add multiplexBatchSellTokenForToken, multiplexMultiHopSellTokenForToken, multiplex TokenForEth functions to metatransactions, add msgSender field to multiplex params

contracts/zero-ex/contracts/src/features/MetaTransactionsFeatureV2.sol

@@ -15,6 +15,7 @@
 pragma solidity ^0.6.5;
 pragma experimental ABIEncoderV2;
 
+import "@0x/contracts-erc20/src/IEtherToken.sol";
 import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
 import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
 import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
@@ -27,6 +28,7 @@ import "../migrations/LibMigrate.sol";
 import "../storage/LibMetaTransactionsStorage.sol";
 import "./interfaces/IFeature.sol";
 import "./interfaces/IMetaTransactionsFeatureV2.sol";
+import "./interfaces/IMultiplexFeature.sol";
 import "./interfaces/INativeOrdersFeature.sol";
 import "./interfaces/ITransformERC20Feature.sol";
 import "./libs/LibSignature.sol";
@@ -63,8 +65,8 @@ contract MetaTransactionsFeatureV2 is
 
     /// @dev Arguments for a `TransformERC20.transformERC20()` call.
     struct ExternalTransformERC20Args {
-        IERC20TokenV06 inputToken;
+        IERC20Token inputToken;
-        IERC20TokenV06 outputToken;
+        IERC20Token outputToken;
         uint256 inputTokenAmount;
         uint256 minOutputTokenAmount;
         ITransformERC20Feature.Transformation[] transformations;
@@ -92,6 +94,9 @@ contract MetaTransactionsFeatureV2 is
             "uint256 amount"
             ")"
         );
+    
+    /// @dev The WETH token contract.
+    IEtherToken private immutable WETH;
 
     /// @dev Refunds up to `msg.value` leftover ETH at the end of the call.
     modifier refundsAttachedEth() {
@@ -110,7 +115,12 @@ contract MetaTransactionsFeatureV2 is
         require(initialBalance <= address(this).balance, "MetaTransactionDataV2/ETH_LEAK");
     }
 
-    constructor(address zeroExAddress) public FixinCommon() FixinEIP712(zeroExAddress) {}
+    constructor(
+        address zeroExAddress,
+        IEtherToken weth
+    ) public FixinCommon() FixinEIP712(zeroExAddress) {
+        WETH = weth;
+    }
 
     /// @dev Initialize and register this feature.
     ///      Should be delegatecalled by `Migrate.migrate()`.
@@ -244,6 +254,14 @@ contract MetaTransactionsFeatureV2 is
             returnResult = _executeFillLimitOrderCall(state);
         } else if (state.selector == INativeOrdersFeature.fillRfqOrder.selector) {
             returnResult = _executeFillRfqOrderCall(state);
+        } else if (state.selector == IMultiplexFeature.multiplexBatchSellTokenForToken.selector) {
+            returnResult = _executeMultiplexBatchSellTokenForTokenCall(state);
+        } else if (state.selector == IMultiplexFeature.multiplexBatchSellTokenForEth.selector) {
+            returnResult = _executeMultiplexBatchSellTokenForEthCall(state);
+        } else if (state.selector == IMultiplexFeature.multiplexMultiHopSellTokenForToken.selector) {
+            returnResult = _executeMultiplexMultiHopSellTokenForTokenCall(state);
+        } else if (state.selector == IMultiplexFeature.multiplexMultiHopSellTokenForEth.selector) {
+            returnResult = _executeMultiplexMultiHopSellTokenForEthCall(state);
         } else {
             LibMetaTransactionsRichErrors.MetaTransactionUnsupportedFunctionError(state.hash, state.selector).rrevert();
         }
@@ -410,7 +428,7 @@ contract MetaTransactionsFeatureV2 is
 
     /// @dev Execute a `INativeOrdersFeature.fillRfqOrder()` meta-transaction call
     ///      by decoding the call args and translating the call to the internal
-    ///      `INativeOrdersFeature._fillRfqOrder()` variant, where we can overrideunimpleme
+    ///      `INativeOrdersFeature._fillRfqOrder()` variant, where we can override
     ///      the taker address.
     function _executeFillRfqOrderCall(ExecuteState memory state) private returns (bytes memory returnResult) {
         LibNativeOrder.RfqOrder memory order;
@@ -438,6 +456,158 @@ contract MetaTransactionsFeatureV2 is
             );
     }
 
