TREX-129 default allowance from develop (#215)

* ✨() TREX-129 Default allowance

* ✅(test) TREX-129 Add tests

* ✅(test) TREX-129 Add more tests

* 🐛() TREX-129 update after review

* 🐛() TREX-129 update after review 2

* 🔧(Token) improve global allowance logic

* 📝(CHANGELOG) update changelog

---------

Co-authored-by: joachimlebrun <joachim@tokeny.com>

.solhint.json

@@ -21,14 +21,15 @@
     "code-complexity": ["error", 7],
     "function-max-lines": ["error", 50],
     "max-line-length": ["error", 130],
-    "max-states-count": ["error", 15],
+    "max-states-count": ["warn", 15],
     "no-empty-blocks": "error",
     "no-unused-vars": "error",
     "payable-fallback": "error",
     "constructor-syntax": "error",
     "not-rely-on-time": "off",
     "reason-string": "off",
-    "no-global-import": "off"
+    "no-global-import": "off",
+    "gas-custom-errors": "off"
   },
   "plugins": ["prettier"]
 }

CHANGELOG.md

@@ -1,6 +1,17 @@
 # Change Log
 All notable changes to this project will be documented in this file.
 
+## [4.2.0]
+
+### Added
+
+- **Default Allowance Mechanism**:
+  - Introduced a new feature allowing the contract owner to set certain addresses as trusted external smart contracts, enabling them to use `transferFrom` without requiring an explicit allowance from users. By default, users are opted in, allowing these contracts to have an "infinite allowance". Users can opt-out if they prefer to control allowances manually.
+  - Added custom errors and events to provide better feedback and traceability:
+    - Custom errors: `DefaultAllowanceAlreadyEnabled`, `DefaultAllowanceAlreadyDisabled`, `DefaultAllowanceAlreadySet`.
+    - Events: `DefaultAllowance`, `DefaultAllowanceDisabled`, `DefaultAllowanceEnabled`.
+  - Enhanced the `allowance` function to return `type(uint256).max` for addresses with default allowance enabled, unless the user has opted out.
+
 ## [4.1.5]
 
 ### Update

contracts/errors/CommonErrors.sol

@@ -121,3 +121,9 @@ error EnforcedPause();
 * @dev The operation failed because the contract is not paused.
 */
 error ExpectedPause();
+
+/**
+* @dev The operation failed because the input array is too big.
+* @param _maxSize maximum size for the array.
+*/
+error ArraySizeLimited(uint256 _maxSize);

contracts/token/IToken.sol

@@ -138,6 +138,18 @@ event AgentRestrictionsSet(
     bool _disablePause,
     bool _disableRecovery);
 
+/// @dev This event is emitted when the owner gives or cancels a default allowance.
+/// @param _to Address of target.
+/// @param _allowance Allowance or disallowance.
+event DefaultAllowance(address _to, bool _allowance);
+
+/// @dev This event is emitted when a user remove the default allowance.
+/// @param _user Address of user.
+event DefaultAllowanceDisabled(address _user);
+
+/// @dev This event is emitted when a user adds the default allowance back after disabling.
+/// @param _user Address of user.
+event DefaultAllowanceEnabled(address _user);
 
 /// @dev interface
 interface IToken is IERC20 {
@@ -325,6 +337,24 @@ interface IToken is IERC20 {
         address _investorOnchainID
     ) external returns (bool);
 
+    /**
+     * @dev The owner of this address can allow or disallow spending without allowance.
+     * Any `TransferFrom` from these targets won't need allowance (allow = true) or will need allowance (allow = false).
+     * @param _allow Allow or disallow spending without allowance.
+     * @param _targets Addresses without allowance needed.
+    */
+    function setAllowanceForAll(bool _allow, address[] calldata _targets) external;
+
+    /**
+     * @dev The caller can remove default allowance globally.
+    */
+    function disableDefaultAllowance() external;
+
+    /**
+     * @dev The caller can get default allowance back globally.
+    */
+    function enableDefaultAllowance() external;
+
     /**
      *  @dev function allowing to issue transfers in batch
      *  Require that the msg.sender and `to` addresses are not frozen.
@@ -518,4 +548,5 @@ interface IToken is IERC20 {
      *  Each flag set to `true` disables the corresponding capability for the agent.
      */
     function getAgentRestrictions(address agent) external view returns (TokenRoles memory);
+
 }

contracts/token/Token.sol

@@ -107,6 +107,15 @@ error TransferNotPossible();
 /// @dev Thrown when identity is not verified.
 error UnverifiedIdentity();
 
