feat(contract): prevent validator resignation below min validators (#766

)

* Check min validators

* Add docs

* Set minValidators

* Use tmp array

* Shuffle temp array

* Move consensus to base

* Move setup to base

* Test resignations

* Init min validators

* Remove todo

* Update abi

contracts/src/consensus/ConsensusV1.sol

@@ -54,6 +54,7 @@ error CallerIsNotValidator();
 error ValidatorNotRegistered();
 error ValidatorAlreadyRegistered();
 error ValidatorAlreadyResigned();
+error BellowMinValidators();
 
 error BlsKeyAlreadyRegistered();
 error BlsKeyIsInvalid();
@@ -64,6 +65,11 @@ error MissingVote();
 
 error InvalidRange(uint256 min, uint256 max);
 
+// Validators:
+// - Registered -> All validators that are registered including resigned validators
+// - Active -> Top N validators with the highest vote balance, that participate in the consensus
+// - Resigned -> Validators that resigned from the consensus
+
 // Voter calls vote funtion
 // Vote function includes valdiator address and balance, whole balance is added to the validator voteBalance
 // Voter can unvote, whole balance is removed from validator voteBalance
@@ -84,18 +90,19 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
     mapping(address => bool) private _hasValidator;
     mapping(bytes32 => bool) private _blsPublicKeys;
     address[] private _validators;
-    uint256 private _validatorsCount = 0;
-    uint256 private _resignedValidatorsCount = 0;
+    uint256 private _validatorsCount; // Default 0
+    uint256 private _resignedValidatorsCount; // Default 0
 
     mapping(address => Vote) private _voters;
-    address private _votersHead = address(0);
-    address private _votersTail = address(0);
-    uint256 private _votersCount = 0;
+    address private _votersHead; // Default address(0)
+    address private _votersTail; // Default address(0)
+    uint256 private _votersCount; // Default 0
 
     mapping(address => address) private _activeValidatorsMap;
     address[] private _activeValidators;
-    address private _activeValidatorsHead;
-    uint256 private _activeValidatorsCount = 0;
+    address private _activeValidatorsHead; // Default address(0)
+    uint256 private _activeValidatorsCount; // Default 0
+    uint256 private _minValidators; // Default 1
 
     RoundValidator[][] private _rounds;
 
@@ -117,6 +124,7 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
     // Initializers
     function initialize() public initializer {
         _owner = msg.sender;
+        _minValidators = 1;
     }
 
     // Overrides
@@ -163,6 +171,10 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
             revert ValidatorAlreadyResigned();
         }
 
+        if (_validatorsCount - _resignedValidatorsCount <= _minValidators) {
+            revert BellowMinValidators();
+        }
+
         validator.isResigned = true;
         _resignedValidatorsCount += 1;
 
@@ -217,6 +229,8 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
     }
 
     function calculateActiveValidators(uint8 n) external onlyOwner {
+        _minValidators = n;
+
         _shuffle(_validators);
         _deleteActiveValidators();
 
@@ -257,18 +271,26 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
             }
         }
 
-        RoundValidator[] storage round = _rounds.push();
-
+        // Prepare temp array. Used when top < _minValidators
         address next = _activeValidatorsHead;
-        delete _activeValidators;
-        _activeValidators = new address[](top);
+        address[] memory tmpValidators = new address[](top);
+
         for (uint256 i = 0; i < top; i++) {
-            _activeValidators[i] = next;
-            round.push(RoundValidator({addr: next, voteBalance: _validatorsData[next].voteBalance}));
+            tmpValidators[i] = next;
             next = _activeValidatorsMap[next];
         }
+        _shuffleMem(tmpValidators);
+
+        // Fill round & _activeValidators
+        RoundValidator[] storage round = _rounds.push();
+        delete _activeValidators;
+        _activeValidators = new address[](_minValidators);
 
-        _shuffle(_activeValidators);
+        for (uint256 i = 0; i < _minValidators; i++) {
+            address addr = tmpValidators[i % top];
+            _activeValidators[i] = addr;
+            round.push(RoundValidator({addr: addr, voteBalance: _validatorsData[addr].voteBalance}));
+        }
     }
 
