Add OrderValidator contract

13 files changed, 1207 insertions, 0 deletions

diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
new file mode 100644
index 000000000..6b17bb29b
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
@@ -0,0 +1,51 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./MixinWeth.sol";
+import "./MixinForwarderCore.sol";
+import "./libs/LibConstants.sol";
+import "./MixinAssets.sol";
+import "./MixinExchangeWrapper.sol";
+
+
+// solhint-disable no-empty-blocks
+contract Forwarder is
+    LibConstants,
+    MixinWeth,
+    MixinAssets,
+    MixinExchangeWrapper,
+    MixinForwarderCore
+{
+
+    constructor (
+        address _exchange,
+        bytes memory _zrxAssetData,
+        bytes memory _wethAssetData
+    )
+        public
+        LibConstants(
+            _exchange,
+            _zrxAssetData,
+            _wethAssetData
+        )
+        MixinForwarderCore()
+    {}
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
new file mode 100644
index 000000000..d6a38aa6e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
@@ -0,0 +1,144 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "../../utils/Ownable/Ownable.sol";
+import "../../tokens/ERC20Token/IERC20Token.sol";
+import "../../tokens/ERC721Token/IERC721Token.sol";
+import "./libs/LibConstants.sol";
+import "./mixins/MAssets.sol";
+
+
+contract MixinAssets is
+    Ownable,
+    LibConstants,
+    MAssets
+{
+
+    using LibBytes for bytes;
+
+    bytes4 constant internal ERC20_TRANSFER_SELECTOR = bytes4(keccak256("transfer(address,uint256)"));
+
+    /// @dev Withdraws assets from this contract. The contract requires a ZRX balance in order to 
+    ///      function optimally, and this function allows the ZRX to be withdrawn by owner. It may also be
+    ///      used to withdraw assets that were accidentally sent to this contract.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of ERC20 token to withdraw.
+    function withdrawAsset(
+        bytes assetData,
+        uint256 amount
+    )
+        external
+        onlyOwner
+    {
+        transferAssetToSender(assetData, amount);
+    }
+
+    /// @dev Transfers given amount of asset to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferAssetToSender(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        bytes4 proxyId = assetData.readBytes4(0);
+
+        if (proxyId == ERC20_DATA_ID) {
+            transferERC20Token(assetData, amount);
+        } else if (proxyId == ERC721_DATA_ID) {
+            transferERC721Token(assetData, amount);
+        } else {
+            revert("UNSUPPORTED_ASSET_PROXY");
+        }
+    }
+
+    /// @dev Decodes ERC20 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        address token = assetData.readAddress(16);
+
+        // Transfer tokens.
+        // We do a raw call so we can check the success separate
+        // from the return data.
+        bool success = token.call(abi.encodeWithSelector(
+            ERC20_TRANSFER_SELECTOR,
+            msg.sender,
+            amount
+        ));
+        require(
+            success,
+            "TRANSFER_FAILED"
+        );
+        
+        // Check return data.
+        // If there is no return data, we assume the token incorrectly
+        // does not return a bool. In this case we expect it to revert
+        // on failure, which was handled above.
+        // If the token does return data, we require that it is a single
+        // value that evaluates to true.
+        assembly {
+            if returndatasize {
+                success := 0
+                if eq(returndatasize, 32) {
+                    // First 64 bytes of memory are reserved scratch space
+                    returndatacopy(0, 0, 32)
+                    success := mload(0)
+                }
+            }
+        }
+        require(
+            success,
+            "TRANSFER_FAILED"
+        );
+    }
+
+    /// @dev Decodes ERC721 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal
+    {
+        require(
+            amount == 1,
+            "INVALID_AMOUNT"
+        );
+        // Decode asset data.
+        address token = assetData.readAddress(16);
+        uint256 tokenId = assetData.readUint256(36);
+
+        // Perform transfer.
