node.js - 检查 ERC-20 token 是否是骗局/蜜 jar

Question

我正在寻找一种方法来获取 token 的买卖税，并检查它是否可以在购买后出售。

为此，这是我想到的方法:

1-在 DEX 路由器合约上模拟购买交易

2-在 DEX 路由器合约上模拟卖出交易

3-如果上述 2 笔交易成功，我可以知道销售税和购买税 + 知道代币是否“可出售”

由于我使用的是调用而非真实交易来模拟代币的买卖，因此我需要进行多次调用来模拟区 block 链状态的改变。

我正在使用 ethereum-multicall library做这个。

这是我的代码:

const multicall = new Multicall({ethersProvider: _EVM.provider, tryAggregate: true});
let amoutIn = ethers.utils.parseUnits('300',18);
  let timestamp = Date.now() + 1000 * 60 * 10;
  const contractCallContext =[
{
  reference: 'Router',
  contractAddress: _EVM.DEX.router,
  abi: JSON.parse(Router_ABI),
  calls:[{reference:'foo', methodName:'swapExactTokensForTokens', methodParameters:[amoutIn,0,[ASDC, MIM],"0xa37Aa5C9A682490C64bDC32e60E627A50B66a485",timestamp]}]
}];

let result = await multicall.call(contractCallContext);

问题是我经常从 Multicall smartcontract 获得不成功的返回值...

还有其他方法可以达到我的要求吗？还是我的代码有问题？

提前致谢

Answer 1

你可以找到an example Python code here to check for any transfer fees .

def estimate_token_taxes(
        uniswap: UniswapV2Deployment,
        base_token: HexAddress,
        quote_token: HexAddress,
        buy_account: HexAddress,
        sell_account: HexAddress,
        buy_amount: float,
        approve=True,
        quote_token_details: Optional[TokenDetails] = None,
        base_token_details: Optional[TokenDetails] = None,
        gas_limit: Optional[int] = None,
        gas_price: Optional[int] = None,
) -> TokenTaxInfo:
    """Estimates different token taxes for a token by running Ganache simulations for it.
    :param uniswap:
        Uniswap deployment on a Ganache mainnet fork.
        Set up prior calling this function.
        See `ganache.py` and `test_ganache.py` for more details.
    :param base_token:
        The token of which tax properties we are figuring out.
    :param quote_token:
        Address of the quote token used for the trading pair. E.g. `BUDS`, `WBNB`
        Based on this information we can derive Uniswap trading pair address.
    :param buy_account:
        The account that does initial buy to measure the buy tax.
        This account must be loaded with gas money (ETH/BNB) and `quote_token`
        for a purchase.
    :param sell_account:
        The account that receives the token transfer and does the sell to measure the sell tax.
        This account must be loaded with gas money for the sell.
    :param approve:
        Perform quote token approval before wap test
   :param base_token_details:
        Pass base token details. If not given automatically fetch.
    :param quote_token_details:
        Pass quote token details. If not given automatically fetch.
    :param gas_limit:
        Use this gas limit for all transactions, so that
        we do not need to call eth_estimateGas on the node.
    :param gas_price:
        Use this gas price for all transactions, so that
        we do not need to call eth_estimateGas on the node.
    :return:
        ToxTaxInfo tells us what we figure out about taxes.
        This can be later recorded to a database.
    """
    web3: Web3 = uniswap.web3
    router = uniswap.router

    if not quote_token_details:
        # No need to consider brokeness of token metadata
        # when calculating tax
        quote_token_details = fetch_erc20_details(web3, quote_token, raise_on_error=False)
    quote_token = quote_token_details.contract

    if not base_token_details:
        # No need to consider brokeness of token metadata
        # when calculating tax
        base_token_details = fetch_erc20_details(web3, base_token, raise_on_error=False)
    base_token = base_token_details.contract

    if gas_limit:
        # Try to eliminate some RPC calls by not doing gas oracle requests
        # https://web3js.readthedocs.io/en/v1.2.11/web3-eth.html#sendtransaction
        generic_tx_params = {
            "gas": gas_limit,
            "gasPrice": gas_price,
        }
    else:
        generic_tx_params = {}

