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Update swarm chequebook for latest Solidity #15425

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Merged
fjl merged 4 commits into from
Nov 10, 2017
Merged

Update swarm chequebook for latest Solidity #15425

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f9b88ba
chequebook: require a modern version of solidity
axic Nov 4, 2017
c9320fd
chequebook: use modern transfer method
axic Nov 4, 2017
57168ad
chequebook: use require keyword
axic Nov 4, 2017
94fb8b1
email address change
Nov 10, 2017
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19 changes: 9 additions & 10 deletions contracts/chequebook/contract/chequebook.sol
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Original file line number Diff line number Diff line change
@@ -1,7 +1,9 @@
import "mortal";
pragma solidity ^0.4.18;

import "https://github.com/ethereum/solidity/std/mortal.sol";

/// @title Chequebook for Ethereum micropayments
/// @author Daniel A. Nagy <daniel@ethdev.com>
/// @author Daniel A. Nagy <daniel@ethereum.org>
contract chequebook is mortal {
// Cumulative paid amount in wei to each beneficiary
mapping (address => uint256) public sent;
Expand All @@ -21,26 +23,23 @@ contract chequebook is mortal {
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.
if(amount <= sent[beneficiary]) return;
require(amount > sent[beneficiary]);
// Check the digital signature of the cheque.
bytes32 hash = sha3(address(this), beneficiary, amount);
if(owner != ecrecover(hash, sig_v, sig_r, sig_s)) return;
bytes32 hash = keccak256(address(this), beneficiary, amount);
require(owner == ecrecover(hash, sig_v, sig_r, sig_s));
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@axic axic Nov 6, 2017

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These two require changes change 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).

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@holiman holiman Nov 9, 2017

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Is that good or bad @nagydani ?

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@nagydani nagydani Nov 10, 2017

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I think, it is okay. The actual effect is the same: nothing changes in the state and remaining gas is not consumed.

// 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;
if (!beneficiary.send(diff)) {
// Upon failure to execute send, revert everything
throw;
}
beneficiary.transfer(diff);
} else {
// Upon failure, punish owner for writing a bounced cheque.
// owner.sendToDebtorsPrison();
Overdraft(owner);
// Compensate beneficiary.
suicide(beneficiary);
selfdestruct(beneficiary);
}
}
}