Implement Pool Escrow for ETH1 withdrawals

abi/PoolEscrow.json

@@ -0,0 +1,144 @@
+[
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "_owner",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "constructor"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "previousOwner",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "newOwner",
+        "type": "address"
+      }
+    ],
+    "name": "OwnershipTransferApplied",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "currentOwner",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "futureOwner",
+        "type": "address"
+      }
+    ],
+    "name": "OwnershipTransferCommitted",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "sender",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "payee",
+        "type": "address"
+      },
+      {
+        "indexed": false,
+        "internalType": "uint256",
+        "name": "amount",
+        "type": "uint256"
+      }
+    ],
+    "name": "Withdrawn",
+    "type": "event"
+  },
+  {
+    "inputs": [],
+    "name": "applyOwnershipTransfer",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "newOwner",
+        "type": "address"
+      }
+    ],
+    "name": "commitOwnershipTransfer",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "futureOwner",
+    "outputs": [
+      {
+        "internalType": "address",
+        "name": "",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "owner",
+    "outputs": [
+      {
+        "internalType": "address",
+        "name": "",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address payable",
+        "name": "payee",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amount",
+        "type": "uint256"
+      }
+    ],
+    "name": "withdraw",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "stateMutability": "payable",
+    "type": "receive"
+  }
+]

contracts/collectors/PoolEscrow.sol

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+
+pragma solidity 0.7.5;
+
+import "@openzeppelin/contracts/utils/Address.sol";
+import "../interfaces/IPoolEscrow.sol";
+
+/**
+ * @title PoolEscrow
+ *
+ * @dev PoolEscrow contract is used to receive transfers from ETH2 system contract for the pool validators.
+ * The withdrawal credentials of the Pool must be set to
+ * https://github.com/ethereum/eth2.0-specs/blob/v1.1.0-alpha.2/specs/phase0/validator.md#eth1_address_withdrawal_prefix
+ * using the address of this contract as a destination.
+ */
+contract PoolEscrow is IPoolEscrow {
+    using Address for address payable;
+
+    // @dev The address of the current contract owner.
+    address public override owner;
+
+    // @dev The address the ownership is planned to be transferred to.
+    address public override futureOwner;
+
+    /**
+    * @dev Constructor for initializing the PoolEscrow contract.
+    * @param _owner - address of the contract owner.
+    */
+    constructor(address _owner) {
+        owner = _owner;
+        emit OwnershipTransferApplied(address(0), _owner);
+    }
+
+    /**
+     * @dev Throws if called by any account other than the owner.
+     */
+    modifier onlyOwner() {
+        require(owner == msg.sender, "PoolEscrow: caller is not the owner");
+        _;
+    }
+
+    /**
+     * @dev See {IPoolEscrow-commitOwnershipTransfer}.
+     */
+    function commitOwnershipTransfer(address newOwner) external override onlyOwner {
+        require(newOwner != address(0), "PoolEscrow: new owner is the zero address");
+        futureOwner = newOwner;
+        emit OwnershipTransferCommitted(msg.sender, newOwner);
+    }
+
+    /**
+     * @dev See {IPoolEscrow-applyOwnershipTransfer}.
+     */
+    function applyOwnershipTransfer() external override onlyOwner {
+        address newOwner = futureOwner;
+        require(newOwner != address(0), "PoolEscrow: new owner is the zero address");
+        (owner, futureOwner) = (newOwner, address(0));
+        emit OwnershipTransferApplied(msg.sender, newOwner);
+    }
+
+    /**
+     * @dev See {IPoolEscrow-withdraw}.
+     */
+    function withdraw(address payable payee, uint256 amount) external override onlyOwner {
+        payee.sendValue(amount);
+        emit Withdrawn(msg.sender, payee, amount);
+    }
+
+    /**
+    * @dev Function for receiving withdrawals from ETH2 system contract.
+    */
+    receive() external payable { }
+}

