364 lines
11 KiB
Solidity
364 lines
11 KiB
Solidity
pragma solidity ^0.4.21;
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import "./Identity.sol";
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import "../token/ERC20Token.sol";
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/**
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* @title IdentityGasRelay
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* @author Ricardo Guilherme Schmidt (Status Research & Development GmbH)
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* @notice enables economic abstraction for Identity
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*/
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contract IdentityGasRelay is Identity {
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bytes4 public constant CALL_PREFIX = bytes4(keccak256("callGasRelay(address,uint256,bytes32,uint256,uint256,address)"));
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bytes4 public constant APPROVEANDCALL_PREFIX = bytes4(keccak256("approveAndCallGasRelay(address,address,uint256,bytes32,uint256,uint256)"));
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event ExecutedGasRelayed(bytes32 signHash, bool success);
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/**
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* @notice include ethereum signed callHash in return of gas proportional amount multiplied by `_gasPrice` of `_gasToken`
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* allows identity of being controlled without requiring ether in key balace
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* @param _to destination of call
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* @param _value call value (ether)
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* @param _data call data
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* @param _nonce current identity nonce
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* @param _gasPrice price in SNT paid back to msg.sender for each gas unit used
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* @param _gasLimit minimal gasLimit required to execute this call
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* @param _gasToken token being used for paying `msg.sender`
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* @param _messageSignatures rsv concatenated ethereum signed message signatures required
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*/
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function callGasRelayed(
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address _to,
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uint256 _value,
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bytes _data,
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uint _nonce,
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uint _gasPrice,
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uint _gasLimit,
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address _gasToken,
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bytes _messageSignatures
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)
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external
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{
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uint startGas = gasleft();
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//verify transaction parameters
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require(startGas >= _gasLimit);
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require(_nonce == nonce);
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// calculates signHash
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bytes32 signHash = getSignHash(
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callGasRelayHash(
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_to,
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_value,
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keccak256(_data),
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_nonce,
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_gasPrice,
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_gasLimit,
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_gasToken
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)
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);
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//verify if signatures are valid and came from correct actors;
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verifySignatures(
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_to == address(this) ? MANAGEMENT_KEY : ACTION_KEY,
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signHash,
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_messageSignatures
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);
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//executes transaction
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nonce++;
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bool success = _to.call.value(_value)(_data);
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emit ExecutedGasRelayed(
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signHash,
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success
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);
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//refund gas used using contract held ERC20 tokens or ETH
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if (_gasPrice > 0) {
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uint256 _amount = 21000 + (startGas - gasleft());
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_amount = _amount * _gasPrice;
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if (_gasToken == address(0)) {
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address(msg.sender).transfer(_amount);
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} else {
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ERC20Token(_gasToken).transfer(msg.sender, _amount);
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}
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}
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}
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/**
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* @notice include ethereum signed approve ERC20 and call hash
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* (`ERC20Token(baseToken).approve(_to, _value)` + `_to.call(_data)`).
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* in return of gas proportional amount multiplied by `_gasPrice` of `_gasToken`
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* fixes race condition in double transaction for ERC20.
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* @param _baseToken token approved for `_to`
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* @param _to destination of call
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* @param _value call value (ether)
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* @param _data call data
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* @param _nonce current identity nonce
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* @param _gasPrice price in SNT paid back to msg.sender for each gas unit used
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* @param _gasLimit minimal gasLimit required to execute this call
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* @param _gasToken token being used for paying `msg.sender`
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* @param _messageSignatures rsv concatenated ethereum signed message signatures required
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*/
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function approveAndCallGasRelayed(
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address _baseToken,
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address _to,
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uint256 _value,
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bytes _data,
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uint _nonce,
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uint _gasPrice,
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uint _gasLimit,
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address _gasToken,
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bytes _messageSignatures
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)
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external
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{
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uint startGas = gasleft();
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//verify transaction parameters
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require(startGas >= _gasLimit);
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require(_nonce == nonce);
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require(_baseToken != address(0)); //_baseToken should be something!
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require(_to != address(this)); //no management with approveAndCall
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// calculates signHash
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bytes32 signHash = getSignHash(
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approveAndCallGasRelayHash(
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_baseToken,
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_to,
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_value,
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keccak256(_data),
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_nonce,
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_gasPrice,
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_gasLimit,
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_gasToken
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)
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);
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//verify if signatures are valid and came from correct actors;
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verifySignatures(
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ACTION_KEY, //no management with approveAndCall
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signHash,
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_messageSignatures
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);
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approveAndCall(
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signHash,
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_baseToken,
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_to,
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_value,
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_data
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);
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//refund gas used using contract held ERC20 tokens or ETH
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if (_gasPrice > 0) {
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uint256 _amount = 21000 + (startGas - gasleft());
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_amount = _amount * _gasPrice;
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if (_gasToken == address(0)) {
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address(msg.sender).transfer(_amount);
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} else {
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ERC20Token(_gasToken).transfer(msg.sender, _amount);
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}
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}
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}
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/**
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* @notice reverts if signatures are not valid for the signed hash and required key type.
