14 files changed, 241 insertions, 23 deletions
diff --git a/packages/contracts/src/2.0.0/forwarder/Forwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
index 6b17bb29b..6b17bb29b 100644
--- a/packages/contracts/src/2.0.0/forwarder/Forwarder.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
index e06f9a8e3..d6a38aa6e 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
@@ -18,10 +18,10 @@
 
 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 "../../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";
 
@@ -67,7 +67,7 @@ contract MixinAssets is
         } else if (proxyId == ERC721_DATA_ID) {
             transferERC721Token(assetData, amount);
         } else {
-            revert("UNSUPPORTED_TOKEN_PROXY");
+            revert("UNSUPPORTED_ASSET_PROXY");
         }
     }
 
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
index 4584bb840..218713d3c 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinExchangeWrapper.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
@@ -21,10 +21,10 @@ 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";
+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
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
index 93cbf79be..42cec4d36 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinForwarderCore.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
@@ -24,10 +24,10 @@ 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";
+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
diff --git a/packages/contracts/src/2.0.0/forwarder/MixinWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
index e07940776..93e85e599 100644
--- a/packages/contracts/src/2.0.0/forwarder/MixinWeth.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
@@ -18,7 +18,7 @@
 
 pragma solidity 0.4.24;
 
-import "../protocol/Exchange/libs/LibMath.sol";
+import "../../protocol/Exchange/libs/LibMath.sol";
 import "./libs/LibConstants.sol";
 import "./mixins/MWeth.sol";
 
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IAssets.sol
index 1e034c003..1e034c003 100644
--- a/packages/contracts/src/2.0.0/forwarder/interfaces/IAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IAssets.sol
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarder.sol
index f5a26e2ba..f5a26e2ba 100644
--- a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarder.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarder.sol
diff --git a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarderCore.sol
index 3ecbb133b..74c7da01d 100644
--- a/packages/contracts/src/2.0.0/forwarder/interfaces/IForwarderCore.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/interfaces/IForwarderCore.sol
@@ -19,8 +19,8 @@
 pragma solidity 0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "../../protocol/Exchange/libs/LibOrder.sol";
-import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../../protocol/Exchange/libs/LibOrder.sol";
+import "../../../protocol/Exchange/libs/LibFillResults.sol";
 
 
 contract IForwarderCore {
diff --git a/packages/contracts/src/2.0.0/forwarder/libs/LibConstants.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibConstants.sol
index fb9691fe8..704e42ce3 100644
--- a/packages/contracts/src/2.0.0/forwarder/libs/LibConstants.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibConstants.sol
@@ -18,10 +18,10 @@
 
 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";
+import "../../../utils/LibBytes/LibBytes.sol";
+import "../../../protocol/Exchange/interfaces/IExchange.sol";
+import "../../../tokens/EtherToken/IEtherToken.sol";
+import "../../../tokens/ERC20Token/IERC20Token.sol";
 
 
 contract LibConstants {
diff --git a/packages/contracts/src/2.0.0/forwarder/libs/LibForwarderErrors.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibForwarderErrors.sol
index cdfb77a0b..fb3ade1db 100644
--- a/packages/contracts/src/2.0.0/forwarder/libs/LibForwarderErrors.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/libs/LibForwarderErrors.sol
@@ -27,7 +27,7 @@ contract LibForwarderErrors {
     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_TOKEN_PROXY = "UNSUPPORTED_TOKEN_PROXY";                          // Proxy in assetData not supported.
+    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/forwarder/mixins/MAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
index 83636432a..83636432a 100644
--- a/packages/contracts/src/2.0.0/forwarder/mixins/MAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MExchangeWrapper.sol
index 360dea0e4..13c26b03a 100644
--- a/packages/contracts/src/2.0.0/forwarder/mixins/MExchangeWrapper.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MExchangeWrapper.sol
@@ -19,8 +19,8 @@
 pragma solidity 0.4.24;
 pragma experimental ABIEncoderV2;
 
