Merge pull request #3 from mountainprotocol/chore/feedback-1

Feedback: 1st iteration
amr080 · Apr 24, 2023 · 70457e5 · 70457e5
2 parents f4ced0f + a055888
commit 70457e5
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diff --git a/.gitignore b/.gitignore
@@ -389,3 +389,10 @@ artifacts
 
 # Mac
 .DS_Store
+
+# VS Code
+.vscode/*
+
+# Forge
+cache_forge/*
+out/*
diff --git a/README.md b/README.md
@@ -1,12 +1,13 @@
-# USDM
+# Mountain Protocol USD
 
-This smart contract implements a rebasing ERC-20 token with additional functionality such as rebasing, reward multiplier, blacklisting, permit support and upgradeability.
+This smart contract implements a custom rebasing ERC-20 token with additional features like pausing, blacklisting, access control, and upgradability. The contract aims to reflect the T-Bills APY into the token value through a reward multiplier mechanism. Users receive a proportional number of shares when they deposit tokens, and the number of tokens they can withdraw is calculated based on the current reward multiplier. The addRewardMultiplier function is called once a day to adjust the reward multiplier, ensuring accurate reflection of the yield from 3 months maturity T-Bills.
 
 ## Features
 
 - Rebasing token mechanism
 - Minting and burning functionality
 - Blacklisting addresses
+- Pausing
 - Reward multiplier system
 - EIP-2612 permit support
 - OpenZeppelin UUPS upgrade pattern
@@ -33,33 +34,33 @@ Try running some of the following tasks:
 
 Testing
 ```shell
-REPORT_GAS=true npx hh test
+hh test
 ```
 
 Coverage
 ```shell
-npx hh coverage
+hh coverage
 ```
 
 Running local node
 ```shell
-npx hh node
+hh node
 ```
 
 Compile
 ```shell
-npx hh compile
+hh compile
 ```
 
 Deploying and contract verification
 ```shell
-npx hh run scripts/deploy.ts--network goerli
-npx hh verify --network goerli <contact-address>
+hh run scripts/deploy.ts--network goerli
+hh verify --network goerli <contact-address>
 ```
 
 Help
 ```shell
-npx hh help
+hh help
 ```
 
 ### Functions
@@ -72,7 +73,8 @@ npx hh help
 - `transfer(address to, uint256 amount)`: Transfers tokens between addresses.
 - `pause()`: Pauses the contract, halting token transfers.
 - `unpause()`: Unpauses the contract, allowing token transfers.
-- `addRewardMultiplier(uint256 rewardMultiplier_)`: Adds a reward multiplier to the contract.
+- `setRewardMultiplier(uint256 rewardMultiplier_)`: Sets the reward multiplier.
+- `addRewardMultiplier(uint256 rewardMultiplier_)`: Adds the provided interest rate to the current reward multiplier.
 - `approve(address spender, uint256 amount)`: Approves an allowance for a spender.
 - `allowance(address owner, address spender)`: Returns the allowance for a spender.
 - `DOMAIN_SEPARATOR()`: Returns the EIP-712 domain separator.
@@ -83,14 +85,14 @@ npx hh help
 
 - `_mint(address to, uint256 shares)`: Internal function to mint tokens to the specified address.
 - `_burn(address account, uint256 shares)`: Internal function to burn tokens from the specified address.
-- `_transferShares(address from, address to, uint256 shares)`: Internal function to transfer tokens between addresses.
+- `_transfer(address from, address to, uint256 amount)`: Internal function to transfer tokens between addresses.
 - `_authorizeUpgrade(address newImplementation)`: Internal function to authorize an upgrade.
 
 #### Events
 
 - `AddressBlacklisted(address indexed addr)`: Emitted when an address is blacklisted.
 - `AddressUnBlacklisted(address indexed addr)`: Emitted when an address is removed from the blacklist.
-- `RewardMultiplier(uint256 indexed addr)`: Emitted when the reward multiplier is updated.
+- `RewardMultiplier(uint256 indexed addr)`: Emitted when the reward multiplier has changed.
 - `Transfer(from indexed addr, to uint256, amount uint256)`: Emitted transfering tokens.
 