     // External functions that are view
@@ -285,7 +307,7 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
     }
 
     function activeValidatorsCount() external view returns (uint256) {
-        return _activeValidators.length;
+        return _activeValidatorsCount;
     }
 
     function isValidatorRegistered(address addr) public view returns (bool) {
@@ -389,6 +411,19 @@ contract ConsensusV1 is Initializable, UUPSUpgradeable {
         }
     }
 
+    function _shuffleMem(address[] memory array) internal view {
+        uint256 n = array.length;
+        for (uint256 i = n - 1; i > 0; i--) {
+            // Get a random index between 0 and i (inclusive)
+            uint256 j = uint256(keccak256(abi.encodePacked(block.timestamp, i))) % (i + 1);
+
+            // Swap elements at index i and j
+            address temp = array[i];
+            array[i] = array[j];
+            array[j] = temp;
+        }
+    }
+
     function _deleteActiveValidators() internal {
         address next = _activeValidatorsHead;
 

contracts/test/consensus/Base.sol

@@ -2,9 +2,18 @@
 pragma solidity ^0.8.13;
 
 import {Test, console} from "@forge-std/Test.sol";
-import {Validator} from "@contracts/consensus/ConsensusV1.sol";
+import {ConsensusV1, Validator} from "@contracts/consensus/ConsensusV1.sol";
+import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract Base is Test {
+    ConsensusV1 public consensus;
+
+    function setUp() public {
+        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
+        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
+        consensus = ConsensusV1(proxy);
+    }
+
     function prepareBLSKey(address addr, uint8 lenght) public pure returns (bytes memory) {
         bytes32 h = keccak256(abi.encode(addr));
         bytes memory validatorKey = new bytes(lenght);
@@ -40,4 +49,27 @@ contract Base is Test {
 
         return validatorA.data.voteBalance > validatorB.data.voteBalance;
     }
+
+    function registerValidator(address addr) internal {
+        bytes32 h = keccak256(abi.encode(addr));
+        bytes memory validatorKey = new bytes(48);
+        for (uint256 j = 0; j < 32; j++) {
+            validatorKey[j] = h[j];
+        }
+
+        vm.startPrank(addr);
+        consensus.registerValidator(validatorKey);
+        vm.stopPrank();
+
+        Validator memory validator = consensus.getValidator(addr);
+        assertEq(validator.addr, addr);
+        assertEq(validator.data.voteBalance, 0 ether);
+        assertEq(validator.data.votersCount, 0);
+    }
+
+    function resignValidator(address addr) internal {
+        vm.startPrank(addr);
+        consensus.resignValidator();
+        vm.stopPrank();
+    }
 }

contracts/test/consensus/Consensus-CalculateTop.sol

@@ -1,25 +1,14 @@
 // SPDX-License-Identifier: GNU GENERAL PUBLIC LICENSE
 pragma solidity ^0.8.13;
 
-import {Test, console} from "@forge-std/Test.sol";
 import {ConsensusV1, ValidatorData, Validator, CallerIsNotOwner} from "@contracts/consensus/ConsensusV1.sol";
 import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_should_work_with_one_validator() public {
         address addr = address(1);
-        vm.startPrank(addr);
-        consensus.registerValidator(prepareBLSKey(addr));
-        vm.stopPrank();
+        registerValidator(addr);
 
         consensus.calculateActiveValidators(1);
         Validator[] memory validators = consensus.getActiveValidators();
@@ -37,14 +26,15 @@ contract ConsensusTest is Base {
     function test_should_ignore_resigned_validators() public {
         address addr = address(1);
 
-        vm.startPrank(addr);
-        consensus.registerValidator(prepareBLSKey(addr));
-        consensus.resignValidator();
-        vm.stopPrank();
+        registerValidator(addr);
+        registerValidator(address(2));
+        resignValidator(addr);
 