+        IERC721Token(token).transferFrom(
+            address(this),
+            msg.sender,
+            tokenId
+        );
+    }
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
new file mode 100644
index 000000000..218713d3c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
@@ -0,0 +1,263 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./mixins/MExchangeWrapper.sol";
+import "../../protocol/Exchange/libs/LibAbiEncoder.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../protocol/Exchange/libs/LibMath.sol";
+
+
+contract MixinExchangeWrapper is
+    LibAbiEncoder,
+    LibFillResults,
+    LibMath,
+    LibConstants,
+    MExchangeWrapper
+{
+
+    /// @dev Fills the input order.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        internal
+        returns (FillResults memory fillResults)
+    {
+        // ABI encode calldata for `fillOrder`
+        bytes memory fillOrderCalldata = abiEncodeFillOrder(
+            order,
+            takerAssetFillAmount,
+            signature
+        );
+
+        address exchange = address(EXCHANGE);
+
+        // Call `fillOrder` and handle any exceptions gracefully
+        assembly {
+            let success := call(
+                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                exchange,                           // call address of Exchange contract
+                0,                                  // transfer 0 wei
+                add(fillOrderCalldata, 32),         // pointer to start of input (skip array length in first 32 bytes)
+                mload(fillOrderCalldata),           // length of input
+                fillOrderCalldata,                  // write output over input
+                128                                 // output size is 128 bytes
+            )
+            switch success
+            case 0 {
+                mstore(fillResults, 0)
+                mstore(add(fillResults, 32), 0)
+                mstore(add(fillResults, 64), 0)
+                mstore(add(fillResults, 96), 0)
+            }
+            case 1 {
+                mstore(fillResults, mload(fillOrderCalldata))
+                mstore(add(fillResults, 32), mload(add(fillOrderCalldata, 32)))
+                mstore(add(fillResults, 64), mload(add(fillOrderCalldata, 64)))
+                mstore(add(fillResults, 96), mload(add(fillOrderCalldata, 96)))
+            }
+        }
+        return fillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of WETH has been sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param wethSellAmount Desired amount of WETH to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellWeth(
+        LibOrder.Order[] memory orders,
+        uint256 wethSellAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+        bytes memory wethAssetData = WETH_ASSET_DATA;
+
+        uint256 ordersLength = orders.length;
+        for (uint256 i = 0; i != ordersLength; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // We assume that asset being sold by taker is WETH for each order.
+            orders[i].makerAssetData = makerAssetData;
+            orders[i].takerAssetData = wethAssetData;
+
+            // Calculate the remaining amount of WETH to sell
+            uint256 remainingTakerAssetFillAmount = safeSub(wethSellAmount, totalFillResults.takerAssetFilledAmount);
+
+            // Attempt to sell the remaining amount of WETH
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of takerAsset has been sold
+            if (totalFillResults.takerAssetFilledAmount >= wethSellAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    ///      The asset being sold by taker must always be WETH.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyExactAmountWithWeth(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+        bytes memory wethAssetData = WETH_ASSET_DATA;
+
+        uint256 ordersLength = orders.length;
+        for (uint256 i = 0; i != ordersLength; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // We assume that asset being sold by taker is WETH for each order.
+            orders[i].makerAssetData = makerAssetData;
+            orders[i].takerAssetData = wethAssetData;
+
+            // Calculate the remaining amount of makerAsset to buy
+            uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
+
+            // Convert the remaining amount of makerAsset to buy into remaining amount
+            // of takerAsset to sell, assuming entire amount can be sold in the current order
+            uint256 remainingTakerAssetFillAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                orders[i].makerAssetAmount,
+                remainingMakerAssetFillAmount
+            );
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of makerAsset has been bought
+            uint256 makerAssetFilledAmount = totalFillResults.makerAssetFilledAmount;
+            if (makerAssetFilledAmount >= makerAssetFillAmount) {
+                break;
+            }
+        }
+
+        require(
+            makerAssetFilledAmount >= makerAssetFillAmount,
+            "COMPLETE_FILL_FAILED"
+        );
+        return totalFillResults;
+    }
+
+    /// @dev Buys zrxBuyAmount of ZRX fee tokens, taking into account ZRX fees for each order. This will guarantee
+    ///      that at least zrxBuyAmount of ZRX is purchased (sometimes slightly over due to rounding issues).
+    ///      It is possible that a request to buy 200 ZRX will require purchasing 202 ZRX
+    ///      as 2 ZRX is required to purchase the 200 ZRX fee tokens. This guarantees at least 200 ZRX for future purchases.
+    ///      The asset being sold by taker must always be WETH. 
+    /// @param orders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset.