 

diff --git a/contracts/Token.sol b/contracts/Token.sol
@@ -5,25 +5,22 @@ import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/access/AccessControlUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol";
-import "@openzeppelin/contracts-upgradeable/utils/math/SafeMathUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/utils/math/MathUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/utils/CountersUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/utils/cryptography/EIP712Upgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/token/ERC20/extensions/draft-IERC20PermitUpgradeable.sol";
 import "@openzeppelin/contracts-upgradeable/utils/cryptography/ECDSAUpgradeable.sol";
 
-// TODO: Upgrade Time lock
-
-// @author: @mattiascaricato
-contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable, PausableUpgradeable, UUPSUpgradeable, IERC20PermitUpgradeable, EIP712Upgradeable {
-    using SafeMathUpgradeable for uint256;
+contract USDM is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable, PausableUpgradeable, UUPSUpgradeable, IERC20PermitUpgradeable, EIP712Upgradeable {
+    using MathUpgradeable for uint256;
     using CountersUpgradeable for CountersUpgradeable.Counter;
 
     string private _name;
     string private _symbol;
-    uint256 private _rewardMultiplier;
     uint256 private _totalShares;
     uint256 private constant BASE = 1e18;
+    uint256 public rewardMultiplier;
 
     mapping (address => uint256) private _shares;
     mapping(address => bool) private _blacklist;
@@ -53,7 +50,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
     function initialize(string memory name_, string memory symbol_, uint256 initialShares) external initializer {
         _name = name_;
         _symbol = symbol_;
-        _rewardMultiplier = BASE;
+        rewardMultiplier = BASE;
 
         __Ownable_init();
         __AccessControl_init();
@@ -107,17 +104,17 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @param amount The amount of tokens to convert
      * @return The equivalent amount of shares
      */
-    function amountToShares(uint256 amount) public view returns (uint256) {
-        return amount.mul(BASE).div(rewardMultiplier());
+    function convertToShares(uint256 amount) public view returns (uint256) {
+        return amount.mulDiv(BASE, rewardMultiplier, MathUpgradeable.Rounding.Down);
     }
 
     /**
      * @notice Converts an amount of shares to tokens
      * @param shares The amount of shares to convert
      * @return The equivalent amount of tokens
      */
-    function sharesToAmount(uint256 shares) public view returns (uint256) {
-        return shares.mul(rewardMultiplier()).div(BASE);
+    function convertToAmount(uint256 shares) public view returns (uint256) {
+        return shares.mulDiv(rewardMultiplier, BASE, MathUpgradeable.Rounding.Down);
     }
 
     /**
@@ -133,7 +130,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @return The total supply of tokens
      */
     function totalSupply() external view returns (uint256) {
-        return sharesToAmount(_totalShares);
+        return convertToAmount(_totalShares);
     }
 
     /**
@@ -153,7 +150,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @return The balance of the specified address
      */
     function balanceOf(address account) external view returns (uint256) {
-        return sharesToAmount(sharesOf(account));
+        return convertToAmount(sharesOf(account));
     }
 
     /**
@@ -167,11 +164,11 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
 
         _beforeTokenTransfer(address(0), to, shares);
 
-        _totalShares = _totalShares.add(shares);
+        _totalShares += shares;
 
         unchecked {
             // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
-            _shares[to] = _shares[to].add(shares);
+            _shares[to] += shares;
         }
 
         _afterTokenTransfer(address(0), to, shares);
@@ -193,35 +190,10 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @param amount The amount of tokens to mint
      */
     function mint(address to, uint256 amount) external onlyRole(MINTER_ROLE) {
-        uint256 shares = amountToShares(amount);
+        uint256 shares = convertToShares(amount);
         _mint(to, shares);
     }
 
