allow permit2 to silently fail to avoid dos

contracts/base/Dispatcher.sol

@@ -107,7 +107,14 @@ abstract contract Dispatcher is Payments, V2SwapRouter, V3SwapRouter, V4SwapRout
                             permitBatch := add(inputs.offset, calldataload(inputs.offset))
                         }
                         bytes calldata data = inputs.toBytes(1);
-                        PERMIT2.permit(msgSender(), permitBatch, data);
+                        (success, output) = address(PERMIT2).call(
+                            abi.encodeWithSignature(
+                                'permit(address,((address,uint160,uint48,uint48)[],address,uint256),bytes)',
+                                msgSender(),
+                                permitBatch,
+                                data
+                            )
+                        );
                     } else if (command == Commands.SWEEP) {
                         // equivalent:  abi.decode(inputs, (address, address, uint256))
                         address token;
@@ -186,7 +193,14 @@ abstract contract Dispatcher is Payments, V2SwapRouter, V3SwapRouter, V4SwapRout
                             permitSingle := inputs.offset
                         }
                         bytes calldata data = inputs.toBytes(6); // PermitSingle takes first 6 slots (0..5)
-                        PERMIT2.permit(msgSender(), permitSingle, data);
+                        (success, output) = address(PERMIT2).call(
+                            abi.encodeWithSignature(
+                                'permit(address,((address,uint160,uint48,uint48),address,uint256),bytes)',
+                                msgSender(),
+                                permitSingle,
+                                data
+                            )
+                        );
                     } else if (command == Commands.WRAP_ETH) {
                         // equivalent: abi.decode(inputs, (address, uint256))
                         address recipient;

test/integration-tests/UniswapMixed.test.ts

@@ -279,6 +279,39 @@ describe('Uniswap V2, V3, and V4 Tests:', () => {
       expect(wethBalanceAfter.sub(wethBalanceBefore)).to.be.gte(minAmountOut1.add(minAmountOut2))
     })
 
+    it('PERMIT2 batch can silently fail', async () => {
+      const v2AmountIn1: BigNumber = expandTo18DecimalsBN(20)
+      const v2AmountIn2: BigNumber = expandTo18DecimalsBN(5)
+
+      const BATCH_PERMIT = {
+        details: [
+          {
+            token: DAI.address,
+            amount: v2AmountIn1,
+            expiration: 0, // expiration of 0 is block.timestamp
+            nonce: 0, // this is his first trade
+          },
+          {
+            token: WETH.address,
+            amount: v2AmountIn2,
+            expiration: 0, // expiration of 0 is block.timestamp
+            nonce: 0, // this is his first trade
+          },
+        ],
+        spender: router.address,
+        sigDeadline: DEADLINE,
+      }
+
+      const sig = await getPermitBatchSignature(BATCH_PERMIT, bob, permit2)
+
+      // transfer funds into DAI-USDC and DAI-USDT pairs to trade
+      planner.addCommand(CommandType.PERMIT2_PERMIT_BATCH, [BATCH_PERMIT, sig])
+
+      planner.addCommand(CommandType.PERMIT2_PERMIT_BATCH_NO_REVERT, [BATCH_PERMIT, sig])
+
+      await executeRouter(planner, bob, router, wethContract, daiContract, usdcContract)
+    })
+
     it('ERC20 --> ERC20 split V2 and V2 different routes, different input tokens, each two hop, with batch permit', async () => {
       const route1 = [DAI.address, WETH.address, USDC.address]
       const route2 = [WETH.address, DAI.address, USDC.address]

test/integration-tests/UniswapV2.test.ts

@@ -20,7 +20,7 @@ import {
 import { expandTo18DecimalsBN, expandTo6DecimalsBN } from './shared/helpers'
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers'
 import deployUniversalRouter from './shared/deployUniversalRouter'
-import { RoutePlanner, CommandType } from './shared/planner'
+import { RoutePlanner, CommandType, ALLOW_REVERT_FLAG } from './shared/planner'
 import hre from 'hardhat'
 import { executeRouter } from './shared/executeRouter'
 import { getPermitSignature, PermitSingle } from './shared/protocolHelpers/permit2'
@@ -77,6 +77,31 @@ describe('Uniswap V2 Tests:', () => {
       await permit2.approve(DAI.address, ADDRESS_ZERO, 0, 0)
     })
 
+    it('Permit2 can silently fail', async () => {
+      const amountInDAI = expandTo18DecimalsBN(100)
+
+      // bob signs a permit to allow the router to access his DAI
+      permit = {
+        details: {
+          token: DAI.address,
+          amount: amountInDAI,
+          expiration: 0, // expiration of 0 is block.timestamp
+          nonce: 0, // this is his first trade
+        },
+        spender: router.address,
+        sigDeadline: DEADLINE,
+      }
+      const sig = await getPermitSignature(permit, bob, permit2)
+
+      // 1) permit the router to access funds, not allowing revert
+      planner.addCommand(CommandType.PERMIT2_PERMIT, [permit, sig])
+
+      // 2) permit the router to access funds again, allowing revert
+      planner.addCommand(CommandType.PERMIT2_NO_REVERT, [permit, sig])
+
+      await executeRouter(planner, bob, router, wethContract, daiContract, usdcContract)
+    })
+
     it('V2 exactIn, permiting the exact amount', async () => {
       const amountInDAI = expandTo18DecimalsBN(100)
       const minAmountOutWETH = expandTo18DecimalsBN(0.02)

test/integration-tests/gas-tests/__snapshots__/CheckOwnership.gas.test.ts.snap

@@ -3,6 +3,6 @@
 exports[`Check Ownership Gas gas: balance check ERC20 1`] = `
 Object {
   "calldataByteLength": 356,
-  "gasUsed": 37698,
+  "gasUsed": 37740,
 }
 `;

test/integration-tests/gas-tests/__snapshots__/Payments.gas.test.ts.snap

@@ -3,48 +3,48 @@
 exports[`Payments Gas Tests Individual Command Tests gas: SWEEP with ERC20 1`] = `
 Object {
   "calldataByteLength": 356,
-  "gasUsed": 37012,
+  "gasUsed": 37042,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: SWEEP_WITH_FEE 1`] = `
 Object {
   "calldataByteLength": 516,
-  "gasUsed": 65726,
+  "gasUsed": 65786,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: TRANSFER with ERC20 1`] = `
 Object {
   "calldataByteLength": 356,
-  "gasUsed": 36040,
+  "gasUsed": 36070,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: TRANSFER with ETH 1`] = `
 Object {
   "calldataByteLength": 356,
-  "gasUsed": 31605,
+  "gasUsed": 31635,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: UNWRAP_WETH 1`] = `
 Object {
   "calldataByteLength": 324,
-  "gasUsed": 44579,
+  "gasUsed": 44621,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: UNWRAP_WETH_WITH_FEE 1`] = `
 Object {
   "calldataByteLength": 644,
-  "gasUsed": 51006,
+  "gasUsed": 51108,
 }
 `;
 
 exports[`Payments Gas Tests Individual Command Tests gas: WRAP_ETH 1`] = `
 Object {
   "calldataByteLength": 324,
-  "gasUsed": 53389,
+  "gasUsed": 53423,
 }
 `;