the check for balanceOf(0) does not seem to detect revert

[wighawag]

I have an ERC721 contract on the mainnet at : 0x266003AfA9976D72565cac0bd840C276b01aE34f

and when I test it against the validator at https://erc721validator.org/?address=0x266003AfA9976D72565cac0bd840C276b01aE34f
It shows that balanceOf(address(0)) does not throw/

But when I execute the eth_call myself to an infura node with

{
	"jsonrpc": "2.0",
	"id": 1,
	"method": "eth_call",
	"params": [{
		"to": "0x266003AfA9976D72565cac0bd840C276b01aE34f",
		"data": "0x70a082310000000000000000000000000000000000000000000000000000000000000000"
	}, "latest"]
}

It gives me

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x08c379a0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000156f776e6572206973207a65726f20616464726573730000000000000000000000"
}

which is a revert-reason string so the call indeed revert

In comparison the 0xcert implementation when called with the same request,

{
	"jsonrpc": "2.0",
	"id": 1,
	"method": "eth_call",
	"params": [{
		"to": "0xf176d7bcdD07f8e474877095870685Ef0CCcCb2D",
		"data": "0x70a082310000000000000000000000000000000000000000000000000000000000000000"
	}, "latest"]
}

I get

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x"
}

which is also the response (albeit different) corresponding to a revert/throw

Maybe it is the web3 estimateGas call that does not error out here :
https://github.com/0xcert/erc721-validator/blob/master/src/validator.ts#L47

because it does not consider the error-reason string as an error
See also ethereum/go-ethereum#19027

[wighawag]

@fulldecent ^

[MoMannn]

@wighawag This indeed seems the reason. We need to change the way we handle reverted calls. We are currently a bit busy with 0xcert framework v2 so it may take a while for us to come to this. For this reason we would appreciate any help on this.

[MoMannn]

#18