+    /// @param zrxBuyAmount Desired amount of ZRX to buy.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
+    function marketBuyExactZrxWithWeth(
+        LibOrder.Order[] memory orders,
+        uint256 zrxBuyAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (FillResults memory totalFillResults)
+    {
+        // Do nothing if zrxBuyAmount == 0
+        if (zrxBuyAmount == 0) {
+            return totalFillResults;
+        }
+
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        bytes memory wethAssetData = WETH_ASSET_DATA;
+        uint256 zrxPurchased = 0;
+
+        uint256 ordersLength = orders.length;
+        for (uint256 i = 0; i != ordersLength; i++) {
+
+            // All of these are ZRX/WETH, so we can drop the respective assetData from calldata.
+            orders[i].makerAssetData = zrxAssetData;
+            orders[i].takerAssetData = wethAssetData;
+
+            // Calculate the remaining amount of ZRX to buy.
+            uint256 remainingZrxBuyAmount = safeSub(zrxBuyAmount, zrxPurchased);
+
+            // Convert the remaining amount of ZRX to buy into remaining amount
+            // of WETH to sell, assuming entire amount can be sold in the current order.
+            uint256 remainingWethSellAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                safeSub(orders[i].makerAssetAmount, orders[i].takerFee),  // our exchange rate after fees 
+                remainingZrxBuyAmount
+            );
+
+            // Attempt to sell the remaining amount of WETH.
+            FillResults memory singleFillResult = fillOrderNoThrow(
+                orders[i],
+                safeAdd(remainingWethSellAmount, 1),  // we add 1 wei to the fill amount to make up for rounding errors
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker.
+            addFillResults(totalFillResults, singleFillResult);
+            zrxPurchased = safeSub(totalFillResults.makerAssetFilledAmount, totalFillResults.takerFeePaid);
+
+            // Stop execution if the entire amount of ZRX has been bought.
+            if (zrxPurchased >= zrxBuyAmount) {
+                break;
+            }
+        }
+
+        require(
+            zrxPurchased >= zrxBuyAmount,
+            "COMPLETE_FILL_FAILED"
+        );
+        return totalFillResults;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
new file mode 100644
index 000000000..42cec4d36
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
@@ -0,0 +1,213 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./mixins/MWeth.sol";
+import "./mixins/MAssets.sol";
+import "./mixins/MExchangeWrapper.sol";
+import "./interfaces/IForwarderCore.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../protocol/Exchange/libs/LibMath.sol";
+
+
+contract MixinForwarderCore is
+    LibFillResults,
+    LibMath,
+    LibConstants,
+    MWeth,
+    MAssets,
+    MExchangeWrapper,
+    IForwarderCore
+{
+
+    using LibBytes for bytes;
+
+    /// @dev Constructor approves ERC20 proxy to transfer ZRX and WETH on this contract's behalf.
+    constructor ()
+        public
+    {
+        address proxyAddress = EXCHANGE.getAssetProxy(ERC20_DATA_ID);
+        if (proxyAddress != address(0)) {
+            ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
+            ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
+        }
+    }
+
+    /// @dev Purchases as much of orders' makerAssets as possible by selling up to 95% of transaction's ETH value.
+    ///      Any ZRX required to pay fees for primary orders will automatically be purchased by this contract.
+    ///      5% of ETH value is reserved for paying fees to order feeRecipients (in ZRX) and forwarding contract feeRecipient (in ETH).
+    ///      Any ETH not spent will be refunded to sender.
+    /// @param orders Array of order specifications used containing desired makerAsset and WETH as takerAsset. 
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @param feeOrders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset. Used to purchase ZRX for primary order fees.
+    /// @param feeSignatures Proofs that feeOrders have been created by makers.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    /// @return Amounts filled and fees paid by maker and taker for both sets of orders.
+    function marketSellOrdersWithEth(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256  feePercentage,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (
+            FillResults memory orderFillResults,
+            FillResults memory feeOrderFillResults
+        )
+    {
+        // Convert ETH to WETH.
+        convertEthToWeth();
+
+        uint256 wethSellAmount;
+        uint256 zrxBuyAmount;
+        uint256 makerAssetAmountPurchased;
+        if (orders[0].makerAssetData.equals(ZRX_ASSET_DATA)) {
+            // Calculate amount of WETH that won't be spent on ETH fees.
+            wethSellAmount = getPartialAmount(
+                PERCENTAGE_DENOMINATOR,
+                safeAdd(PERCENTAGE_DENOMINATOR, feePercentage),
+                msg.value
+            );
+            // Market sell available WETH.