+    /// @dev Execute a `IMultiplexFeature.multiplexBatchSellTokenForToken()` meta-transaction
+    ///      call by decoding the call args and translating the call to the internal
+    ///      `IMultiplexFeature._multiplexBatchSell()` variant, where we can override the
+    ///      msgSender address.
+    function _executeMultiplexBatchSellTokenForTokenCall(ExecuteState memory state) private returns (bytes memory returnResult) {
+        IERC20Token inputToken;
+        IERC20Token outputToken;
+        IMultiplexFeature.BatchSellSubcall[] memory calls;
+        uint256 sellAmount;
+        uint256 minBuyAmount;
+
+        bytes memory args = _extractArgumentsFromCallData(state.mtx.callData);
+        (inputToken, outputToken, calls, sellAmount, minBuyAmount) = abi.decode(
+            args,
+            (IERC20Token, IERC20Token, IMultiplexFeature.BatchSellSubcall[], uint256, uint256)
+        );
+
+        return
+            _callSelf(
+                state.hash,
+                abi.encodeWithSelector(
+                    IMultiplexFeature._multiplexBatchSell.selector,
+                    IMultiplexFeature.BatchSellParams({
+                        inputToken: inputToken,
+                        outputToken: outputToken,
+                        sellAmount: sellAmount,
+                        calls: calls,
+                        useSelfBalance: false,
+                        recipient: state.mtx.signer,
+                        msgSender: state.mtx.signer
+                    }),
+                    minBuyAmount
+                )
+            );
+    }
+
+    /// @dev Execute a `IMultiplexFeature.multiplexBatchSellTokenForEth()` meta-transaction
+    ///      call by decoding the call args and translating the call to the internal
+    ///      `IMultiplexFeature._multiplexBatchSellTokenForEth()` variant, where we can override the
+    ///      msgSender address.
+    function _executeMultiplexBatchSellTokenForEthCall(ExecuteState memory state) private returns (bytes memory returnResult) {
+        IERC20Token inputToken;
+        IMultiplexFeature.BatchSellSubcall[] memory calls;
+        uint256 sellAmount;
+        uint256 minBuyAmount;
+
+        bytes memory args = _extractArgumentsFromCallData(state.mtx.callData);
+        (inputToken, calls, sellAmount, minBuyAmount) = abi.decode(
+            args,
+            (IERC20Token, IMultiplexFeature.BatchSellSubcall[], uint256, uint256)
+        );
+
+        returnResult = _callSelf(
+            state.hash,
+            abi.encodeWithSelector(
+                IMultiplexFeature._multiplexBatchSell.selector,
+                IMultiplexFeature.BatchSellParams({
+                    inputToken: inputToken,
+                    outputToken: IERC20Token(WETH),
+                    sellAmount: sellAmount,
+                    calls: calls,
+                    useSelfBalance: false,
+                    recipient: address(this),
+                    msgSender: state.mtx.signer
+                }),
+                minBuyAmount
+            )
+        );
+
+        // Unwrap and transfer WETH
+        uint256 boughtAmount = abi.decode(returnResult, (uint256));
+        WETH.withdraw(boughtAmount);
+        _transferEth(state.mtx.signer, boughtAmount);
+    }
+
+    /// @dev Execute a `IMultiplexFeature.multiplexMultiHopSellTokenForToken()` meta-transaction
+    ///      call by decoding the call args and translating the call to the internal
+    ///      `IMultiplexFeature._multiplexMultiHopSell()` variant, where we can override the
+    ///      msgSender address.
+    function _executeMultiplexMultiHopSellTokenForTokenCall(ExecuteState memory state) private returns (bytes memory returnResult) {
+        address[] memory tokens;
+        IMultiplexFeature.MultiHopSellSubcall[] memory calls;
+        uint256 sellAmount;
+        uint256 minBuyAmount;
+
+        bytes memory args = _extractArgumentsFromCallData(state.mtx.callData);
+        (tokens, calls, sellAmount, minBuyAmount) = abi.decode(
+            args,
+            (address[], IMultiplexFeature.MultiHopSellSubcall[], uint256, uint256)
+        );
+
+        return
+            _callSelf(
+                state.hash,
+                abi.encodeWithSelector(
+                    IMultiplexFeature._multiplexMultiHopSell.selector,
+                    IMultiplexFeature.MultiHopSellParams({
+                        tokens: tokens,
+                        sellAmount: sellAmount,
+                        calls: calls,
+                        useSelfBalance: false,
+                        recipient: state.mtx.signer,
+                        msgSender: state.mtx.signer
+                    }),
+                    minBuyAmount
+                )
+            );
+    }
+
+    /// @dev Execute a `IMultiplexFeature.multiplexMultiHopSellTokenForEth()` meta-transaction
+    ///      call by decoding the call args and translating the call to the internal
+    ///      `IMultiplexFeature._multiplexMultiHopSellTokenForEth()` variant, where we can override the
+    ///      msgSender address.
+    function _executeMultiplexMultiHopSellTokenForEthCall(ExecuteState memory state) private returns (bytes memory returnResult) {
+        address[] memory tokens;
+        IMultiplexFeature.MultiHopSellSubcall[] memory calls;
+        uint256 sellAmount;
+        uint256 minBuyAmount;
+
+        bytes memory args = _extractArgumentsFromCallData(state.mtx.callData);
+        (tokens, calls, sellAmount, minBuyAmount) = abi.decode(
+            args,
+            (address[], IMultiplexFeature.MultiHopSellSubcall[], uint256, uint256)
+        );
+
+        require(
+            tokens[tokens.length - 1] == address(WETH),
+            "MetaTransactionsFeature::multiplexMultiHopSellTokenForEth/NOT_WETH"
+        );
+
+        returnResult = _callSelf(
+            state.hash,
+            abi.encodeWithSelector(
+                IMultiplexFeature._multiplexMultiHopSell.selector,
+                IMultiplexFeature.MultiHopSellParams({
+                    tokens: tokens,
+                    sellAmount: sellAmount,
+                    calls: calls,
+                    useSelfBalance: false,
+                    recipient: address(this),
+                    msgSender: state.mtx.signer
+                }),
+                minBuyAmount
+            )
+        );
+
+        // Unwrap and transfer WETH
+        uint256 boughtAmount = abi.decode(returnResult, (uint256));
+        WETH.withdraw(boughtAmount);
+        _transferEth(state.mtx.signer, boughtAmount);
+    }
+
     /// @dev Make an arbitrary internal, meta-transaction call.
     ///      Warning: Do not let unadulterated `callData` into this function.
     function _callSelf(bytes32 hash, bytes memory callData) private returns (bytes memory returnResult) {