    # approve router to spend tokens
    if approve:
        quote_token.functions.approve(router.address, quote_token_details.convert_to_raw(buy_amount)).transact(
            {"from": buy_account} | generic_tx_params)

    path = [quote_token.address, base_token.address]
    amountIn = quote_token_details.convert_to_raw(buy_amount)
    # Figure out base_token/quote_token trading pair
    initial_base_bal = base_token.functions.balanceOf(buy_account).call()

    # Buy base_token with buy_account
    try:
        logger.info("Attempting to buy for path %s", path)
        router.functions.swapExactTokensForTokensSupportingFeeOnTransferTokens(
            amountIn,
            0,
            path,
            buy_account,
            FOREVER_DEADLINE
        ).transact({"from": buy_account} | generic_tx_params)
    except ContractLogicError as e:
        msg = str(e)
        if "TRANSFER_FAILED" in msg:
            raise TransferFromError(f"Token does not co-operate:{base_token_details.symbol} - {quote_token_details.symbol}, {e} to router {router.address}") from e
        raise
    except Exception as e:
        raise SwapError(f"swapExactTokensForTokensSupportingFeeOnTransferTokens() buy failed:{base_token_details.symbol} - {quote_token_details.symbol}, {e} to router {router.address}") from e

    received_amt = base_token.functions.balanceOf(buy_account).call() - initial_base_bal

    if received_amt == 0:
        # Nothing was received when we bought the token, so assume 100% tax
        # Would cause division by zero later
        return TokenTaxInfo(base_token.address, quote_token.address, 1.0, 1.0, 1.0)

    uniswap_price = router.functions.getAmountsOut(amountIn, path).call()[1]

    # Measure the loss as "buy tax"
    buy_tax_percent = (uniswap_price - received_amt) / uniswap_price

    # Transfer tokens to sell_account
    # Measure the loss as "transfer tax"
    try:
        base_token.functions.transfer(sell_account, received_amt).transact({"from": buy_account} | generic_tx_params)
    except ValueError as e:
        if "out of gas" in str(e):
            raise OutOfGasDuringTransfer(f"Out of gas during transfer: {e}") from e
        else:
            raise TransferFailure(f"Transfer failure: {e}") from e

    received_amt_by_seller = base_token.functions.balanceOf(sell_account).call()

    transfer_tax_percent = (received_amt - received_amt_by_seller) / received_amt

    # Sell tokens
    try:
        base_token.functions.approve(router.address, received_amt_by_seller).transact({"from": sell_account} | generic_tx_params)
    except ValueError as e:
        if "out of gas" in str(e):
            raise ApprovalFailure() from e

    path = [base_token.address, quote_token.address]

    sell_tax = 0
    sell_tax_percent = 0
    try:
        # this method will revert in case of low liquidity of the token
        logger.info("Attempting to see for path %s", path)
        router.functions.swapExactTokensForTokensSupportingFeeOnTransferTokens(
            received_amt_by_seller,
            0,
            path,
            sell_account,
            FOREVER_DEADLINE
        ).transact({"from": sell_account} | generic_tx_params)
    except ValueError as e:
        if "VM Exception while processing transaction: revert" in str(e):
            raise SellFailed(f"Could not sell {base_token_details.symbol} - {quote_token_details.symbol}: {e}") from e
        elif "out of gas" in str(e):
            raise OutOfGasDuringTransfer() from e
        raise
    except Exception as e:
        raise SwapError(f"Sell failed. swapExactTokensForTokensSupportingFeeOnTransferTokens() method failed: {base_token_details.symbol} - {quote_token_details.symbol}: {e}") from e

    # Measure the loss as "sell tax"
    received_amt_after_sell = quote_token.functions.balanceOf(sell_account).call()
    uniswap_price = router.functions.getAmountsOut(received_amt_by_seller, path).call()[1]

    if received_amt_after_sell > 0:
        sell_tax = uniswap_price - received_amt_after_sell
        sell_tax_percent = (sell_tax / uniswap_price) if uniswap_price > 0 else 0

    return TokenTaxInfo(base_token.address, quote_token.address, buy_tax_percent, transfer_tax_percent,
                        sell_tax_percent)

You can also find the API and dataset dump for existing token tax data here