Questions tagged [delegatecall]

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Usecase for approve and allowance functions of ERC20 token

Could you please enlighten me on how approve and allowance functions work using a usecase? I dont understand the underlying operations of these functions. Especially, when a token owner delegates the ...
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1answer
24 views

How do you call a fallback function that uses msg.data for parameters

I am trying to complete a homework assignment, so I am not doing something malicious. The goal is to learn the vulnerabilities of contracts. I want to call the fallback function of wallet to trigger ...
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1answer
54 views

How to perform delegate call inside of view call (staticall)?

Inside view method it's not possible to do delegatecall due to compilation errors. Is there any way to delegate view calls?
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1answer
34 views

Dynamic Delegate Proxy contract

I'm familiar with proxy contracts in solidity using the 'delegatecall' to separate out the proxy contract from the logic contract. Is there a simple way to choose the logic contract based on an ...
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1answer
50 views

Factory contract to clone existing contracts

I am researching about Factory contract to clone existing contracts, First is the implementation present at https://github.com/optionality/clone-factory/blob/master/contracts/CloneFactory.sol. I don't ...
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38 views

What are “if” and “this” in this function?

function() public { if(delegate.delegatecall(msg.data)) { this; What are the requirements for "if" to execute "this" and what does "this" refer to in this function?
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Safe usage of delegatecall

Hey guys I have a few questions about delegatecall. The setup: I have 2 contracts A and B. A has 2 uint state variables B has 4 uint state variables To ensure storage layout compatibility, B ...
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1answer
39 views

Upgradable contract proxy pattern: Get the invoked method name in the fallback function

I have a proxy smart contract and I would like to get the name of the called method in the fallback function. Is there a way? For example, if I call the function getName() (stored in the logic ...
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20 views

How dangerous is this: number of contracts contain a function like “approveandcall” which lets anyone call any contract (some thoughts?)

The most common implementation is as follows: function approveAndCall(address _spender, uint256 _value, bytes _extraData) public returns (bool success) { tokenRecipient spender = tokenRecipient(...
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1answer
49 views

How to use call, delegate call?

I have created two contracts A and B as follow: Contract A: pragma solidity 0.4.25; contract A{ // uint public X ; event MyName(address _from, address sender); function checkMe(uint val)...
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55 views

How to use delegate call with or without arguments functions?

Below is my contract: contract A{ mapping (address => uint) public balances; function put() payable public { balances[msg.sender] = msg.value; } function get(address ...
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1answer
58 views

Using delegatecall for multiple parameters fuction in solidity

Does someone have a exemple of solidity delegatecall for multiple parameters function?
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2answers
359 views

Pros and Cons of smart contract upgradable patterns

There have been quite many arguments around how to achieve smart contract updates like Upgradeable smart contracts. I feel Proxycontract with Delegate-call is currently the most famous one. But aside ...
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No Events After Deploying Another Contract in Remix

I am trying to write an upgradable smart contract in Remix. This involves a Proxy contract, a Logic_0_1_0 contract, and a Logic_0_2_0 contract. I uploaded Proxy and Logic_0_1_0 only, and the ...
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1answer
220 views

Delegatecall return values solidity 5.0

With solidity 5.0+ , the delegatecall function can return a boolean and a bytes representing return value. I want to understand how does one convert the returned bytes to various datatypes. ex If ...
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1answer
26 views

Calling Msg.sender Natively

Caller -> Contract B -> Contract A Contract A has a msg.sender variable. I want to use the Caller as Msg.Sender for Contract A through Contract B. How is this done?
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1answer
41 views

How do you pause a Proxy-Logic pattern?

Suppose we have a Proxy contract that forwards to call to a Logic contract by using delegatecall. If we pause the Proxy, users will still be able to directly interact with the Logic contract. While ...
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1answer
132 views

What's the equivalent of Vyper's create_forwarder_to in Solidity?

In Vyper, there's a built-in function called create_forwarder_to, which Duplicates a contract’s code and deploys it as a new instance, by means of a DELEGATECALL. If my understanding is correct, ...
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0answers
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delegatecall (assembly) didn't change state variable in Remix with Web3 Provider

I am trying to test proxy pattern in Remix, which connected to my private chain with Web3 Provider. By the way, miner is working all the time. After invoking add function of Proxy contract, the state ...
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0answers
114 views

Anything like a static delegatecall from a view function?

let's say there are two contracts A and B, where A calls methods in B. I understand that A can modify and read storage in B with B.call() and B.staticcall(), ie. A can execute B's methods in the ...
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1answer
42 views

pass storage through interface to library

Here is what am i doing: There is a library, accept storage argument as parameter, then do some math and return the result. And there is a contract to call the function in the library, and an extra ...
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1answer
112 views

Correct way to make a delegatecall? [duplicate]

I made a delegatecall to the REP contract to approve my contract to spend tokens on behalf of a user and my transaction is failing for some reason here is my code: (bool b,) = REPAddress.delegatecall(...
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1answer
43 views

Unstructured storage proxies. Variables not being overwritten?

When using delegate call I was under the impression that storage slots declared in the proxy will be overwritten by the implementation. Unstructured storage implementations declare bytes32 variables ...
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1answer
67 views

How to prevent the code of my contract being used in a CALLCODE?