contracts/interfaces/IPoolEscrow.sol

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+
+pragma solidity 0.7.5;
+
+/**
+ * @dev Interface of the PoolEscrow contract.
+ */
+interface IPoolEscrow {
+    /**
+    * @dev Event for tracking withdrawn ether.
+    * @param sender - the address of the transaction sender.
+    * @param payee - the address where the funds were transferred to.
+    * @param amount - the amount of ether transferred to payee.
+    */
+    event Withdrawn(address indexed sender, address indexed payee, uint256 amount);
+
+    /**
+    * @dev Event for tracking ownership transfer commits.
+    * @param currentOwner - the address of the current owner.
+    * @param futureOwner - the address the ownership is planned to be transferred to.
+    */
+    event OwnershipTransferCommitted(address indexed currentOwner, address indexed futureOwner);
+
+    /**
+    * @dev Event for tracking ownership transfers.
+    * @param previousOwner - the address the ownership was transferred from.
+    * @param newOwner - the address the ownership was transferred to.
+    */
+    event OwnershipTransferApplied(address indexed previousOwner, address indexed newOwner);
+
+    /**
+    * @dev Function for retrieving the address of the current owner.
+    */
+    function owner() external view returns (address);
+
+    /**
+    * @dev Function for retrieving the address of the future owner.
+    */
+    function futureOwner() external view returns (address);
+
+    /**
+     * @dev Commit contract ownership transfer to a new account (`newOwner`).
+     * Can only be called by the current owner.
+     */
+    function commitOwnershipTransfer(address newOwner) external;
+
+    /**
+     * @dev Apply contract ownership transfer to a new account (`futureOwner`).
+     * Can only be called by the current owner.
+     */
+    function applyOwnershipTransfer() external;
+
+    /**
+     * @dev Withdraw balance for a payee, forwarding all gas to the
+     * recipient. Can only be called by the current owner.
+     *
+     * WARNING: Forwarding all gas opens the door to reentrancy vulnerabilities.
+     * Make sure you trust the recipient, or are either following the
+     * checks-effects-interactions pattern or using {ReentrancyGuard}.
+     *
+     * @param payee - the address where the funds will be transferred to.
+     * @param amount - the amount of ether to transfer to payee.
+     */
+    function withdraw(address payable payee, uint256 amount) external;
+}

deployments/collectors.js

@@ -0,0 +1,12 @@
+const { ethers } = require('hardhat');
+
+async function deployPoolEscrow(adminAddress) {
+  const PoolEscrow = await ethers.getContractFactory('PoolEscrow');
+  const poolEscrow = await PoolEscrow.deploy(adminAddress);
+  await poolEscrow.deployed();
+  return poolEscrow.address;
+}
+
+module.exports = {
+  deployPoolEscrow,
+};

deployments/index.js

@@ -1,4 +1,5 @@
 const hre = require('hardhat');
+const { deployPoolEscrow } = require('./collectors');
 const { white, green } = require('chalk');
 const { contractSettings, contracts } = require('./settings');
 const { deployAndInitializeStakeWiseToken } = require('./tokens');
@@ -48,10 +49,18 @@ async function upgradeContracts() {
     )
   );
 
+  let poolEscrowContractAddress = await deployPoolEscrow(
+    contractSettings.admin
+  );
+  log(
+    white(`Deployed PoolEscrow contract: ${green(poolEscrowContractAddress)}`)
+  );
+
   return {
     ...contracts,
     vestingEscrowFactory: vestingEscrowFactoryContractAddress,
     vestingEscrow: vestingEscrowContractAddress,
+    poolEscrow: poolEscrowContractAddress,
     stakeWiseToken: stakeWiseTokenContractAddress,
   };
 }

hardhat.config.js

@@ -140,6 +140,7 @@ module.exports = {
       'Validators',
       'VestingEscrow',
       'VestingEscrowFactory',
+      'PoolEscrow',
     ],
     clear: true,
     flat: true,

package.json

@@ -50,7 +50,7 @@
     "@nomiclabs/hardhat-etherscan": "^2.1.1",
     "@nomiclabs/hardhat-truffle5": "^2.0.0",
     "@nomiclabs/hardhat-web3": "^2.0.0",
-    "@openzeppelin/contracts": "3.3.0",
+    "@openzeppelin/contracts": "3.4.1",
     "@openzeppelin/contracts-upgradeable": "3.4.1",
     "@openzeppelin/hardhat-upgrades": "^1.6.0",
     "@openzeppelin/test-helpers": "^0.5.10",