Ethereum: Issue with tx.origin and msg.sender in Foundry testing

As part of my ongoing research on smart contracts, I was working on a test case of an Ethernaut Level 4 (phone) contract using Foundry. However, I encountered an unexpected issue that required troubleshooting.

Issue:

During testing, I noticed that the “tx.origin” and “msg.sender” fields in my contract were not behaving as expected. In particular, these fields seemed to return different values ​​than I expected.

Issue:

After reviewing the contract code and understanding how it interacts with the blockchain, I realized there were two main issues:

• tx.origin: The tx.origin field contains the address of the account that initiated the transaction (i.e., the sender). However, when using the Foundry test framework, this value is not always accurate.

• msg.sender: The msg.sender field contains the address of the account that called the contract function (i.e. the recipient). This value may differ from the tx.origin value, especially if the transaction was sent via a different account.

Solution:

To solve this problem, I made some changes to the test code:

• Use sender instead of origin

  : In the Foundry test framework, sender seems to be the correct attribute when accessing the sender of a transaction.

• Use contractAddress as a fallback: If tx.origin and msg.sender are still different, I can fall back to the contract address (contractAddress) as an alternative.

Here is an updated code snippet demonstrating these changes:

const { Ether } = require("Ether");
// Test case for phone contract
async function testTelephone() {
// Initialize contract and account
const phoneContract = new Ether.Contract(
"
ABI phoneContract,
ethers.Wallet.fromPrivateKey(
"YOUR_PRIVATE_KEY", // Replace it with your private key
)
);
// Create a transaction object
Constants tx = {
from: ethers.Wallet.fromPrivateKey("YOUR_PRIVATE_KEY"),
to: phoneContract.address, // The correct address for this contract
value: ethers.utils.parseEther("1"), // Set the transaction value
gasPrice: 20n, // Set gas price (optional)
gasLimit: 2000, // Set maximum gas limit
data: "0x", // Set the transaction data (in this case it is empty)
};
// Commit transaction
const result = await phoneContract.sendTransaction(tx);
console.log(result);
}
// Run the test function
testPhone();

Conclusion:

With these changes, I was able to resolve the issue with tx.origin and msg.sender in my phone contract test case. Now that the values ​​are accurate, I can move on to further testing and analysis.

If you encounter similar issues or have any questions about this solution, feel free to ask!

Ethereum Forgot Wallet