Simple question but I couldn’t find the answer anywhere. How to know if the code of my contract is used in a CALLCODE or DELEGATECALL by third party sinceaddress(this)returns the address of the caller ...
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0answers
60 views

Delegatecall not changing state

I was trying the code in https://gist.github.com/sogoiii/f0ced0a4e569b5f38d302e7072d78b43 to observe the difference between call and delegatecall. pragma solidity ^0.4.18; contract D { uint public ...
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1answer
206 views

Difference in “delegate call via assembly”

I came across a different version of delegate call via assembly and also tried all of them - no different result so far. How does it differ and which is the best version to use? OpenZepplin version: ...
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68 views

Subtraces of delegatecall in Parity trace

I'm investigating transactions using Parity trace which provides useful data over a transaction flow. Among this data is the Subtraces field which allows me to understand how many sub-calls each ...
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1answer
59 views

DelegateCall to internal function doesn't store variable

Why isn't delegate call able to run internal functions? What is the difference between a self directed delegate call and a contract normally calling one of it's internal function? contract ...
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2answers
136 views

Code Example from “Mastering Ethereum: Building Smart Contracts and DApps” doesn't work

I'm reading the Ethereum book of Gavin Wood right know and the following code example gives an error message when I try to compile it with truffle: pragma solidity ^0.4.22; contract calledContract { ...
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0answers
122 views

Proxy contract DELEGATECALL to pass a DYNAMIC array to a function in the target contract

I'm trying to get a Proxy contract to correctly do a delegatecall to a function in another 'target' contract. The problem is, that I need to pass a dynamic array as the parameter to this function. Q: ...
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0answers
39 views

Replaying the Bad Parity Hack

On a locally hosted instance of Ethererum I am trying to replay and understand the Bad Parity hack. I have a Wallet and a Wallet Library Contract. Wallet.sol constructor(address lib) public payable {...
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1answer
290 views

Is it possible to send Ether using delegatecall?

I tested this in Remix and it seems that the ether remains in the delegator contract and doesn't get forwarded. Using the code below to test: contract SomeContract { address public sender; ...
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0answers
152 views

How would you use a proxy erc20 contract if you cannot preserve msg.sender?

Let's say I use a proxy contract which allows me to make an ERC20 token transfer from my account. At the moment the only way to do so is to use tx.origin which gets the original EOA address of the ...
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1answer
149 views

Delegatecall: Storing values

Using a delegatecall() to call another contract will have that contract run from within your context (e.g. if it calls a contract on its turn as a result, msg.sender will be your address). I am aware ...
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153 views

How to allow delegatecall only from specific contract?

I have a token contract, when transfer is called it calls other contract's transfer with data. Other contract checks msg.sender and allows only the first contract to pass and performs some important ...
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1answer
411 views

How to use Role-Based Access Control via Proxy?

I have a PermissionsManager contract that uses OpenZeppelin's Role-Based Access Control (RBAC) template as a base. Currently function modifiers in my app call PermissionsManager directly to check for ...
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1answer
2k views

How does delegatecall work from Solidity 0.5.0 onwards?

I am trying, for learning purposes only, to make a mutable smart contract, but I couldn't find anything useful on stackexchange because everything I found was using pragma solidity ^0.4.x; So, I have ...
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Can anyone give me a working DELEGATECALL example? [duplicate]

I tried many variants of DELEGATECALL, but not one of them gave me the desired result. When used in assembly: = delegatecall (), I also don't get the result. I also used different versions of Solidity ...
2
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1answer
358 views

Calling fallback function in truffle to delegate a call

I'm playing with the upgradeable contracts via DelegateProxy in Solidity. This pattern posits that a MutableForwarder contract is deployed once, and all the subsequent calls to the upgradeable ...
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1answer
168 views

Proxy Contract Not Updating Store Data

I want to setup a proxy contract that my users can interact with. The proxy contract is a store contract with stores the user's age for now. When I call writeData to update my age, I expect it to call ...
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1answer
236 views

contract kill function

as per ethereum docs Even if a contract’s code does not contain a call to selfdestruct, it can still perform that operation using delegatecall or callcode. is this real? 1.if it is then even if ...
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1answer
119 views

How does a contract know which library to query or know the library address?

How does a contract know which library to query? For Example in the code below (The code is from solidity docs: https://solidity.readthedocs.io/en/v0.4.24/contracts.html?highlight=library#libraries ...
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Delegatecall Scope - Correct me if I'm wrong

When any contract function is called - delegatecall or otherwise - the EVM loads the requisite pointers & values into that call frame's volatile stack/memory. Example: Let's say we have contract ...
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3answers
597 views

Scope confusion using delegate call

I am having trouble understanding the scope with delegatecall method. Here are my two contracts: contract Caller { uint public testVar = 88; uint public myVariable = 6; function ...
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2answers
552 views

Double delegate call doesn't work

To create an upgradeable contract I have to use multiple proxies. The contract applies to Proxy A, then Proxy A applies to Proxy B. But delegatecall doesn't work in this case. The simplified code of ...
2
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1answer
352 views

Use of delegatecall with msg.data

I'm trying to understand below code: pragma solidity ^0.4.23; contract Relay { address public currentVersion; address public owner; modifier onlyOwner() { require(msg.sender == ...
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1answer
168 views

Delegatecall require statement does not cause an abortion in any way

This is a sequel to a previous question of mine. I want to implement a validation function (e.g. for passwords) within a central contract, that could be used by other contracts. It is important to ...
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1answer
122 views

What method can I use instead of delegatecall?

I see the warning security/no-low-level-calls: Avoid using low-level function 'delegatecall' when I use delegatecall function in my code. I understand why it's not a good way, but I still need that ...
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delegatecall for Smart Contract versioning

I've a state variable address public current; which stores the address of the latest updated contract. This value can be modified with a function. Then, I've a function of this kind function ...
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1answer
784 views

Solidity - selfdestruct

I'm just wondering what would happen if I don't put a selfdestrut() method in my smart contract. As I read from the Solidity documentation (Self-destruct): Even if a contract’s code does not ...