+            // ZRX fees are paid with this contract's balance.
+            orderFillResults = marketSellWeth(
+                orders,
+                wethSellAmount,
+                signatures
+            );
+            // The fee amount must be deducted from the amount transfered back to sender.
+            makerAssetAmountPurchased = safeSub(orderFillResults.makerAssetFilledAmount, orderFillResults.takerFeePaid);
+        } else {
+            // 5% of WETH is reserved for filling feeOrders and paying feeRecipient.
+            wethSellAmount = getPartialAmount(
+                MAX_WETH_FILL_PERCENTAGE,
+                PERCENTAGE_DENOMINATOR,
+                msg.value
+            );
+            // Market sell 95% of WETH.
+            // ZRX fees are payed with this contract's balance.
+            orderFillResults = marketSellWeth(
+                orders,
+                wethSellAmount,
+                signatures
+            );
+            // Buy back all ZRX spent on fees.
+            zrxBuyAmount = orderFillResults.takerFeePaid;
+            feeOrderFillResults = marketBuyExactZrxWithWeth(
+                feeOrders,
+                zrxBuyAmount,
+                feeSignatures
+            );
+            makerAssetAmountPurchased = orderFillResults.makerAssetFilledAmount;
+        }
+
+        // Transfer feePercentage of total ETH spent on primary orders to feeRecipient.
+        // Refund remaining ETH to msg.sender.
+        transferEthFeeAndRefund(
+            orderFillResults.takerAssetFilledAmount,
+            feeOrderFillResults.takerAssetFilledAmount,
+            feePercentage,
+            feeRecipient
+        );
+
+        // Transfer purchased assets to msg.sender.
+        transferAssetToSender(orders[0].makerAssetData, makerAssetAmountPurchased);
+    }
+
+    /// @dev Attempt to purchase makerAssetFillAmount of makerAsset by selling ETH provided with transaction.
+    ///      Any ZRX required to pay fees for primary orders will automatically be purchased by this contract.
+    ///      Any ETH not spent will be refunded to sender.
+    /// @param orders Array of order specifications used containing desired makerAsset and WETH as takerAsset. 
+    /// @param makerAssetFillAmount Desired amount of makerAsset to purchase.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @param feeOrders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset. Used to purchase ZRX for primary order fees.
+    /// @param feeSignatures Proofs that feeOrders have been created by makers.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    /// @return Amounts filled and fees paid by maker and taker for both sets of orders.
+    function marketBuyOrdersWithEth(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256  feePercentage,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (
+            FillResults memory orderFillResults,
+            FillResults memory feeOrderFillResults
+        )
+    {
+        // Convert ETH to WETH.
+        convertEthToWeth();
+
+        uint256 zrxBuyAmount;
+        uint256 makerAssetAmountPurchased;
+        if (orders[0].makerAssetData.equals(ZRX_ASSET_DATA)) {
+            // If the makerAsset is ZRX, it is not necessary to pay fees out of this
+            // contracts's ZRX balance because fees are factored into the price of the order.
+            orderFillResults = marketBuyExactZrxWithWeth(
+                orders,
+                makerAssetFillAmount,
+                signatures
+            );
+            // The fee amount must be deducted from the amount transfered back to sender.
+            makerAssetAmountPurchased = safeSub(orderFillResults.makerAssetFilledAmount, orderFillResults.takerFeePaid);
+        } else {
+            // Attemp to purchase desired amount of makerAsset.
+            // ZRX fees are payed with this contract's balance.
+            orderFillResults = marketBuyExactAmountWithWeth(
+                orders,
+                makerAssetFillAmount,
+                signatures
+            );
+            // Buy back all ZRX spent on fees.
+            zrxBuyAmount = orderFillResults.takerFeePaid;
+            feeOrderFillResults = marketBuyExactZrxWithWeth(
+                feeOrders,
+                zrxBuyAmount,
+                feeSignatures
+            );
+            makerAssetAmountPurchased = orderFillResults.makerAssetFilledAmount;
+        }
+
+        // Transfer feePercentage of total ETH spent on primary orders to feeRecipient.
+        // Refund remaining ETH to msg.sender.
+        transferEthFeeAndRefund(
+            orderFillResults.takerAssetFilledAmount,
+            feeOrderFillResults.takerAssetFilledAmount,
+            feePercentage,
+            feeRecipient
+        );
+
+        // Transfer purchased assets to msg.sender.
