19
votes
Accepted
What exactly is a proxy contract and why is there a security vulnerability involved in it?
A proxy contract is a contract which delegates calls to another contract. To interact with the actual contract you have to go through the proxy, and the proxy knows which contract to delegate the call ...
- 28.8k
16
votes
Accepted
How do I get the implementation contract address from the proxy contract address?
Most proxy contracts typically have a public variable defined as a:
address public implementation;
Which defines the address of the implementation contract. You could then call it as a view function ...
- 10.5k
11
votes
forward revert message from low level solidity call
The following code performs a delegate call, and if the delegate call reverts, the transaction is reverted with the reason given by the delegate call.
(bool success, bytes memory result) = address(...
- 211
10
votes
forward revert message from low level solidity call
It is simpler than you think:
require(success, string (returndata));
See documentation for details. You may also forward raw bytes, but you will need to use assembly.
- 7,273
10
votes
Accepted
Difference between __init and __init_unchained
From OpenZeppelin's docs, there is the following section:
Initializer functions are not linearized by the compiler like constructors. Because of this, each __{ContractName}_init function embeds the ...
- 4,436
9
votes
Accepted
What is the value of "address(this)" when delegate calling?
Remember how DELEGATECALL works:
DELEGATECALL basically says that I'm a contract and I'm allowing (delegating) you to do whatever you want to my storage. DELEGATECALL is a security risk for the ...
- 17.3k
9
votes
Accepted
How can I use a proxy contract with ethers.js?
I used attach to call the implementation functions from my proxy contract:
adder = Delegate.attach(proxy.address) as Delegate
- 106
8
votes
Accepted
Finding the address of the proxied to address of a proxy
Implementation is stored as value in IMPLEMENTATION_SLOT (see the source code), so you can get the underlined Contract with:
let proxyContract = "0x4fabb145d64652a948d72533023f6e7a623c7c53";
...
- 1,979
6
votes
What exactly is a proxy contract and why is there a security vulnerability involved in it?
Proxies (or "diamonds", which is just a name for a specific proxy system specified as an EIP) allow part or all of a contract to be swapped out at any time, without changing the address of ...
- 410
5
votes
What's the difference between Truffle Migrations and ZeppelinOS upgradeable contracts?
Smart contracts are immutable (code cannot be changed) by design.
Truffle and ZeppelinOS are platforms for the development of smart contracts for Ethereum based blockchains.
Truffle migrate manages ...
- 1,338
5
votes
Accepted
hardhat-deploy deterministic deployment
In order to use Create2 and get the same address, you have to pass the same variables:
create2(someValueToPreventCollisionWithCreate, msg.sender, salt, contractBytecode)
So if your contractBytecode ...
- 10.5k
5
votes
Why is Bitwise AND operator used for comparing singleton address and 0xfff... in GnosisSafeProxy.sol
General objective of doing this and operation is to get extract the 20 bytes address with in a 32 bytes slot. There can be packed values with the address to clean up this is needed. The following ...
- 518
4
votes
Accepted
What's the difference between Truffle Migrations and ZeppelinOS upgradeable contracts?
In case of truffle the stored values will not remain in the upgraded contract whereas in proxy approach it is possible to obtain the stored values in the upgraded contract too.
In truffle upgrade a ...
- 186
4
votes
Accepted
Ownable in upgradeable contracts
You simply need to call the init method of OpenZeppelinUpgradesOwnable, which is __Ownable_init(), inside your initialize(...) method body. Also, remember to use the initializer to so as to restrict ...
- 4,436
4
votes
OpenZippelin upgradeability pattern | How can both implementation and proxy contracts share the same storage tho they were implemented independently?
good question, yes you are right the proxy contract and the implementation are deployed independently and have different storage layouts.
The magic here is, that when calling the Proxy contract, ...