-import "../../protocol/Exchange/libs/LibOrder.sol";
-import "../../protocol/Exchange/libs/LibFillResults.sol";
+import "../../../protocol/Exchange/libs/LibOrder.sol";
+import "../../../protocol/Exchange/libs/LibFillResults.sol";
 
 
 contract MExchangeWrapper {
diff --git a/packages/contracts/src/2.0.0/forwarder/mixins/MWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MWeth.sol
index 88e77be4e..88e77be4e 100644
--- a/packages/contracts/src/2.0.0/forwarder/mixins/MWeth.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MWeth.sol
diff --git a/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
new file mode 100644
index 000000000..a18345245
--- /dev/null
+++ b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
@@ -0,0 +1,218 @@
+/*
+
+  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/interfaces/IExchange.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../tokens/ERC20Token/IERC20Token.sol";
+import "../../tokens/ERC721Token/IERC721Token.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+
+
+contract OrderValidator {
+
+    bytes4 constant internal ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
+    bytes4 constant internal ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256)"));
+
+    using LibBytes for bytes;
+
+    struct TraderInfo {
+        uint256 makerBalance;       // Maker's balance of makerAsset
+        uint256 makerAllowance;     // Maker's allowance to corresponding AssetProxy
+        uint256 takerBalance;       // Taker's balance of takerAsset
+        uint256 takerAllowance;     // Taker's allowance to corresponding AssetProxy
+        uint256 makerZrxBalance;    // Maker's balance of ZRX
+        uint256 makerZrxAllowance;  // Maker's allowance of ZRX to ERC20Proxy
+        uint256 takerZrxBalance;    // Taker's balance of ZRX
+        uint256 takerZrxAllowance;  // Taker's allowance of ZRX to ERC20Proxy
+    }
+
+    // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+    bytes internal ZRX_ASSET_DATA;
+    // solhint-enable var-name-mixedcase
+
+    constructor (address _exchange, bytes memory _zrxAssetData)
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+        ZRX_ASSET_DATA = _zrxAssetData;
+    }
+
+    /// @dev Fetches information for order and maker/taker of order.
+    /// @param order The order structure.
+    /// @param takerAddress Address that will be filling the order.
+    /// @return OrderInfo and TraderInfo instances for given order.
+    function getOrderAndTraderInfo(LibOrder.Order memory order, address takerAddress)
+        public
+        view
+        returns (LibOrder.OrderInfo memory orderInfo, TraderInfo memory traderInfo)
+    {
+        orderInfo = EXCHANGE.getOrderInfo(order);
+        traderInfo = getTraderInfo(order, takerAddress);
+        return (orderInfo, traderInfo);
+    }
+
+    /// @dev Fetches information for all passed in orders and the makers/takers of each order.
+    /// @param orders Array of order specifications.
+    /// @param takerAddresses Array of taker addresses corresponding to each order.
+    /// @return Arrays of OrderInfo and TraderInfo instances that correspond to each order.
+    function getOrdersAndTradersInfo(LibOrder.Order[] memory orders, address[] memory takerAddresses)
+        public
+        view
+        returns (LibOrder.OrderInfo[] memory ordersInfo, TraderInfo[] memory tradersInfo)
+    {
+        ordersInfo = EXCHANGE.getOrdersInfo(orders);
+        tradersInfo = getTradersInfo(orders, takerAddresses);
+        return (ordersInfo, tradersInfo);
+    }
+
+    /// @dev Fetches balance and allowances for maker and taker of order.
+    /// @param order The order structure.
+    /// @param takerAddress Address that will be filling the order.
+    /// @return Balances and allowances of maker and taker of order.
+    function getTraderInfo(LibOrder.Order memory order, address takerAddress)
+        public
+        view
+        returns (TraderInfo memory traderInfo)
+    {
+        (traderInfo.makerBalance, traderInfo.makerAllowance) = getBalanceAndAllowance(order.makerAddress, order.makerAssetData);
+        (traderInfo.takerBalance, traderInfo.takerAllowance) = getBalanceAndAllowance(takerAddress, order.takerAssetData);
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        (traderInfo.makerZrxBalance, traderInfo.makerZrxAllowance) = getBalanceAndAllowance(order.makerAddress, zrxAssetData);
+        (traderInfo.takerZrxBalance, traderInfo.takerZrxAllowance) = getBalanceAndAllowance(takerAddress, zrxAssetData);
+        return traderInfo;
+    }
+
+    /// @dev Fetches balances and allowances of maker and taker for each provided order.
+    /// @param orders Array of order specifications.
+    /// @param takerAddresses Array of taker addresses corresponding to each order.
+    /// @return Array of balances and allowances for maker and taker of each order.
