feat(contracts): Add the WithdrawalFinalizer Contract (#314)

# What ❔

This PR adds the WithdrawalFinalizer contract.

## Why ❔

To open source the already deployed contract.

## Checklist

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<!-- For draft PRs check the boxes as you complete them. -->

- [x] PR title corresponds to the body of PR (we generate changelog
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- [ ] Tests for the changes have been added / updated.
- [ ] Documentation comments have been added / updated.
- [ ] Code has been formatted via `cargo fmt`.

---------

Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>

.gitignore

@@ -1 +1,7 @@
 /target
+node_modules
+cache
+artifacts
+typechain-types
+*.log
+dev.env

README.md

@@ -75,6 +75,29 @@ You may specify `All`, `None`, `BlackList` or `WhiteList` as json documents:
 1. `TOKENS_TO_FINALIZE = '{ "WhiteList":[ "0x3355df6D4c9C3035724Fd0e3914dE96A5a83aaf4" ] }'` - Finalize only these tokens
 1. `TOKENS_TO_FINALIZE = '{ "BlackList":[ "0x3355df6D4c9C3035724Fd0e3914dE96A5a83aaf4" ] }'` - Finalize all tokens but these
 
+## Deploying the finalizer smart contract
+
+The finalizer smart contract needs to reference the addresses of the diamond proxy contract and l1 erc20 proxy contract.
+You also need to know the key of the account you want to use to deploy the finalizer contract.
+
+When you know those to deploy the contract you need to run (assume you are running `anvil` in a separate terminal):
+
+```
+$ yarn
+$ env CONTRACTS_DIAMOND_PROXY_ADDR="0x9A6DE0f62Aa270A8bCB1e2610078650D539B1Ef9" CONTRACTS_L1_ERC20_BRIDGE_PROXY_ADDR="0x2Ae09702F77a4940621572fBcDAe2382D44a2cbA" MNEMONIC="test test test test test test test test test test test junk" ETH_CLIENT_WEB3_URL="http://localhost:8545" npx hardhat run ./scripts/deploy.ts
+```
+
+If all goes well the the result would be
+
+```
+...
+Compiled 18 Solidity files successfully (evm target: paris).
+CONTRACTS_WITHDRAWAL_FINALIZER_ADDRESS=0x712516e61C8B383dF4A63CFe83d7701Bce54B03e
+```
+
+And so you know the address of the deployed contract.
+
+
 ## License
 
 zkSync Withdrawal Finalizer is distributed under the terms of either

contracts/WithdrawalFinalizer.sol

@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-3.0
+
+pragma solidity ^0.8.0;
+
+import "@matterlabs/zksync-contracts/l1/contracts/bridge/interfaces/IL1Bridge.sol";
+import "@matterlabs/zksync-contracts/l1/contracts/zksync/interfaces/IMailbox.sol";
+import "@matterlabs/zksync-contracts/l1/contracts/common/libraries/UncheckedMath.sol";
+
+
+contract WithdrawalFinalizer {
+    using UncheckedMath for uint256;
+    IMailbox constant ZKSYNC_MAILBOX = IMailbox($(ZKSYNC_ADDRESS));
+    IL1Bridge constant ERC20_BRIDGE = IL1Bridge($(ERC20_BRIDGE_ADDRESS));
+
+    struct RequestFinalizeWithdrawal {
+        uint256 _l2BlockNumber;
+        uint256 _l2MessageIndex;
+        uint16 _l2TxNumberInBlock;
+        bytes _message;
+        bytes32[] _merkleProof;
+        bool _isEth;
+        uint256 _gas;
+    }
+
+    struct Result {
+        uint256 _l2BlockNumber;
+        uint256 _l2MessageIndex;
+        uint256 _gas;
+        bool success;
+    }
+
+    function finalizeWithdrawals(
+        RequestFinalizeWithdrawal[] calldata requests
+    ) external returns (Result[] memory) {
+        uint256 requestsLength = requests.length;
+        Result[] memory results = new Result[](requestsLength);
+        for (uint256 i = 0; i < requestsLength; i = i.uncheckedInc()) {
+            require(gasleft() >= ((requests[i]._gas * 64) / 63) + 500, "i");
+            uint256 gasBefore = gasleft();
+            if (requests[i]._isEth) {
+                try
+                    ZKSYNC_MAILBOX.finalizeEthWithdrawal{gas: requests[i]._gas}(
+                        requests[i]._l2BlockNumber,
+                        requests[i]._l2MessageIndex,
+                        requests[i]._l2TxNumberInBlock,
+                        requests[i]._message,
+                        requests[i]._merkleProof
+                    )
+                {
+                    results[i] = Result({
+                        _l2BlockNumber: requests[i]._l2BlockNumber,
+                        _l2MessageIndex: requests[i]._l2MessageIndex,
+                        _gas: gasBefore - gasleft(),
+                        success: true
+                    });
+                } catch {
+                    results[i] = Result({
+                        _l2BlockNumber: requests[i]._l2BlockNumber,
+                        _l2MessageIndex: requests[i]._l2MessageIndex,
+                        _gas: 0,
+                        success: false
+                    });
+                }
+            } else {
+                try
+                    ERC20_BRIDGE.finalizeWithdrawal{gas: requests[i]._gas}(
+                        requests[i]._l2BlockNumber,
+                        requests[i]._l2MessageIndex,
+                        requests[i]._l2TxNumberInBlock,
+                        requests[i]._message,
+                        requests[i]._merkleProof
+                    )
+                {
+                    results[i] = Result({
+                        _l2BlockNumber: requests[i]._l2BlockNumber,
+                        _l2MessageIndex: requests[i]._l2MessageIndex,
+                        _gas: gasBefore - gasleft(),
+                        success: true
+                    });
+                } catch {
+                    results[i] = Result({
+                        _l2BlockNumber: requests[i]._l2BlockNumber,
+                        _l2MessageIndex: requests[i]._l2MessageIndex,
+                        _gas: 0,
+                        success: false
+                    });
+                }
+            }
+        }
+        return results;
+    }
+}

