Can I replicate ethereum transaction knowing hash/input data?

Question

I found puzzling transaction that I would like to replicate or understand how its done. Can it be done from the hash/input data?

https://etherscan.io/tx/0x4a7c5c53af00834b33db5a5d4e3a1f75c6a36125dd5bc514e6f8249a644725d2

Answer 1

Etherscan gives you:

• The ABI of the contract which this transaction was sent to here
• The bytecode (aka input data) of the transaction here (under click to see more)

Taking these two pieces of information, you can run the following NodeJS script (web3 v1.2.1):

const Web3 = require("web3");

const ABI = [{"constant":false,"inputs":[{"name":"marketId","type":"uint256"},{"components":[{"name":"value","type":"uint256"}],"name":"spreadPremium","type":"tuple"}],"name":"ownerSetSpreadPremium","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"operator","type":"address"}],"name":"getIsGlobalOperator","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketTokenAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"marketId","type":"uint256"},{"name":"interestSetter","type":"address"}],"name":"ownerSetInterestSetter","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"components":[{"name":"owner","type":"address"},{"name":"number","type":"uint256"}],"name":"account","type":"tuple"}],"name":"getAccountValues","outputs":[{"components":[{"name":"value","type":"uint256"}],"name":"","type":"tuple"},{"components":[{"name":"value","type":"uint256"}],"name":"","type":"tuple"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketPriceOracle","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketInterestSetter","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketSpreadPremium","outputs":[{"components":[{"name":"value","type":"uint256"}],"name":"","type":"tuple"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"getNumMarkets","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"token","type":"address"},{"name":"recipient","type":"address"}],"name":"ownerWithdrawUnsupportedTokens","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"components":[{"name":"value","type":"uint256"}],"name":"minBorrowedValue","type":"tuple"}],"name":"ownerSetMinBorrowedValue","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"components":[{"name":"value","type":"uint256"}],"name":"spread","type":"tuple"}],"name":"ownerSetLiquidationSpread","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"components":[{"name":"value","type":"uint256"}],"name":"earningsRate","type":"tuple"}],"name":"ownerSetEarningsRate","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"},{"name":"operator","type":"address"}],"name":"getIsLocalOperator","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"components":[{"name":"owner","type":"address"},{"name":"number","type":"uint256"}],"name":"account","type":"tuple"},{"name":"marketId","type":"uint256"}],"name":"getAccountPar","outputs":[{"components":[{"name":"sign","type":"bool"},{"name":"value","type":"uint128"}],"name":"","type":"tuple"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"marketId","type":"uint256"},{"components":[{"name":"value","type":"uint256"}],"name":"marginPremium","type":"tuple"}],"name":"ownerSetMarginPremium","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"getMarginRatio","outputs":[{"components":[{"name":"value","type":"uint256"}],"name":"","type":"tuple"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketCurrentIndex","outputs":[{"components":[{"name":"borrow","type":"uint96"},{"name":"supply","type":"uint96"},{"name":"lastUpdate","type":"uint32"}],"name":"","type":"tuple"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"marketId","type":"uint256"}],"name":"getMarketIsClosing","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"getRiskParams","outputs":[{"components":[{"components":[{"name":"value","type":"uint256"}],"name":"marginRatio","type":"tuple"},{"components":[{"name":"value","type":"uint256"}],"name":"liquidationSpread","type":"tuple"},{"components":[{"name":"value","type":"uint256"}],"name":"earningsRate","type":"tuple"},{"components":[{"name":"value","type":"uint256"}],"name":"minBorrowedValue"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const DATA = "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";

const web3 = new Web3();
const contract = new web3.eth.Contract(ABI);

for (const object of contract._jsonInterface) {
    if (DATA.startsWith(object.signature)) {
        const args = web3.eth.abi.decodeParameters(object.inputs, DATA.slice(object.signature.length));
        console.log(`Function Name: ${object.name}`);
        for (let i = 0; i < args.__length__; i++)
            console.log(`Arg #${i + 1}: ${JSON.stringify(args[i], null, 4)}`);
    }
}

And discover that the given transaction has executed the following:

Function Name: operate
Arg #1: [
    [
        "0x8ebaB0129fFEA1145a505D8D6D5d046770dd97e6",
        "0"
    ]
]
Arg #2: [
    [
        "1",
        "0",
        [
            false,
            "0",
            "0",
            "10029599020000000000000"
        ],
        "3",
        "0",
        "0x8ebaB0129fFEA1145a505D8D6D5d046770dd97e6",
        "0",
        "0x"
    ],
    [
        "0",
        "0",
        [
            true,
            "0",
            "0",
            "10029599020"
        ],
        "2",
        "0",
        "0x8ebaB0129fFEA1145a505D8D6D5d046770dd97e6",
        "0",
        "0x"
    ]
]

Some further explanation regarding the transaction bytecode structure:

• The first 4 bytes are the function selector (first 4 bytes in the 32-byte hash of the function signature)
• The remaining bytes are the input passed to this function (encoded as a single hexadecimal string)