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adding permit #2

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adding permit #2

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61 changes: 59 additions & 2 deletions WSYS.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,63 @@ contract WSYS {

mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) public allowance;
mapping (address => uint256) public nonces;

bytes32 public PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
bytes32 public DOMAIN_SEPARATOR;

constructor() public {
uint256 chainId;
assembly {
chainId := chainid()
}

DOMAIN_SEPARATOR = keccak256(
abi.encode(
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
keccak256(bytes(name)),
chainId,
address(this)
)
);
}

function permit(address owner,
address spender,
uint256 amount,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s) external {
require(deadline >= block.timestamp, "ERC20Permit: expired deadline");

bytes32 hashStruct = keccak256(
abi.encode(
PERMIT_TYPEHASH,
owner,
spender,
amount,
nonces[owner]++,
deadline
)
);

bytes32 hash = keccak256(
abi.encodePacked(
'\x19\x01',
DOMAIN_SEPARATOR,
hashStruct
)
);

address signer = ecrecover(hash, v, r, s);
require(
signer != address(0) && signer == owner,
"ERC20Permit: invalid signature"
);

approve(spender, amount);
}

function() external payable {
deposit();
Expand Down Expand Up @@ -60,7 +117,7 @@ contract WSYS {
return transferFrom(msg.sender, dst, wad);
}

function transferFrom(
function transferFrom(
address src,
address dst,
uint256 wad
Expand Down Expand Up @@ -757,4 +814,4 @@ the library. If this is what you want to do, use the GNU Lesser General
Public License instead of this License. But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/
*/