Perform provider.call() with State Override Set

[toriqahmads]

Hi,
I want to perform a call with overriding the states. It's for easier debugging a contract without publish it on the network.
In the geth ethereum documentation, it's possible to do it. This is the link geth State Override Set

In web3js it can be performed by extending the eth_call with 3 parameters and then pass the override state set values.

...
web3.extend({
   methods: [{
      name: 'callWithState',
      call: 'eth_call',
      params: 3,
  }]
});

web3.callWithState({
        to: '0x....',
        from: '0x...',
        value: '0x...',
        gas: '0x...',
        data: '0x....,
    }, 'latest', {
        '0xaddress1': {
            'code': '0x60806.....',
        },
        '0xaddress2': {
            'code': '0x608060.....,
        },
        '0xaddress3': {
            'balance': '0x.....',
        }
})

How can I perform it with ethers.js?

Thank you

[alex88]

I've tried with

  const result = await provider.send("eth_call", [
    {
      from: "0x...",
      to: "0x...",
      value: hexValue(parseEther("1.0")),
      data,
    },
    "latest",
    {
      '0x...': {
        code: myContract.bytecode
      }
    },
  ]);

however geth always returns 0x

[ricmoo]

I’ve never used this feature. My guess is that you would require an archive node, or possible some custom environment for this to work.

Keep in mind you should not use hexValue on addresses; it is for converting values to quantity values and can corrupt addresses.

If you find a way to make it work though, it could be added as a separate injected provider. I should add something like that as an ancillary package at some point. :)

[alex88]

Thanks for the answer, in the meantime I was able to figure out that hexValue isn't necessary on addresses looking at other examples, however the error persist. Afaik you don't really need a detached environment as all those overrides are done in memory and discarded.

I'll check with the node logs to see if I can get some insights on why it's not working

(I'll update the post removing the hexValue)

[alex88]

Update: nvm the address I was calling was wrong, the call works as expected!

[dkuppitz]

Took me a while to figure out state diffs. Since there's not a single example to be found online, here it comes:

const provider = new JsonRpcProvider('https://polygon-rpc.com');

const DAI = '0x8f3Cf7ad23Cd3CaDbD9735AFf958023239c6A063';
const wallet = '0xF977814e90dA44bFA03b6295A0616a897441aceC';

const slot = utils.keccak256(utils.defaultAbiCoder.encode(['address', 'uint256'], [wallet.toLowerCase(), 0]));
const resultWithoutOverride = await provider.getStorageAt(DAI, slot);

const stateDiff = {
    [DAI]: {
        stateDiff: {
            [slot]: utils.hexZeroPad(utils.hexValue(12345678), 32),
        },
    },
};
const resultWithOverride = await provider.send('eth_call', [
    {
        from: constants.AddressZero,
        to: DAI,
        data: dai.interface.encodeFunctionData('balanceOf', [wallet]),
    },
    'latest',
    stateDiff,
]);

console.log('DAI balance w/o override:', utils.defaultAbiCoder.decode(['uint256'], resultWithoutOverride));
console.log('DAI balance w/ override:', utils.defaultAbiCoder.decode(['uint256'], resultWithOverride));

Output:

DAI balance w/o override: [ BigNumber { value: "22000000000000000000000000" } ]
DAI balance w/ override: [ BigNumber { value: "12345678" } ]