From 51892f1808aaa4ee5793081ff2dea3eef7c0ac5f Mon Sep 17 00:00:00 2001
From: Brendan Asselstine <mail.asselstine@gmail.com>
Date: Wed, 30 Aug 2023 09:59:15 -0700
Subject: [PATCH 1/3] Added address(0) protections for mint and transfer

---
 src/TwabController.sol    |  9 +++++++++
 test/TwabController.t.sol | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/TwabController.sol b/src/TwabController.sol
index d53d41d..fa68b2c 100644
--- a/src/TwabController.sol
+++ b/src/TwabController.sol
@@ -18,6 +18,9 @@ error PeriodLengthTooShort();
 /// @param periodOffset The period offset that was passed in
 error PeriodOffsetInFuture(uint48 periodOffset);
 
+/// @notice Emitted when a user to tries to mint or transfer to the zero address
+error TransferToZeroAddress();
+
 // The minimum period length
 uint48 constant MINIMUM_PERIOD_LENGTH = 1 hours;
 
@@ -447,6 +450,9 @@ contract TwabController {
    * @param _amount The amount to mint
    */
   function mint(address _to, uint112 _amount) external {
+    if (_to == address(0)) {
+      revert TransferToZeroAddress();
+    }
     _transferBalance(msg.sender, address(0), _to, _amount);
   }
 
@@ -471,6 +477,9 @@ contract TwabController {
    * @param _amount The amount to transfer
    */
   function transfer(address _from, address _to, uint112 _amount) external {
+    if (_to == address(0)) {
+      revert TransferToZeroAddress();
+    }
     _transferBalance(msg.sender, _from, _to, _amount);
   }
 
diff --git a/test/TwabController.t.sol b/test/TwabController.t.sol
index f0eeb6a..8acee6d 100644
--- a/test/TwabController.t.sol
+++ b/test/TwabController.t.sol
@@ -11,6 +11,7 @@ import {
   MINIMUM_PERIOD_LENGTH,
   PeriodLengthTooShort,
   SPONSORSHIP_ADDRESS,
+  TransferToZeroAddress,
   PeriodOffsetInFuture
 } from "../src/TwabController.sol";
 import {
@@ -735,6 +736,23 @@ contract TwabControllerTest is BaseTest {
     assertEq(twabController.delegateOf(mockVault, alice), bob);
   }
 
+  function testMint_toZero() public {
+    vm.startPrank(mockVault);
+
+    uint96 _amount = 1000e18;
+    vm.expectRevert(abi.encodeWithSelector(TransferToZeroAddress.selector));
+    twabController.mint(address(0), _amount);
+  }
+
+  function testTransfer_toZero() public {
+    vm.startPrank(mockVault);
+
+    uint96 _amount = 1000e18;
+    twabController.mint(alice, _amount);
+    vm.expectRevert(abi.encodeWithSelector(TransferToZeroAddress.selector));
+    twabController.transfer(alice, address(0), _amount);
+  }
+
   function testDelegate_toSelf() public {
     vm.startPrank(mockVault);
 

From 8bb13a00814e3b8c0e74608629080f3e2af5fb93 Mon Sep 17 00:00:00 2001
From: Brendan Asselstine <mail.asselstine@gmail.com>
Date: Wed, 30 Aug 2023 10:10:13 -0700
Subject: [PATCH 2/3] Update src/TwabController.sol

Co-authored-by: Pierrick Turelier <pierrick@turelier.com>
---
 src/TwabController.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/TwabController.sol b/src/TwabController.sol
index fa68b2c..6a3ab95 100644
--- a/src/TwabController.sol
+++ b/src/TwabController.sol
@@ -18,7 +18,7 @@ error PeriodLengthTooShort();
 /// @param periodOffset The period offset that was passed in
 error PeriodOffsetInFuture(uint48 periodOffset);
 
-/// @notice Emitted when a user to tries to mint or transfer to the zero address
+/// @notice Emitted when a user tries to mint or transfer to the zero address
 error TransferToZeroAddress();
 
 // The minimum period length

From 49240b4fdf715f258104168da5321d675c6af003 Mon Sep 17 00:00:00 2001
From: Brendan Asselstine <mail.asselstine@gmail.com>
Date: Wed, 30 Aug 2023 10:14:29 -0700
Subject: [PATCH 3/3] Moved natspec

---
 src/TwabController.sol | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/TwabController.sol b/src/TwabController.sol
index 6a3ab95..9ebf77c 100644
--- a/src/TwabController.sol
+++ b/src/TwabController.sol
@@ -24,6 +24,7 @@ error TransferToZeroAddress();
 // The minimum period length
 uint48 constant MINIMUM_PERIOD_LENGTH = 1 hours;
 
+// Allows users to revoke their chances to win by delegating to the sponsorship address.
 address constant SPONSORSHIP_ADDRESS = address(1);
 
 /**
@@ -40,8 +41,6 @@ address constant SPONSORSHIP_ADDRESS = address(1);
  */
 contract TwabController {
   using SafeCast for uint256;
-
-  /// @notice Allows users to revoke their chances to win by delegating to the sponsorship address.
   
   /// @notice Sets the minimum period length for Observations. When a period elapses, a new Observation is recorded, otherwise the most recent Observation is updated.
   uint48 public immutable PERIOD_LENGTH;