contracts/zero-ex/contracts/src/features/UniswapV3Feature.sol

@@ -70,6 +70,7 @@ contract UniswapV3Feature is IFeature, IUniswapV3Feature, FixinCommon, FixinToke
         _registerFeatureFunction(this.sellEthForTokenToUniswapV3.selector);
         _registerFeatureFunction(this.sellTokenForEthToUniswapV3.selector);
         _registerFeatureFunction(this.sellTokenForTokenToUniswapV3.selector);
+        _registerFeatureFunction(this._sellTokenForTokenToUniswapV3.selector);
         _registerFeatureFunction(this._sellHeldTokenForTokenToUniswapV3.selector);
         _registerFeatureFunction(this.uniswapV3SwapCallback.selector);
         return LibMigrate.MIGRATE_SUCCESS;
@@ -139,6 +140,23 @@ contract UniswapV3Feature is IFeature, IUniswapV3Feature, FixinCommon, FixinToke
         buyAmount = _swap(encodedPath, sellAmount, minBuyAmount, msg.sender, _normalizeRecipient(recipient));
     }
 
+    /// @dev Sell a token for another token directly against uniswap v3. Internal variant.
+    /// @param encodedPath Uniswap-encoded path.
+    /// @param sellAmount amount of the first token in the path to sell.
+    /// @param minBuyAmount Minimum amount of the last token in the path to buy.
+    /// @param recipient The recipient of the bought tokens. Can be zero for payer.
+    /// @param payer The address to pull the sold tokens from.
+    /// @return buyAmount Amount of the last token in the path bought.
+    function _sellTokenForTokenToUniswapV3(
+        bytes memory encodedPath,
+        uint256 sellAmount,
+        uint256 minBuyAmount,
+        address recipient,
+        address payer
+    ) public override onlySelf returns (uint256 buyAmount) {
+        buyAmount = _swap(encodedPath, sellAmount, minBuyAmount, payer, _normalizeRecipient(recipient, payer));
+    }
+
     /// @dev Sell a token for another token directly against uniswap v3.
     ///      Private variant, uses tokens held by `address(this)`.
     /// @param encodedPath Uniswap-encoded path.
@@ -337,8 +355,13 @@ contract UniswapV3Feature is IFeature, IUniswapV3Feature, FixinCommon, FixinToke
         }
     }
 
+    // Convert null address values to alternative address.
+    function _normalizeRecipient(address recipient, address alternative) private pure returns (address payable normalizedRecipient) {
+        return recipient == address(0) ? payable(alternative) : payable(recipient);
+    }
+
     // Convert null address values to msg.sender.
     function _normalizeRecipient(address recipient) private view returns (address payable normalizedRecipient) {
-        return recipient == address(0) ? msg.sender : payable(recipient);
+        return _normalizeRecipient(recipient, msg.sender);
     }
 }

contracts/zero-ex/contracts/src/features/interfaces/IMetaTransactionsFeatureV2.sol

@@ -15,7 +15,7 @@
 pragma solidity ^0.6.5;
 pragma experimental ABIEncoderV2;
 
-import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
+import "@0x/contracts-erc20/src/IERC20Token.sol";
 import "../libs/LibSignature.sol";
 
 /// @dev Meta-transactions feature.
@@ -40,7 +40,7 @@ interface IMetaTransactionsFeatureV2 {
         // Encoded call data to a function on the exchange proxy.
         bytes callData;
         // ERC20 fee `signer` pays `sender`.
-        IERC20TokenV06 feeToken;
+        IERC20Token feeToken;
         // ERC20 fees.
         MetaTransactionFeeData[] fees;
     }

contracts/zero-ex/contracts/src/features/interfaces/IMultiplexFeature.sol

@@ -46,6 +46,8 @@ interface IMultiplexFeature {
         bool useSelfBalance;
         // The recipient of the bought output tokens.
         address recipient;
+        // The sender of the transaction.
+        address msgSender;
     }
 