+    function getTradersInfo(LibOrder.Order[] memory orders, address[] memory takerAddresses)
+        public
+        view
+        returns (TraderInfo[] memory)
+    {
+        uint256 ordersLength = orders.length;
+        TraderInfo[] memory tradersInfo = new TraderInfo[](ordersLength);
+        for (uint256 i = 0; i != ordersLength; i++) {
+            tradersInfo[i] = getTraderInfo(orders[i], takerAddresses[i]);
+        }
+        return tradersInfo;
+    }
+
+    /// @dev Fetches token balances and allowances of an address to given assetProxy. Supports ERC20 and ERC721.
+    /// @param target Address to fetch balances and allowances of.
+    /// @param assetData Encoded data that can be decoded by a specified proxy contract when transferring asset.
+    /// @return Balance of asset and allowance set to given proxy of asset.
+    ///         For ERC721 tokens, these values will always be 1 or 0.
+    function getBalanceAndAllowance(address target, bytes memory assetData)
+        public
+        view
+        returns (uint256 balance, uint256 allowance)
+    {
+        bytes4 assetProxyId = assetData.readBytes4(0);
+        address token = assetData.readAddress(16);
+        address assetProxy = EXCHANGE.getAssetProxy(assetProxyId);
+
+        if (assetProxyId == ERC20_DATA_ID) {
+            // Query balance
+            balance = IERC20Token(token).balanceOf(target);
+
+            // Query allowance
+            allowance = IERC20Token(token).allowance(target, assetProxy);
+        } else if (assetProxyId == ERC721_DATA_ID) {
+            uint256 tokenId = assetData.readUint256(36);
+
+            // Query owner of tokenId
+            address owner = getERC721TokenOwner(token, tokenId);
+
+            // Set balance to 1 if tokenId is owned by target
+            balance = target == owner ? 1 : 0;
+
+            // Check if ERC721Proxy is approved to spend tokenId
+            bool isApproved = IERC721Token(token).isApprovedForAll(target, assetProxy) || IERC721Token(token).getApproved(tokenId) == assetProxy;
+            
+            // Set alowance to 1 if ERC721Proxy is approved to spend tokenId
+            allowance = isApproved ? 1 : 0;
+        } else {
+            revert("UNSUPPORTED_ASSET_PROXY");
+        }
+        return (balance, allowance);
+    }
+
+    /// @dev Fetches token balances and allowances of an address for each given assetProxy. Supports ERC20 and ERC721.
+    /// @param target Address to fetch balances and allowances of.
+    /// @param assetData Array of encoded byte arrays that can be decoded by a specified proxy contract when transferring asset.
+    /// @return Balances and allowances of assets.
+    ///         For ERC721 tokens, these values will always be 1 or 0.
+    function getBalancesAndAllowances(address target, bytes[] memory assetData)
+        public
+        view
+        returns (uint256[] memory, uint256[] memory)
+    {
+        uint256 length = assetData.length;
+        uint256[] memory balances = new uint256[](length);
+        uint256[] memory allowances = new uint256[](length);
+        for (uint256 i = 0; i != length; i++) {
+            (balances[i], allowances[i]) = getBalanceAndAllowance(target, assetData[i]);
+        }
+        return (balances, allowances);
+    }
+
+    /// @dev Calls `token.ownerOf(tokenId)`, but returns a null owner instead of reverting on an unowned token.
+    /// @param token Address of ERC721 token.
+    /// @param tokenId The identifier for the specific NFT.
+    /// @return Owner of tokenId or null address if unowned.
+    function getERC721TokenOwner(address token, uint256 tokenId)
+        public
+        view
+        returns (address owner)
+    {
+        assembly {
+            // load free memory pointer
+            let cdStart := mload(64)
+
+            // bytes4(keccak256(ownerOf(uint256))) = 0x6352211e
+            mstore(cdStart, 0x6352211e00000000000000000000000000000000000000000000000000000000)
+            mstore(add(cdStart, 4), tokenId)
+
+            // staticcall `ownerOf(tokenId)`
+            // `ownerOf` will revert if tokenId is not owned
+            let success := staticcall(
+                gas,      // forward all gas
+                token,    // call token contract
+                cdStart,  // start of calldata
+                36,       // length of input is 36 bytes
+                cdStart,  // write output over input
+                32        // size of output is 32 bytes
+            )
+
+            // Success implies that tokenId is owned
+            // Copy owner from return data if successful
+            if success {
+                owner := mload(cdStart)
+            }    
+        }
+
+        // Owner initialized to address(0), no need to modify if call is unsuccessful
+        return owner;
+    }
+}