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add withdrawing delay to allow to catch security issues (#23)
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* add withdrawing delay to allow to catch security issues

* document withdraw function
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@ETeissonniere
ETeissonniere authored Apr 3, 2024
1 parent fba19f3 commit 01577c0
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Showing 2 changed files with 109 additions and 16 deletions.
49 changes: 36 additions & 13 deletions src/dot-migration/NODLMigration.sol
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,13 +11,15 @@ contract NODLMigration {
struct Proposal {
address target;
uint256 amount;
uint256 lastVote;
uint8 totalVotes;
bool executed;
}

NODL public nodl;
mapping(address => bool) public isOracle;
uint8 public threshold;
uint256 public delay;

// We track votes in a seperate mapping to avoid having to write helper functions to
// expose the votes for each proposal.
Expand All @@ -28,16 +30,19 @@ contract NODLMigration {
error AlreadyExecuted(bytes32 proposal);
error ParametersChanged(bytes32 proposal);
error NotAnOracle(address user);
error NotYetWithdrawable(bytes32 proposal);
error NotEnoughVotes(bytes32 proposal);

event VoteStarted(bytes32 indexed proposal, address oracle, address indexed user, uint256 amount);
event Voted(bytes32 indexed proposal, address oracle);
event Bridged(bytes32 indexed proposal, address indexed user, uint256 amount);
event Withdrawn(bytes32 indexed proposal, address indexed user, uint256 amount);

/// @param bridgeOracles Array of oracle accounts that will be able to bridge the tokens.
/// @param token Contract address of the NODL token.
/// @param minVotes Minimum number of votes required to bridge the tokens. This needs to be
/// less than or equal to the number of oracles and is expected to be above 1.
constructor(address[] memory bridgeOracles, NODL token, uint8 minVotes) {
/// @param minDelay Minimum delay in blocks before bridged tokens can be minted.
constructor(address[] memory bridgeOracles, NODL token, uint8 minVotes, uint256 minDelay) {
assert(bridgeOracles.length >= minVotes);
assert(minVotes > 1);

Expand All @@ -46,10 +51,11 @@ contract NODLMigration {
}
nodl = token;
threshold = minVotes;
delay = minDelay;
}

/// @notice Bridge some tokens from the Nodle Parachain to the ZkSync contracts. This
/// tracks "votes" from each oracle and only bridges the tokens if the threshold is met.
/// tracks "votes" from each oracle and unlocks execution after a withdrawal delay.
/// @param paraTxHash The transaction hash on the Parachain for this transfer.
/// @param user The user address.
/// @param amount The amount of NODL tokens that the user has burnt on the Parachain.
Expand All @@ -61,15 +67,22 @@ contract NODLMigration {
_mustNotHaveVotedYet(paraTxHash, msg.sender);
_mustNotBeChangingParameters(paraTxHash, user, amount);
_recordVote(paraTxHash, msg.sender);

if (_enoughVotes(paraTxHash)) {
_mintTokens(paraTxHash, user, amount);
}
} else {
_createVote(paraTxHash, msg.sender, user, amount);
}
}

/// @notice Withdraw the NODL tokens from the contract to the user's address if the
/// proposal has enough votes and has passed the safety delay.
/// @param paraTxHash The transaction hash on the Parachain for this transfer.
function withdraw(bytes32 paraTxHash) external {
_mustNotHaveExecutedYet(paraTxHash);
_mustHaveEnoughVotes(paraTxHash);
_mustBePastSafetyDelay(paraTxHash);

_withdraw(paraTxHash, proposals[paraTxHash].target, proposals[paraTxHash].amount);
}

function _mustBeAnOracle(address maybeOracle) internal view {
if (!isOracle[maybeOracle]) {
revert NotAnOracle(maybeOracle);
Expand All @@ -94,6 +107,18 @@ contract NODLMigration {
}
}

function _mustBePastSafetyDelay(bytes32 proposal) internal view {
if (block.number - proposals[proposal].lastVote < delay) {
revert NotYetWithdrawable(proposal);
}
}

function _mustHaveEnoughVotes(bytes32 proposal) internal view {
if (proposals[proposal].totalVotes < threshold) {
revert NotEnoughVotes(proposal);
}
}

function _proposalExists(bytes32 proposal) internal view returns (bool) {
return proposals[proposal].totalVotes > 0 && proposals[proposal].amount > 0;
}
Expand All @@ -103,6 +128,7 @@ contract NODLMigration {
proposals[proposal].target = user;
proposals[proposal].amount = amount;
proposals[proposal].totalVotes = 1;
proposals[proposal].lastVote = block.number;

emit VoteStarted(proposal, oracle, user, amount);
}
Expand All @@ -111,18 +137,15 @@ contract NODLMigration {
voted[oracle][proposal] = true;
// this is safe since we are unlikely to have maxUint8 oracles to manage
proposals[proposal].totalVotes += 1;
proposals[proposal].lastVote = block.number;