     // Represents a constituent call of a batch sell.
@@ -75,6 +77,8 @@ interface IMultiplexFeature {
         bool useSelfBalance;
         // The recipient of the bought output tokens.
         address recipient;
+        // The sender of the transaction.
+        address msgSender;
     }
 
     // Represents a constituent call of a multi-hop sell.
@@ -153,6 +157,17 @@ interface IMultiplexFeature {
         uint256 minBuyAmount
     ) external returns (uint256 boughtAmount);
 
+    /// @dev Executes a multiplex BatchSell using the given
+    ///      parameters. Internal only.
+    /// @param params The parameters for the BatchSell.
+    /// @param minBuyAmount The minimum amount of `params.outputToken`
+    ///        that must be bought for this function to not revert.
+    /// @return boughtAmount The amount of `params.outputToken` bought.
+    function _multiplexBatchSell(
+        BatchSellParams memory params,
+        uint256 minBuyAmount
+    ) external returns (uint256 boughtAmount);
+
     /// @dev Sells attached ETH via the given sequence of tokens
     ///      and calls. `tokens[0]` must be WETH.
     ///      The last token in `tokens` is the output token that
@@ -204,4 +219,15 @@ interface IMultiplexFeature {
         uint256 sellAmount,
         uint256 minBuyAmount
     ) external returns (uint256 boughtAmount);
+
+    /// @dev Executes a multiplex MultiHopSell using the given
+    ///      parameters. Internal only.
+    /// @param params The parameters for the MultiHopSell.
+    /// @param minBuyAmount The minimum amount of the output token
+    ///        that must be bought for this function to not revert.
+    /// @return boughtAmount The amount of the output token bought.
+    function _multiplexMultiHopSell(
+        MultiHopSellParams memory params,
+        uint256 minBuyAmount
+    ) external returns (uint256 boughtAmount);
 }

contracts/zero-ex/contracts/src/features/interfaces/IUniswapV3Feature.sol

@@ -54,6 +54,21 @@ interface IUniswapV3Feature {
         address recipient
     ) external returns (uint256 buyAmount);
 
+    /// @dev Sell a token for another token directly against uniswap v3. Internal variant.
+    /// @param encodedPath Uniswap-encoded path.
+    /// @param sellAmount amount of the first token in the path to sell.
+    /// @param minBuyAmount Minimum amount of the last token in the path to buy.
+    /// @param recipient The recipient of the bought tokens. Can be zero for payer.
+    /// @param payer The address to pull the sold tokens from.
+    /// @return buyAmount Amount of the last token in the path bought.
+    function _sellTokenForTokenToUniswapV3(
+        bytes memory encodedPath,
+        uint256 sellAmount,
+        uint256 minBuyAmount,
+        address recipient,
+        address payer
+    ) external returns (uint256 buyAmount);
+
     /// @dev Sell a token for another token directly against uniswap v3.
     ///      Private variant, uses tokens held by `address(this)`.
     /// @param encodedPath Uniswap-encoded path.

contracts/zero-ex/contracts/src/features/multiplex/MultiplexFeature.sol

@@ -80,9 +80,11 @@ contract MultiplexFeature is
         _registerFeatureFunction(this.multiplexBatchSellEthForToken.selector);
         _registerFeatureFunction(this.multiplexBatchSellTokenForEth.selector);
         _registerFeatureFunction(this.multiplexBatchSellTokenForToken.selector);
+        _registerFeatureFunction(this._multiplexBatchSell.selector);
         _registerFeatureFunction(this.multiplexMultiHopSellEthForToken.selector);
         _registerFeatureFunction(this.multiplexMultiHopSellTokenForEth.selector);
         _registerFeatureFunction(this.multiplexMultiHopSellTokenForToken.selector);
+        _registerFeatureFunction(this._multiplexMultiHopSell.selector);
         return LibMigrate.MIGRATE_SUCCESS;
     }
 
@@ -103,14 +105,15 @@ contract MultiplexFeature is
         // WETH is now held by this contract,
         // so `useSelfBalance` is true.
         return
-            _multiplexBatchSell(
+            _multiplexBatchSellPrivate(
                 BatchSellParams({
                     inputToken: WETH,
                     outputToken: outputToken,
                     sellAmount: msg.value,
                     calls: calls,
                     useSelfBalance: true,
-                    recipient: msg.sender
+                    recipient: msg.sender,
+                    msgSender: msg.sender
                 }),
                 minBuyAmount
             );
@@ -133,14 +136,15 @@ contract MultiplexFeature is
         // The outputToken is implicitly WETH. The `recipient`
         // of the WETH is set to  this contract, since we
         // must unwrap the WETH and transfer the resulting ETH.
-        boughtAmount = _multiplexBatchSell(
+        boughtAmount = _multiplexBatchSellPrivate(
             BatchSellParams({
                 inputToken: inputToken,
                 outputToken: WETH,
                 sellAmount: sellAmount,
                 calls: calls,
                 useSelfBalance: false,
-                recipient: address(this)
+                recipient: address(this),
+                msgSender: msg.sender
             }),
             minBuyAmount
         );
@@ -167,26 +171,40 @@ contract MultiplexFeature is
         uint256 minBuyAmount
     ) public override returns (uint256 boughtAmount) {
         return
-            _multiplexBatchSell(
+            _multiplexBatchSellPrivate(
                 BatchSellParams({
                     inputToken: inputToken,
                     outputToken: outputToken,
                     sellAmount: sellAmount,
                     calls: calls,
                     useSelfBalance: false,
-                    recipient: msg.sender
+                    recipient: msg.sender,
+                    msgSender: msg.sender
                 }),
                 minBuyAmount
             );
     }
 
