feat: block transfers to/from known pools in SuperGoodDollar

contracts/token/superfluid/ISuperGoodDollar.sol

@@ -32,6 +32,8 @@ interface IGoodDollarCustom {
 
 	function isPauser(address _pauser) external view returns (bool);
 
+	function isBlocked(address account) external view returns (bool);
+
 	function owner() external view returns (address);
 
 	// state changing functions
@@ -57,6 +59,8 @@ interface IGoodDollarCustom {
 
 	function adminBurn(address account, uint256 amount) external;
 
+	function setBlocked(address[] calldata accounts, bool blocked) external;
+
 	function addMinter(address _minter) external;
 
 	function renounceMinter() external;

contracts/token/superfluid/SuperGoodDollar.sol

@@ -29,6 +29,13 @@ contract SuperGoodDollar is
 	IGoodDollarCustom // without storage
 {
 	error SUPER_GOODDOLLAR_PAUSED();
+	error SUPER_GOODDOLLAR_BLOCKED();
+	error SUPER_GOODDOLLAR_NOT_PAUSER();
+	error SUPER_GOODDOLLAR_NOT_MINTER();
+	error SUPER_GOODDOLLAR_CAP_EXCEEDED();
+	error SUPER_GOODDOLLAR_BURN_EXCEEDS_ALLOWANCE();
+	error SUPER_GOODDOLLAR_FALLBACK_FAILED();
+	error SUPER_GOODDOLLAR_FEE_EXCEEDS_BALANCE();
 
 	// IMPORTANT! Never change the type (storage size) or order of state variables.
 	// If a variable isn't needed anymore, leave it as padding (renaming is ok).
@@ -37,6 +44,8 @@ contract SuperGoodDollar is
 	IIdentity public identity;
 	uint256 public cap;
 	bool public disableHostOperations;
+	/// @dev accounts (eg. known DEX pools) that can neither send nor receive G$
+	mapping(address => bool) public isBlocked;
 	// Append additional state variables here!
 
 	// ============== constants and immutables ==============
@@ -45,6 +54,8 @@ contract SuperGoodDollar is
 	bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
 	bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
 
+	event BlockedUpdated(address indexed account, bool blocked);
+
 	event TransferFee(
 		address from,
 		address to,
@@ -199,10 +210,8 @@ contract SuperGoodDollar is
 		bool res = super._transferFrom(msg.sender, msg.sender, to, netAmount);
 		emit ERC677.Transfer(msg.sender, to, netAmount, data);
 		if (isContract(to)) {
-			require(
-				contractFallback(to, netAmount, data),
-				"Contract fallback failed"
-			);
+			if (!contractFallback(to, netAmount, data))
+				revert SUPER_GOODDOLLAR_FALLBACK_FAILED();
 		}
 		return res;
 	}
@@ -261,6 +270,7 @@ contract SuperGoodDollar is
 		bytes memory operatorData
 	) internal virtual override {
 		_onlyNotPaused();
+		_onlyNotBlocked(from);
 		// handing over to the wrapper of SuperToken.transferFrom
 		super._burn(operator, from, amount, userData, operatorData);
 	}
@@ -275,12 +285,10 @@ contract SuperGoodDollar is
 		uint256 amount
 	) public override(IGoodDollarCustom) onlyMinter returns (bool) {
 		_onlyNotPaused();
+		_onlyNotBlocked(to);
 
 		if (cap > 0) {
-			require(
-				totalSupply() + amount <= cap,
-				"Cannot increase supply beyond cap"
-			);
+			if (totalSupply() + amount > cap) revert SUPER_GOODDOLLAR_CAP_EXCEEDED();
 		}
 		_mint(
 			msg.sender,
@@ -296,7 +304,7 @@ contract SuperGoodDollar is
 
 	function burnFrom(address account, uint256 amount) public {
 		uint256 currentAllowance = allowance(account, _msgSender());
-		require(currentAllowance >= amount, "ERC20: burn amount exceeds allowance");
+		if (currentAllowance < amount) revert SUPER_GOODDOLLAR_BURN_EXCEEDS_ALLOWANCE();
 		unchecked {
 			_approve(account, _msgSender(), currentAllowance - amount);
 		}
@@ -321,6 +329,27 @@ contract SuperGoodDollar is
 		emit IERC20.Transfer(account, address(0), amount);
 	}
 
