checkSpendingCondition returns misleading error message

[vrde]

Bounty

Calling checkSpendingCondition to calculate the outputs of a transaction returns a misleading error message, e.g.:

{
  "jsonrpc": "2.0",
  "id": 666,
  "result": {
    "error": "outputs do not match computation results. \n outputs  \n calculated: {\"address\":\"0x513ab0d35ea18a8a36f16d7e7762b61f893c34ba\",\"value\":\"99999978434176\",\"color\":0}",
    "outputs": [
      {
        "address": "0x513ab0d35ea18a8a36f16d7e7762b61f893c34ba",
        "value": "99999978434176",
        "color": 0
      }
    ]
  }
}

As you can see, result.error says:

outputs do not match computation results. 
 outputs  
 calculated: {"address":"0x513ab0d35ea18a8a36f16d7e7762b61f893c34ba","value":"99999978434176","color":0}

And result.outputs is:

[
  {
    "address": "0x513ab0d35ea18a8a36f16d7e7762b61f893c34ba",
    "value": "99999978434176",
    "color": 0
  }
]

(The only difference between the value in result.error and result.outputs is that the latter is wrapped in an array).

How to reproduce

The steps are:

• create and compile a simple contract
• put some leap in it
• call checkSpendingCondition on a method of the contract

Check the bug on the testnet

I've already put some leap on the target contract. You can try to reproduce it in the test network by running:

curl --data '{"jsonrpc":"2.0","id":666,"method":"checkSpendingCondition","params":["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"]}' -H "Content-Type: application/json" -X POST https://testnet-node.leapdao.org

Actual code

The script I use to reproduce the error is the following:

const Web3 = require("web3");
const { Tx, Input, helpers } = require("leap-core");
const { bufferToHex, ripemd160 } = require("ethereumjs-util");

const web3 = helpers.extendWeb3(new Web3("https://testnet-node.leapdao.org"));
const privateKey = "MY PRIVATE KEY";
const wallet = web3.eth.accounts.privateKeyToAccount(privateKey);

const abi = [
  {
    constant: false,
    inputs: [
      {
        name: "a",
        type: "uint256"
      }
    ],
    name: "aMethod",
    outputs: [],
    payable: false,
    stateMutability: "nonpayable",
    type: "function"
  }
];

let deployedBytecode =
  "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";

const contractAddress = bufferToHex(ripemd160(deployedBytecode));
console.log(contractAddress);
deployedBytecode = Buffer.from(deployedBytecode.replace("0x", ""), "hex");

async function send() {
  const leapOutput = await web3.getUnspent(contractAddress, 0);

  const inputs = [
    {
      prevout: leapOutput[0].outpoint,
      script: deployedBytecode,
      address: contractAddress
    }
  ];

  const contract = new web3.eth.Contract(abi);
  const data = contract.methods.aMethod(55).encodeABI();
  console.log(data);
  let transaction = Tx.spendCond(
    inputs.map(input => {
      const i = new Input(input);
      i.address = input.address;
      return i;
    })
  );
  transaction.inputs[0].setMsgData(data);
  transaction = transaction.signAll(privateKey);
  //transaction = signMatching(transaction, privateKey);
  //
  console.log(
    JSON.stringify({
      jsonrpc: "2.0",
      id: 666,
      method: "checkSpendingCondition",
      params: [transaction.hex()]
    })
  );
  web3.currentProvider.send(
    {
      jsonrpc: "2.0",
      id: 666,
      method: "checkSpendingCondition",
      params: [transaction.hex()]
    },
    (err, response) => {
      if (err) {
        throw new Error("smth went wrong", err.toString());
      }
      console.log("checkSpendingCondition", err, JSON.stringify(response));
    }
  );
}

send();

Scope

• reproduce and fix the issue

Deliverables

• fix the issue 😃

Gain for the project

Less confused devs.

Roles

bounty gardener: @vrde / 15%
bounty worker: name / share
bounty reviewer: name / share