support multi permits but spender specified transfers (#118)

.forge-snapshots/permitBatchTransferFromMultipleTokens.snap

@@ -1 +1 @@
-143500
+143701

.forge-snapshots/permitBatchTransferFromSingleToken.snap

@@ -1 +1 @@
-88950
+89017

.forge-snapshots/permitTransferFromBatchTypedWitness.snap

@@ -1 +1 @@
-121317
+121451

.forge-snapshots/single recipient 2 tokens.snap

@@ -1 +1 @@
-118623
+118757

.forge-snapshots/single recipient many tokens.snap

@@ -1 +1 @@
-133765
+134435

.gas-snapshot

@@ -50,28 +50,29 @@ Permit2LibTest:testTransferFrom2() (gas: 38404)
 Permit2LibTest:testTransferFrom2Full() (gas: 53437)
 Permit2LibTest:testTransferFrom2InvalidAmount() (gas: 12519)
 Permit2LibTest:testTransferFrom2NonPermitToken() (gas: 53305)
-SignatureTransferTest:testGasMultiplePermitBatchTransferFrom() (gas: 270959)
-SignatureTransferTest:testGasSinglePermitBatchTransferFrom() (gas: 186309)
-SignatureTransferTest:testGasSinglePermitTransferFrom() (gas: 124095)
-SignatureTransferTest:testInvalidateUnorderedNonces() (gas: 56540)
-SignatureTransferTest:testPermitBatchTransferFrom() (gas: 162076)
-SignatureTransferTest:testPermitBatchTransferFromSingleRecipient() (gas: 190355)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitness() (gas: 242493)
+SignatureTransferTest:testGasMultiplePermitBatchTransferFrom() (gas: 271182)
+SignatureTransferTest:testGasSinglePermitBatchTransferFrom() (gas: 186398)
+SignatureTransferTest:testGasSinglePermitTransferFrom() (gas: 124117)
+SignatureTransferTest:testInvalidateUnorderedNonces() (gas: 56562)
+SignatureTransferTest:testPermitBatchMultiPermitSingleTransfer() (gas: 133761)
+SignatureTransferTest:testPermitBatchTransferFrom() (gas: 162210)
+SignatureTransferTest:testPermitBatchTransferFromSingleRecipient() (gas: 190511)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitness() (gas: 242649)
 SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidType() (gas: 87340)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeHash() (gas: 86803)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeName() (gas: 88276)
-SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidWitness() (gas: 88321)
-SignatureTransferTest:testPermitBatchTransferInvalidAmountsLengthMismatch() (gas: 43738)
-SignatureTransferTest:testPermitBatchTransferMultiAddr() (gas: 160450)
-SignatureTransferTest:testPermitBatchTransferSingleRecipientManyTokens() (gas: 211974)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeHash() (gas: 86825)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidTypeName() (gas: 88298)
+SignatureTransferTest:testPermitBatchTransferFromTypedWitnessInvalidWitness() (gas: 88343)
+SignatureTransferTest:testPermitBatchTransferInvalidAmountsLengthMismatch() (gas: 43760)
+SignatureTransferTest:testPermitBatchTransferMultiAddr() (gas: 160606)
+SignatureTransferTest:testPermitBatchTransferSingleRecipientManyTokens() (gas: 212666)
 SignatureTransferTest:testPermitTransferFrom() (gas: 93208)
-SignatureTransferTest:testPermitTransferFromCompactSig() (gas: 124159)
+SignatureTransferTest:testPermitTransferFromCompactSig() (gas: 124181)
 SignatureTransferTest:testPermitTransferFromIncorrectSigLength() (gas: 51430)
-SignatureTransferTest:testPermitTransferFromInvalidNonce() (gas: 93215)
-SignatureTransferTest:testPermitTransferFromRandomNonceAndAmount(uint256,uint128) (runs: 256, μ: 95842, ~: 96818)
-SignatureTransferTest:testPermitTransferFromToSpender() (gas: 93494)
+SignatureTransferTest:testPermitTransferFromInvalidNonce() (gas: 93237)
+SignatureTransferTest:testPermitTransferFromRandomNonceAndAmount(uint256,uint128) (runs: 256, μ: 95864, ~: 96840)
+SignatureTransferTest:testPermitTransferFromToSpender() (gas: 93516)
 SignatureTransferTest:testPermitTransferFromTypedWitness() (gas: 127964)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidType() (gas: 58668)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypeName() (gas: 59722)
-SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypehash() (gas: 57658)
-SignatureTransferTest:testPermitTransferSpendLessThanFull(uint256,uint128) (runs: 256, μ: 98177, ~: 99895)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidType() (gas: 58690)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypeName() (gas: 59744)
+SignatureTransferTest:testPermitTransferFromTypedWitnessInvalidTypehash() (gas: 57680)
+SignatureTransferTest:testPermitTransferSpendLessThanFull(uint256,uint128) (runs: 256, μ: 98199, ~: 99917)