emit Voted(proposal, oracle);
}

function _enoughVotes(bytes32 proposal) internal view returns (bool) {
return proposals[proposal].totalVotes >= threshold;
}

function _mintTokens(bytes32 proposal, address user, uint256 amount) internal {
function _withdraw(bytes32 proposal, address user, uint256 amount) internal {
proposals[proposal].executed = true;
nodl.mint(user, amount);

emit Bridged(proposal, user, amount);
emit Withdrawn(proposal, user, amount);
}
}
76 changes: 73 additions & 3 deletions test/dot-migration/NODLMigration.t.sol
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,12 +10,13 @@ contract NODLMigrationTest is Test {
NODLMigration migration;
NODL nodl;

uint256 delay = 100;
address[] oracles = [vm.addr(1), vm.addr(2), vm.addr(3)];
address user = vm.addr(4);

function setUp() public {
nodl = new NODL();
migration = new NODLMigration(oracles, nodl, 2);
migration = new NODLMigration(oracles, nodl, 2, delay);

nodl.grantRole(nodl.MINTER_ROLE(), address(migration));
}
Expand All @@ -25,6 +26,7 @@ contract NODLMigrationTest is Test {
assertEq(migration.isOracle(oracles[i]), true);
}
assertEq(migration.threshold(), 2);
assertEq(migration.delay(), delay);
}

function test_configuredProperToken() public {
Expand Down Expand Up @@ -55,6 +57,9 @@ contract NODLMigrationTest is Test {
vm.prank(oracles[1]);
migration.bridge(0x0, user, 100);

vm.roll(block.number + delay + 1);
migration.withdraw(0x0);

vm.expectRevert(abi.encodeWithSelector(NODLMigration.AlreadyExecuted.selector, 0x0));
vm.prank(oracles[2]);
migration.bridge(0x0, user, 100);
Expand All @@ -73,18 +78,83 @@ contract NODLMigrationTest is Test {
migration.bridge(0x0, oracles[1], 100);
}

function test_recordsVotesAndMintTokens() public {
function test_recordsVotes() public {
vm.expectEmit();
emit NODLMigration.VoteStarted(0x0, oracles[0], user, 100);
vm.prank(oracles[0]);
migration.bridge(0x0, user, 100);

(address target, uint256 amount, uint256 lastVote, uint256 totalVotes, bool executed) = migration.proposals(0x0);
assertEq(target, user);
assertEq(amount, 100);
assertEq(lastVote, block.number);
assertEq(totalVotes, 1);
assertEq(executed, false);

vm.expectEmit();
emit NODLMigration.Voted(0x0, oracles[1]);
emit NODLMigration.Bridged(0x0, user, 100);
vm.prank(oracles[1]);
migration.bridge(0x0, user, 100);

(target, amount, lastVote, totalVotes, executed) = migration.proposals(0x0);
assertEq(target, user);
assertEq(amount, 100);
assertEq(lastVote, block.number);
assertEq(totalVotes, 2);
assertEq(executed, false);
}

function test_mayNotWithdrawIfNotEnoughVotes() public {
vm.prank(oracles[0]);
migration.bridge(0x0, user, 100);

vm.expectRevert(abi.encodeWithSelector(NODLMigration.NotEnoughVotes.selector, 0x0));
migration.withdraw(0x0);
}

function test_mayNotWithdrawBeforeDelay() public {
vm.prank(oracles[0]);
migration.bridge(0x0, user, 100);

vm.prank(oracles[1]);
migration.bridge(0x0, user, 100);

vm.expectRevert(abi.encodeWithSelector(NODLMigration.NotYetWithdrawable.selector, 0x0));
migration.withdraw(0x0);
}

function test_mayNotWithdrawTwice() public {
vm.prank(oracles[0]);
migration.bridge(0x0, user, 100);

vm.prank(oracles[1]);
migration.bridge(0x0, user, 100);

vm.roll(block.number + delay + 1);

migration.withdraw(0x0);

vm.expectRevert(abi.encodeWithSelector(NODLMigration.AlreadyExecuted.selector, 0x0));
migration.withdraw(0x0);
}

function test_mayWithdrawAfterDelay() public {
vm.prank(oracles[0]);
migration.bridge(0x0, user, 100);

vm.prank(oracles[1]);
migration.bridge(0x0, user, 100);

vm.roll(block.number + delay + 1);

vm.expectEmit();
emit NODLMigration.Withdrawn(0x0, user, 100);
vm.prank(user); // anybody can call withdraw
migration.withdraw(0x0);

(,,,, bool executed) = migration.proposals(0x0);
assertEq(executed, true);

assertEq(nodl.balanceOf(user), 100);
}
}

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