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Diffstat (limited to 'packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol')
| -rw-r--r-- | packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol new file mode 100644 index 000000000..9e9d88ce7 --- /dev/null +++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol @@ -0,0 +1,175 @@ +/* + + 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/Ownable/Ownable.sol"; +import "../../utils/LibBytes/LibBytes.sol"; +import "./mixins/MAssetProxyDispatcher.sol"; +import "../AssetProxy/interfaces/IAssetProxy.sol"; + +contract MixinAssetProxyDispatcher is + Ownable, + MAssetProxyDispatcher +{ + using LibBytes for bytes; + + // Mapping from Asset Proxy Id's to their respective Asset Proxy + mapping (bytes4 => IAssetProxy) public assetProxies; + + /// @dev Registers an asset proxy to its asset proxy id. + /// Once an asset proxy is registered, it cannot be unregistered. + /// @param assetProxy Address of new asset proxy to register. + function registerAssetProxy(address assetProxy) + external + onlyOwner + { + IAssetProxy assetProxyContract = IAssetProxy(assetProxy); + + // Ensure that no asset proxy exists with current id. + bytes4 assetProxyId = assetProxyContract.getProxyId(); + address currentAssetProxy = assetProxies[assetProxyId]; + require( + currentAssetProxy == address(0), + "ASSET_PROXY_ALREADY_EXISTS" + ); + + // Add asset proxy and log registration. + assetProxies[assetProxyId] = assetProxyContract; + emit AssetProxyRegistered( + assetProxyId, + assetProxy + ); + } + + /// @dev Gets an asset proxy. + /// @param assetProxyId Id of the asset proxy. + /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered. + function getAssetProxy(bytes4 assetProxyId) + external + view + returns (address) + { + return assetProxies[assetProxyId]; + } + + /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws. + /// @param assetData Byte array encoded for the asset. + /// @param from Address to transfer token from. + /// @param to Address to transfer token to. + /// @param amount Amount of token to transfer. + function dispatchTransferFrom( + bytes memory assetData, + address from, + address to, + uint256 amount + ) + internal + { + // Do nothing if no amount should be transferred. + if (amount > 0) { + // Ensure assetData length is valid + require( + assetData.length > 3, + "LENGTH_GREATER_THAN_3_REQUIRED" + ); + + // Lookup assetProxy + bytes4 assetProxyId; + assembly { + assetProxyId := and(mload( + add(assetData, 32)), + 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000 + ) + } + address assetProxy = assetProxies[assetProxyId]; + + // Ensure that assetProxy exists + require( + assetProxy != address(0), + "ASSET_PROXY_DOES_NOT_EXIST" + ); + + // We construct calldata for the `assetProxy.transferFrom` ABI. + // The layout of this calldata is in the table below. + // + // | Area | Offset | Length | Contents | + // | -------- |--------|---------|-------------------------------------------- | + // | Header | 0 | 4 | function selector | + // | Params | | 4 * 32 | function parameters: | + // | | 4 | | 1. offset to assetData (*) | + // | | 36 | | 2. from | + // | | 68 | | 3. to | + // | | 100 | | 4. amount | + // | Data | | | assetData: | + // | | 132 | 32 | assetData Length | + // | | 164 | ** | assetData Contents | + + assembly { + /////// Setup State /////// + // `cdStart` is the start of the calldata for `assetProxy.transferFrom` (equal to free memory ptr). + let cdStart := mload(64) + // `dataAreaLength` is the total number of words needed to store `assetData` + // As-per the ABI spec, this value is padded up to the nearest multiple of 32, + // and includes 32-bytes for length. + let dataAreaLength := and(add(mload(assetData), 63), 0xFFFFFFFFFFFE0) + // `cdEnd` is the end of the calldata for `assetProxy.transferFrom`. + let cdEnd := add(cdStart, add(132, dataAreaLength)) + + + /////// Setup Header Area /////// + // This area holds the 4-byte `transferFromSelector`. + // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4 + mstore(cdStart, 0xa85e59e400000000000000000000000000000000000000000000000000000000) + + /////// Setup Params Area /////// + // Each parameter is padded to 32-bytes. The entire Params Area is 128 bytes. + // Notes: + // 1. The offset to `assetData` is the length of the Params Area (128 bytes). + // 2. A 20-byte mask is applied to addresses to zero-out the unused bytes. + mstore(add(cdStart, 4), 128) + mstore(add(cdStart, 36), and(from, 0xffffffffffffffffffffffffffffffffffffffff)) + mstore(add(cdStart, 68), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) + mstore(add(cdStart, 100), amount) + + /////// Setup Data Area /////// + // This area holds `assetData`. + let dataArea := add(cdStart, 132) + for {} lt(dataArea, cdEnd) {} { + mstore(dataArea, mload(assetData)) + dataArea := add(dataArea, 32) + assetData := add(assetData, 32) + } + + /////// Call `assetProxy.transferFrom` using the constructed calldata /////// + let success := call( + gas, // forward all gas + assetProxy, // call address of asset proxy + 0, // don't send any ETH + cdStart, // pointer to start of input + sub(cdEnd, cdStart), // length of input + cdStart, // write output over input + 512 // reserve 512 bytes for output + ) + if iszero(success) { + revert(cdStart, returndatasize()) + } + } + } + } +} |