2

I am following the tutorial at https://medium.com/@gus_tavo_guim/reentrancy-attack-on-smart-contracts-how-to-identify-the-exploitable-and-an-example-of-an-attack-4470a2d8dfe4 and deploying the following contract:

pragma solidity ^0.4.16;
contract HoneyPot {
  mapping (address => uint) public balances;
  function HoneyPot() payable {
    put();
  }
  function put() payable {
    balances[msg.sender] = msg.value;
  }
  function get() {
    if (!msg.sender.call.value(balances[msg.sender])()) {
      revert();
    }
      balances[msg.sender] = 0;
  }
  function() {
    revert();
  }
}

When this contract receives ether, the HoneyPot() constructor should be executed, which will call the put() function and run the balances[msg.sender] = msg.value; line. However, when I send ether to this contract I get a "bad instruction" error on etherscan (after waiting a couple of minutes and using the ropsten test network). What might the issue be here? as both HoneyPot() and put() functions are payable (as is required when receiving ether).

2

HoneyPot() is the constructor of the contract and it is called only once in the contract's lifetime, in particular during the creation of the contract. When you send funds to a contract without specifying a function to call, the fallback function function() is called instead.

Your fallback function contains a revert command, and then it correctly throws an exception.

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