feat(ethexe): support late commitments validation (#4426)

ethexe/contracts/script/Deployment.s.sol

@@ -48,6 +48,7 @@ contract DeploymentScript is Script {
                         address(wrappedVara),
                         1 days,
                         2 hours,
+                        5 minutes,
                         validatorsArray
                     )
                 )

ethexe/contracts/src/Router.sol

@@ -28,6 +28,7 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
         address _wrappedVara,
         uint256 _eraDuration,
         uint256 _electionDuration,
+        uint256 _validationDelay,
         address[] calldata _validators
     ) public initializer {
         __Ownable_init(_owner);
@@ -36,6 +37,9 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
         require(block.timestamp > 0, "current timestamp must be greater than 0");
         require(_electionDuration > 0, "election duration must be greater than 0");
         require(_eraDuration > _electionDuration, "era duration must be greater than election duration");
+        // _validationDelay must be small enough,
+        // in order to restrict old era validators to make commitments, which can damage the system.
+        require(_validationDelay < (_eraDuration - _electionDuration) / 10, "validation delay is too big");
 
         _setStorageSlot("router.storage.RouterV1");
         Storage storage router = _router();
@@ -44,7 +48,7 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
         router.implAddresses = Gear.AddressBook(_mirror, _mirrorProxy, _wrappedVara);
         router.validationSettings.signingThresholdPercentage = Gear.SIGNING_THRESHOLD_PERCENTAGE;
         router.computeSettings = Gear.defaultComputationSettings();
-        router.timelines = Gear.Timelines(_eraDuration, _electionDuration);
+        router.timelines = Gear.Timelines(_eraDuration, _electionDuration, _validationDelay);
 
         // Set validators for the era 0.
         _resetValidators(router.validationSettings.validators0, _validators, block.timestamp);
@@ -310,15 +314,24 @@ contract Router is IRouter, OwnableUpgradeable, ReentrancyGuardTransient {
         Storage storage router = _router();
         require(router.genesisBlock.hash != bytes32(0), "router genesis is zero; call `lookupGenesisHash()` first");
 
+        require(_blockCommitments.length > 0, "no block commitments to commit");
+
         bytes memory blockCommitmentsHashes;
+        uint256 maxTimestamp = 0;
 
         for (uint256 i = 0; i < _blockCommitments.length; i++) {
             Gear.BlockCommitment calldata blockCommitment = _blockCommitments[i];
             blockCommitmentsHashes = bytes.concat(blockCommitmentsHashes, _commitBlock(router, blockCommitment));
+            if (blockCommitment.timestamp > maxTimestamp) {
+                maxTimestamp = blockCommitment.timestamp;
+            }
         }
 
+        // NOTE: Use maxTimestamp to validate signatures for all block commitments.
+        // This means that if at least one commitment is for block from current era,
+        // then all commitments should be checked with current era validators.
         require(
-            Gear.validateSignatures(router, keccak256(blockCommitmentsHashes), _signatures),
+            Gear.validateSignaturesAt(router, keccak256(blockCommitmentsHashes), _signatures, maxTimestamp),
             "signatures verification failed"
         );
     }

ethexe/contracts/src/libraries/Gear.sol

@@ -104,6 +104,7 @@ library Gear {
     struct Timelines {
         uint256 era;
         uint256 election;
+        uint256 validationDelay;
     }
 
     struct ValidationSettings {
@@ -191,7 +192,34 @@ library Gear {
         view
         returns (bool)
     {
-        Validators storage validators = currentEraValidators(router);
+        return validateSignaturesAt(router, _dataHash, _signatures, block.timestamp);
+    }
+
+    /// @dev Validates signatures of the given data hash at the given timestamp.
+    function validateSignaturesAt(
+        IRouter.Storage storage router,
+        bytes32 _dataHash,
+        bytes[] calldata _signatures,
+        uint256 ts
+    ) internal view returns (bool) {
+        uint256 eraStarted = eraStartedAt(router, block.timestamp);
+        if (ts < eraStarted && block.timestamp < eraStarted + router.timelines.validationDelay) {
+            require(ts >= router.genesisBlock.timestamp, "cannot validate before genesis");
+            require(ts + router.timelines.era >= eraStarted, "timestamp is older than previous era");
+
+            // Validation must be done using validators from previous era,
+            // because `ts` is in the past and we are in the validation delay period.
+        } else {
+            require(ts <= block.timestamp, "timestamp cannot be in the future");
+
+            if (ts < eraStarted) {
+                ts = eraStarted;
+            }
+
+            // Validation must be done using current era validators.
+        }
+
+        Validators storage validators = validatorsAt(router, ts);
 