+    /// @dev Executes a batch sell and checks that at least
+    ///      `minBuyAmount` of `outputToken` was bought. Internal variant.
+    /// @param params Batch sell parameters.
+    /// @param minBuyAmount The minimum amount of `outputToken` that
+    ///        must be bought for this function to not revert.
+    /// @return boughtAmount The amount of `outputToken` bought.
+    function _multiplexBatchSell(
+        BatchSellParams memory params,
+        uint256 minBuyAmount
+    ) public override onlySelf returns (uint256 boughtAmount) {
+        return _multiplexBatchSellPrivate(params, minBuyAmount);
+    }
+
     /// @dev Executes a batch sell and checks that at least
     ///      `minBuyAmount` of `outputToken` was bought.
     /// @param params Batch sell parameters.
     /// @param minBuyAmount The minimum amount of `outputToken` that
     ///        must be bought for this function to not revert.
     /// @return boughtAmount The amount of `outputToken` bought.
-    function _multiplexBatchSell(
+    function _multiplexBatchSellPrivate(
         BatchSellParams memory params,
         uint256 minBuyAmount
     ) private returns (uint256 boughtAmount) {
@@ -226,13 +244,14 @@ contract MultiplexFeature is
         // WETH is now held by this contract,
         // so `useSelfBalance` is true.
         return
-            _multiplexMultiHopSell(
+            _multiplexMultiHopSellPrivate(
                 MultiHopSellParams({
                     tokens: tokens,
                     sellAmount: msg.value,
                     calls: calls,
                     useSelfBalance: true,
-                    recipient: msg.sender
+                    recipient: msg.sender,
+                    msgSender: msg.sender
                 }),
                 minBuyAmount
             );
@@ -262,13 +281,14 @@ contract MultiplexFeature is
         );
         // The `recipient of the WETH is set to  this contract, since
         // we must unwrap the WETH and transfer the resulting ETH.
-        boughtAmount = _multiplexMultiHopSell(
+        boughtAmount = _multiplexMultiHopSellPrivate(
             MultiHopSellParams({
                 tokens: tokens,
                 sellAmount: sellAmount,
                 calls: calls,
                 useSelfBalance: false,
-                recipient: address(this)
+                recipient: address(this),
+                msgSender: msg.sender
             }),
             minBuyAmount
         );
@@ -297,25 +317,38 @@ contract MultiplexFeature is
         uint256 minBuyAmount
     ) public override returns (uint256 boughtAmount) {
         return
-            _multiplexMultiHopSell(
+            _multiplexMultiHopSellPrivate(
                 MultiHopSellParams({
                     tokens: tokens,
                     sellAmount: sellAmount,
                     calls: calls,
                     useSelfBalance: false,
-                    recipient: msg.sender
+                    recipient: msg.sender,
+                    msgSender: msg.sender
                 }),
                 minBuyAmount
             );
     }
 
