[Ethereum] How to decode input data from a transaction

blockchainethereumjsprivate-blockchaintransactions

I'm sending a transaction to an account with some data with the following command:

eth.sendTransaction({from:eth.accounts[0],to:eth.accounts[1],value:web3.toWei(1,"ether"),data:web3.toHex("http://localhost:8545")})

I'm getting this result, by extracting the log of the transaction (running with testRPC):

   tx hash         : 0xf654aee5ed23f9aeebd2d73c69c7b9c21a4862787966d09bcb09ed44efc1f252
   nonce           : 0
   blockHash       : 0x6ff8a0e3ac606abd2ede4331b82af52a0daa98448025051fb3b3d50f749aa49f
   blockNumber     : 1
   transactionIndex: 0
   from            : 0xf64918835bc21dff9e8210a807b3964d1be35dd0
   to              : 0x08f986b7535c2b72687d3cb193135f1c6e27c336
   value           : 1000000000000000000
   time            : 1483614904 Thu, 05 Jan 2017 11:15:04 GMT
   gasPrice        : 1
   gas             : 90000
   input           : 0x687474703a2f2f6c6f63616c686f73743a38353435

I want to decode the last line "input" and try to get "http://localhost:8545".
I saw some work similar to my question here and here, but this is not working in my case. Moreover, i tried .toString('hex')) but it remains as hex.

How can I achieve this?

Thanks in advance

Best Answer

You can do web3.toAscii(transactionID.input) to return the data in readable format.

Read web3.toAscii

Related Solutions

[Ethereum] How to decode input data from tx using python3

If you know the contract ABI, call data could be decoded using pyethereum:

from ethereum.abi import (
    decode_abi,
    normalize_name as normalize_abi_method_name,
    method_id as get_abi_method_id)
from ethereum.utils import encode_int, zpad, decode_hex

def decode_contract_call(contract_abi: list, call_data: str):
    call_data_bin = decode_hex(call_data)
    method_signature = call_data_bin[:4]
    for description in contract_abi:
        if description.get('type') != 'function':
            continue
        method_name = normalize_abi_method_name(description['name'])
        arg_types = [item['type'] for item in description['inputs']]
        method_id = get_abi_method_id(method_name, arg_types)
        if zpad(encode_int(method_id), 4) == method_signature:
            try:
                args = decode_abi(arg_types, call_data_bin[4:])
            except AssertionError:
                # Invalid args
                continue
            return method_name, args

[Ethereum] decode ethereum input data

you are missing a vital piece. You wont be able to decode the input or logs until you have the ABI of the "receiver" contract for TX input and the FROM contract for the logs.

To get the ABI: either use etherscan, use https://sourcify.dev/ or find it in IPFS/BZZ by reading the bytecode and parsing out the address if the solidity compiler was allowed to upload it.

AFTER you have the ABI, you pass it to the ethersjs/web3js/web3py and those libraries will be able to parse the input/output.

Edit: Also please keep in mind: if the receiver contract is a "Proxy" contract, you will then need to hunt down the "end receiver" contract address from the internal transactions.

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