plugeth/contracts/chequebook/contract/chequebook.sol
Alex Beregszaszi b31cc71ff6 contracts/chequebook: update for latest Solidity (#15425)
This changes behaviour: before if the owner/amount didn't match, it
resulted in a successful execution without doing anything; now it
results in a failed execution using the revert opcode (remainder gas
is not consumed).
2017-11-10 10:19:51 +01:00

46 lines
1.9 KiB
Solidity

pragma solidity ^0.4.18;
import "https://github.com/ethereum/solidity/std/mortal.sol";
/// @title Chequebook for Ethereum micropayments
/// @author Daniel A. Nagy <daniel@ethereum.org>
contract chequebook is mortal {
// Cumulative paid amount in wei to each beneficiary
mapping (address => uint256) public sent;
/// @notice Overdraft event
event Overdraft(address deadbeat);
/// @notice Cash cheque
///
/// @param beneficiary beneficiary address
/// @param amount cumulative amount in wei
/// @param sig_v signature parameter v
/// @param sig_r signature parameter r
/// @param sig_s signature parameter s
/// The digital signature is calculated on the concatenated triplet of contract address, beneficiary address and cumulative amount
function cash(address beneficiary, uint256 amount,
uint8 sig_v, bytes32 sig_r, bytes32 sig_s) {
// Check if the cheque is old.
// Only cheques that are more recent than the last cashed one are considered.
require(amount > sent[beneficiary]);
// Check the digital signature of the cheque.
bytes32 hash = keccak256(address(this), beneficiary, amount);
require(owner == ecrecover(hash, sig_v, sig_r, sig_s));
// Attempt sending the difference between the cumulative amount on the cheque
// and the cumulative amount on the last cashed cheque to beneficiary.
uint256 diff = amount - sent[beneficiary];
if (diff <= this.balance) {
// update the cumulative amount before sending
sent[beneficiary] = amount;
beneficiary.transfer(diff);
} else {
// Upon failure, punish owner for writing a bounced cheque.
// owner.sendToDebtorsPrison();
Overdraft(owner);
// Compensate beneficiary.
selfdestruct(beneficiary);
}
}
}