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@MrChico @rainbreak @gbalabasquer
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// Copyright (C) 2017, 2018, 2019 dbrock, rain, mrchico
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
pragma solidity >=0.5.0;
import "./lib.sol";
contract Dai is DSNote {
// --- Auth ---
mapping (address => uint) public wards;
function rely(address guy) external note auth { wards[guy] = 1; }
function deny(address guy) external note auth { wards[guy] = 0; }
modifier auth { require(wards[msg.sender] == 1); _; }
// --- ERC20 Data ---
string public constant name = "Dai Stablecoin";
string public constant symbol = "DAI";
string public constant version = "1";
uint8 public constant decimals = 18;
uint256 public totalSupply;
mapping (address => uint) public balanceOf;
mapping (address => mapping (address => uint)) public allowance;
mapping (address => uint) public nonces;
event Approval(address indexed src, address indexed guy, uint wad);
event Transfer(address indexed src, address indexed dst, uint wad);
// --- Math ---
function add(uint x, uint y) internal pure returns (uint z) {
require((z = x + y) >= x);
}
function sub(uint x, uint y) internal pure returns (uint z) {
require((z = x - y) <= x);
}
// --- EIP712 niceties ---
bytes32 public DOMAIN_SEPARATOR;
bytes32 public constant PERMIT_TYPEHASH = keccak256(
"Permit(address holder,address spender,uint256 nonce,uint256 expiry,bool allowed)"
);
constructor(uint256 chainId_) public {
wards[msg.sender] = 1;
DOMAIN_SEPARATOR = keccak256(abi.encode(
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
keccak256(bytes(name)),
keccak256(bytes(version)),
chainId_,
address(this)
));
}
// --- Token ---
function transfer(address dst, uint wad) external returns (bool) {
return transferFrom(msg.sender, dst, wad);
}
function transferFrom(address src, address dst, uint wad)
public returns (bool)
{
require(balanceOf[src] >= wad, "dai/insufficient-balance");
if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
require(allowance[src][msg.sender] >= wad, "dai/insufficient-allowance");
allowance[src][msg.sender] = sub(allowance[src][msg.sender], wad);
}
balanceOf[src] = sub(balanceOf[src], wad);
balanceOf[dst] = add(balanceOf[dst], wad);
emit Transfer(src, dst, wad);
return true;
}
function mint(address usr, uint wad) external auth {
balanceOf[usr] = add(balanceOf[usr], wad);
totalSupply = add(totalSupply, wad);
emit Transfer(address(0), usr, wad);
}
function burn(address usr, uint wad) external {
require(balanceOf[usr] >= wad, "dai/insufficient-balance");
if (usr != msg.sender && allowance[usr][msg.sender] != uint(-1)) {
require(allowance[usr][msg.sender] >= wad, "dai/insufficient-allowance");
allowance[usr][msg.sender] = sub(allowance[usr][msg.sender], wad);
}
balanceOf[usr] = sub(balanceOf[usr], wad);
totalSupply = sub(totalSupply, wad);
emit Transfer(usr, address(0), wad);
}
function approve(address usr, uint wad) external returns (bool) {
allowance[msg.sender][usr] = wad;
emit Approval(msg.sender, usr, wad);
return true;
}
// --- Alias ---
function push(address usr, uint wad) external {
transferFrom(msg.sender, usr, wad);
}
function pull(address usr, uint wad) external {
transferFrom(usr, msg.sender, wad);
}
function move(address src, address dst, uint wad) external {
transferFrom(src, dst, wad);
}
// --- Approve by signature ---
function permit(address holder, address spender, uint256 nonce, uint256 expiry,
bool allowed, uint8 v, bytes32 r, bytes32 s) external
{
bytes32 digest =
keccak256(abi.encodePacked(
"\x19\x01",
DOMAIN_SEPARATOR,
keccak256(abi.encode(PERMIT_TYPEHASH,
holder,
spender,
nonce,
expiry,
allowed))
));
require(holder == ecrecover(digest, v, r, s), "dai/invalid-permit");
require(expiry == 0 || now <= expiry, "dai/permit-expired");
require(nonce == nonces[holder]++, "dai/invalid-nonce");
uint wad = allowed ? uint(-1) : 0;
allowance[holder][spender] = wad;
emit Approval(holder, spender, wad);
}
}
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