How to check if the address is an ERC20 contract?

Question

edit) VM execution error was a bug on Web3, confirmed my code works fine.

I am trying to fetch random addresses from blockchain and trying to categorize them if it is an ERC20 contract address or not.

I've tried with web3.eth.call to check if the contract has a method totalSupply() but there was no success on that thing, with the single address it works fine however at the production stage it returns an odd (node:10722) UnhandledPromiseRejectionWarning: Error: Returned error: VM execution error.

Referring related documents or codes wouldn't help with me unless with web3 1.0.

Here is my code that doesn't work

var Web3 = require('web3');
var web3 = new Web3(new Web3.providers.HttpProvider("http://127.0.0.1:8545"));

var ABI = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}];

var myContract = new web3.eth.Contract(ABI, "0x085b0fdf115aa9e16ae1bddd396ce1f993c52220");

async function checkAddress() {
  var call = await web3.eth.call({ to: "0x085fb4f24031eaedbc2b611aa528f22343eb52db", data:web3.utils.sha3("totalSupply()")});
  if (call != '0x') {
    console.log('ERC20 token detected');
  } else {
    console.log('Not an ERC20 token address');
  }
}
checkAddress();

Answer 1

I think you should check a few conditions with different ABIs:

1. Events Transfer(address,address,uint256) and Approval(address,address,uint256) should be emitted in case of any existing transactions to this smart contract

2. Methods name(), symbol() could return bytes32 or string

3. Method decimals() could return uint8 or uint256

4. Method totalSupply() should return uint256

5. Method balanceOf(address) should return uint256 for any argument

Answer 2

This answer is not exactly for your web3 needs but more of a generic answer. I asked a very similar question some time ago here: How is a contract determined to be ERC20 compliant?

So, in the end, if the signatures are correct then it's considered an ERC20 contract. The actual implementation doesn't matter as long as the signatures are correct.

As for how to finding signatures from a deployed contract: as I see it you have two options:

1) Reverse-engineer the bytecode and try to find the signatures from there. This isn't necessarily possible or very easy: How can you decompile a smart contract?

2) Issue all the relevant transactions (calling each ERC20 function) to the contract and see if they go through. This basically requires that you guess the ABI, part by part (it's easy enough to guess if it's ERC20 contract).

Answer 3

If you want to use an API it's dead simple. Amberdata's /addresses/:hash/information endpoint returns of list of contract types like so...

Request:

curl --request GET \
  --url https://web3api.io/api/v1/addresses/0x06012c8cf97bead5deae237070f9587f8e7a266d/information \
  --header 'x-api-key: <x-api_key>'

Response:

{
  "status": 200,
  "title": "OK",
  "description": "Successful request",
  "payload": [
    { 
      "firstSeen": "2017-11-23T05:41:19.000Z",
      "type": "contract",
      "contractTypes": [
        "ERC721"      // <-- Here's what you are looking for
      ],
      "probability": 1,
      "network": {
        "name": "Ethereum",
        "network": "Mainnet",
        "slug": "ethereum-mainnet",
        "blockchainId": "1c9c969065fcd1cf",
        "link": "https://ethereum-mainnet.amberdata.io/addresses/0x06012c8cf97bead5deae237070f9587f8e7a266d"
      }
    },
    ...
  ]
}

This is the Cryptokitties address and as you can see it returns a contract type of ERC712.

If you have an API key (it's free) you can try it out here.