         uint256 threshold =
             validatorsThreshold(validators.list.length, router.validationSettings.signingThresholdPercentage);
@@ -215,25 +243,33 @@ library Gear {
     }
 
     function currentEraValidators(IRouter.Storage storage router) internal view returns (Validators storage) {
-        if (currentEraValidatorsStoredInValidators1(router)) {
-            return router.validationSettings.validators1;
-        } else {
-            return router.validationSettings.validators0;
-        }
+        return validatorsAt(router, block.timestamp);
     }
 
+    /// @dev Returns previous era validators, if there is no previous era,
+    /// then returns free validators slot, which must be zeroed.
     function previousEraValidators(IRouter.Storage storage router) internal view returns (Validators storage) {
-        if (currentEraValidatorsStoredInValidators1(router)) {
+        if (validatorsStoredInSlot1At(router, block.timestamp)) {
             return router.validationSettings.validators0;
         } else {
             return router.validationSettings.validators1;
         }
     }
 
-    /// @dev Returns whether current era validators are stored in `router.validationSettings.validators1`.
+    /// @dev Returns validators at the given timestamp.
+    /// @param ts Timestamp for which to get the validators.
+    function validatorsAt(IRouter.Storage storage router, uint256 ts) internal view returns (Validators storage) {
+        if (validatorsStoredInSlot1At(router, ts)) {
+            return router.validationSettings.validators1;
+        } else {
+            return router.validationSettings.validators0;
+        }
+    }
+
+    /// @dev Returns whether validators at `ts` are stored in `router.validationSettings.validators1`.
     ///      `false` means that current era validators are stored in `router.validationSettings.validators0`.
-    function currentEraValidatorsStoredInValidators1(IRouter.Storage storage router) internal view returns (bool) {
-        uint256 ts = block.timestamp;
+    /// @param ts Timestamp for which to check the validators slot.
+    function validatorsStoredInSlot1At(IRouter.Storage storage router, uint256 ts) internal view returns (bool) {
         uint256 ts0 = router.validationSettings.validators0.useFromTimestamp;
         uint256 ts1 = router.validationSettings.validators1.useFromTimestamp;
 
@@ -244,8 +280,8 @@ library Gear {
         bool tsGE0 = ts0 <= ts;
         bool tsGE1 = ts1 <= ts;
 
-        // Both eras are in the future - impossible case because of implementation.
-        require(tsGE0 || tsGE1, "could not identify validators for current timestamp");
+        // Both eras are in the future - not supported by this function.
+        require(tsGE0 || tsGE1, "could not identify validators for the given timestamp");
 
         // Two impossible cases, because of math rules:
         // 1)  ts1Greater && !tsGE0 &&  tsGE1
@@ -266,4 +302,12 @@ library Gear {
     function valueClaimBytes(ValueClaim memory claim) internal pure returns (bytes memory) {
         return abi.encodePacked(claim.messageId, claim.destination, claim.value);
     }
+
+    function eraIndexAt(IRouter.Storage storage router, uint256 ts) internal view returns (uint256) {
+        return (ts - router.genesisBlock.timestamp) / router.timelines.era;
+    }
+
+    function eraStartedAt(IRouter.Storage storage router, uint256 ts) internal view returns (uint256) {
+        return router.genesisBlock.timestamp + eraIndexAt(router, ts) * router.timelines.era;
+    }
 }

ethexe/contracts/test/Base.t.sol

@@ -29,6 +29,7 @@ contract Base is POCBaseTest {
     address public admin;
     uint48 public eraDuration;
     uint48 public electionDuration;
+    uint256 public validationDelay;
     uint256 public blockDuration;
     uint256 public maxValidators;
 