+    /// @dev Executes a multi-hop sell. Internal variant.
+    /// @param params Multi-hop sell parameters.
+    /// @param minBuyAmount The minimum amount of output tokens that
+    ///        must be bought for this function to not revert.
+    /// @return boughtAmount The amount of output tokens bought.
+    function _multiplexMultiHopSell(
+        MultiHopSellParams memory params,
+        uint256 minBuyAmount
+    ) public override onlySelf returns (uint256 boughtAmount) {
+        return _multiplexMultiHopSellPrivate(params, minBuyAmount);
+    }
+
     /// @dev Executes a multi-hop sell and checks that at least
     ///      `minBuyAmount` of output tokens were bought.
     /// @param params Multi-hop sell parameters.
     /// @param minBuyAmount The minimum amount of output tokens that
     ///        must be bought for this function to not revert.
     /// @return boughtAmount The amount of output tokens bought.
-    function _multiplexMultiHopSell(
+    function _multiplexMultiHopSellPrivate(
         MultiHopSellParams memory params,
         uint256 minBuyAmount
     ) private returns (uint256 boughtAmount) {
@@ -387,14 +420,14 @@ contract MultiplexFeature is
         // amount of the multi-hop fill.
         state.outputTokenAmount = params.sellAmount;
         // The first call may expect the input tokens to be held by
-        // `msg.sender`, `address(this)`, or some other address.
+        // `msgSender`, `address(this)`, or some other address.
         // Compute the expected address and transfer the input tokens
         // there if necessary.
         state.from = _computeHopTarget(params, 0);
-        // If the input tokens are currently held by `msg.sender` but
+        // If the input tokens are currently held by `msgSender` but
         // the first hop expects them elsewhere, perform a `transferFrom`.
-        if (!params.useSelfBalance && state.from != msg.sender) {
+        if (!params.useSelfBalance && state.from != params.msgSender) {
-            _transferERC20TokensFrom(IERC20Token(params.tokens[0]), msg.sender, state.from, params.sellAmount);
+            _transferERC20TokensFrom(IERC20Token(params.tokens[0]), params.msgSender, state.from, params.sellAmount);
         }
         // If the input tokens are currently held by `address(this)` but
         // the first hop expects them elsewhere, perform a `transfer`.
@@ -411,7 +444,7 @@ contract MultiplexFeature is
             if (subcall.id == MultiplexSubcall.UniswapV2) {
                 _multiHopSellUniswapV2(state, params, subcall.data);
             } else if (subcall.id == MultiplexSubcall.UniswapV3) {
-                _multiHopSellUniswapV3(state, subcall.data);
+                _multiHopSellUniswapV3(state, params, subcall.data);
             } else if (subcall.id == MultiplexSubcall.LiquidityProvider) {
                 _multiHopSellLiquidityProvider(state, params, subcall.data);
             } else if (subcall.id == MultiplexSubcall.BatchSell) {
@@ -443,6 +476,8 @@ contract MultiplexFeature is
         // Likewise, the recipient of the multi-hop sell is
         // equal to the recipient of its containing batch sell.
         multiHopParams.recipient = params.recipient;
+        // The msgSender is the same too.
+        multiHopParams.msgSender = params.msgSender;
         // Execute the nested multi-hop sell.
         uint256 outputTokenAmount = _executeMultiHopSell(multiHopParams).outputTokenAmount;
         // Increment the sold and bought amounts.
@@ -469,7 +504,7 @@ contract MultiplexFeature is
         // If the nested batch sell is the first hop
         // and `useSelfBalance` for the containing multi-
         // hop sell is false, the nested batch sell should
-        // pull tokens from `msg.sender` (so  `batchSellParams.useSelfBalance`
+        // pull tokens from `msgSender` (so  `batchSellParams.useSelfBalance`
         // should be false). Otherwise `batchSellParams.useSelfBalance`
         // should be true.
         batchSellParams.useSelfBalance = state.hopIndex > 0 || params.useSelfBalance;
@@ -477,6 +512,8 @@ contract MultiplexFeature is
         // that should receive the output tokens of the
         // batch sell.
         batchSellParams.recipient = state.to;
+        // msgSender shound be the same too.
+        batchSellParams.msgSender = params.msgSender;
         // Execute the nested batch sell.
         state.outputTokenAmount = _executeBatchSell(batchSellParams).boughtAmount;
     }
@@ -509,25 +546,25 @@ contract MultiplexFeature is
                 // UniswapV3 uses a callback to pull in the tokens being
                 // sold to it. The callback implemented in `UniswapV3Feature`
                 // can either:
-                // - call `transferFrom` to move tokens from `msg.sender` to the
+                // - call `transferFrom` to move tokens from `msgSender` to the
                 //   UniswapV3 pool, or
                 // - call `transfer` to move tokens from `address(this)` to the
                 //   UniswapV3 pool.
                 // A nested batch sell is similar, in that it can either:
-                // - use tokens from `msg.sender`, or
+                // - use tokens from `msgSender`, or
                 // - use tokens held by `address(this)`.
 
                 // Suppose UniswapV3/BatchSell is the first call in the multi-hop
-                // path. The input tokens are either held by `msg.sender`,
+                // path. The input tokens are either held by `msgSender`,
                 // or in the case of `multiplexMultiHopSellEthForToken` WETH is
                 // held by `address(this)`. The target is set accordingly.
 
                 // If this is _not_ the first call in the multi-hop path, we
                 // are dealing with an "intermediate" token in the multi-hop path,
-                // which `msg.sender` may not have an allowance set for. Thus
+                // which `msgSender` may not have an allowance set for. Thus
                 // target must be set to `address(this)` for `i > 0`.
                 if (i == 0 && !params.useSelfBalance) {
-                    target = msg.sender;
+                    target = params.msgSender;
                 } else {
                     target = address(this);
                 }

contracts/zero-ex/contracts/src/features/multiplex/MultiplexLiquidityProvider.sol

