[2/2] Decouple ETH Bridge from signal service (#113)

Co-authored-by: Nikesh Nazareth <[email protected]>
Co-authored-by: Gustavo Gonzalez <[email protected]>

Author: 3 people

foundry.toml

@@ -11,7 +11,8 @@ gas_reports_ignore = ["MockDelayedInclusionStore", "MockCheckpointTracker", ""]
 
 remappings = [
     "@optimism/=lib/optimism/",
-    "@vendor/=src/vendor/"
+    "@vendor/=src/vendor/",
+    "@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/"
 ]
 
 [fmt]

offchain/deposit_signal_proof.rs

@@ -1,11 +1,11 @@
-use alloy::primitives::{address, bytes, U256};
+use alloy::primitives::{address, bytes, B256, U256};
 use eyre::Result;
 
 mod utils;
-use utils::{deploy_signal_service, get_proofs, get_provider};
+use utils::{deploy_eth_bridge, deploy_signal_service, get_proofs, get_provider};
 
 mod signal_slot;
-use signal_slot::{get_signal_slot, NameSpaceConst};
+use signal_slot::get_signal_slot;
 
 #[tokio::main]
 async fn main() -> Result<()> {
@@ -23,6 +23,9 @@ async fn main() -> Result<()> {
     let sender = address!("0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266");
     let amount = U256::from(4000000000000000000_u128);
 
+    // This is the checkpoint tracker
+    let trusted_publisher = address!("0xCafac3dD18aC6c6e92c921884f9E4176737C052c");
+
     let (provider, _anvil) = get_provider()?;
 
     let signal_service = deploy_signal_service(&provider).await?;
@@ -32,16 +35,23 @@ async fn main() -> Result<()> {
         signal_service.address()
     );
 
-    println!("Sending ETH deposit signal...");
-    let builder = signal_service.deposit(sender, data).value(amount);
+    let eth_bridge =
+        deploy_eth_bridge(&provider, *signal_service.address(), trusted_publisher).await?;
+
+    println!("Deployed ETH bridge at address: {}", eth_bridge.address());
+
+    println!("Sending ETH deposit...");
+    let builder = eth_bridge.deposit(sender, data).value(amount);
     let tx = builder.send().await?.get_receipt().await?;
 
     // Get deposit ID from the transaction receipt logs
     // possibly a better way to do this, but this works :)
     let receipt_logs = tx.logs().get(0).unwrap().topics();
     let deposit_id = receipt_logs.get(1).unwrap();
+    let depid: B256 =
+        "0xf9c183d2de58fbeb1a8917170139e980fa1b6e5a358ec83721e11c9f6e25eb18".parse()?;
 
-    let slot = get_signal_slot(deposit_id, &sender, NameSpaceConst::ETHBridge);
+    let slot = get_signal_slot(&depid, &eth_bridge.address());
     get_proofs(&provider, slot, &signal_service).await?;
 
     Ok(())

offchain/generic_signal_proof.rs

@@ -4,7 +4,7 @@ use alloy::primitives::{Address, B256};
 use eyre::{eyre, Result};
 
 mod signal_slot;
-use signal_slot::{get_signal_slot, NameSpaceConst};
+use signal_slot::get_signal_slot;
 
 mod utils;
 use utils::{deploy_signal_service, get_proofs, get_provider};
@@ -48,7 +48,7 @@ async fn main() -> Result<()> {
     let builder = signal_service.sendSignal(signal);
     builder.send().await?.watch().await?;
 
-    let slot = get_signal_slot(&signal, &sender, NameSpaceConst::Signal);
+    let slot = get_signal_slot(&signal, &sender);
     get_proofs(&provider, slot, &signal_service).await?;
 
     Ok(())

offchain/signal_slot.rs

@@ -6,28 +6,6 @@ use alloy::{
 };
 use eyre::{eyre, Result};
 