@@ -119,6 +120,7 @@ contract Base is POCBaseTest {
                             wrappedVaraAddress,
                             uint256(eraDuration),
                             uint256(electionDuration),
+                            uint256(validationDelay),
                             _validators
                         )
                     )

ethexe/contracts/test/Router.t.sol

@@ -29,6 +29,7 @@ contract RouterTest is Base {
         electionDuration = 100;
         blockDuration = 12;
         maxValidators = 3;
+        validationDelay = 60;
 
         setUpWrappedVara();
 
@@ -116,6 +117,186 @@ contract RouterTest is Base {
         commitValidators(wrongValidatorPrivateKeys, commitment);
     }
 
+    function test_lateCommitments() public {
+        address[] memory _validators = new address[](3);
+        uint256[] memory _validatorPrivateKeys = new uint256[](3);
+        for (uint256 i = 0; i < 3; i++) {
+            (address addr, uint256 key) = makeAddrAndKey(vm.toString(i));
+            _validators[i] = addr;
+            _validatorPrivateKeys[i] = key;
+        }
+
+        Gear.ValidatorsCommitment memory _commitment = Gear.ValidatorsCommitment(_validators, 1);
+
+        vm.warp(router.genesisTimestamp() + eraDuration - electionDuration);
+        commitValidators(_commitment);
+
+        // Go to the next era, setting block hash to the last 1 blocks of the era
+        vm.warp(router.genesisTimestamp() + eraDuration - uint48(blockDuration));
+        rollBlocks(1);
+
+        uint256 _eraStartNumber = vm.getBlockNumber();
+        uint48 _eraStartTimestamp = uint48(vm.getBlockTimestamp());
+
+        Gear.BlockCommitment memory _blockCommitment = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber - 1),
+            timestamp: _eraStartTimestamp - uint48(blockDuration),
+            previousCommittedBlock: router.latestCommittedBlockHash(),
+            predecessorBlock: blockHash(_eraStartNumber - 1),
+            transitions: new Gear.StateTransition[](0)
+        });
+
+        // Try to commit block from the previous era using new validators
+        vm.expectRevert();
+        commitBlock(_validatorPrivateKeys, _blockCommitment);
+
+        // Now try to commit block from the previous era using old validators
+        commitBlock(validatorsPrivateKeys, _blockCommitment);
+
+        rollBlocks(1);
+        _blockCommitment = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber),
+            timestamp: _eraStartTimestamp,
+            previousCommittedBlock: router.latestCommittedBlockHash(),
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+
+        // Try to commit block from the new era using old validators
+        vm.expectRevert();
+        commitBlock(validatorsPrivateKeys, _blockCommitment);
+
+        // Now try to commit block from the new era using new validators
+        commitBlock(_validatorPrivateKeys, _blockCommitment);
+    }
+
+    function test_lateCommitmentsAfterDelay() public {
+        address[] memory _validators = new address[](3);
+        uint256[] memory _validatorPrivateKeys = new uint256[](3);
+        for (uint256 i = 0; i < 3; i++) {
+            (address addr, uint256 key) = makeAddrAndKey(vm.toString(i));
+            _validators[i] = addr;
+            _validatorPrivateKeys[i] = key;
+        }
+
+        Gear.ValidatorsCommitment memory _commitment = Gear.ValidatorsCommitment(_validators, 1);
+
+        vm.warp(router.genesisTimestamp() + eraDuration - electionDuration);
+        commitValidators(_commitment);
+
+        // Go to the next era, setting block hash to the last 5 blocks of the era and first 5 blocks of the new era
+        vm.warp(router.genesisTimestamp() + eraDuration - 5 * uint48(blockDuration));
+        rollBlocks(10);
+
+        Gear.BlockCommitment memory _blockCommitment = Gear.BlockCommitment({
+            hash: blockHash(vm.getBlockNumber() - 6),
+            timestamp: uint48(vm.getBlockTimestamp() - 6 * blockDuration),
+            previousCommittedBlock: router.latestCommittedBlockHash(),
+            predecessorBlock: blockHash(vm.getBlockNumber() - 1),
+            transitions: new Gear.StateTransition[](0)
+        });
+
+        // Try to commit block from the previous era using old validators
+        // Must be failed because the validation delay is already passed
+        vm.expectRevert();
+        commitBlock(validatorsPrivateKeys, _blockCommitment);
+
+        // Now try to commit block from the previous era using new validators
