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38 lines
1.1 KiB
38 lines
1.1 KiB
4 years ago
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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.0;
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import "../utils/Context.sol";
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/*
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* @dev Context variant with ERC2771 support.
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*/
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abstract contract ERC2771Context is Context {
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address immutable _trustedForwarder;
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constructor(address trustedForwarder) {
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_trustedForwarder = trustedForwarder;
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}
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function isTrustedForwarder(address forwarder) public view virtual returns(bool) {
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return forwarder == _trustedForwarder;
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}
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function _msgSender() internal view virtual override returns (address sender) {
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if (isTrustedForwarder(msg.sender)) {
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// The assembly code is more direct than the Solidity version using `abi.decode`.
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assembly { sender := shr(96, calldataload(sub(calldatasize(), 20))) }
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} else {
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return super._msgSender();
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}
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}
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function _msgData() internal view virtual override returns (bytes calldata) {
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if (isTrustedForwarder(msg.sender)) {
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return msg.data[:msg.data.length-20];
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} else {
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return super._msgData();
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}
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}
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}
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