-    /**
-     * @notice Transfers a specified number of shares from one address to another.
-     * @dev This is an internal function.
-     * @param from The address from which shares will be transferred.
-     * @param to The address to which shares will be transferred.
-     * @param shares The number of shares to transfer.
-     */
-    function _transferShares(address from, address to, uint256 shares) private {
-        require(from != address(0), "ERC20: transfer from the zero address");
-        require(to != address(0), "ERC20: transfer to the zero address");
-
-        _beforeTokenTransfer(from, to, shares);
-
-        uint256 fromShares = _shares[from];
-        require(fromShares >= shares, "ERC20: transfer amount exceeds balance");
-        unchecked {
-            _shares[from] = fromShares.sub(shares);
-            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
-            // decrementing then incrementing.
-            _shares[to] = _shares[to].add(shares);
-        }
-
-        _afterTokenTransfer(from, to, shares);
-    }
-
     /**
      * @notice Burns a specified number of shares from the given address.
      * @dev This is an internal function.
@@ -236,9 +208,9 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
         uint256 accountShares = sharesOf(account);
         require(accountShares >= shares, "ERC20: burn amount exceeds balance");
         unchecked {
-            _shares[account] = accountShares.sub(shares);
+            _shares[account] = accountShares - shares;
             // Overflow not possible: amount <= accountBalance <= totalSupply.
-            _totalShares = _totalShares.sub(shares);
+            _totalShares -= shares;
         }
 
         _afterTokenTransfer(account, address(0), shares);
@@ -261,10 +233,50 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @param amount The amount of tokens to burn.
      */
     function burn(address from, uint256 amount) external onlyRole(BURNER_ROLE) {
-        uint256 shares = amountToShares(amount);
+        uint256 shares = convertToShares(amount);
         _burn(from, shares);
     }
 
+    function _beforeTokenTransfer(address from, address to, uint256 amount) private view {
+        // Each blacklist check is an SLOAD, which is gas intensive.
+        // We only block sender not receiver, so we don't tax every user
+        require(!isBlacklisted(from), "Address is blacklisted");
+        // Useful for scenarios such as preventing trades until the end of an evaluation
+        // period, or having an emergency switch for freezing all token transfers in the
+        // event of a large bug.
+        require(!paused(), "Transfers not allowed while paused");
+    }
+
+    function _afterTokenTransfer(address from, address to, uint256 amount) private {
+        emit Transfer(from, to, amount);
+    }
+
+    /**
+     * @notice Transfers a specified number of tokens from one address to another.
+     * @dev This is an internal function.
+     * @param from The address from which shares will be transferred.
+     * @param to The address to which shares will be transferred.
+     * @param amount The number of tokens to transfer.
+     */
+    function _transfer(address from, address to, uint256 amount) private {
+        require(from != address(0), "ERC20: transfer from the zero address");
+        require(to != address(0), "ERC20: transfer to the zero address");
+
+        _beforeTokenTransfer(from, to, amount);
+
+        uint256 shares = convertToShares(amount);
+        uint256 fromShares = _shares[from];
+        require(fromShares >= shares, "ERC20: transfer amount exceeds balance");
+        unchecked {
+            _shares[from] = fromShares - shares;
+            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
+            // decrementing then incrementing.
+            _shares[to] += shares;
+        }
+
+        _afterTokenTransfer(from, to, amount);
+    }
+
     /**
      * @notice Transfers a specified number of tokens from the caller's address to the recipient.
      * @dev This function converts the token amount to shares and calls the _transferShares function.
@@ -278,8 +290,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      */
     function transfer(address to, uint256 amount) external returns (bool) {
         address owner = _msgSender();
-        uint256 shares = amountToShares(amount);
-        _transferShares(owner, to, shares);
+        _transfer(owner, to, amount);
 
         return true;
     }
@@ -288,7 +299,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @notice Blacklists the specified address
      * @param account The address to blacklist
      */
-    function _blacklistAccount(address account) internal onlyRole(BLACKLIST_ROLE) {
+    function _blacklistAccount(address account) internal {
         require(!_blacklist[account], "Address already blacklisted");
         _blacklist[account] = true;
         emit AccountBlacklisted(account);
@@ -298,7 +309,7 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      * @notice Removes the specified address from the blacklist
      * @param account The address to remove from the blacklist
      */
-    function _unblacklistAccount(address account) internal onlyRole(BLACKLIST_ROLE) {
+    function _unblacklistAccount(address account) internal {
         require(_blacklist[account], "Address is not blacklisted");
         _blacklist[account] = false;
         emit AccountUnblacklisted(account);
@@ -335,20 +346,6 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
         return _blacklist[account];
     }
 
