to help verify the proxy contract itself, please also provide:

• The proxy address
• Which versions of @openzeppelin/hardhat-upgrades and @openzeppelin/upgrades-core you used to deploy the proxy

Thanks!