@@ -67,7 +67,7 @@ abstract contract MultiplexLiquidityProvider is FixinCommon, FixinTokenSpender {
             _transferERC20Tokens(params.inputToken, provider, sellAmount);
         } else {
             // Otherwise, transfer the input tokens from `msg.sender`.
-            _transferERC20TokensFrom(params.inputToken, msg.sender, provider, sellAmount);
+            _transferERC20TokensFrom(params.inputToken, params.msgSender, provider, sellAmount);
         }
         // Cache the recipient's balance of the output token.
         uint256 balanceBefore = params.outputToken.balanceOf(params.recipient);

contracts/zero-ex/contracts/src/features/multiplex/MultiplexOtc.sol

@@ -55,7 +55,7 @@ abstract contract MultiplexOtc is FixinEIP712 {
                 order,
                 signature,
                 sellAmount.safeDowncastToUint128(),
-                msg.sender,
+                params.msgSender,
                 params.useSelfBalance,
                 params.recipient
             )

contracts/zero-ex/contracts/src/features/multiplex/MultiplexRfq.sol

@@ -54,7 +54,7 @@ abstract contract MultiplexRfq is FixinEIP712 {
                 order,
                 signature,
                 sellAmount.safeDowncastToUint128(),
-                msg.sender,
+                params.msgSender,
                 params.useSelfBalance,
                 params.recipient
             )

contracts/zero-ex/contracts/src/features/multiplex/MultiplexTransformERC20.sol

@@ -30,8 +30,8 @@ abstract contract MultiplexTransformERC20 {
     ) internal {
         ITransformERC20Feature.TransformERC20Args memory args;
         // We want the TransformedERC20 event to have
-        // `msg.sender` as the taker.
+        // `msgSender` as the taker.
-        args.taker = msg.sender;
+        args.taker = payable(params.msgSender);
         args.inputToken = params.inputToken;
         args.outputToken = params.outputToken;
         args.inputTokenAmount = sellAmount;

contracts/zero-ex/contracts/src/features/multiplex/MultiplexUniswapV2.sol

@@ -77,7 +77,7 @@ abstract contract MultiplexUniswapV2 is FixinCommon, FixinTokenSpender {
         if (params.useSelfBalance) {
             _transferERC20Tokens(IERC20Token(tokens[0]), firstPairAddress, sellAmount);
         } else {
-            _transferERC20TokensFrom(IERC20Token(tokens[0]), msg.sender, firstPairAddress, sellAmount);
+            _transferERC20TokensFrom(IERC20Token(tokens[0]), params.msgSender, firstPairAddress, sellAmount);
         }
         // Execute the Uniswap/Sushiswap trade.
         return _sellToUniswapV2(tokens, sellAmount, isSushi, firstPairAddress, params.recipient);

contracts/zero-ex/contracts/src/features/multiplex/MultiplexUniswapV3.sol

@@ -45,16 +45,16 @@ abstract contract MultiplexUniswapV3 is FixinTokenSpender {
                 )
             );
         } else {
-            // Otherwise, we self-delegatecall the normal variant
+            // Otherwise, we self-delegatecall `_sellTokenForTokenToUniswapV3`,
-            // `sellTokenForTokenToUniswapV3`, which pulls the input token
+            // which pulls the input token from a specified `payer`.
-            // from `msg.sender`.
             (success, resultData) = address(this).delegatecall(
                 abi.encodeWithSelector(
-                    IUniswapV3Feature.sellTokenForTokenToUniswapV3.selector,
+                    IUniswapV3Feature._sellTokenForTokenToUniswapV3.selector,
                     wrappedCallData,
                     sellAmount,
                     0,
-                    params.recipient
+                    params.recipient,
+                    params.msgSender
                 )
             );
         }
@@ -69,6 +69,7 @@ abstract contract MultiplexUniswapV3 is FixinTokenSpender {
 
     function _multiHopSellUniswapV3(
         IMultiplexFeature.MultiHopSellState memory state,
+        IMultiplexFeature.MultiHopSellParams memory params,
         bytes memory wrappedCallData
     ) internal {
         bool success;
@@ -87,16 +88,16 @@ abstract contract MultiplexUniswapV3 is FixinTokenSpender {
                 )
             );
         } else {
-            // Otherwise, we self-delegatecall the normal variant
+            // Otherwise, we self-delegatecall `_sellTokenForTokenToUniswapV3`,
-            // `sellTokenForTokenToUniswapV3`, which pulls the input token
+            // which pulls the input token from `msgSender`.
-            // from `msg.sender`.
             (success, resultData) = address(this).delegatecall(
                 abi.encodeWithSelector(
-                    IUniswapV3Feature.sellTokenForTokenToUniswapV3.selector,
+                    IUniswapV3Feature._sellTokenForTokenToUniswapV3.selector,
                     wrappedCallData,
                     state.outputTokenAmount,
                     0,
-                    state.to
+                    state.to,
+                    params.msgSender
                 )
             );
         }

contracts/zero-ex/tests/MetaTransactionV2Test.t.sol

@@ -26,16 +26,16 @@ import "../contracts/src/features/libs/LibSignature.sol";
 import "src/features/libs/LibNativeOrder.sol";
 import "../contracts/test/tokens/TestMintableERC20Token.sol";
 import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
-import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
+import "@0x/contracts-erc20/src/IEtherToken.sol";
 