+        // Must be successful because the validation delay is already passed
+        commitBlock(_validatorPrivateKeys, _blockCommitment);
+    }
+
+    function test_manyLateCommitments() public {
+        address[] memory _validators = new address[](3);
+        uint256[] memory _validatorPrivateKeys = new uint256[](3);
+        for (uint256 i = 0; i < 3; i++) {
+            (address addr, uint256 key) = makeAddrAndKey(vm.toString(i));
+            _validators[i] = addr;
+            _validatorPrivateKeys[i] = key;
+        }
+
+        Gear.ValidatorsCommitment memory _commitment = Gear.ValidatorsCommitment(_validators, 1);
+
+        vm.warp(router.genesisTimestamp() + eraDuration - electionDuration);
+        commitValidators(_commitment);
+
+        // Go to the next era, setting block hash to the last 4 blocks of the era
+        vm.warp(router.genesisTimestamp() + eraDuration - 4 * uint48(blockDuration));
+        rollBlocks(4);
+
+        uint256 _eraStartNumber = vm.getBlockNumber();
+        uint48 _eraStartTimestamp = uint48(vm.getBlockTimestamp());
+
+        // Try to commit blocks: [n - 4] <- [n - 3] <- [n]
+        // Where [n] is a start of the new era
+        Gear.BlockCommitment[] memory _commitments = new Gear.BlockCommitment[](3);
+        _commitments[0] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber - 4),
+            timestamp: _eraStartTimestamp - 4 * uint48(blockDuration),
+            previousCommittedBlock: router.latestCommittedBlockHash(),
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        _commitments[1] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber - 3),
+            timestamp: _eraStartTimestamp - 3 * uint48(blockDuration),
+            previousCommittedBlock: _commitments[0].hash,
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        _commitments[2] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber),
+            timestamp: _eraStartTimestamp,
+            previousCommittedBlock: _commitments[1].hash,
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+
+        // Roll to next block to be possible to make commitment for the era start block
+        rollBlocks(1);
+
+        // Validation must fail because the last block is from new era, so must be committed by new validators
+        vm.expectRevert();
+        commitBlocks(validatorsPrivateKeys, _commitments);
+
+        // Now try to commit [n - 4] <- [n - 3] <- [n - 2]
+        _commitments[2] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber - 2),
+            timestamp: _eraStartTimestamp - 2 * uint48(blockDuration),
+            previousCommittedBlock: _commitments[1].hash,
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        // Must be successful, because all blocks are from the previous era
+        commitBlocks(validatorsPrivateKeys, _commitments);
+
+        // Now try to commit [n - 1] <- [n] <- [n + 1] using new validators
+        rollBlocks(1);
+        _commitments[0] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber - 1),
+            timestamp: _eraStartTimestamp - uint48(blockDuration),
+            previousCommittedBlock: router.latestCommittedBlockHash(),
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        _commitments[1] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber),
+            timestamp: _eraStartTimestamp,
+            previousCommittedBlock: _commitments[0].hash,
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        _commitments[2] = Gear.BlockCommitment({
+            hash: blockHash(_eraStartNumber + 1),
+            timestamp: _eraStartTimestamp + uint48(blockDuration),
+            previousCommittedBlock: _commitments[1].hash,
+            predecessorBlock: blockHash(_eraStartNumber),
+            transitions: new Gear.StateTransition[](0)
+        });
+        // Must be successful, because the newest blocks are from the new era
+        commitBlocks(_validatorPrivateKeys, _commitments);
+    }
+
     /* helper functions */
 
     function commitValidators(Gear.ValidatorsCommitment memory commitment) private {

ethexe/ethereum/src/lib.rs

@@ -156,6 +156,7 @@ impl Ethereum {
                     _wrappedVara: wvara_address,
                     _eraDuration: U256::from(24 * 60 * 60),
                     _electionDuration: U256::from(2 * 60 * 60),
+                    _validationDelay: U256::from(60),
                     _validators: validators,
                 }
                 .abi_encode(),