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/*
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 "@0x/contracts-utils/contracts/src/Ownable.sol";
import "./mixins/MAssetProxyDispatcher.sol";
import "./interfaces/IAssetProxy.sol";
contract MixinAssetProxyDispatcher is
Ownable,
MAssetProxyDispatcher
{
// 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 && from != to) {
// Ensure assetData length is valid
require(
assetData.length > 3,
"LENGTH_GREATER_THAN_3_REQUIRED"
);
// Lookup assetProxy. We do not use `LibBytes.readBytes4` for gas efficiency reasons.
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)
// solhint-disable-next-line no-empty-blocks
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())
}
}
}
}
}
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