 contract MetaTransactionTest is BaseTest, TestUtils {
     DeployZeroEx.ZeroExDeployed zeroExDeployed;
     address private constant ZERO_ADDRESS = 0x0000000000000000000000000000000000000000;
     address private constant USER_ADDRESS = 0x6dc3a54FeAE57B65d185A7B159c5d3FA7fD7FD0F;
     uint256 private constant USER_KEY = 0x1fc1630343b31e60b7a197a53149ca571ed9d9791e2833337bbd8110c30710ec;
-    IEtherTokenV06 private wethToken;
+    IEtherToken private wethToken;
-    IERC20TokenV06 private usdcToken;
+    IERC20Token private usdcToken;
-    IERC20TokenV06 private zrxToken;
+    IERC20Token private zrxToken;
     uint256 private constant oneEth = 1e18;
     address private signerAddress;
     uint256 private signerKey;
@@ -47,8 +47,8 @@ contract MetaTransactionTest is BaseTest, TestUtils {
         (signerAddress, signerKey) = getSigner();
         zeroExDeployed = new DeployZeroEx().deployZeroEx();
         wethToken = zeroExDeployed.weth;
-        usdcToken = IERC20TokenV06(address(new TestMintableERC20Token()));
+        usdcToken = IERC20Token(address(new TestMintableERC20Token()));
-        zrxToken = IERC20TokenV06(address(new TestMintableERC20Token()));
+        zrxToken = IERC20Token(address(new TestMintableERC20Token()));
 
         transformerNonce = zeroExDeployed.transformerDeployer.nonce();
         vm.prank(zeroExDeployed.transformerDeployer.authorities(0));

contracts/zero-ex/tests/utils/DeployZeroEx.sol

@@ -204,7 +204,7 @@ contract DeployZeroEx is Test {
         );
         ZERO_EX_DEPLOYED.features.fundRecoveryFeature = new FundRecoveryFeature();
         ZERO_EX_DEPLOYED.features.metaTransactionsFeature = new MetaTransactionsFeature(address(ZERO_EX));
-        ZERO_EX_DEPLOYED.features.metaTransactionsFeatureV2 = new MetaTransactionsFeatureV2(address(ZERO_EX));
+        ZERO_EX_DEPLOYED.features.metaTransactionsFeatureV2 = new MetaTransactionsFeatureV2(address(ZERO_EX), ZERO_EX_DEPLOYED.weth);
         ZERO_EX_DEPLOYED.features.erc1155OrdersFeature = new ERC1155OrdersFeature(
             address(ZERO_EX),
             ZERO_EX_DEPLOYED.weth

contracts/zero-ex/tests/utils/TestUtils.sol

@@ -22,7 +22,7 @@ import "src/transformers/LibERC20Transformer.sol";
 import "src/features/libs/LibSignature.sol";
 import "src/features/libs/LibNativeOrder.sol";
 import "../../contracts/test/tokens/TestMintableERC20Token.sol";
-import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
+import "@0x/contracts-erc20/src/IEtherToken.sol";
 
 contract TestUtils is Test {
     address private constant ZERO_ADDRESS = 0x0000000000000000000000000000000000000000;
@@ -54,8 +54,8 @@ contract TestUtils is Test {
 
     function makeTestRfqOrder(
         DeployZeroEx.ZeroExDeployed memory zeroExDeployed, 
-        IERC20TokenV06 makerToken, 
+        IERC20Token makerToken, 
-        IERC20TokenV06 takerToken,
+        IERC20Token takerToken,
         address makerAddress,
         address takerAddress,
         uint256 makerKey
@@ -93,8 +93,8 @@ contract TestUtils is Test {
 
     function makeTestLimitOrder(
         DeployZeroEx.ZeroExDeployed memory zeroExDeployed, 
-        IERC20TokenV06 makerToken, 
+        IERC20Token makerToken, 
-        IERC20TokenV06 takerToken,
+        IERC20Token takerToken,
         address makerAddress,
         address takerAddress,
         uint256 makerKey
@@ -133,8 +133,8 @@ contract TestUtils is Test {
 
     function transformERC20Call(
         DeployZeroEx.ZeroExDeployed memory zeroExDeployed, 
-        IERC20TokenV06 makerToken, 
+        IERC20Token makerToken, 
-        IERC20TokenV06 takerToken,
+        IERC20Token takerToken,
         address takerAddress,
         uint256 transformerNonce
     ) public returns (bytes memory) {
@@ -158,11 +158,11 @@ contract TestUtils is Test {
         );
     }
 
-    function mintTo(IERC20TokenV06 token, address recipient, uint256 amount) public {
+    function mintTo(IERC20Token token, address recipient, uint256 amount) public {
         TestMintableERC20Token(address(token)).mint(recipient, amount);
     }
 
-    function mintToWETH(IEtherTokenV06 wethToken, address recipient, uint256 amount) public {
+    function mintToWETH(IEtherToken wethToken, address recipient, uint256 amount) public {
         wethToken.deposit{value: amount}();
         WETH9V06(payable(address(wethToken))).transfer(recipient, amount);
     }