+	/**
+	 * @dev Blocks/unblocks accounts (eg. known liquidity pools) from sending or receiving G$.
+	 * Owner only.
+	 * Note: this covers the ERC20/ERC677/ERC777 surface (incl. the host batch operations).
+	 * Superfluid streams settle via the agreement layer and are not covered - a stream can still
+	 * credit a blocked account, but that account will not be able to move the funds out.
+	 * @param accounts the addresses to update
+	 * @param blocked true to block, false to unblock
+	 */
+	function setBlocked(address[] calldata accounts, bool blocked) external {
+		_onlyOwner();
+		for (uint256 i; i < accounts.length; ) {
+			address account = accounts[i];
+			isBlocked[account] = blocked;
+			emit BlockedUpdated(account, blocked);
+			unchecked {
+				++i;
+			}
+		}
+	}
+
 	/**
 	 * @dev Gets the current transaction fees
 	 * @return fee senderPays  that represents the current transaction fees and bool true if sender pays the fee or receiver
@@ -356,7 +385,8 @@ contract SuperGoodDollar is
 	// internal functions
 
 	/**
-	 * @dev Sends transactional fees to feeRecipient address from given address
+	 * @dev Enforces the blocklist and sends transactional fees to feeRecipient address from given address.
+	 * Called by every G$ movement (ERC20/ERC677/ERC777 and the superfluid host batch operations).
 	 * @param account The account that sends the fees
 	 * @param amount The amount to subtract fees from
 	 * @return an uint256 that represents the given amount minus the transactional fees
@@ -366,12 +396,12 @@ contract SuperGoodDollar is
 		address recipient,
 		uint256 amount
 	) internal returns (uint256) {
+		_onlyNotBlocked(account);
+		_onlyNotBlocked(recipient);
 		(uint256 txFees, bool senderPays) = getFees(amount, account, recipient);
 		if (txFees > 0 && !identity.isDAOContract(msg.sender)) {
-			require(
-				senderPays == false || amount + txFees <= balanceOf(account),
-				"Not enough balance to pay TX fee"
-			);
+			if (senderPays && amount + txFees > balanceOf(account))
+				revert SUPER_GOODDOLLAR_FEE_EXCEEDS_BALANCE();
 			super._transferFrom(account, account, feeRecipient, txFees);
 			emit TransferFee(account, recipient, amount, txFees, senderPays);
 			return senderPays ? amount : amount - txFees;
@@ -408,15 +438,19 @@ contract SuperGoodDollar is
 	}
 
 	function _onlyPauser() internal view {
-		require(hasRole(PAUSER_ROLE, msg.sender), "not pauser");
+		if (!hasRole(PAUSER_ROLE, msg.sender)) revert SUPER_GOODDOLLAR_NOT_PAUSER();
 	}
 
 	function _onlyNotPaused() internal view {
 		if (paused()) revert SUPER_GOODDOLLAR_PAUSED();
 	}
 
+	function _onlyNotBlocked(address account) internal view {
+		if (isBlocked[account]) revert SUPER_GOODDOLLAR_BLOCKED();
+	}
+
 	modifier onlyMinter() {
-		require(hasRole(MINTER_ROLE, msg.sender), "not minter");
+		if (!hasRole(MINTER_ROLE, msg.sender)) revert SUPER_GOODDOLLAR_NOT_MINTER();
 		_;
 	}
 }

scripts/upgrades/blocked-pools.json

@@ -0,0 +1,30 @@
+{
+  "production-celo": {
+    "blocked": true,
+    "pools": [
+      "0x6619871118D144c1c28eC3b23036FC1f0829ed3a",
+      "0x059ee811414230d1Fb157878D2b491240F4D8d3B",
+      "0x991f1AA7e0901f9AB3d583846bf5BE0EbACE1d7f",
+      "0x3D9e27C04076288eBfdC4815b4f6d81b0ED1b341",
+      "0x9491d57c5687AB75726423B55AC2d87D1cDa2c3F",
+      "0x31f9DeE850B4284b81B52b25a3194F2FC8fF18CF",
+      "0x07F86B39728Be613062bc7413FC2CA7293Eef022",
+      "0x25878951ae130014E827e6f54fd3B4CCa057a7e8",
+      "0xCB037f27eB3952222810966e28E0cEB650c65CD9",
+      "0x8b393470bef8bb27a9a5169531b4eBA5209b0b26",
+      "0xA0BeF7ff637c10b9Ec67a00687B4d4364A7f1c55",
+      "0x288dc841A52FCA2707c6947B3A777c5E56cd87BC",
+      "0xC10eE9031F2a0B84766A86B55a8D90F357910fb4",
+      "0xb92fe925DC43a0ECdE6c8b1a2709c170Ec4fFf4f",
+      "0x89c6340B1a1f4b25D36cd8B063D49045caF3f818"
+    ]
+  },
+  "staging-celo": {
+    "blocked": true,
+    "pools": []
+  },
+  "development-celo": {
+    "blocked": true,
+    "pools": []
+  }
+}