+/// @dev Thrown when default allowance is already enabled for _user.
+error DefaultAllowanceAlreadyEnabled(address _user);
+
+/// @dev Thrown when default allowance is already disabled for _user.
+error DefaultAllowanceAlreadyDisabled(address _user);
+
+/// @dev Thrown when default allowance is already set for _target.
+error DefaultAllowanceAlreadySet(address _target);
+
 
 contract Token is IToken, AgentRoleUpgradeable, TokenStorage {
 
@@ -288,7 +297,9 @@ contract Token is IToken, AgentRoleUpgradeable, TokenStorage {
         uint256 balance = balanceOf(_from) - (_frozenTokens[_from]);
         require(_amount <= balance, ERC20InsufficientBalance(_from, balance, _amount));
         if (_tokenIdentityRegistry.isVerified(_to) && _tokenCompliance.canTransfer(_from, _to, _amount)) {
-            _approve(_from, msg.sender, _allowances[_from][msg.sender] - (_amount));
+            if (!_defaultAllowances[msg.sender] || _defaultAllowanceOptOuts[_from]) {
+                _approve(_from, msg.sender, _allowances[_from][msg.sender] - (_amount));
+            }
             _transfer(_from, _to, _amount);
             _tokenCompliance.transferred(_from, _to, _amount);
             return true;
@@ -385,6 +396,31 @@ contract Token is IToken, AgentRoleUpgradeable, TokenStorage {
         revert RecoveryNotPossible();
     }
 
+    /// @dev See {IToken-setAllowanceForAll}.
+    function setAllowanceForAll(bool _allow, address[] calldata _targets) external override onlyOwner {
+        uint256 targetsCount = _targets.length;
+        require(targetsCount <= 100, ArraySizeLimited(100));
+        for (uint256 i = 0; i < targetsCount; i++) {
+            require(_defaultAllowances[_targets[i]] != _allow, DefaultAllowanceAlreadySet(_targets[i]));
+            _defaultAllowances[_targets[i]] = _allow;
+            emit DefaultAllowance(_targets[i], _allow);
+        }
+    }
+
+    /// @dev See {IToken-disableDefaultAllowance}.
+    function disableDefaultAllowance() external override {
+        require(!_defaultAllowanceOptOuts[msg.sender], DefaultAllowanceAlreadyDisabled(msg.sender));
+        _defaultAllowanceOptOuts[msg.sender] = true;
+        emit DefaultAllowanceDisabled(msg.sender);
+    }
+
+    /// @dev See {IToken-enableDefaultAllowance}.
+    function enableDefaultAllowance() external override {
+        require(_defaultAllowanceOptOuts[msg.sender], DefaultAllowanceAlreadyEnabled(msg.sender));
+        _defaultAllowanceOptOuts[msg.sender] = false;
+        emit DefaultAllowanceEnabled(msg.sender);
+    }
+
     /**
      *  @dev See {IERC20-totalSupply}.
      */
@@ -396,6 +432,10 @@ contract Token is IToken, AgentRoleUpgradeable, TokenStorage {
      *  @dev See {IERC20-allowance}.
      */
     function allowance(address _owner, address _spender) external view virtual override returns (uint256) {
+        if (_defaultAllowances[_spender] && !_defaultAllowanceOptOuts[_owner]) {
+            return type(uint256).max;
+        }
+
         return _allowances[_owner][_spender];
     }
 
@@ -676,4 +716,5 @@ contract Token is IToken, AgentRoleUpgradeable, TokenStorage {
      */
     // solhint-disable-next-line no-empty-blocks
     function _beforeTokenTransfer(address _from, address _to, uint256 _amount) internal virtual {}
+
 }

contracts/token/TokenStorage.sol

@@ -93,9 +93,13 @@ contract TokenStorage {
 
     mapping(address => TokenRoles) internal _agentsRestrictions;
 
+    mapping(address spender => bool allowance) internal _defaultAllowances;
+
+    mapping(address user => bool optOut) internal _defaultAllowanceOptOuts;
+
     /**
      * @dev This empty reserved space is put in place to allow future versions to add new
      * variables without shifting down storage in the inheritance chain.
      */
-    uint256[48] private __gap;
+    uint256[46] private __gap;
 }

hardhat.config.ts

@@ -5,6 +5,7 @@ import '@openzeppelin/hardhat-upgrades';
 import 'solidity-coverage';
 import '@nomiclabs/hardhat-solhint';
 import '@primitivefi/hardhat-dodoc';
+import 'hardhat-tracer';
 
 const config: HardhatUserConfig = {
   solidity: {