Transaction context (tx.origin vs msg.sender) in Blockchain / Solidity - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the address of the immediate caller.

Blockchain / Solidity

address caller = [1];

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Amsg.sender

Btx.origin

Cthis

Daddress(this)

Attempts:

3 left

💡 Hint

Common Mistakes

Using tx.origin instead of msg.sender when you want the immediate caller.

msg.sender is the address of the immediate caller of the function, which is what you want here.

2fill in blank

medium

Complete the code to get the original external account that started the transaction.

Blockchain / Solidity

address origin = [1];

Drag options to blanks, or click blank then click option'

Amsg.sender

Baddress(this)

Ctx.origin

Dblock.coinbase

Attempts:

3 left

💡 Hint

Common Mistakes

Using msg.sender instead of tx.origin to get the original transaction sender.

tx.origin is the original external account that started the transaction, even through multiple calls.

3fill in blank

hard

Fix the error in the require statement to check the immediate caller is the owner.

Blockchain / Solidity

require([1] == owner, "Not owner");

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Amsg.sender

Baddress(this)

Cowner

Dtx.origin

Attempts:

3 left

💡 Hint

Common Mistakes

Using tx.origin in authorization checks, which can be exploited.

You should use msg.sender to check the immediate caller, not tx.origin.

4fill in blank

hard

Fill both blanks to create a function that returns the original transaction sender and the immediate caller.

Blockchain / Solidity

function getSenders() public view returns (address origin, address sender) {
    origin = [1];
    sender = [2];
}

Drag options to blanks, or click blank then click option'

Atx.origin

Bmsg.sender

Caddress(this)

Dblock.coinbase

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping tx.origin and msg.sender in the return values.

This function returns tx.origin as the original transaction sender and msg.sender as the immediate caller.

5fill in blank

hard

Fill all three blanks to create a function that returns the original sender, immediate caller, and contract address.

Blockchain / Solidity

function getContext() public view returns (address origin, address sender, address contractAddr) {
    origin = [1];
    sender = [2];
    contractAddr = [3];
}

Drag options to blanks, or click blank then click option'

Atx.origin

Bmsg.sender

Caddress(this)

Dblock.coinbase

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing contract address with sender addresses.

This function returns tx.origin as the original transaction sender, msg.sender as the immediate caller, and address(this) as the contract's own address.