diff --git a/contracts/examples/SimpleSavingsWallet.sol b/contracts/examples/SimpleSavingsWallet.sol new file mode 100644 index 00000000000..e6d11d5a208 --- /dev/null +++ b/contracts/examples/SimpleSavingsWallet.sol @@ -0,0 +1,40 @@ +pragma solidity ^0.4.11; + +import "../ownership/Heritable.sol"; + + +/** + * @title SimpleSavingsWallet + * @dev Simplest form of savings wallet whose ownership can be claimed by a heir + * if owner dies. + * In this example, we take a very simple savings wallet providing two operations + * (to send and receive funds) and extend its capabilities by making it Heritable. + * The account that creates the contract is set as owner, who has the authority to + * choose an heir account. Heir account can reclaim the contract ownership in the + * case that the owner dies. + */ +contract SimpleSavingsWallet is Heritable { + + event Sent(address payee, uint amount, uint balance); + event Received(address payer, uint amount, uint balance); + + + function SimpleSavingsWallet(uint _heartbeatTimeout) Heritable(_heartbeatTimeout) public {} + + /** + * @dev wallet can receive funds. + */ + function () public payable { + Received(msg.sender, msg.value, this.balance); + } + + /** + * @dev wallet can send funds + */ + function sendTo(address payee, uint amount) public onlyOwner { + require(payee != 0 && payee != address(this)); + require(amount > 0); + payee.transfer(amount); + Sent(payee, amount, this.balance); + } +} diff --git a/contracts/ownership/Heritable.sol b/contracts/ownership/Heritable.sol new file mode 100644 index 00000000000..11aa22f8cb5 --- /dev/null +++ b/contracts/ownership/Heritable.sol @@ -0,0 +1,100 @@ +pragma solidity ^0.4.11; + + +import './Ownable.sol'; + + +/** + * @title Heritable + * @dev The Heritable contract provides ownership transfer capabilities, in the + * case that the current owner stops "heartbeating". Only the heir can pronounce the + * owner's death. + */ +contract Heritable is Ownable { + address public heir; + + // Time window the owner has to notify they are alive. + uint public heartbeatTimeout; + + // Timestamp of the owner's death, as pronounced by the heir. + uint public timeOfDeath; + + + event HeirChanged(address indexed owner, address indexed newHeir); + event OwnerHeartbeated(address indexed owner); + event OwnerProclaimedDead(address indexed owner, address indexed heir, uint timeOfDeath); + event HeirOwnershipClaimed(address indexed previousOwner, address indexed newOwner); + + + /** + * @dev Throw an exception if called by any account other than the heir's. + */ + modifier onlyHeir() { + require(msg.sender == heir); + _; + } + + + /** + * @notice Create a new Heritable Contract with heir address 0x0. + * @param _heartbeatTimeout time available for the owner to notify they are alive, + * before the heir can take ownership. + */ + function Heritable(uint _heartbeatTimeout) public { + setHeartbeatTimeout(_heartbeatTimeout); + } + + function setHeir(address newHeir) public onlyOwner { + require(newHeir != owner); + heartbeat(); + HeirChanged(owner, newHeir); + heir = newHeir; + } + + /** + * @dev set heir = 0x0 + */ + function removeHeir() public onlyOwner { + heartbeat(); + heir = 0; + } + + /** + * @dev Heir can pronounce the owners death. To claim the ownership, they will + * have to wait for `heartbeatTimeout` seconds. + */ + function proclaimDeath() public onlyHeir { + require(ownerLives()); + OwnerProclaimedDead(owner, heir, timeOfDeath); + timeOfDeath = now; + } + + /** + * @dev Owner can send a heartbeat if they were mistakenly pronounced dead. + */ + function heartbeat() public onlyOwner { + OwnerHeartbeated(owner); + timeOfDeath = 0; + } + + /** + * @dev Allows heir to transfer ownership only if heartbeat has timed out. + */ + function claimHeirOwnership() public onlyHeir { + require(!ownerLives()); + require(now >= timeOfDeath + heartbeatTimeout); + OwnershipTransferred(owner, heir); + HeirOwnershipClaimed(owner, heir); + owner = heir; + timeOfDeath = 0; + } + + function setHeartbeatTimeout(uint newHeartbeatTimeout) internal onlyOwner { + require(ownerLives()); + heartbeatTimeout = newHeartbeatTimeout; + } + + function ownerLives() internal view returns (bool) { + return timeOfDeath == 0; + } +} diff --git a/test/Heritable.js b/test/Heritable.js new file mode 100644 index 00000000000..028abf92516 --- /dev/null +++ b/test/Heritable.js @@ -0,0 +1,112 @@ +'use strict' +import increaseTime from './helpers/increaseTime' +import expectThrow from './helpers/expectThrow'; + +const NULL_ADDRESS = '0x0000000000000000000000000000000000000000' + +const Heritable = artifacts.require('../contracts/ownership/Heritable.sol') + +contract('Heritable', function(accounts) { + let heritable + let owner + + beforeEach(async function() { + heritable = await Heritable.new(4141) + owner = await heritable.owner() + }) + + it('should start off with an owner, but without heir', async function() { + const heir = await heritable.heir() + + assert.equal(typeof(owner), 'string') + assert.equal(typeof(heir), 'string') + assert.notStrictEqual( + owner, NULL_ADDRESS, + "Owner shouldn't be the null address" + ) + assert.isTrue( + heir === NULL_ADDRESS, + "Heir should be the null address" + ) + }) + + it('only owner should set heir', async function() { + const newHeir = accounts[1] + const someRandomAddress = accounts[2] + assert.isTrue(owner !