+        transferAssetToSender(orders[0].makerAssetData, makerAssetAmountPurchased);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
new file mode 100644
index 000000000..93e85e599
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
@@ -0,0 +1,114 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "../../protocol/Exchange/libs/LibMath.sol";
+import "./libs/LibConstants.sol";
+import "./mixins/MWeth.sol";
+
+
+contract MixinWeth is
+    LibMath,
+    LibConstants,
+    MWeth
+{
+
+    /// @dev Default payabale function, this allows us to withdraw WETH
+    function ()
+        public
+        payable
+    {
+        require(
+            msg.sender == address(ETHER_TOKEN),
+            "DEFAULT_FUNCTION_WETH_CONTRACT_ONLY"
+        );
+    }
+
+    /// @dev Converts message call's ETH value into WETH.
+    function convertEthToWeth()
+        internal
+    {
+        require(
+            msg.value > 0,
+            "INVALID_MSG_VALUE"
+        );
+        ETHER_TOKEN.deposit.value(msg.value)();
+    }
+
+    /// @dev Transfers feePercentage of WETH spent on primary orders to feeRecipient.
+    ///      Refunds any excess ETH to msg.sender.
+    /// @param wethSoldExcludingFeeOrders Amount of WETH sold when filling primary orders.
+    /// @param wethSoldForZrx Amount of WETH sold when purchasing ZRX required for primary order fees.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    function transferEthFeeAndRefund(
+        uint256 wethSoldExcludingFeeOrders,
+        uint256 wethSoldForZrx,
+        uint256 feePercentage,
+        address feeRecipient
+    )
+        internal
+    {
+        // Ensure feePercentage is less than 5%.
+        require(
+            feePercentage <= MAX_FEE_PERCENTAGE,
+            "FEE_PERCENTAGE_TOO_LARGE"
+        );
+
+        // Ensure that no extra WETH owned by this contract has been sold.
+        uint256 wethSold = safeAdd(wethSoldExcludingFeeOrders, wethSoldForZrx);
+        require(
+            wethSold <= msg.value,
+            "OVERSOLD_WETH"
+        );
+
+        // Calculate amount of WETH that hasn't been sold.
+        uint256 wethRemaining = safeSub(msg.value, wethSold);
+
+        // Calculate ETH fee to pay to feeRecipient.
+        uint256 ethFee = getPartialAmount(
+            feePercentage,
+            PERCENTAGE_DENOMINATOR,
+            wethSoldExcludingFeeOrders
+        );
+
+        // Ensure fee is less than amount of WETH remaining.
+        require(
+            ethFee <= wethRemaining,
+            "INSUFFICIENT_ETH_REMAINING"
+        );
+    
+        // Do nothing if no WETH remaining
+        if (wethRemaining > 0) {
+            // Convert remaining WETH to ETH
+            ETHER_TOKEN.withdraw(wethRemaining);
+
+            // Pay ETH to feeRecipient
+            if (ethFee > 0) {
+                feeRecipient.transfer(ethFee);
+            }
+
+            // Refund remaining ETH to msg.sender.
+            uint256 ethRefund = safeSub(wethRemaining, ethFee);
+            if (ethRefund > 0) {
+                msg.sender.transfer(ethRefund);
+            }
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IAssets.sol
new file mode 100644
index 000000000..1e034c003
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IAssets.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract IAssets {
+
+    /// @dev Withdraws assets from this contract. The contract requires a ZRX balance in order to 
+    ///      function optimally, and this function allows the ZRX to be withdrawn by owner. It may also be
+    ///      used to withdraw assets that were accidentally sent to this contract.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of ERC20 token to withdraw.
+    function withdrawAsset(
+        bytes assetData,
+        uint256 amount
+    )
+        external;
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarder.sol
new file mode 100644
index 000000000..f5a26e2ba
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarder.sol
@@ -0,0 +1,30 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IForwarderCore.sol";
+import "./IAssets.sol";
+
+
+// solhint-disable no-empty-blocks
+contract IForwarder is
+    IForwarderCore,
+    IAssets
+{}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarderCore.sol
new file mode 100644
index 000000000..74c7da01d
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarderCore.sol
@@ -0,0 +1,80 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../../protocol/Exchange/libs/LibOrder.sol";
+import "../../../protocol/Exchange/libs/LibFillResults.sol";
+
+
+contract IForwarderCore {
+
+    /// @dev Purchases as much of orders' makerAssets as possible by selling up to 95% of transaction's ETH value.