hardhat.config.ts

@@ -0,0 +1,38 @@
+import '@nomiclabs/hardhat-solpp';
+import '@nomiclabs/hardhat-ethers';
+import '@nomiclabs/hardhat-etherscan';
+import '@typechain/hardhat';
+
+const config = {
+    ZKSYNC_ADDRESS: process.env.CONTRACTS_DIAMOND_PROXY_ADDR,
+    ERC20_BRIDGE_ADDRESS: process.env.CONTRACTS_L1_ERC20_BRIDGE_PROXY_ADDR
+};
+
+export default {
+    solidity: {
+        version: '0.8.18',
+        settings: {
+            optimizer: {
+                enabled: true,
+                runs: 200
+            },
+            outputSelection: {
+                '*': {
+                    '*': ['storageLayout']
+                }
+            }
+        }
+    },
+    contractSizer: {
+        runOnCompile: false
+    },
+    paths: {
+        sources: './contracts'
+    },
+    solpp: {
+        defs: config
+    },
+    etherscan: {
+        apiKey: process.env.MISC_ETHERSCAN_API_KEY
+    }
+};

package.json

@@ -0,0 +1,38 @@
+{
+    "name": "withdrawal-finalizer",
+    "version": "0.1.0",
+    "license": "MIT",
+    "dependencies": {
+        "@matterlabs/zksync-contracts": "^0.5.2",
+        "@openzeppelin/contracts": "^4.8.1",
+        "@sentry/node": "^7.2.0",
+        "@sentry/tracing": "^7.2.0",
+        "ethers": "^5.6.0",
+        "node-fetch": "^2.6.1",
+        "prom-client": "^14.2.0",
+        "zksync-web3": "^0.13.3"
+    },
+    "devDependencies": {
+        "@nomiclabs/hardhat-ethers": "^2.0.5",
+        "@nomiclabs/hardhat-etherscan": "^3.0.3",
+        "@nomiclabs/hardhat-solpp": "^2.0.1",
+        "@typechain/ethers-v5": "^9.0.0",
+        "@typechain/hardhat": "^5.0.0",
+        "@types/chai": "^4.2.0",
+        "@types/mocha": "^9.1.0",
+        "@types/node": "^14.14.5",
+        "chai": "^4.3.6",
+        "hardhat": "^2.12.7",
+        "mocha": "^9.2.1",
+        "prettier": "^2.5.1",
+        "prettier-plugin-solidity": "^1.1.2",
+        "ts-generator": "^0.1.1",
+        "ts-node": "^10.8.1",
+        "typechain": "^7.0.0",
+        "typescript": "^4.0.5"
+    },
+    "scripts": {
+        "deploy": "ts-node scripts/deploy.ts",
+        "contracts:build": "hardhat compile"
+    }
+}

scripts/deploy.ts

@@ -0,0 +1,26 @@
+import { Wallet } from 'ethers';
+
+const hardhat = require('hardhat');
+
+async function main() {
+    const provider = new hardhat.ethers.providers.JsonRpcProvider(process.env.ETH_CLIENT_WEB3_URL as string);
+    const wallet  = Wallet.fromMnemonic(
+          process.env.MNEMONIC as string,
+          "m/44'/60'/0'/0/1"
+      ).connect(provider);
+
+
+      const contractFactory = await hardhat.ethers.getContractFactory("WithdrawalFinalizer", {
+          signer: wallet
+      });
+      const contract = await contractFactory.deploy();
+      await contract.deployTransaction.wait();    
+      console.log(`CONTRACTS_WITHDRAWAL_FINALIZER_ADDRESS=${contract.address}`);
+  }
+
+  main()
+    .then(() => process.exit(0))
+    .catch((error) => {
+      console.error(error);
+      process.exit(1);
+    });