Solidity – How to Call Selfdestruct Without Writing It in Contract

ethereumjselfdestructsolidity

as mentioned in documentation "Even if a contract’s code does not contain a call to selfdestruct, it can still perform that operation using delegatecall or callcode." so my question is how does it possible , my purpose is to release Eth which stuck in a contract due to code mistake, and there is no way to withdraw now

Best Answer

If your contract has a function to run delegatecall with some way to provide the function to call, you can in make it run a function in another contract, which calls selfdestruct. Since functions ran by delegatecall will execute in the context of the first contract, this will self destruct the first contract. For example:

contract A {
  function kill (address payable to) public {
    selfdestruct(to);
  }
}

contract B {
  function run (address target, string calldata func, address to) public {
    target.delegatecall(abi.encodeWithSignature(func, to));
  }
}

Calling run with the address of contract A, kill(address) as func and any address as to, will cause contract B to self destruct and send the Ether to address to.

This run function is not very secure, as you can see. If your contract does not have such a function built-in, you're out of luck, and your ETH is unfortunately stuck.

Related Solutions

Solidity – How to Get Delegatecall to Return Data

The issue is that the response variable is not a memory pointer, it's a stack variable. When you use it as the pointer for your out data in the delegatecall, you're actually just writing the data to the 0 memory location. This doesn't cause errors because that space is reserved for "scratch space", but it also never loads the result into your return variable.

What you want to do is

assembly {
        let status := delegatecall(sub(gas,5000), dest, add(calldata, 0x20), mload(calldata), 0, 32)
        response := mload(0)
        jumpi(invalidJumpLabel, iszero(status))
}

Delegatecall in Transactions – Usage and Best Practices

DELEGATECALL is an instruction interpreted by EVM. So to execute DELEGATECALL you have to have a program (contract) that gets executed on EVM.

DELEGATECALL takes six operands, one of them is the address of the calee. So it can only call deployed contracts. Note that so called library is just a special contract which operations are called with DELEGATECALL.

So to answer your question directly as I understand it: No - it is not possible to execute arbitrary code from an external account.

What you can do though is you can create a contract that implements the logic as you want it and uses DELEGATECALL to preserve sender and value when calling other contracts.

Best Answer

Related Solutions

Solidity – How to Get Delegatecall to Return Data

Delegatecall in Transactions – Usage and Best Practices

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