“out of gas” when trying to send back ETH from a contract to tx.origin

Question

(UPDATED)

The contract should have more than enough ETH. I deploy the contract with 0.1 ETH: https://git.io/JUBdy

const consumerExample = await ConsumerExampleFactory.deploy(process.env.REGISTRATION_GATEWAY_ADDRESS, { value: ethers.utils.parseEther("0.1") });

The contract then sends a transaction with a value of 100 wei to another contract: https://git.io/JUBd9

constructor(address simplorRegistrationGatewayAddress) SimplorConsumer(simplorRegistrationGatewayAddress) payable {
    registerSimplorEvent("RequestEthPriceEvent");
}

and

function registerSimplorEvent(string memory eventName) public payable {
  _registrationGateway.registerEvent{ value: 100 }(
    eventName,
    address(this)
  );
}

Then an event is triggered (https://git.io/JUBd7) to which a node responds (https://git.io/JUBd5) to fulfillInt (https://git.io/JUBdF) which then (in the SimplorFulfill modifier) is supposed to send 100 wei back to the node's address (https://git.io/JUBdN).

Calling the method that triggers the event:

const ethPrice = await consumerExample.requestEthPrice()

A node listening for it and sending back data:

consumers[callbackContractAddress].methods[fulfillTypeMethod](fulfillCallback, response.value, requestId, response.requestPrice).send({
  from: process.env.NODE_ACCOUNT
}).then(tx => { ...

(fulfillTypeMethod = "fulfilInt", response.requestPrice = 100)

The receiving function:

function fulfillInt(
  bytes4 fulfillCallback,
  uint256 value,
  uint256 requestId,
  uint256 requestPrice
) external onlySimplOracle SimplorFulfill(requestId, requestPrice) {...

and finally in it's second modfier:

modifier SimplorFulfill(uint256 requestId, uint256 requestPrice) {
  // check/increase confirmations
  require(_simplorCurrentResponses[requestId] < _simplorRequiredResponses[requestId], "Request already confirmed.");
  require(address(this).balance > requestPrice, "Consumer does not have enough ETH to pay for the fulfillment.");
  _simplorCurrentResponses[requestId]++;
  // transfer 100 wei (TODO: calculate/set fees)
  payable(tx.origin).transfer(requestPrice); // This seems to cause the "out ouf gas" error.

  _;
}

UPDATE I added the second require(...) to check if the consumer has anough ETH.

Causes: Returned error: VM Exception while processing transaction: out of gas

Remember the contract was deployed with 0.1 ETH and already managed to send 100 Wei to the _registrationGateway when calling registerSimplorEvent in its constructor.

The requestPrice comes from another package (https://git.io/JUBb9):

return {
  value: result.data.ethereum.usd * 100,
  type: 'int', // currently supported: 'bool', 'int' and 'string'
  requestPrice: 100 // Wei
}

Here is my repository with the full code: https://github.com/mktcode/simplor/blob/master/contracts/SimplorConsumer.sol#L81

Answer 1

Edit: Sorry, the below information is only for in-memory arrays as said by @goodvibration.

You're not allocating memory for your array, i.e., you don't instantiate it with the new operator, see https://solidity.readthedocs.io/en/v0.7.1/types.html#allocating-memory-arrays.

So when trying to push on an array that wasn't instantiated yet, it will fail.

_simplorIntResponses[requestId] = new uint256[]()