Merge pull request #44 from delegatable/passthrough-errors

Passthrough errors

Author: danfinlay

contracts/DelegatableCore.sol

@@ -42,8 +42,35 @@ abstract contract DelegatableCore is EIP712Decoder {
         address sender
     ) internal returns (bool success) {
         bytes memory full = abi.encodePacked(data, sender);
+        bytes memory errorMessage;
+        (success, errorMessage) = address(to).call{gas: gasLimit}(full);
+
+        if (!success) {
+            if (errorMessage.length > 0) {
+                string memory reason = extractRevertReason(errorMessage);
+                revert(reason);
+            } else {
+                revert("DelegatableCore::execution-failed");
+            }
+        }
+    }
+
+    function extractRevertReason(bytes memory revertData)
+        internal
+        pure
+        returns (string memory reason)
+    {
+        uint256 l = revertData.length;
+        if (l < 68) return "";
+        uint256 t;
+        assembly {
+            revertData := add(revertData, 4)
+            t := mload(revertData) // Save the content of the length slot
+            mstore(revertData, sub(l, 4)) // Set proper length
+        }
+        reason = abi.decode(revertData, (string));
         assembly {
-            success := call(gasLimit, to, 0, add(full, 0x20), mload(full), 0, 0)
+            mstore(revertData, t) // Restore the content of the length slot
         }
     }
 

contracts/DelegatableRelayCore.sol

@@ -35,15 +35,43 @@ abstract contract DelegatableRelayCore is EIP712Decoder {
         multiNonce[intendedSender][queue] = nonce;
     }
 
+
     function _execute(
         address to,
         bytes memory data,
         uint256 gasLimit,
         address sender
     ) internal returns (bool success) {
         bytes memory full = abi.encodePacked(data, sender);
+        bytes memory errorMessage;
+        (success, errorMessage) = address(to).call{gas: gasLimit}(full);
+
+        if (!success) {
+            if (errorMessage.length > 0) {
+                string memory reason = extractRevertReason(errorMessage);
+                revert(reason);
+            } else {
+                revert("DelegatableCore::execution-failed");
+            }
+        }
+    }
+
+    function extractRevertReason(bytes memory revertData)
+        internal
+        pure
+        returns (string memory reason)
+    {
+        uint256 l = revertData.length;
+        if (l < 68) return "";
+        uint256 t;
+        assembly {
+            revertData := add(revertData, 4)
+            t := mload(revertData) // Save the content of the length slot
+            mstore(revertData, sub(l, 4)) // Set proper length
+        }
+        reason = abi.decode(revertData, (string));
         assembly {
-            success := call(gasLimit, to, 0, add(full, 0x20), mload(full), 0, 0)
+            mstore(revertData, t) // Restore the content of the length slot
         }
     }
 

contracts/mock/MockDelegatable.sol

@@ -13,6 +13,10 @@ contract MockDelegatable is Delegatable, Ownable {
         purpose = purpose_;
     }
 
+    function alwaysFail() public pure {
+        revert("I always fail");
+    }
+
     function _msgSender()
         internal
         view

test/Delegatable.test.ts

@@ -95,6 +95,35 @@ describe("Delegatable", () => {
       "0xf6e94ae88b8b72d51444924d7cf26f28b4eaf7d5d274dffbdc83cb92cb4eeac5"
     );
   });
+
+  it("INVOKE alwaysFail() bubbles out error", async () => {
+    const INVOCATION_MESSAGE = {
+      replayProtection: {
+        nonce: "0x01",
+        queue: "0x00",
+      },
+      batch: [
+        {
+          authority: [],
+          transaction: {
+            to: Delegatable.address,
+            gasLimit: "21000000000000",
+            data: (await Delegatable.populateTransaction.alwaysFail()).data,
+          },
+        },
+      ],
+    };
+    const invocation = delegatableUtils.signInvocation(INVOCATION_MESSAGE, pk0);
+    await expect(
+      Delegatable.invoke([
+        {
+          signature: invocation.signature,
+          invocations: invocation.invocations,
+        },
+      ])
+    ).to.be.revertedWith("I always fail");
+  });
+
   it("READ getEIP712DomainHash(string,string,uint256,address)", async () => {});
   it("READ verifyDelegationSignature(SignedDelegation memory signedDelegation)`", async () => {
     const _delegation = generateDelegation(