Merge pull request #489 from bancorprotocol/burn-network-fees

burn network fees

contracts/network/BancorNetwork.sol

@@ -95,9 +95,6 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
     // the emergency manager role is required to pause/unpause the network
     bytes32 private constant ROLE_EMERGENCY_STOPPER = keccak256("ROLE_EMERGENCY_STOPPER");
 
-    // the network fee manager role is required to pull the accumulated pending network fees
-    bytes32 private constant ROLE_NETWORK_FEE_MANAGER = keccak256("ROLE_NETWORK_FEE_MANAGER");
-
     // the address of the BNT token
     IERC20 private immutable _bnt;
 
@@ -149,15 +146,18 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
     // a mapping between pools and their respective pool collections
     mapping(Token => IPoolCollection) private _collectionByPool;
 
-    // the pending network fee amount to be burned by the vortex
+    // the pending network fee amount to be burned
     uint256 internal _pendingNetworkFeeAmount;
 
     bool private _depositingEnabled = true;
 
     uint32 private _polRewardsPPM;
 
+    // min network fee amount that can be burned
+    uint256 private _minNetworkFeeBurn;
+
     // upgrade forward-compatibility storage gap
-    uint256[MAX_GAP - 11] private __gap;
+    uint256[MAX_GAP - 12] private __gap;
 
     /**
      * @dev triggered when a new pool collection is added
@@ -217,9 +217,9 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
     event FlashLoanCompleted(Token indexed token, address indexed borrower, uint256 amount, uint256 feeAmount);
 
     /**
-     * @dev triggered when network fees are withdrawn
+     * @dev triggered when network fees are burned
      */
-    event NetworkFeesWithdrawn(address indexed caller, address indexed recipient, uint256 amount);
+    event NetworkFeesBurned(address indexed caller, uint256 amount);
 
     /**
      * @dev triggered when pool surplus tokens are withdrawn
@@ -231,6 +231,11 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
      */
     event POLRewardsPPMUpdated(uint32 oldRewardsPPM, uint32 newRewardsPPM);
 
+    /**
+     * @dev triggered when the min network fee burn is updated
+     */
+    event MinNetworkFeeBurnUpdated(uint256 oldMinNetworkFeeBurn, uint256 newMinNetworkFeeBurn);
+
     /**
      * @dev a "virtual" constructor that is only used to set immutable state variables
      */
@@ -315,11 +320,11 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
         // set up administrative roles
         _setRoleAdmin(ROLE_MIGRATION_MANAGER, ROLE_ADMIN);
         _setRoleAdmin(ROLE_EMERGENCY_STOPPER, ROLE_ADMIN);
-        _setRoleAdmin(ROLE_NETWORK_FEE_MANAGER, ROLE_ADMIN);
 
         _depositingEnabled = true;
 
         _setPOLRewardsPPM(2000);
+        _setMinNetworkFeeBurn(1_000_000e18);
     }
 
     // solhint-enable func-name-mixedcase
@@ -342,7 +347,7 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
      * @inheritdoc Upgradeable
      */
     function version() public pure override(IVersioned, Upgradeable) returns (uint16) {
-        return 9;
+        return 10;
     }
 
     /**
@@ -360,14 +365,7 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
     }
 
     /**
-     * @dev returns the network fee manager role
-     */
-    function roleNetworkFeeManager() external pure returns (bytes32) {
-        return ROLE_NETWORK_FEE_MANAGER;
-    }
-
-    /**
-     * @dev returns the pending network fee amount to be burned by the vortex
+     * @dev returns the pending network fee amount to be burned
      */
     function pendingNetworkFeeAmount() external view returns (uint256) {
         return _pendingNetworkFeeAmount;
@@ -820,26 +818,18 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
     /**
      * @inheritdoc IBancorNetwork
      */
-    function withdrawNetworkFees(
-        address recipient
-    )
-        external
-        whenNotPaused
-        onlyRoleMember(ROLE_NETWORK_FEE_MANAGER)
-        validAddress(recipient)
-        nonReentrant
-        returns (uint256)
-    {
+    function burnNetworkFees() external whenNotPaused nonReentrant returns (uint256) {
         uint256 currentPendingNetworkFeeAmount = _pendingNetworkFeeAmount;
-        if (currentPendingNetworkFeeAmount == 0) {
+        if (currentPendingNetworkFeeAmount < _minNetworkFeeBurn) {
             return 0;
         }
 
         _pendingNetworkFeeAmount = 0;
 
-        _masterVault.withdrawFunds(Token(address(_bnt)), payable(recipient), currentPendingNetworkFeeAmount);
+        // transferring bnt to the token's address burns the tokens
+        _masterVault.withdrawFunds(Token(address(_bnt)), payable(address(_bnt)), currentPendingNetworkFeeAmount);
 
-        emit NetworkFeesWithdrawn(msg.sender, recipient, currentPendingNetworkFeeAmount);
+        emit NetworkFeesBurned(msg.sender, currentPendingNetworkFeeAmount);
 
         return currentPendingNetworkFeeAmount;
     }
@@ -915,6 +905,35 @@ contract BancorNetwork is IBancorNetwork, Upgradeable, ReentrancyGuardUpgradeabl
         emit POLRewardsPPMUpdated(oldRewardsPPM, newRewardsPPM);
     }
 
