Providers do not support static calls using signed transactions

[m1cm1c]

Describe the bug
I only have access to a signed transaction; not to an unsigned one. If I pass the signed transaction to provider.call() or provider.estimateGas(), no error is thrown. In fact, provider.estimateGas() even returns some number. While I do understand that this feature might not be intended to be supported, passing a signed transaction to one of these methods should at least throw an error if it is not supported. However, I do not really see a reason why it should not be supported as passing a signed transaction to a provider would let you control msg.sender and be generally more similar to provider.sendTransaction().

Reproduction steps

const provider = new (ethers.getDefaultProvider as any) ('wss://rinkeby.infura.io/ws/v3/...');
const sk = '1111111111111111111111111111111111111111111111111111111111111111';
const wallet = new ethers.Wallet(sk);
const nonce = await provider.getTransactionCount(wallet.address);
const tx = {
  to: '0x08116A07d64eF1A3f1bbE83736ac0829302B54ef',
  value: ethers.BigNumber.from('5'),
  data: '0x3333333333333333333333333333333333333333333333333333333333333333',
  type: 2,
  maxFeePerGas: 5000000000,
  maxPriorityFeePerGas: 5000000000,
  chainId: 4,
  nonce: nonce,
  gasLimit: 210000,
};

const signedTx = await wallet.signTransaction(tx);
const gasEstimateSigned = await provider.estimateGas(signedTx);
console.log('gas estimate signed', gasEstimateSigned);
const gasEstimateUnsigned = await provider.estimateGas(tx);
console.log('gas estimate unsigned', gasEstimateUnsigned);

await provider.estimateGas(tx) correctly fails with the following error message:

Error: cannot estimate gas; transaction may fail or may require manual gas limit (error={"code":-32000,"response":"{\"jsonrpc\":\"2.0\",\"id\":6,\"error\":{\"code\":-32000,\"message\":\"execution reverted\"}}"}, method="estimateGas", transaction={"gasLimit":{"type":"BigNumber","hex":"0x033450"},"maxPriorityFeePerGas":{"type":"BigNumber","hex":"0x012a05f200"},"maxFeePerGas":{"type":"BigNumber","hex":"0x012a05f200"},"to":"0x08116A07d64eF1A3f1bbE83736ac0829302B54ef","value":{"type":"BigNumber","hex":"0x05"},"data":"0x3333333333333333333333333333333333333333333333333333333333333333","type":2,"accessList":null}, code=UNPREDICTABLE_GAS_LIMIT, version=providers/5.5.1)

However, await provider.estimateGas(signedTx) returns: BigNumber { _hex: '0xcf08', _isBigNumber: true }

Environment:

• I'm using ethers.getDefaultProvider with a websocket connected to Infura (Rinkeby).
• Ethers version: 5.5.2
• Node v16.9.1

[zemse]

I do not really see a reason why it should not be supported as passing a signed transaction to a provider would let you control msg.sender

Simulating a transaction using eth_estimateGas or eth_call, that allows you to control the msg.sender is very supported by the ethereum node (you can see rpc spec which allows specifying from as an address). Ethers.js also allows you to specify a plain from address, or also look for a signature as in your example.

await provider.estimateGas({
  to: '0xContractAddr',
  data: '0xData',
  from: '0xFriendsAddress'
})

There can be a number of use-cases, for example, if you want to see if a particular address can perform a transaction or not, and how much it'd cost them (as same transaction can cost different for different msg.sender).

await provider.estimateGas(tx) correctly fails with the following error message:

If you do not specify a from address (or a signature), the ethereum node will consider Zero address by default for simulating your transaction to get a gas estimate. If it turns out that the contract reverts due to some condition set in it (like msg.sender should not be zero or whatever), then you would get that error.

[m1cm1c]

Ethers.js also allows you to specify a plain from address, or also look for a signature as in your example.

Is both the signed tx and the unsigned tx needed for this? How is the signature passed to ethers?

If you do not specify a from address (or a signature), the ethereum node will consider Zero address by default for simulating your transaction to get a gas estimate. If it turns out that the contract reverts due to some condition set in it (like msg.sender should not be zero or whatever), then you would get that error.

The problem I'm experiencing is that I do not get this error message, even if the contract reverts regardless of what msg.sender is set to. However, the problem only occurs if I pass a signed tx to provider.estimateGas() (the problem does not occur if I pass an unsigned tx).

[zemse]

Oh I see, let me correct myself. The wallet.signTransaction returns a string. And when this is passed, the actual request made to eth_estimateGas is an empty object {}. Hence the estimate you get is invalid.

const signedTxObject = ethers.utils.parseTransaction(signedTxStr);
provider.estimateGas(signedTxObject) // this should work as intended