polish: use Initializable.sol from OpenZeppelin (#303)

* Initializable Common

* Initializable Home

* Initializable GovernanceRouter

* Initializable Replica

solidity/optics-core/contracts/Common.sol

@@ -3,6 +3,7 @@ pragma solidity >=0.6.11;
 
 import "../libs/Message.sol";
 
+import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol";
 import "@openzeppelin/contracts/cryptography/ECDSA.sol";
 
 /**
@@ -10,7 +11,7 @@ import "@openzeppelin/contracts/cryptography/ECDSA.sol";
  * @author Celo Labs Inc.
  * @notice Shared utilities between Home and Replica.
  **/
-abstract contract Common {
+abstract contract Common is Initializable {
     enum States {UNINITIALIZED, ACTIVE, FAILED}
 
     /// @notice Domain of owning contract
@@ -56,9 +57,7 @@ abstract contract Common {
         localDomain = _localDomain;
     }
 
-    function initialize(address _updater) public virtual {
-        require(state == States.UNINITIALIZED, "already initialized");
-
+    function initialize(address _updater) public virtual initializer {
         updater = _updater;
 
         state = States.ACTIVE;

solidity/optics-core/contracts/Home.sol

@@ -6,6 +6,7 @@ import "./Merkle.sol";
 import "./Queue.sol";
 import "../interfaces/IUpdaterManager.sol";
 
+import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol";
 import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
 import "@openzeppelin/contracts/utils/Address.sol";
 
@@ -15,7 +16,13 @@ import "@openzeppelin/contracts/utils/Address.sol";
  * @notice Contract responsible for managing production of the message tree and
  * holding custody of the updater bond.
  */
-contract Home is Ownable, MerkleTreeManager, QueueManager, Common {
+contract Home is
+    Ownable,
+    Initializable,
+    MerkleTreeManager,
+    QueueManager,
+    Common
+{
     using QueueLib for QueueLib.Queue;
     using MerkleLib for MerkleLib.Tree;
 
@@ -63,9 +70,7 @@ contract Home is Ownable, MerkleTreeManager, QueueManager, Common {
 
     constructor(uint32 _localDomain) Common(_localDomain) {} // solhint-disable-line no-empty-blocks
 
-    function initialize(address _updaterManager) public override {
-        require(state == States.UNINITIALIZED, "already initialized");
-
+    function initialize(address _updaterManager) public override initializer {
         _setUpdaterManager(_updaterManager);
         address _updater = updaterManager.updater();
         _setUpdater(_updater);

solidity/optics-core/contracts/Replica.sol

@@ -6,6 +6,7 @@ import "./Merkle.sol";
 import "./Queue.sol";
 import {IMessageRecipient} from "../interfaces/IMessageRecipient.sol";
 
+import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol";
 import "@summa-tx/memview-sol/contracts/TypedMemView.sol";
 
 /**
@@ -14,7 +15,7 @@ import "@summa-tx/memview-sol/contracts/TypedMemView.sol";
  * @notice Contract responsible for tracking root updates on home,
  * and dispatching messages on Replica to end recipients.
  */
-contract Replica is Common, QueueManager {
+contract Replica is Initializable, Common, QueueManager {
     using QueueLib for QueueLib.Queue;
     using MerkleLib for MerkleLib.Tree;
     using TypedMemView for bytes;
@@ -54,9 +55,7 @@ contract Replica is Common, QueueManager {
         bytes32 _current,
         uint256 _optimisticSeconds,
         uint256 _lastProcessed
-    ) public {
-        require(state == States.UNINITIALIZED, "already initialized");
-
+    ) public initializer {
         remoteDomain = _remoteDomain;
 
         queue.initialize();

solidity/optics-core/contracts/governance/GovernanceRouter.sol

@@ -2,6 +2,7 @@
 pragma solidity >=0.6.11;
 pragma experimental ABIEncoderV2;
 
+import {Initializable} from "@openzeppelin/contracts/proxy/Initializable.sol";
 import {TypedMemView} from "@summa-tx/memview-sol/contracts/TypedMemView.sol";
 
 import {Home} from "../Home.sol";
@@ -9,7 +10,7 @@ import {XAppConnectionManager, TypeCasts} from "../XAppConnectionManager.sol";
 import {IMessageRecipient} from "../../interfaces/IMessageRecipient.sol";
 import {GovernanceMessage} from "./GovernanceMessage.sol";
 
-contract GovernanceRouter is IMessageRecipient {
+contract GovernanceRouter is Initializable, IMessageRecipient {
     using TypedMemView for bytes;
     using TypedMemView for bytes29;
     using GovernanceMessage for bytes29;
@@ -39,13 +40,8 @@ contract GovernanceRouter is IMessageRecipient {
         localDomain = _localDomain;
     }
 
-    function initialize(address _xAppConnectionManager) public {
+    function initialize(address _xAppConnectionManager) public initializer {
         // initialize governor
-        require(
-            governorDomain == 0 && governor == address(0),
-            "governor already initialized"
-        );
-
         address _governorAddr = msg.sender;
         bool _isLocalGovernor = true;
         _transferGovernor(localDomain, _governorAddr, _isLocalGovernor);

solidity/optics-core/lib/index.js

@@ -8,6 +8,7 @@ const {
   deployImplementation,
   deployUpgradeBeaconController,
   deployProxyWithImplementation,
+  getInitializeData,
 } = require('../scripts/deployUpgradeSetup');
 const { deployOptics } = require('../scripts/deployOptics');
 const HomeAbi = require('../../../abis/Home.abi.json');
@@ -181,5 +182,6 @@ extendEnvironment((hre) => {
     deployUpgradeSetup,
     deployOptics,
     deployProxyWithImplementation,
+    getInitializeData,
   };
 });

solidity/optics-core/scripts/deployUpgradeSetup.js

@@ -30,30 +30,45 @@ async function deployProxy(upgradeBeaconAddress, initializeData = '0x') {
   return proxy.deployed();
 }
 