+    /**
+     * @dev returns the min network fee burn
+     */
+    function minNetworkFeeBurn() external view returns (uint256) {
+        return _minNetworkFeeBurn;
+    }
+
+    /**
+     * @dev set the min network fee burn
+     */
+    function setMinNetworkFeeBurn(
+        uint256 newMinNetworkFeeBurn
+    ) external onlyAdmin greaterThanZero(newMinNetworkFeeBurn) {
+        _setMinNetworkFeeBurn(newMinNetworkFeeBurn);
+    }
+
+    /**
+     * @dev set the min network fee burn
+     */
+    function _setMinNetworkFeeBurn(uint256 newMinNetworkFeeBurn) private {
+        uint256 oldMinNetworkFeeBurn = _minNetworkFeeBurn;
+        if (oldMinNetworkFeeBurn == newMinNetworkFeeBurn) {
+            return;
+        }
+
+        _minNetworkFeeBurn = newMinNetworkFeeBurn;
+        emit MinNetworkFeeBurnUpdated(oldMinNetworkFeeBurn, newMinNetworkFeeBurn);
+    }
+
     /**
      * @dev generates context ID for a deposit request
      */

contracts/network/interfaces/IBancorNetwork.sol

@@ -218,13 +218,9 @@ interface IBancorNetwork is IUpgradeable {
     ) external payable;
 
     /**
-     * @dev withdraws pending network fees, and returns the amount of fees withdrawn
-     *
-     * requirements:
-     *
-     * - the caller must have the ROLE_NETWORK_FEE_MANAGER privilege
+     * @dev burns pending network fees, and returns the amount of fees burned
      */
-    function withdrawNetworkFees(address recipient) external returns (uint256);
+    function burnNetworkFees() external returns (uint256);
 
     /**
      * @dev withdraws surplus tokens from a given pool to CarbonPOL contract,

deploy/scripts/000064-upgrade-network-v10.ts

@@ -0,0 +1,44 @@
+import { DeployedContracts, execute, InstanceName, setDeploymentMetadata, upgradeProxy } from '../../utils/Deploy';
+import { toWei } from '../../utils/Types';
+import { DeployFunction } from 'hardhat-deploy/types';
+import { HardhatRuntimeEnvironment } from 'hardhat/types';
+
+const func: DeployFunction = async ({ getNamedAccounts }: HardhatRuntimeEnvironment) => {
+    const { deployer, bancorArbitrageAddress, carbonPOLAddress } = await getNamedAccounts();
+
+    // get the deployed contracts
+    const externalProtectionVault = await DeployedContracts.ExternalProtectionVault.deployed();
+    const masterVault = await DeployedContracts.MasterVault.deployed();
+    const networkSettings = await DeployedContracts.NetworkSettings.deployed();
+    const bntGovernance = await DeployedContracts.BNTGovernance.deployed();
+    const vbntGovernance = await DeployedContracts.VBNTGovernance.deployed();
+    const bnBNT = await DeployedContracts.bnBNT.deployed();
+
+    // upgrade the BancorNetwork contract
+    await upgradeProxy({
+        name: InstanceName.BancorNetwork,
+        args: [
+            bntGovernance.address,
+            vbntGovernance.address,
+            networkSettings.address,
+            masterVault.address,
+            externalProtectionVault.address,
+            bnBNT.address,
+            bancorArbitrageAddress,
+            carbonPOLAddress
+        ],
+        from: deployer
+    });
+
+    // set the min network fee burn to 1M
+    await execute({
+        name: InstanceName.BancorNetwork,
+        methodName: 'setMinNetworkFeeBurn',
+        args: [toWei(1_000_000)],
+        from: deployer
+    });
+
+    return true;
+};
+
+export default setDeploymentMetadata(__filename, func);

deploy/tests/000064-upgrade-network-v10.ts

@@ -0,0 +1,18 @@
+import { BancorNetwork } from '../../components/Contracts';
+import { describeDeployment } from '../../test/helpers/Deploy';
+import { DeployedContracts } from '../../utils/Deploy';
+import { toWei } from '../../utils/Types';
+import { expect } from 'chai';
+
+describeDeployment(__filename, () => {
+    let network: BancorNetwork;
+
+    beforeEach(async () => {
+        network = await DeployedContracts.BancorNetwork.deployed();
+    });
+
+    it('should upgrade the network contract properly', async () => {
+        expect(await network.version()).to.equal(10);
+        expect(await network.minNetworkFeeBurn()).to.equal(toWei(1_000_000));
+    });
+});

deploy/tests/network.ts

@@ -187,7 +187,6 @@ import { getNamedAccounts } from 'hardhat';
             await expectRoleMembers(network, Roles.Upgradeable.ROLE_ADMIN, [daoMultisig.address]);
             await expectRoleMembers(network, Roles.BancorNetwork.ROLE_MIGRATION_MANAGER, [liquidityProtection.address]);
             await expectRoleMembers(network, Roles.BancorNetwork.ROLE_EMERGENCY_STOPPER);
-            await expectRoleMembers(network, Roles.BancorNetwork.ROLE_NETWORK_FEE_MANAGER, [daoMultisig.address]);
 
             await expectRoleMembers(standardRewards, Roles.Upgradeable.ROLE_ADMIN, [daoMultisig.address]);