From 8e6a20aa0de6faccd2eea4e354680354e379dfb9 Mon Sep 17 00:00:00 2001
From: didi <git@d10r.net>
Date: Tue, 5 Nov 2024 18:42:30 +0100
Subject: [PATCH] make SuperToken 2771 recipient which trusts DMZForwarder,
 example use with increaseAllowance

---
 .../interfaces/superfluid/ISuperfluid.sol     |  5 +++
 .../contracts/superfluid/SuperToken.sol       | 32 +++++++++++++++++--
 .../contracts/superfluid/Superfluid.sol       |  4 +++
 .../superfluid/Superfluid.BatchCall.t.sol     | 14 ++++++++
 4 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/packages/ethereum-contracts/contracts/interfaces/superfluid/ISuperfluid.sol b/packages/ethereum-contracts/contracts/interfaces/superfluid/ISuperfluid.sol
index b698648111..388c253217 100644
--- a/packages/ethereum-contracts/contracts/interfaces/superfluid/ISuperfluid.sol
+++ b/packages/ethereum-contracts/contracts/interfaces/superfluid/ISuperfluid.sol
@@ -645,6 +645,11 @@ interface ISuperfluid {
      */
     function forwardBatchCall(Operation[] calldata operations) external payable;
 
+    /**
+     * @dev Get the current DMZForwarder
+     */
+    function getDMZForwarder() external view returns(address);
+
     /**************************************************************************
      * Function modifiers for access control and parameter validations
      *
diff --git a/packages/ethereum-contracts/contracts/superfluid/SuperToken.sol b/packages/ethereum-contracts/contracts/superfluid/SuperToken.sol
index dbb0db043f..905901acbb 100644
--- a/packages/ethereum-contracts/contracts/superfluid/SuperToken.sol
+++ b/packages/ethereum-contracts/contracts/superfluid/SuperToken.sol
@@ -14,6 +14,7 @@ import {
 } from "../interfaces/superfluid/ISuperfluid.sol";
 import { SuperfluidToken } from "./SuperfluidToken.sol";
 import { ERC777Helper } from "../libs/ERC777Helper.sol";
+import { IRelayRecipient } from "../interfaces/utils/IRelayRecipient.sol";
 import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 import { SafeMath } from "@openzeppelin/contracts/utils/math/SafeMath.sol";
 import { SafeCast } from "@openzeppelin/contracts/utils/math/SafeCast.sol";
@@ -35,7 +36,8 @@ interface IConstantInflowNFT {}
 contract SuperToken is
     UUPSProxiable,
     SuperfluidToken,
-    ISuperToken
+    ISuperToken,
+    IRelayRecipient
 {
 
     using SafeMath for uint256;
@@ -543,8 +545,10 @@ contract SuperToken is
     }
 
     function increaseAllowance(address spender, uint256 addedValue)
-        public virtual override returns (bool) {
-        _approve(msg.sender, spender, _allowances[msg.sender][spender] + addedValue);
+        public virtual override returns (bool)
+    {
+        address msgSender = _msgSender();
+        _approve(msgSender, spender, _allowances[msgSender][spender] + addedValue);
         return true;
     }
 
@@ -886,6 +890,28 @@ contract SuperToken is
         _downgrade(msg.sender, account, to, amount, "", "");
     }
 
+    /**************************************************************************
+    * IRelayRecipient
+    *************************************************************************/
+
+    /// @dev IRelayRecipient.isTrustedForwarder implementation
+    function isTrustedForwarder(address forwarder) public view override returns(bool) {
+        return forwarder == _host.getDMZForwarder();
+    }
+
+    /// @dev IRelayRecipient.versionRecipient implementation
+    function versionRecipient() external override pure returns (string memory) {
+        return "v1";
+    }
+
+    function _msgSender() internal virtual view returns (address) {
+        if(msg.data.length >= 20 && isTrustedForwarder(msg.sender)) {
+            return address(bytes20(msg.data[msg.data.length - 20:]));
+        } else {
+            return msg.sender;
+        }
+    }
+
     /**************************************************************************
     * Modifiers
     *************************************************************************/
diff --git a/packages/ethereum-contracts/contracts/superfluid/Superfluid.sol b/packages/ethereum-contracts/contracts/superfluid/Superfluid.sol
index 9528c99748..06e9fb72fc 100644
--- a/packages/ethereum-contracts/contracts/superfluid/Superfluid.sol
+++ b/packages/ethereum-contracts/contracts/superfluid/Superfluid.sol
@@ -949,6 +949,10 @@ contract Superfluid is
         return "v1";
     }
 
+    function getDMZForwarder() external view override returns(address) {
+        return address(DMZ_FORWARDER);
+    }
+
     /**************************************************************************
     * Internal
     **************************************************************************/
diff --git a/packages/ethereum-contracts/test/foundry/superfluid/Superfluid.BatchCall.t.sol b/packages/ethereum-contracts/test/foundry/superfluid/Superfluid.BatchCall.t.sol
index ad56918876..5352396efb 100644
--- a/packages/ethereum-contracts/test/foundry/superfluid/Superfluid.BatchCall.t.sol
+++ b/packages/ethereum-contracts/test/foundry/superfluid/Superfluid.BatchCall.t.sol
@@ -628,4 +628,18 @@ contract SuperfluidBatchCallTest is FoundrySuperfluidTester {
         assertEq(address(forwarder).balance, 0, "DMZForwarder: balance still not 0");
         assertEq(bob.balance, amount, "DMZForwarder: where did the money go?");
     }
+
+    function testIncreaseAllowanceUsing2771ForwardCall(uint256 allowanceAmount) public {
+        ISuperfluid.Operation[] memory ops = new ISuperfluid.Operation[](1);
+        uint256 aliceToBobAllowanceBefore = superToken.allowance(alice, bob);
+        ops[0] = ISuperfluid.Operation({
+            operationType: BatchOperation.OPERATION_TYPE_ERC2771_FORWARD_CALL,
+            target: address(superToken),
+            data: abi.encodeCall(superToken.increaseAllowance, (bob, allowanceAmount))
+        });
+        vm.prank(alice);
+        sf.host.batchCall(ops);
+        uint256 aliceToBobAllowanceAfter = superToken.allowance(alice, bob);
+        assertEq(aliceToBobAllowanceAfter, aliceToBobAllowanceBefore + allowanceAmount);
+    }
 }