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Copy pathERC721MetaTransactionMaticSample.sol
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ERC721MetaTransactionMaticSample.sol
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//SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
/**
* https://github.com/maticnetwork/pos-portal/blob/master/contracts/common/ContextMixin.sol
*/
abstract contract ContextMixin {
function msgSender()
internal
view
returns (address payable sender)
{
if (msg.sender == address(this)) {
bytes memory array = msg.data;
uint256 index = msg.data.length;
assembly {
// Load the 32 bytes word from memory with the address on the lower 20 bytes, and mask those.
sender := and(
mload(add(array, index)),
0xffffffffffffffffffffffffffffffffffffffff
)
}
} else {
sender = payable(msg.sender);
}
return sender;
}
}
/**
* https://github.com/maticnetwork/pos-portal/blob/master/contracts/common/Initializable.sol
*/
contract Initializable {
bool inited = false;
modifier initializer() {
require(!inited, "already inited");
_;
inited = true;
}
}
/**
* https://github.com/maticnetwork/pos-portal/blob/master/contracts/common/EIP712Base.sol
*/
contract EIP712Base is Initializable {
struct EIP712Domain {
string name;
string version;
address verifyingContract;
bytes32 salt;
}
string constant public ERC712_VERSION = "1";
bytes32 internal constant EIP712_DOMAIN_TYPEHASH = keccak256(
bytes(
"EIP712Domain(string name,string version,address verifyingContract,bytes32 salt)"
)
);
bytes32 internal domainSeperator;
// supposed to be called once while initializing.
// one of the contractsa that inherits this contract follows proxy pattern
// so it is not possible to do this in a constructor
function _initializeEIP712(
string memory name
)
internal
initializer
{
_setDomainSeperator(name);
}
function _setDomainSeperator(string memory name) internal {
domainSeperator = keccak256(
abi.encode(
EIP712_DOMAIN_TYPEHASH,
keccak256(bytes(name)),
keccak256(bytes(ERC712_VERSION)),
address(this),
bytes32(getChainId())
)
);
}
function getDomainSeperator() public view returns (bytes32) {
return domainSeperator;
}
function getChainId() public view returns (uint256) {
uint256 id;
assembly {
id := chainid()
}
return id;
}
/**
* Accept message hash and returns hash message in EIP712 compatible form
* So that it can be used to recover signer from signature signed using EIP712 formatted data
* https://eips.ethereum.org/EIPS/eip-712
* "\\x19" makes the encoding deterministic
* "\\x01" is the version byte to make it compatible to EIP-191
*/
function toTypedMessageHash(bytes32 messageHash)
internal
view
returns (bytes32)
{
return
keccak256(
abi.encodePacked("\x19\x01", getDomainSeperator(), messageHash)
);
}
}
/**
* https://github.com/maticnetwork/pos-portal/blob/master/contracts/common/NativeMetaTransaction.sol
*/
contract NativeMetaTransaction is EIP712Base {
bytes32 private constant META_TRANSACTION_TYPEHASH = keccak256(
bytes(
"MetaTransaction(uint256 nonce,address from,bytes functionSignature)"
)
);
event MetaTransactionExecuted(
address userAddress,
address payable relayerAddress,
bytes functionSignature
);
mapping(address => uint256) nonces;
/*
* Meta transaction structure.
* No point of including value field here as if user is doing value transfer then he has the funds to pay for gas
* He should call the desired function directly in that case.
*/
struct MetaTransaction {
uint256 nonce;
address from;
bytes functionSignature;
}
function executeMetaTransaction(
address userAddress,
bytes memory functionSignature,
bytes32 sigR,
bytes32 sigS,
uint8 sigV
) public payable returns (bytes memory) {
MetaTransaction memory metaTx = MetaTransaction({
nonce: nonces[userAddress],
from: userAddress,
functionSignature: functionSignature
});
require(
verify(userAddress, metaTx, sigR, sigS, sigV),
"Signer and signature do not match"
);
// increase nonce for user (to avoid re-use)
nonces[userAddress] = nonces[userAddress] + 1;
emit MetaTransactionExecuted(
userAddress,
payable(msg.sender),
functionSignature
);
// Append userAddress and relayer address at the end to extract it from calling context
(bool success, bytes memory returnData) = address(this).call(
abi.encodePacked(functionSignature, userAddress)
);
require(success, "Function call not successful");
return returnData;
}
function hashMetaTransaction(MetaTransaction memory metaTx)
internal
pure
returns (bytes32)
{
return
keccak256(
abi.encode(
META_TRANSACTION_TYPEHASH,
metaTx.nonce,
metaTx.from,
keccak256(metaTx.functionSignature)
)
);
}
function getNonce(address user) public view returns (uint256 nonce) {
nonce = nonces[user];
}
function verify(
address signer,
MetaTransaction memory metaTx,
bytes32 sigR,
bytes32 sigS,
uint8 sigV
) internal view returns (bool) {
require(signer != address(0), "NativeMetaTransaction: INVALID_SIGNER");
return
signer ==
ecrecover(
toTypedMessageHash(hashMetaTransaction(metaTx)),
sigV,
sigR,
sigS
);
}
}
contract ERC721MetaTransactionMaticSample is ERC721, ContextMixin, NativeMetaTransaction {
constructor (string memory name_, string memory symbol_) ERC721(name_, symbol_) {
_initializeEIP712(name_);
}
/**
* This is used instead of msg.sender as transactions won't be sent by the original token owner, but by OpenSea.
*/
function _msgSender()
internal
override
view
returns (address sender)
{
return ContextMixin.msgSender();
}
/**
* As another option for supporting trading without requiring meta transactions, override isApprovedForAll to whitelist OpenSea proxy accounts on Matic
*/
function isApprovedForAll(
address _owner,
address _operator
) public override view returns (bool isOperator) {
if (_operator == address(0x58807baD0B376efc12F5AD86aAc70E78ed67deaE)) {
return true;
}
return ERC721.isApprovedForAll(_owner, _operator);
}
}