- 1,383
3
votes
Accepted
forward revert message from low level solidity call
You can do it very concisely:
(bool success, bytes memory result) = addr.delegatecall(data);
if (success == false) {
assembly {
revert(add(result,32),mload(result))
}
}
3
votes
Accepted
How do Proxy Upgraded Logic Contracts Share Data
It might be cognitively useful to think of the proxy contract importing bytecode from the logic contracts for its own use because they execute in the context of the proxy and use the proxy for storage....
- 54.7k
3
votes
How do Proxy Upgraded Logic Contracts Share Data
Upgradability in smart contracts is nice feature that gives you the option to upgrade your logic and keep the contract data safe. Let's take for example we have 2 contracts first one is where the data ...
- 3,396
3
votes
Using a high level delegate call in upgradable contracts since Byzantium
One issue is that you copy your data into memory starting at address 0. This will work for return sizes less than 64 bytes, but will start overwriting other memory at that point.
Instead you should ...
- 36.7k
3
votes
Accepted
On the unstructured storage upgrade pattern, why do we have to follow the structure of the previous contract?
This is because Solidity sets up the variables in storage sequentially. So if you move the references of storage variables in the upgraded one, they'll be referring to the wrong slot in storage. Here'...
- 11.9k
3
votes
Accepted
How to make Solidity Contracts Upgradable with a mapping and state variables?
First the short answers:
As we know the mappings can grow, how to allot a slot for them, and what would be the setters and getters look like?
You could define a hash function that uses both a "...
- 54.7k
3
votes
Accepted
Call fallback function from eth-brownie from proxy
You need to use
The actual ABI of the implementation instead of the ABI file of the proxy contract
Address of the proxy contract
from brownie import Box, TransparentUpgradeableProxy, Contract
...
- 21.7k
3
votes
Accepted
EIP-2535 Diamond implementation how-to?
Answering myself:
Diamond proxy MUST NOT implement the interfaces.
Client code using contract-like code-style to build the transaction (vs building them manually) need to instantiate the contract-...
- 596
3
votes
Ethernauts level 25 solution help
Your issues are here :
(bool success, bytes memory data) = address(originalContract).call{gas:7000}(abi.encodeWithSignature("initialize()"));
And here :
(bool success, bytes memory data) = ...
- 7,386
3
votes
How can I decode the event log I receive in my txn where there more than 1 smart contract involved and the emitted event cannot be found in ABI
The ABI posted to Mumbai implementation contract is probably lacking.
Take transaction 0x32e3230a7478315092a04ef57fc2426947ec5031c6977c7b184e7bcd02be9216 for instance, if you look at Mumbai Explorer ...
- 2,934
3
votes
Accepted
Chainlink Oracle - What events are emitted and which should i listen to for price updates?
The address that you mentioned is actually the Price Feed and not the Aggregator contract itself. The Price Feed acts as a "Proxy" contract that reads the submitted price data on the current ...
- 330
3
votes
How can I create a Factory of TransparentUpgradeableProxy?
The second parameter of TransparentUpgradeableProxy sets the proxy admin address. When initializing proxy in the first line of the constructor of SmartWalletProxy.sol, you're specifying the zero ...
- 376
3
votes
Accepted
OZ transparent upgradeable proxy admin reverts when trying upgrade an implementation
OpenZeppelin v5 TransparentUpgradeableProxy creates(deploys) its own ProxyAdmin contract. Now, in the proxy constructor you should provide not the ProxyAdmin contract address, but let's say the Admin'...
- 1,979
2
votes
Accepted
What happens with the balance of a contract after it is upgraded using ZeppelinOS?
ZeppelinOS' unstructured storage, like most proxy patterns, works by presenting a front-end contract (the proxy) with its logic delegated to an implementation contract.
This way, the balance (eth) ...
- 427
2
votes
Accepted
Upgradable contract proxy pattern: Get the invoked method name in the fallback function
Full name of the function being called is not passed to the smart contract, but only the first 4 bytes of the hash of function signature. These 4 bytes you can obtain as msg.sig. See documentation ...
- 7,273
Only top scored, non community-wiki answers of a minimum length are eligible