src/SignatureTransfer.sol

@@ -123,7 +123,10 @@ contract SignatureTransfer is ISignatureTransfer, EIP712 {
 
                 if (requestedAmount > permitted.amount) revert InvalidAmount();
 
-                ERC20(permitted.token).safeTransferFrom(owner, transferDetails[i].to, requestedAmount);
+                if (requestedAmount != 0) {
+                    // allow spender to specify which of the permitted tokens should be transferred
+                    ERC20(permitted.token).safeTransferFrom(owner, transferDetails[i].to, requestedAmount);
+                }
             }
         }
     }

test/SignatureTransfer.t.sol

@@ -186,7 +186,6 @@ contract SignatureTransferTest is Test, PermitSignature, TokenProvider, GasSnaps
         ISignatureTransfer.PermitBatchTransferFrom memory permit = defaultERC20PermitMultiple(tokens, nonce);
         bytes memory sig = getPermitBatchTransferSignature(permit, fromPrivateKey, DOMAIN_SEPARATOR);
 
-        // address(0) gets sent to spender
         address[] memory to = AddressBuilder.fill(1, address(address2)).push(address(address0));
         ISignatureTransfer.SignatureTransferDetails[] memory toAmountPairs =
             StructBuilder.fillSigTransferDetails(defaultAmount, to);
@@ -204,6 +203,34 @@ contract SignatureTransferTest is Test, PermitSignature, TokenProvider, GasSnaps
         assertEq(token1.balanceOf(address0), startBalanceTo1 + defaultAmount);
     }
 
+    function testPermitBatchMultiPermitSingleTransfer() public {
+        uint256 nonce = 0;
+        address[] memory tokens = AddressBuilder.fill(1, address(token0)).push(address(token1));
+        ISignatureTransfer.PermitBatchTransferFrom memory permit = defaultERC20PermitMultiple(tokens, nonce);
+
+        bytes memory sig = getPermitBatchTransferSignature(permit, fromPrivateKey, DOMAIN_SEPARATOR);
+
+        // must fill address to even though token0 wont get sent.
+        // transfer details must be lenght of permit
+        address[] memory to = AddressBuilder.fill(1, address(address0)).push(address(address0));
+        ISignatureTransfer.SignatureTransferDetails[] memory toAmountPairs =
+            StructBuilder.fillSigTransferDetails(defaultAmount, to);
+        // spender doesnt need token0 even though user permitted it
+        toAmountPairs[0].requestedAmount = 0;
+
+        uint256 startBalanceFrom0 = token0.balanceOf(from);
+        uint256 startBalanceFrom1 = token1.balanceOf(from);
+        uint256 startBalanceTo0 = token0.balanceOf(address2);
+        uint256 startBalanceTo1 = token1.balanceOf(address0);
+
+        permit2.permitTransferFrom(permit, from, toAmountPairs, sig);
+
+        assertEq(token0.balanceOf(from), startBalanceFrom0);
+        assertEq(token1.balanceOf(from), startBalanceFrom1 - defaultAmount);
+        assertEq(token0.balanceOf(address2), startBalanceTo0);
+        assertEq(token1.balanceOf(address0), startBalanceTo1 + defaultAmount);
+    }
+
     function testPermitBatchTransferFromSingleRecipient() public {
         uint256 nonce = 0;
         address[] memory tokens = AddressBuilder.fill(1, address(token0)).push(address(token1));