ImmutableCreate2Factory

Author: 0age

This contract provides a safeCreate2 function that takes a salt value and a block of initialization code as arguments and passes them into inline assembly. The contract prevents redeploys by maintaining a mapping of all contracts that have already been deployed, and prevents frontrunning or other collisions by requiring that the first 20 bytes of the salt are equal to the address of the caller (this can be bypassed by setting the first 20 bytes to the null address). There is also a view function that computes the address of the contract that will be created when submitting a given salt or nonce along with a given block of initialization code.

This contract has not yet been fully tested or audited - proceed with caution and please share any exploits or optimizations you discover.

State Variables

_deployed

mapping(address => bool) private _deployed;

Functions

safeCreate2Internal

function safeCreate2Internal(bytes32 salt, bytes memory initializationCode)
    internal
    returns (address deploymentAddress);

safeCreate2

Create a contract using CREATE2 by submitting a given salt or nonce along with the initialization code for the contract. Note that the first 20 bytes of the salt must match those of the calling address, which prevents contract creation events from being submitted by unintended parties.

function safeCreate2(bytes32 salt, bytes memory initializationCode)
    public
    payable
    containsCaller(salt)
    returns (address deploymentAddress);

Parameters

Name	Type	Description
`salt`	`bytes32`	bytes32 The nonce that will be passed into the CREATE2 call.
`initializationCode`	`bytes`	bytes The initialization code that will be passed into the CREATE2 call.

Returns

Name	Type	Description
`deploymentAddress`	`address`	Address of the contract that will be created, or the null address if a contract already exists at that address.

findCreate2Address

Compute the address of the contract that will be created when submitting a given salt or nonce to the contract along with the contract's initialization code. The CREATE2 address is computed in accordance with EIP-1014, and adheres to the formula therein of keccak256( 0xff ++ address ++ salt ++ keccak256(init_code)))[12:] when performing the computation. The computed address is then checked for any existing contract code - if so, the null address will be returned instead.

function findCreate2Address(bytes32 salt, bytes calldata initCode) external view returns (address deploymentAddress);

Parameters

Name	Type	Description
`salt`	`bytes32`	bytes32 The nonce passed into the CREATE2 address calculation.
`initCode`	`bytes`	bytes The contract initialization code to be used. that will be passed into the CREATE2 address calculation.

Returns

Name	Type	Description
`deploymentAddress`	`address`	Address of the contract that will be created, or the null address if a contract has already been deployed to that address.

findCreate2AddressViaHash

Compute the address of the contract that will be created when submitting a given salt or nonce to the contract along with the keccak256 hash of the contract's initialization code. The CREATE2 address is computed in accordance with EIP-1014, and adheres to the formula therein of keccak256( 0xff ++ address ++ salt ++ keccak256(init_code)))[12:] when performing the computation. The computed address is then checked for any existing contract code - if so, the null address will be returned instead.

function findCreate2AddressViaHash(bytes32 salt, bytes32 initCodeHash)
    external
    view
    returns (address deploymentAddress);

Parameters

Name	Type	Description
`salt`	`bytes32`	bytes32 The nonce passed into the CREATE2 address calculation.
`initCodeHash`	`bytes32`	bytes32 The keccak256 hash of the initialization code that will be passed into the CREATE2 address calculation.

Returns

Name	Type	Description
`deploymentAddress`	`address`	Address of the contract that will be created, or the null address if a contract has already been deployed to that address.

hasBeenDeployed

Determine if a contract has already been deployed by the factory to a given address.

function hasBeenDeployed(address deploymentAddress) external view returns (bool);

Parameters

Name	Type	Description
`deploymentAddress`	`address`	address The contract address to check.

Returns

Name	Type	Description
`<none>`	`bool`	True if the contract has been deployed, false otherwise.

containsCaller

Modifier to ensure that the first 20 bytes of a submitted salt match those of the calling account. This provides protection against the salt being stolen by frontrunners or other attackers. The protection can also be bypassed if desired by setting each of the first 20 bytes to zero.

modifier containsCaller(bytes32 salt);

Parameters

Name	Type	Description
`salt`	`bytes32`	bytes32 The salt value to check against the calling address.

safeCreate2AndTransfer

function safeCreate2AndTransfer(bytes32 salt, bytes calldata initializationCode)
    external
    payable
    containsCaller(salt)
    returns (address deploymentAddress);