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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 "./libs/LibExchangeErrors.sol";
import "./mixins/MSignatureValidator.sol";
import "./mixins/MTransactions.sol";
import "./libs/LibEIP712.sol";
contract MixinTransactions is
LibEIP712,
MSignatureValidator,
MTransactions
{
// Mapping of transaction hash => executed
// This prevents transactions from being executed more than once.
mapping (bytes32 => bool) public transactions;
// Address of current transaction signer
address public currentContextAddress;
// Hash for the EIP712 ZeroEx Transaction Schema
bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
"ZeroExTransaction(",
"uint256 salt,",
"address signerAddress,",
"bytes data",
")"
));
/// @dev Executes an exchange method call in the context of signer.
/// @param salt Arbitrary number to ensure uniqueness of transaction hash.
/// @param signerAddress Address of transaction signer.
/// @param data AbiV2 encoded calldata.
/// @param signature Proof of signer transaction by signer.
function executeTransaction(
uint256 salt,
address signerAddress,
bytes data,
bytes signature
)
external
{
// Prevent reentrancy
require(
currentContextAddress == address(0),
"REENTRANCY_ILLEGAL"
);
bytes32 transactionHash = hashEIP712Message(hashZeroExTransaction(
salt,
signerAddress,
data
));
// Validate transaction has not been executed
require(
!transactions[transactionHash],
"INVALID_TX_HASH"
);
// Transaction always valid if signer is sender of transaction
if (signerAddress != msg.sender) {
// Validate signature
require(
isValidSignature(
transactionHash,
signerAddress,
signature
),
"INVALID_TX_SIGNATURE"
);
// Set the current transaction signer
currentContextAddress = signerAddress;
}
// Execute transaction
transactions[transactionHash] = true;
require(
address(this).delegatecall(data),
"FAILED_EXECUTION"
);
// Reset current transaction signer if it was previously updated
if (signerAddress != msg.sender) {
currentContextAddress = address(0);
}
}
/// @dev Calculates EIP712 hash of the Transaction.
/// @param salt Arbitrary number to ensure uniqueness of transaction hash.
/// @param signerAddress Address of transaction signer.
/// @param data AbiV2 encoded calldata.
/// @return EIP712 hash of the Transaction.
function hashZeroExTransaction(
uint256 salt,
address signerAddress,
bytes memory data
)
internal
pure
returns (bytes32 result)
{
bytes32 schemaHash = EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH;
bytes32 dataHash = keccak256(data);
// Assembly for more efficiently computing:
// keccak256(abi.encodePacked(
// EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
// salt,
// bytes32(signerAddress),
// keccak256(data)
// ));
assembly {
// Load free memory pointer
let memPtr := mload(64)
mstore(memPtr, schemaHash) // hash of schema
mstore(add(memPtr, 32), salt) // salt
mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff)) // signerAddress
mstore(add(memPtr, 96), dataHash) // hash of data
// Compute hash
result := keccak256(memPtr, 128)
}
return result;
}
/// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
/// If calling a fill function, this address will represent the taker.
/// If calling a cancel function, this address will represent the maker.
/// @return Signer of 0x transaction if entry point is `executeTransaction`.
/// `msg.sender` if entry point is any other function.
function getCurrentContextAddress()
internal
view
returns (address)
{
address currentContextAddress_ = currentContextAddress;
address contextAddress = currentContextAddress_ == address(0) ? msg.sender : currentContextAddress_;
return contextAddress;
}
}
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