+    ///      Any ZRX required to pay fees for primary orders will automatically be purchased by this contract.
+    ///      5% of ETH value is reserved for paying fees to order feeRecipients (in ZRX) and forwarding contract feeRecipient (in ETH).
+    ///      Any ETH not spent will be refunded to sender.
+    /// @param orders Array of order specifications used containing desired makerAsset and WETH as takerAsset. 
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @param feeOrders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset. Used to purchase ZRX for primary order fees.
+    /// @param feeSignatures Proofs that feeOrders have been created by makers.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    /// @return Amounts filled and fees paid by maker and taker for both sets of orders.
+    function marketSellOrdersWithEth(
+        LibOrder.Order[] memory orders,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256  feePercentage,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (
+            LibFillResults.FillResults memory orderFillResults,
+            LibFillResults.FillResults memory feeOrderFillResults
+        );
+
+    /// @dev Attempt to purchase makerAssetFillAmount of makerAsset by selling ETH provided with transaction.
+    ///      Any ZRX required to pay fees for primary orders will automatically be purchased by this contract.
+    ///      Any ETH not spent will be refunded to sender.
+    /// @param orders Array of order specifications used containing desired makerAsset and WETH as takerAsset. 
+    /// @param makerAssetFillAmount Desired amount of makerAsset to purchase.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @param feeOrders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset. Used to purchase ZRX for primary order fees.
+    /// @param feeSignatures Proofs that feeOrders have been created by makers.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    /// @return Amounts filled and fees paid by maker and taker for both sets of orders.
+    function marketBuyOrdersWithEth(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures,
+        LibOrder.Order[] memory feeOrders,
+        bytes[] memory feeSignatures,
+        uint256  feePercentage,
+        address feeRecipient
+    )
+        public
+        payable
+        returns (
+            LibFillResults.FillResults memory orderFillResults,
+            LibFillResults.FillResults memory feeOrderFillResults
+        );
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibConstants.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibConstants.sol
new file mode 100644
index 000000000..704e42ce3
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibConstants.sol
@@ -0,0 +1,62 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "../../../utils/LibBytes/LibBytes.sol";
+import "../../../protocol/Exchange/interfaces/IExchange.sol";
+import "../../../tokens/EtherToken/IEtherToken.sol";
+import "../../../tokens/ERC20Token/IERC20Token.sol";
+
+
+contract LibConstants {
+
+    using LibBytes for bytes;
+
+    bytes4 constant internal ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
+    bytes4 constant internal ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256)"));
+    uint256 constant internal MAX_UINT = 2**256 - 1;
+    uint256 constant internal PERCENTAGE_DENOMINATOR = 10**18; 
+    uint256 constant internal MAX_FEE_PERCENTAGE = 5 * PERCENTAGE_DENOMINATOR / 100;         // 5%
+    uint256 constant internal MAX_WETH_FILL_PERCENTAGE = 95 * PERCENTAGE_DENOMINATOR / 100;  // 95%
+ 
+     // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+    IEtherToken internal ETHER_TOKEN;
+    IERC20Token internal ZRX_TOKEN;
+    bytes internal ZRX_ASSET_DATA;
+    bytes internal WETH_ASSET_DATA;
+    // solhint-enable var-name-mixedcase
+
+    constructor (
+        address _exchange,
+        bytes memory _zrxAssetData,
+        bytes memory _wethAssetData
+    )
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+        ZRX_ASSET_DATA = _zrxAssetData;
+        WETH_ASSET_DATA = _wethAssetData;
+
+        address etherToken = _wethAssetData.readAddress(16);
+        address zrxToken = _zrxAssetData.readAddress(16);
+        ETHER_TOKEN = IEtherToken(etherToken);
+        ZRX_TOKEN = IERC20Token(zrxToken);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibForwarderErrors.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibForwarderErrors.sol
new file mode 100644
index 000000000..fb3ade1db
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibForwarderErrors.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+// solhint-disable
+pragma solidity 0.4.24;
+
+
+/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
+contract LibForwarderErrors {
+    string constant FEE_PERCENTAGE_TOO_LARGE = "FEE_PROPORTION_TOO_LARGE";                        // Provided fee percentage greater than 5%.