-    function _beforeTokenTransfer(address from, address to, uint256 amount) private view {
-        // Each blacklist check is an SLOAD, which is gas intensive.
-        // We only block sender not receiver, so we don't tax every user
-        require(!isBlacklisted(from), "Address is blacklisted");
-        // Useful for scenarios such as preventing trades until the end of an evaluation
-        // period, or having an emergency switch for freezing all token transfers in the
-        // event of a large bug.
-        require(!paused(), "Transfers not allowed while paused");
-    }
-
-    function _afterTokenTransfer(address from, address to, uint256 amount) private {
-        emit Transfer(from, to, amount);
-    }
-
     /**
      * @notice Pauses token transfers and other operations.
      * @dev Only the contract owner can call this function. Inherits the _pause function from @openzeppelin/PausableUpgradeable contract.
@@ -366,25 +363,26 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
     }
 
     /**
-     * @notice Returns the current reward multiplier
-     * @return The current reward multiplier
+     * @notice Sets the reward multiplier.
+     * @dev Only users with ORACLE_ROLE can call this function.
+     * @param _rewardMultiplier The new reward multiplier.
      */
-    function rewardMultiplier() public view returns (uint256) {
-        return _rewardMultiplier;
+    function setRewardMultiplier(uint256 _rewardMultiplier) public onlyRole(ORACLE_ROLE) {
+        require(_rewardMultiplier > 1 ether, "Invalid reward multiplier");
+        rewardMultiplier = _rewardMultiplier;
+
+        emit RewardMultiplier(rewardMultiplier);
     }
 
     /**
-     * @notice Adds a new reward multiplier to the existing reward multiplier.
+     * @notice Adds the provided interest rate to the current reward multiplier.
      * @dev Only users with ORACLE_ROLE can call this function.
-     * @param rewardMultiplier_ The new reward multiplier to be added.
+     * @param _rewardMultiplier The new reward multiplier.
      */
-    function addRewardMultiplier(uint256 rewardMultiplier_) external onlyRole(ORACLE_ROLE) {
-        require(rewardMultiplier_ > 0, "Invalid RewardMultiplier");
-        require(rewardMultiplier_ < 500000000000000, "Invalid RewardMultiplier"); // 5bps
-
-        _rewardMultiplier = _rewardMultiplier.add(rewardMultiplier_);
+    function addRewardMultiplier(uint256 _rewardMultiplier) external onlyRole(ORACLE_ROLE) {
+        require(_rewardMultiplier > 0, "Invalid reward multiplier");
 
-        emit RewardMultiplier(_rewardMultiplier);
+        setRewardMultiplier(rewardMultiplier + _rewardMultiplier);
     }
 
     /**
@@ -480,9 +478,8 @@ contract Usdm is IERC20Upgradeable, OwnableUpgradeable, AccessControlUpgradeable
      */
     function transferFrom(address from, address to, uint256 amount) external returns (bool) {
         address spender = _msgSender();
-        uint256 shares = amountToShares(amount);
-        _spendAllowance(from, spender, shares);
-        _transferShares(from, to, shares);
+        _spendAllowance(from, spender, amount);
+        _transfer(from, to, amount);
 
         return true;
     }

diff --git a/hardhat.config.ts b/hardhat.config.ts
@@ -3,7 +3,6 @@ import "@nomicfoundation/hardhat-toolbox";
 import "@nomiclabs/hardhat-solhint";
 import "@nomicfoundation/hardhat-chai-matchers";
 import "@openzeppelin/hardhat-upgrades";
-import "hardhat-gas-reporter";
 import dotenv from "dotenv";
 
 dotenv.config();