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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 "./MixinAssetProxyDispatcher.sol";
import "./MixinAuthorizable.sol";
contract MultiAssetProxy is
MixinAssetProxyDispatcher,
MixinAuthorizable
{
// Id of this proxy.
bytes4 constant internal PROXY_ID = bytes4(keccak256("MultiAsset(uint256[],bytes[])"));
// solhint-disable-next-line payable-fallback
function ()
external
{
// NOTE: The below assembly assumes that clients do some input validation and that the input is properly encoded according to the AbiV2 specification.
// It is technically possible for inputs with very large lengths and offsets to cause overflows. However, this would make the calldata prohibitively
// expensive and we therefore do not check for overflows in these scenarios.
assembly {
// The first 4 bytes of calldata holds the function selector
let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
// `transferFrom` will be called with the following parameters:
// assetData Encoded byte array.
// from Address to transfer asset from.
// to Address to transfer asset to.
// amount Amount of asset to transfer.
// bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
// To lookup a value in a mapping, we load from the storage location keccak256(k, p),
// where k is the key left padded to 32 bytes and p is the storage slot
mstore(0, caller)
mstore(32, authorized_slot)
// Revert if authorized[msg.sender] == false
if iszero(sload(keccak256(0, 64))) {
// Revert with `Error("SENDER_NOT_AUTHORIZED")`
mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
mstore(96, 0)
revert(0, 100)
}
// `transferFrom`.
// The function is marked `external`, so no abi decoding is done for
// us. Instead, we expect the `calldata` memory to contain the
// following:
//
// | 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 |
//
// (*): offset is computed from start of function parameters, so offset
// by an additional 4 bytes in the calldata.
//
// (**): see table below to compute length of assetData Contents
//
// WARNING: The ABIv2 specification allows additional padding between
// the Params and Data section. This will result in a larger
// offset to assetData.
// Load offset to `assetData`
let assetDataOffset := calldataload(4)
// Asset data itself is encoded as follows:
//
// | Area | Offset | Length | Contents |
// |----------|-------------|---------|-------------------------------------|
// | Header | 0 | 4 | assetProxyId |
// | Params | | 2 * 32 | function parameters: |
// | | 4 | | 1. offset to amounts (*) |
// | | 36 | | 2. offset to nestedAssetData (*) |
// | Data | | | amounts: |
// | | 68 | 32 | amounts Length |
// | | 100 | a | amounts Contents |
// | | | | nestedAssetData: |
// | | 100 + a | 32 | nestedAssetData Length |
// | | 132 + a | b | nestedAssetData Contents (offsets) |
// | | 132 + a + b | | nestedAssetData[0, ..., len] |
// In order to find the offset to `amounts`, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
let amountsOffset := calldataload(add(assetDataOffset, 40))
// In order to find the offset to `nestedAssetData`, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + 32 (amounts offset)
let nestedAssetDataOffset := calldataload(add(assetDataOffset, 72))
// In order to find the start of the `amounts` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + amountsOffset
// + 32 (amounts len)
let amountsContentsStart := add(assetDataOffset, add(amountsOffset, 72))
// Load number of elements in `amounts`
let amountsLen := calldataload(sub(amountsContentsStart, 32))
// In order to find the start of the `nestedAssetData` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + nestedAssetDataOffset
// + 32 (nestedAssetData len)
let nestedAssetDataContentsStart := add(assetDataOffset, add(nestedAssetDataOffset, 72))
// Load number of elements in `nestedAssetData`
let nestedAssetDataLen := calldataload(sub(nestedAssetDataContentsStart, 32))
// Revert if number of elements in `amounts` differs from number of elements in `nestedAssetData`
if sub(amountsLen, nestedAssetDataLen) {
// Revert with `Error("LENGTH_MISMATCH")`
mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
mstore(64, 0x0000000f4c454e4754485f4d49534d4154434800000000000000000000000000)
mstore(96, 0)
revert(0, 100)
}
// Copy `transferFrom` selector, offset to `assetData`, `from`, and `to` from calldata to memory
calldatacopy(
0, // memory can safely be overwritten from beginning