-        consensus.calculateActiveValidators(1);
+        consensus.calculateActiveValidators(2);
         Validator[] memory validators = consensus.getActiveValidators();
-        assertEq(validators.length, 0);
+        assertEq(validators.length, 2);
+        assertEq(validators[0].addr, address(2));
+        assertEq(validators[1].addr, address(2)); // Second validator is duplicated
     }
 
     function test_consensus_200_topValidators() public {
@@ -90,6 +80,7 @@ contract ConsensusTest is Base {
         validators = sortValidators(validators);
         assertEq(validators[activeValidators - 1].addr, highest);
 
+        // Seccond attempt shoudl return the same result
         consensus.calculateActiveValidators(uint8(activeValidators));
 
         validators = consensus.getActiveValidators();

contracts/test/consensus/Consensus-GetAllValidators.sol

@@ -1,20 +1,11 @@
 // SPDX-License-Identifier: GNU GENERAL PUBLIC LICENSE
 pragma solidity ^0.8.13;
 
-import {Test, console} from "@forge-std/Test.sol";
 import {ConsensusV1, ValidatorData, Validator} from "@contracts/consensus/ConsensusV1.sol";
 import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_200_validators() public {
         vm.pauseGasMetering();
         assertEq(consensus.registeredValidatorsCount(), 0);

contracts/test/consensus/Consensus-Proxy.sol

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GNU GENERAL PUBLIC LICENSE
 pragma solidity ^0.8.13;
 
-import {Test, console} from "@forge-std/Test.sol";
 import {ConsensusV1, ValidatorData, Validator, CallerIsNotOwner} from "@contracts/consensus/ConsensusV1.sol";
 import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
@@ -14,20 +13,12 @@ contract ConsensusVTest is ConsensusV1 {
 }
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_initialize_should_revert() public {
         vm.expectRevert(Initializable.InvalidInitialization.selector);
         consensus.initialize();
     }
 
-    function test_shoudl_have_valid_UPGRADE_INTERFACE_VERSION() public {
+    function test_shoudl_have_valid_UPGRADE_INTERFACE_VERSION() public view {
         assertEq(consensus.UPGRADE_INTERFACE_VERSION(), "5.0.0");
     }
 

contracts/test/consensus/Consensus-Rounds.sol

@@ -1,20 +1,11 @@
 // SPDX-License-Identifier: GNU GENERAL PUBLIC LICENSE
 pragma solidity ^0.8.13;
 
-import {Test, console} from "@forge-std/Test.sol";
 import {ConsensusV1, Round, CallerIsNotOwner} from "@contracts/consensus/ConsensusV1.sol";
 import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_revert_if_caller_is_not_owner() public {
         vm.startPrank(address(1));
 

contracts/test/consensus/Consensus-UpdateVoters.sol

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GNU GENERAL PUBLIC LICENSE
 pragma solidity ^0.8.13;
 
-import {Test, console} from "@forge-std/Test.sol";
 import {
     ConsensusV1,
     ValidatorData,
@@ -10,17 +9,10 @@ import {
     Voted,
     CallerIsNotOwner
 } from "@contracts/consensus/ConsensusV1.sol";
+import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
-contract ConsensusTest is Test {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
+contract ConsensusTest is Base {
     function test_updateVoters_should_allow_only_caller() public {
         address addr = address(1);
         vm.startPrank(addr);

contracts/test/consensus/Consensus-ValidatoUpdate.sol

@@ -16,14 +16,6 @@ import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_updateBlsPublicKey_revert_if_caller_is_not_validator() public {
         vm.expectRevert(CallerIsNotValidator.selector);
         consensus.resignValidator();

contracts/test/consensus/Consensus-ValidatorRegistration.sol

@@ -15,14 +15,6 @@ import {Base} from "./Base.sol";
 import {ERC1967Proxy} from "@openzeppelin/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 contract ConsensusTest is Base {
-    ConsensusV1 public consensus;
-
-    function setUp() public {
-        bytes memory data = abi.encode(ConsensusV1.initialize.selector);
-        address proxy = address(new ERC1967Proxy(address(new ConsensusV1()), data));
-        consensus = ConsensusV1(proxy);
-    }
-
     function test_validator_registration_pass() public {
         assertEq(consensus.registeredValidatorsCount(), 0);
         address addr = address(1);