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openzeppelin-contracts/contracts/metatx/ERC2771Context.sol

75 lines
2.9 KiB

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (metatx/ERC2771Context.sol)
pragma solidity ^0.8.20;
import {Context} from "../utils/Context.sol";
/**
* @dev Context variant with ERC2771 support.
*
* WARNING: Avoid using this pattern in contracts that rely in a specific calldata length as they'll
* be affected by any forwarder whose `msg.data` is suffixed with the `from` address according to the ERC2771
* specification adding the address size in bytes (20) to the calldata size. An example of an unexpected
* behavior could be an unintended fallback (or another function) invocation while trying to invoke the `receive`
* function only accessible if `msg.data.length == 0`.
*/
abstract contract ERC2771Context is Context {
/// @custom:oz-upgrades-unsafe-allow state-variable-immutable
address private immutable _trustedForwarder;
/**
* @dev Initializes the contract with a trusted forwarder, which will be able to
* invoke functions on this contract on behalf of other accounts.
*
* NOTE: The trusted forwarder can be replaced by overriding {trustedForwarder}.
*/
/// @custom:oz-upgrades-unsafe-allow constructor
constructor(address trustedForwarder_) {
_trustedForwarder = trustedForwarder_;
}
/**
* @dev Returns the address of the trusted forwarder.
*/
function trustedForwarder() public view virtual returns (address) {
return _trustedForwarder;
}
/**
* @dev Indicates whether any particular address is the trusted forwarder.
*/
function isTrustedForwarder(address forwarder) public view virtual returns (bool) {
return forwarder == trustedForwarder();
}
/**
* @dev Override for `msg.sender`. Defaults to the original `msg.sender` whenever
* a call is not performed by the trusted forwarder or the calldata length is less than
* 20 bytes (an address length).
*/
function _msgSender() internal view virtual override returns (address sender) {
if (isTrustedForwarder(msg.sender) && msg.data.length >= 20) {
// The assembly code is more direct than the Solidity version using `abi.decode`.
/// @solidity memory-safe-assembly
assembly {
sender := shr(96, calldataload(sub(calldatasize(), 20)))
}
} else {
return super._msgSender();
}
}
/**
* @dev Override for `msg.data`. Defaults to the original `msg.data` whenever
* a call is not performed by the trusted forwarder or the calldata length is less than
* 20 bytes (an address length).
*/
function _msgData() internal view virtual override returns (bytes calldata) {
if (isTrustedForwarder(msg.sender) && msg.data.length >= 20) {
return msg.data[:msg.data.length - 20];
} else {
return super._msgData();
}
}
}