+    string constant INSUFFICIENT_ETH_REMAINING = "INSUFFICIENT_ETH_REMAINING";                    // Not enough ETH remaining to pay feeRecipient.
+    string constant OVERSOLD_WETH = "OVERSOLD_WETH";                                              // More WETH sold than provided with current message call.
+    string constant COMPLETE_FILL_FAILED = "COMPLETE_FILL_FAILED";                                // Desired purchase amount not completely filled (required for ZRX fees only).
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                          // Asset transfer failed.
+    string constant UNSUPPORTED_ASSET_PROXY = "UNSUPPORTED_ASSET_PROXY";                          // Proxy in assetData not supported.
+    string constant DEFAULT_FUNCTION_WETH_CONTRACT_ONLY = "DEFAULT_FUNCTION_WETH_CONTRACT_ONLY";  // Fallback function may only be used for WETH withdrawals.
+    string constant INVALID_MSG_VALUE = "INVALID_MSG_VALUE";                                      // msg.value must be greater than 0.
+    string constant INVALID_AMOUNT = "INVALID_AMOUNT";                                            // Amount must equal 1.
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
new file mode 100644
index 000000000..83636432a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
@@ -0,0 +1,54 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "../interfaces/IAssets.sol";
+
+
+contract MAssets is
+    IAssets
+{
+
+    /// @dev Transfers given amount of asset to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferAssetToSender(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Decodes ERC20 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC20Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+
+    /// @dev Decodes ERC721 assetData and transfers given amount to sender.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param amount Amount of asset to transfer to sender.
+    function transferERC721Token(
+        bytes memory assetData,
+        uint256 amount
+    )
+        internal;
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MExchangeWrapper.sol
new file mode 100644
index 000000000..13c26b03a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MExchangeWrapper.sol
@@ -0,0 +1,87 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../../protocol/Exchange/libs/LibOrder.sol";
+import "../../../protocol/Exchange/libs/LibFillResults.sol";
+
+
+contract MExchangeWrapper {
+
+    /// @dev Fills the input order.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        internal
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of WETH has been sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param wethSellAmount Desired amount of WETH to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellWeth(
+        LibOrder.Order[] memory orders,
+        uint256 wethSellAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    ///      The asset being sold by taker must always be WETH.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyExactAmountWithWeth(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Buys zrxBuyAmount of ZRX fee tokens, taking into account ZRX fees for each order. This will guarantee
+    ///      that at least zrxBuyAmount of ZRX is purchased (sometimes slightly over due to rounding issues).
+    ///      It is possible that a request to buy 200 ZRX will require purchasing 202 ZRX
+    ///      as 2 ZRX is required to purchase the 200 ZRX fee tokens. This guarantees at least 200 ZRX for future purchases.
+    ///      The asset being sold by taker must always be WETH. 
+    /// @param orders Array of order specifications containing ZRX as makerAsset and WETH as takerAsset.
+    /// @param zrxBuyAmount Desired amount of ZRX to buy.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return totalFillResults Amounts filled and fees paid by maker and taker.
+    function marketBuyExactZrxWithWeth(
+        LibOrder.Order[] memory orders,
+        uint256 zrxBuyAmount,
+        bytes[] memory signatures
+    )
+        internal
+        returns (LibFillResults.FillResults memory totalFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MWeth.sol
new file mode 100644
index 000000000..88e77be4e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MWeth.sol
@@ -0,0 +1,41 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+
+contract MWeth {
+
+    /// @dev Converts message call's ETH value into WETH.
+    function convertEthToWeth()
+        internal;
+
+    /// @dev Transfers feePercentage of WETH spent on primary orders to feeRecipient.
+    ///      Refunds any excess ETH to msg.sender.
+    /// @param wethSoldExcludingFeeOrders Amount of WETH sold when filling primary orders.
+    /// @param wethSoldForZrx Amount of WETH sold when purchasing ZRX required for primary order fees.
+    /// @param feePercentage Percentage of WETH sold that will payed as fee to forwarding contract feeRecipient.
+    /// @param feeRecipient Address that will receive ETH when orders are filled.
+    function transferEthFeeAndRefund(
+        uint256 wethSoldExcludingFeeOrders,
+        uint256 wethSoldForZrx,
+        uint256 feePercentage,
+        address feeRecipient
+    )
+        internal;
+}