73 lines
2.4 KiB
Solidity
73 lines
2.4 KiB
Solidity
// SPDX-License-Identifier: MIT
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pragma solidity ^0.6.0;
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import "./GSNRecipient.sol";
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import "../cryptography/ECDSA.sol";
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/**
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* @dev A xref:ROOT:gsn-strategies.adoc#gsn-strategies[GSN strategy] that allows relayed transactions through when they are
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* accompanied by the signature of a trusted signer. The intent is for this signature to be generated by a server that
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* performs validations off-chain. Note that nothing is charged to the user in this scheme. Thus, the server should make
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* sure to account for this in their economic and threat model.
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*/
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contract GSNRecipientSignature is GSNRecipient {
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using ECDSA for bytes32;
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address private _trustedSigner;
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enum GSNRecipientSignatureErrorCodes {
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INVALID_SIGNER
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}
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/**
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* @dev Sets the trusted signer that is going to be producing signatures to approve relayed calls.
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*/
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constructor(address trustedSigner) public {
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require(trustedSigner != address(0), "GSNRecipientSignature: trusted signer is the zero address");
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_trustedSigner = trustedSigner;
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}
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/**
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* @dev Ensures that only transactions with a trusted signature can be relayed through the GSN.
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*/
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function acceptRelayedCall(
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address relay,
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address from,
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bytes memory encodedFunction,
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uint256 transactionFee,
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uint256 gasPrice,
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uint256 gasLimit,
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uint256 nonce,
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bytes memory approvalData,
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uint256
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)
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public
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view
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virtual
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override
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returns (uint256, bytes memory)
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{
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bytes memory blob = abi.encodePacked(
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relay,
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from,
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encodedFunction,
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transactionFee,
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gasPrice,
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gasLimit,
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nonce, // Prevents replays on RelayHub
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getHubAddr(), // Prevents replays in multiple RelayHubs
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address(this) // Prevents replays in multiple recipients
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);
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if (keccak256(blob).toEthSignedMessageHash().recover(approvalData) == _trustedSigner) {
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return _approveRelayedCall();
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} else {
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return _rejectRelayedCall(uint256(GSNRecipientSignatureErrorCodes.INVALID_SIGNER));
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}
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}
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function _preRelayedCall(bytes memory) internal virtual override returns (bytes32) { }
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function _postRelayedCall(bytes memory, bool, uint256, bytes32) internal virtual override { }
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}
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