ethereum-input-data-decoder

ethereum-input-data-decoder

Ethereum smart contract transaction input data decoder

Demo

https://lab.miguelmota.com/ethereum-input-data-decoder

Install

npm install ethereum-input-data-decoder

Getting started

Pass ABI file path to decoder constructor:

const InputDataDecoder = require('ethereum-input-data-decoder');
const decoder = new InputDataDecoder(`${__dirname}/abi.json`);

Alternatively, you can pass ABI array object to constructor;

const abi = [{ ... }]
const decoder = new InputDataDecoder(abi);

example abi

Then you can decode input data:

const data = `0x67043cae0000000000000000000000005a9dac9315fdd1c3d13ef8af7fdfeb522db08f020000000000000000000000000000000000000000000000000000000058a20230000000000000000000000000000000000000000000000000000000000040293400000000000000000000000000000000000000000000000000000000000000a0f3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c800000000000000000000000000000000000000000000000000000000000000034254430000000000000000000000000000000000000000000000000000000000`;

const result = decoder.decodeData(data);

console.log(result);

{
  "name": "registerOffChainDonation",
  "types": [
    "address",
    "uint256",
    "uint256",
    "string",
    "bytes32"
    ],
    "inputs": [
      <BN: 5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02>,
      <BN: 58a20230>,
      <BN: 402934>,
      "BTC",
      <Buffer f3 df ... 71 c8>
    ]
}

Example using input response from web3.getTransaction:

web3.eth.getTransaction(txHash, (error, txResult) => {
  const result = decoder.decodeData(txResult.input);
  console.log(result);
});

Decoding Big Numbers

All numbers are returned in big number format to preserve precision.

Here's an example of how to convert the big number to a human readable format.

console.log(result.inputs[0].toString(10)) // "5"
console.log(result.inputs[0].toNumber()) // 55

Please keep in mind that JavaScript only supports numbers up to 64 bits. Solidity numbers can be up to 256 bits, so you run the risk of truncation when casting or having the big number library error out when trying to parse a large number to a JavaScript Number type.

const n = new BN("543534254523452352345234523455")
console.log(n.toString(10)) // "543534254523452352345234523455"
console.log(n.toNumber()) // ERROR!

CLI

Install

npm install -g ethereum-input-data-decoder

Usage

$ ethereum_input_data_decoder --help

  Ethereum smart contract transaction input data decoder

  Usage
    $ ethereum_input_data_decoder [flags] [input]

  Options
    --abi, -a  ABI file path
    --input, -i Input data file path

  Examples
    $ ethereum_input_data_decoder --abi token.abi --input data.txt
    $ ethereum_input_data_decoder --abi token.abi "0x23b872dd..."

Example

Pass ABI file and input data as file:

$ ethereum_input_data_decoder --abi abi.json --input data.tx

name      registerOffChainDonation
address   0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02
uint256   1487012400
uint256   4204852
string    BTC
bytes32   0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8

Pass ABI file and input data as string:

$ ethereum_input_data_decoder --abi abi.json 0x67043cae0...000000

name      registerOffChainDonation
address   0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02
uint256   1487012400
uint256   4204852
string    BTC
bytes32   0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8

You can also pipe the input data:

$ cat data.txt | ethereum_input_data_decoder --abi abi.json

name      registerOffChainDonation
address   0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02
uint256   1487012400
uint256   4204852
string    BTC
bytes32   0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8

Test

npm test

Development

1. Clone repository:

git clone [e-mail]:miguelmota/ethereum-input-data-decoder.git

cd ethereum-input-data-decoder/

1. Install dependencies:

npm install

1. Make changes.

2. Run tests:

npm test

1. Run linter:

npm run lint:fix

FAQ

• Q: How can I retrieve the ABI?

  • A: You can generate the ABI from the solidity source files using the Solidity Compiler.

    solc --abi MyContract.sol -o build
    

• Q: Can this library decode contract creation input data?

  • A: Yes, it can decode contract creation input data.

License

MIT