+async function getInitializeData(
+  implementationName,
+  initializeArgs,
+  initializeIdentifier = 'initialize',
+) {
+  if (initializeArgs.length === 0) {
+    return '0x';
+  }
+
+  const Implementation = await ethers.getContractFactory(implementationName);
+
+  const initializeFunction = Implementation.interface.getFunction(
+    initializeIdentifier,
+  );
+
+  const initializeData = Implementation.interface.encodeFunctionData(
+    initializeFunction,
+    initializeArgs,
+  );
+
+  return initializeData;
+}
+
 async function deployProxyWithImplementation(
   upgradeBeaconAddress,
   implementationName,
   initializeArgs = [],
   initializeIdentifier = 'initialize',
 ) {
-  const Implementation = await ethers.getContractFactory(implementationName);
-
-  let initializeData;
-  if (initializeArgs.length === 0) {
-    initializeData = '0x';
-  } else {
-    const initializeFunction = Implementation.interface.getFunction(
-      initializeIdentifier,
-    );
-    initializeData = Implementation.interface.encodeFunctionData(
-      initializeFunction,
-      initializeArgs,
-    );
-  }
+  const initializeData = await getInitializeData(
+    implementationName,
+    initializeArgs,
+    initializeIdentifier,
+  );
 
   const proxy = await deployProxy(upgradeBeaconAddress, initializeData);
 
   // instantiate proxy with Proxy Contract address + Implementation interface
+  const Implementation = await ethers.getContractFactory(implementationName);
   const [signer] = await ethers.getSigners();
   const proxyWithImplementation = new ethers.Contract(
     proxy.address,
@@ -152,4 +167,5 @@ module.exports = {
   deployUpgradeSetupAndProxy,
   deployProxy,
   deployProxyWithImplementation,
+  getInitializeData,
 };

solidity/optics-core/test/Common.test.js

@@ -26,6 +26,12 @@ describe('Common', async () => {
     common = contracts.proxyWithImplementation;
   });
 
+  it('Cannot be initialized twice', async () => {
+    await expect(common.initialize(signer.address)).to.be.revertedWith(
+      'Initializable: contract is already initialized',
+    );
+  });
+
   it('Accepts updater signature', async () => {
     const oldRoot = ethers.utils.formatBytes32String('old root');
     const newRoot = ethers.utils.formatBytes32String('new root');

solidity/optics-core/test/Home.test.js

@@ -52,6 +52,12 @@ describe('Home', async () => {
     home = contracts.proxyWithImplementation;
   });
 
+  it('Cannot be initialized twice', async () => {
+    await expect(home.initialize(signer.address)).to.be.revertedWith(
+      'Initializable: contract is already initialized',
+    );
+  });
+
   it('Halts on fail', async () => {
     await home.setFailed();
     expect(await home.state()).to.equal(optics.State.FAILED);

solidity/optics-core/test/Replica.test.js

@@ -20,9 +20,12 @@ const localDomain = 2000;
 const optimisticSeconds = 3;
 const initialCurrentRoot = ethers.utils.formatBytes32String('current');
 const initialLastProcessed = 0;
+const replicaContractName = 'TestReplica';
+const replicaInitializeIdentifier =
+  'initialize(uint32, address, bytes32, uint256, uint256)';
 
 describe('Replica', async () => {
-  let replica, signer, fakeSigner, updater, fakeUpdater;
+  let replica, signer, fakeSigner, updater, fakeUpdater, initializeArgs;
 
   const enqueueValidUpdate = async (newRoot) => {
     let oldRoot;
@@ -45,23 +48,40 @@ describe('Replica', async () => {
 
   beforeEach(async () => {
     const controller = null;
+    initializeArgs = [
+      remoteDomain,
+      updater.signer.address,
+      initialCurrentRoot,
+      optimisticSeconds,
+      initialLastProcessed,
+    ];
+
     const { contracts } = await optics.deployUpgradeSetupAndProxy(
-      'TestReplica',
+      replicaContractName,
       [localDomain],
-      [
-        remoteDomain,
-        updater.signer.address,
-        initialCurrentRoot,
-        optimisticSeconds,
-        initialLastProcessed,
-      ],
+      initializeArgs,
       controller,
-      'initialize(uint32, address, bytes32, uint256, uint256)',
+      replicaInitializeIdentifier,
     );
 
     replica = contracts.proxyWithImplementation;
   });
 
+  it('Cannot be initialized twice', async () => {
+    const initializeData = await optics.getInitializeData(
+      replicaContractName,
+      initializeArgs,
+      replicaInitializeIdentifier,
+    );
+
+    await expect(
+      signer.sendTransaction({
+        to: replica.address,
+        data: initializeData,
+      }),
+    ).to.be.revertedWith('Initializable: contract is already initialized');
+  });
+
   it('Halts on fail', async () => {
     await replica.setFailed();
     expect(await replica.state()).to.equal(optics.State.FAILED);