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* @param _requiredKey key required to call, if _to from payload is the identity itself, is `MANAGEMENT_KEY`, else `ACTION_KEY`
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* @param _signHash ethereum signable callGasRelayHash message provided for the payload
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* @param _messageSignatures ethereum signed `_signHash` messages
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* @return true case valid
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*/
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function verifySignatures(
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uint256 _requiredKey,
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bytes32 _signHash,
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bytes _messageSignatures
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)
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public
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view
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returns(bool)
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{
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uint _amountSignatures = _messageSignatures.length / 72;
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require(_amountSignatures == purposeThreshold[_requiredKey]);
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bytes32 _lastKey = 0;
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for (uint256 i = 0; i < _amountSignatures; i++) {
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bytes32 _currentKey = recoverKey(
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_signHash,
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_messageSignatures,
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i
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);
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require(_currentKey > _lastKey); //assert keys are different
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require(isKeyPurpose(_currentKey, _requiredKey));
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_lastKey = _currentKey;
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}
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return true;
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}
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/**
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* @notice get callHash
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* @param _to destination of call
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* @param _value call value (ether)
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* @param _dataHash call data hash
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* @param _nonce current identity nonce
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* @param _gasPrice price in SNT paid back to msg.sender for each gas unit used
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* @param _gasLimit minimal gasLimit required to execute this call
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* @param _gasToken token being used for paying `msg.sender`
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* @return callGasRelayHash the hash to be signed by wallet
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*/
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function callGasRelayHash(
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address _to,
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uint256 _value,
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bytes32 _dataHash,
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uint _nonce,
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uint256 _gasPrice,
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uint256 _gasLimit,
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address _gasToken
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)
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public
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view
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returns (bytes32 _callGasRelayHash)
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{
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_callGasRelayHash = keccak256(
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address(this),
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CALL_PREFIX,
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_to,
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_value,
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_dataHash,
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_nonce,
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_gasPrice,
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_gasLimit,
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_gasToken
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);
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}
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/**
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* @notice get callHash
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* @param _to destination of call
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* @param _value call value (ether)
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* @param _dataHash call data hash
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* @param _nonce current identity nonce
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* @param _gasPrice price in SNT paid back to msg.sender for each gas unit used
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* @param _gasLimit minimal gasLimit required to execute this call
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* @param _gasToken token being used for paying `msg.sender`
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* @return callGasRelayHash the hash to be signed by wallet
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*/
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function approveAndCallGasRelayHash(
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address _baseToken,
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address _to,
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uint256 _value,
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bytes32 _dataHash,
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uint _nonce,
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uint256 _gasPrice,
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uint256 _gasLimit,
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address _gasToken
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)
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public
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view
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returns (bytes32 _callGasRelayHash)
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{
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_callGasRelayHash = keccak256(
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address(this),
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APPROVEANDCALL_PREFIX,
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_baseToken,
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_to,
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_value,
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_dataHash,
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_nonce,
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_gasPrice,
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_gasLimit,
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_gasToken
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);
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}
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/**
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* @notice Hash a hash with `"\x19Ethereum Signed Message:\n32"`
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* @param _hash Sign to hash.
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* @return signHash Hash ethereum wallet signs.
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*/
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function getSignHash(
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bytes32 _hash
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)
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pure
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public
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returns(bytes32 signHash)
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{
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signHash = keccak256("\x19Ethereum Signed Message:\n32", _hash);
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}
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/**
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* @notice recovers address who signed the message
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* @param _signHash operation ethereum signed message hash
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* @param _messageSignature message `_signHash` signature
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* @param _pos which signature to read
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*/
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function recoverKey (
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bytes32 _signHash,
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bytes _messageSignature,
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uint256 _pos
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)
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pure
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public
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returns(bytes32)
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{
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uint8 v;
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bytes32 r;
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bytes32 s;
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(v,r,s) = signatureSplit(_messageSignature, _pos);
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return bytes32(
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ecrecover(
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_signHash,
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v,
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r,
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s
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)
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);
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}
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/**
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* @dev divides bytes signature into `uint8 v, bytes32 r, bytes32 s`
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* @param _pos which signature to read
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* @param _signatures concatenated vrs signatures
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*/
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function signatureSplit(bytes _signatures, uint256 _pos)
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pure
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public
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returns (uint8 v, bytes32 r, bytes32 s)
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{
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uint pos = _pos + 1;
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// The signature format is a compact form of:
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// {bytes32 r}{bytes32 s}{uint8 v}
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// Compact means, uint8 is not padded to 32 bytes.
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assembly {
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r := mload(add(_signatures, mul(32,pos)))
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s := mload(add(_signatures, mul(64,pos)))
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// Here we are loading the last 32 bytes, including 31 bytes
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// of 's'. There is no 'mload8' to do this.
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//
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// 'byte' is not working due to the Solidity parser, so lets
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// use the second best option, 'and'
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v := and(mload(add(_signatures, mul(65,pos))), 0xff)
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}
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require(v == 27 || v == 28);
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}
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function approveAndCall(
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bytes32 _signHash,
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address _token,
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address _to,
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uint256 _value,
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bytes _data
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)
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private
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{
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//executes transaction
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nonce++;
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ERC20Token(_token).approve(_to, _value);
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emit ExecutedGasRelayed(
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_signHash,
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_to.call(_data)
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);
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}
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} |