== someRandomAddress) + + await heritable.setHeir(newHeir, {from: owner}) + await expectThrow(heritable.setHeir(newHeir, {from: someRandomAddress})) + }) + + it('owner can remove heir', async function() { + const newHeir = accounts[1] + await heritable.setHeir(newHeir, {from: owner}) + let heir = await heritable.heir() + + assert.notStrictEqual(heir, NULL_ADDRESS) + await heritable.removeHeir() + heir = await heritable.heir() + assert.isTrue(heir === NULL_ADDRESS) + }) + + it('heir can claim ownership only if owner is dead and timeout was reached', async function() { + const heir = accounts[1] + await heritable.setHeir(heir, {from: owner}) + await expectThrow(heritable.claimHeirOwnership({from: heir})) + + await heritable.proclaimDeath({from: heir}) + await increaseTime(1) + await expectThrow(heritable.claimHeirOwnership({from: heir})) + + await increaseTime(4141) + await heritable.claimHeirOwnership({from: heir}) + assert.isTrue(await heritable.heir() === heir) + }) + + it('heir can\'t claim ownership if owner heartbeats', async function() { + const heir = accounts[1] + await heritable.setHeir(heir, {from: owner}) + + await heritable.proclaimDeath({from: heir}) + await heritable.heartbeat({from: owner}) + await expectThrow(heritable.claimHeirOwnership({from: heir})) + + await heritable.proclaimDeath({from: heir}) + await increaseTime(4141) + await heritable.heartbeat({from: owner}) + await expectThrow(heritable.claimHeirOwnership({from: heir})) + }) + + it('should log events appropriately', async function() { + const heir = accounts[1] + + const setHeirLogs = (await heritable.setHeir(heir, {from: owner})).logs + const setHeirEvent = setHeirLogs.find(e => e.event === 'HeirChanged') + + assert.isTrue(setHeirEvent.args.owner === owner) + assert.isTrue(setHeirEvent.args.newHeir === heir) + + const heartbeatLogs = (await heritable.heartbeat({from: owner})).logs + const heartbeatEvent = heartbeatLogs.find(e => e.event === 'OwnerHeartbeated') + + assert.isTrue(heartbeatEvent.args.owner === owner) + + const proclaimDeathLogs = (await heritable.proclaimDeath({from: heir})).logs + const ownerDeadEvent = proclaimDeathLogs.find(e => e.event === 'OwnerProclaimedDead') + + assert.isTrue(ownerDeadEvent.args.owner === owner) + assert.isTrue(ownerDeadEvent.args.heir === heir) + + await increaseTime(4141) + const claimHeirOwnershipLogs = (await heritable.claimHeirOwnership({from: heir})).logs + const ownershipTransferredEvent = claimHeirOwnershipLogs.find(e => e.event === 'OwnershipTransferred') + const heirOwnershipClaimedEvent = claimHeirOwnershipLogs.find(e => e.event === 'HeirOwnershipClaimed') + + assert.isTrue(ownershipTransferredEvent.args.previousOwner === owner) + assert.isTrue(ownershipTransferredEvent.args.newOwner === heir) + assert.isTrue(heirOwnershipClaimedEvent.args.previousOwner === owner) + assert.isTrue(heirOwnershipClaimedEvent.args.newOwner === heir) + + }) +}) diff --git a/test/SimpleSavingsWallet.js b/test/SimpleSavingsWallet.js new file mode 100644 index 00000000000..8ae34d58505 --- /dev/null +++ b/test/SimpleSavingsWallet.js @@ -0,0 +1,35 @@ +'use strict' +import expectThrow from './helpers/expectThrow'; + +const SimpleSavingsWallet = artifacts.require('../contracts/examples/SimpleSavingsWallet.sol') + +contract('SimpleSavingsWallet', function(accounts) { + let savingsWallet + let owner + + const paymentAmount = 4242 + + beforeEach(async function() { + savingsWallet = await SimpleSavingsWallet.new(4141) + owner = await savingsWallet.owner() + }) + + it('should receive funds', async function() { + await web3.eth.sendTransaction({from: owner, to: savingsWallet.address, value: paymentAmount}) + assert.isTrue( + (new web3.BigNumber(paymentAmount)).equals(web3.eth.getBalance(savingsWallet.address)) + ) + }) + + it('owner can send funds', async function() { + // Receive payment so we have some money to spend. + await web3.eth.sendTransaction({from: accounts[9], to: savingsWallet.address, value: 1000000}) + await expectThrow(savingsWallet.sendTo(0, paymentAmount, {from: owner})) + await expectThrow(savingsWallet.sendTo(savingsWallet.address, paymentAmount, {from: owner})) + await expectThrow(savingsWallet.sendTo(accounts[1], 0, {from: owner})) + + const balance = web3.eth.getBalance(accounts[1]) + await savingsWallet.sendTo(accounts[1], paymentAmount, {from: owner}) + assert.isTrue(balance.plus(paymentAmount).equals(web3.eth.getBalance(accounts[1]))) + }) +})