Make pubkey uniqueness per megapool

Author: kanewallmann

contracts/contract/megapool/RocketMegapoolManager.sol

@@ -32,12 +32,6 @@ contract RocketMegapoolManager is RocketBase, RocketMegapoolManagerInterface {
         return getUint(setCountKey);
     }
 
-    /// @notice Get a megapool address by validator pubkey
-    /// @param _pubkey The pubkey to query
-    function getMegapoolByPubkey(bytes calldata _pubkey) override external view returns (address) {
-        return getAddress(keccak256(abi.encodePacked("validator.megapool", _pubkey)));
-    }
-
     /// @notice Adds a validator record to the global megapool validator set
     /// @param _megapoolAddress Address of the megapool which manages this validator
     /// @param _validatorId Internal validator ID of the new validator
@@ -47,7 +41,7 @@ contract RocketMegapoolManager is RocketBase, RocketMegapoolManagerInterface {
         uint256 encoded = (uint256(uint160(_megapoolAddress)) << 96) | _validatorId;
         setUint(keccak256(abi.encodePacked("megapool.validator.set", index)), encoded);
         // Add pubkey => megapool mapping and ensure uniqueness
-        bytes32 key = keccak256(abi.encodePacked("validator.megapool", _pubkey));
+        bytes32 key = keccak256(abi.encodePacked("validator.megapool", _megapoolAddress, _pubkey));
         require(getAddress(key) == address(0x0), "Pubkey in use");
         setAddress(key, _megapoolAddress);
     }

contracts/interface/megapool/RocketMegapoolManagerInterface.sol

@@ -12,7 +12,6 @@ interface RocketMegapoolManagerInterface {
     }
 
     function getValidatorCount() external view returns (uint256);
-    function getMegapoolByPubkey(bytes calldata _pubkey) external view returns (address);
     function addValidator(address _megapoolAddress, uint32 _validatorId, bytes calldata _pubkey) external;
     function getLastChallenger() external view returns (address);
     function getValidatorInfo(uint256 _index) external view returns (bytes memory pubkey, RocketMegapoolStorageLayout.ValidatorInfo memory validatorInfo, address megapool, uint32 validatorId);