0, // start of calldata
100 // length of selector (4) and 3 params (32 * 3)
)
// Overwrite existing offset to `assetData` with our own
mstore(4, 128)
// Load `amount`
let amount := calldataload(100)
// Calculate number of bytes in `amounts` contents
let amountsByteLen := mul(amountsLen, 32)
// Initialize `assetProxyId` and `assetProxy` to 0
let assetProxyId := 0
let assetProxy := 0
// Loop through `amounts` and `nestedAssetData`, calling `transferFrom` for each respective element
for {let i := 0} lt(i, amountsByteLen) {i := add(i, 32)} {
// Calculate the total amount
let amountsElement := calldataload(add(amountsContentsStart, i))
let totalAmount := mul(amountsElement, amount)
// Revert if `amount` != 0 and multiplication resulted in an overflow
if iszero(or(
iszero(amount),
eq(div(totalAmount, amount), amountsElement)
)) {
// Revert with `Error("UINT256_OVERFLOW")`
mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
mstore(64, 0x0000001055494e543235365f4f564552464c4f57000000000000000000000000)
mstore(96, 0)
revert(0, 100)
}
// Write `totalAmount` to memory
mstore(100, totalAmount)
// Load offset to `nestedAssetData[i]`
let nestedAssetDataElementOffset := calldataload(add(nestedAssetDataContentsStart, i))
// In order to find the start of the `nestedAssetData[i]` contents, we must add:
// 4 (function selector)
// + assetDataOffset
// + 32 (assetData len)
// + 4 (assetProxyId)
// + nestedAssetDataOffset
// + 32 (nestedAssetData len)
// + nestedAssetDataElementOffset
// + 32 (nestedAssetDataElement len)
let nestedAssetDataElementContentsStart := add(assetDataOffset, add(nestedAssetDataOffset, add(nestedAssetDataElementOffset, 104)))
// Load length of `nestedAssetData[i]`
let nestedAssetDataElementLenStart := sub(nestedAssetDataElementContentsStart, 32)
let nestedAssetDataElementLen := calldataload(nestedAssetDataElementLenStart)
// Revert if the `nestedAssetData` does not contain a 4 byte `assetProxyId`
if lt(nestedAssetDataElementLen, 4) {
// Revert with `Error("LENGTH_GREATER_THAN_3_REQUIRED")`
mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
mstore(64, 0x0000001e4c454e4754485f475245415445525f5448414e5f335f524551554952)
mstore(96, 0x4544000000000000000000000000000000000000000000000000000000000000)
revert(0, 100)
}
// Load AssetProxy id
let currentAssetProxyId := and(
calldataload(nestedAssetDataElementContentsStart),
0xffffffff00000000000000000000000000000000000000000000000000000000
)
// Only load `assetProxy` if `currentAssetProxyId` does not equal `assetProxyId`
// We do not need to check if `currentAssetProxyId` is 0 since `assetProxy` is also initialized to 0
if sub(currentAssetProxyId, assetProxyId) {
// Update `assetProxyId`
assetProxyId := currentAssetProxyId
// To lookup a value in a mapping, we load from the storage location keccak256(k, p),
// where k is the key left padded to 32 bytes and p is the storage slot
mstore(132, assetProxyId)
mstore(164, assetProxies_slot)
assetProxy := sload(keccak256(132, 64))
}
// Revert if AssetProxy with given id does not exist
if iszero(assetProxy) {
// Revert with `Error("ASSET_PROXY_DOES_NOT_EXIST")`
mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
mstore(64, 0x0000001a41535345545f50524f58595f444f45535f4e4f545f45584953540000)
mstore(96, 0)
revert(0, 100)
}
// Copy `nestedAssetData[i]` from calldata to memory
calldatacopy(
132, // memory slot after `amounts[i]`
nestedAssetDataElementLenStart, // location of `nestedAssetData[i]` in calldata
add(nestedAssetDataElementLen, 32) // `nestedAssetData[i].length` plus 32 byte length
)
// call `assetProxy.transferFrom`
let success := call(
gas, // forward all gas
assetProxy, // call address of asset proxy
0, // don't send any ETH
0, // pointer to start of input
add(164, nestedAssetDataElementLen), // length of input
0, // write output over memory that won't be reused
0 // don't copy output to memory
)
// Revert with reason given by AssetProxy if `transferFrom` call failed
if iszero(success) {
returndatacopy(
0, // copy to memory at 0
0, // copy from return data at 0
returndatasize() // copy all return data
)
revert(0, returndatasize())
}
}
// Return if no `transferFrom` calls reverted
return(0, 0)
}
// Revert if undefined function is called
revert(0, 0)
}
}
/// @dev Gets the proxy id associated with the proxy address.
/// @return Proxy id.
function getProxyId()
external
pure
returns (bytes4)
{
return PROXY_ID;
}
}
|