-pub enum NameSpaceConst {
-    Signal,
-    ETHBridge,
-}
-
-impl NameSpaceConst {
-    pub fn value(&self) -> B256 {
-        match self {
-            NameSpaceConst::Signal => keccak256("generic-signal"),
-            NameSpaceConst::ETHBridge => keccak256("eth-bridge"),
-        }
-    }
-
-    pub fn from_arg(arg: &str) -> Result<Self> {
-        match arg {
-            "1" => Ok(NameSpaceConst::Signal),
-            "2" => Ok(NameSpaceConst::ETHBridge),
-            _ => Err(eyre!("Invalid namespace selection: must be '1' for normal signals or '2' for eth deposits")),
-        }
-    }
-}
-
 pub fn erc7201_slot(namespace: &Vec<u8>) -> B256 {
     let namespace_hash = keccak256(namespace);
 
@@ -41,8 +19,8 @@ pub fn erc7201_slot(namespace: &Vec<u8>) -> B256 {
     aligned_slot
 }
 
-pub fn get_signal_slot(signal: &B256, sender: &Address, namespace: NameSpaceConst) -> B256 {
-    let namespace = (signal, sender, namespace.value()).abi_encode_packed();
+pub fn get_signal_slot(signal: &B256, sender: &Address) -> B256 {
+    let namespace = (signal, sender).abi_encode_packed();
     return erc7201_slot(namespace.as_ref());
 }
 
@@ -51,7 +29,7 @@ fn main() -> Result<()> {
     let args: Vec<String> = env::args().collect();
     if args.len() != 4 {
         return Err(eyre!(
-            "Usage: cargo run --bin signal_slot <signal (0x...)> <sender (0x...)> <namespace (1 or 2)>"
+            "Usage: cargo run --bin signal_slot <signal (0x...)> <sender (0x...)>"
         ));
     }
 
@@ -65,11 +43,6 @@ fn main() -> Result<()> {
         .parse()
         .map_err(|_| eyre!("Invalid sender format: {}", sender_str))?;
 
-    let namespace = NameSpaceConst::from_arg(&args[3])?;
-
-    println!(
-        "Signal Slot: {:?}",
-        get_signal_slot(&signal, &sender, namespace)
-    );
+    println!("Signal Slot: {:?}", get_signal_slot(&signal, &sender));
     Ok(())
 }

offchain/utils.rs

@@ -6,24 +6,28 @@ use alloy::{
     sol,
 };
 
+use ETHBridge::ETHBridgeInstance;
 use SignalService::SignalServiceInstance;
 
 use eyre::Result;
 use serde_json::to_string_pretty;
 
 const BLOCK_TIME: u64 = 5;
 
-// NOTE: This needs to match the address of the rollup operator in the tests
-// to ensure the signal service is deployed to the same address.
-const ROLLUP_OPERATOR: Address = address!("0xCf03Dd0a894Ef79CB5b601A43C4b25E3Ae4c67eD");
-
 sol!(
     #[allow(missing_docs)]
     #[sol(rpc)]
     SignalService,
     "./out/SignalService.sol/SignalService.json",
 );
 
+sol!(
+    #[allow(missing_docs)]
+    #[sol(rpc)]
+    ETHBridge,
+    "./out/ETHBridge.sol/ETHBridge.json"
+);
+
 pub fn get_provider() -> Result<(impl Provider, AnvilInstance)> {
     let anvil = Anvil::new()
         .block_time(BLOCK_TIME)
@@ -40,7 +44,23 @@ pub fn get_provider() -> Result<(impl Provider, AnvilInstance)> {
 pub async fn deploy_signal_service(
     provider: &impl Provider,
 ) -> Result<SignalServiceInstance<(), &impl Provider>> {
-    let contract = SignalService::deploy(provider, ROLLUP_OPERATOR).await?;
+    let contract = SignalService::deploy(provider).await?;
+    Ok(contract)
+}
+
+pub async fn deploy_eth_bridge(
+    provider: &impl Provider,
+    signal_service: Address,
+    trusted_publisher: Address,
+) -> Result<ETHBridgeInstance<(), &impl Provider>> {
+    // L2 Eth bridge address
+    let counterpart = address!("0xDC9e4C83bDe3912E9B63A9BF9cE263F3309aB5d4");
+    // WARN: This is a slight hack for now to make sure the contract is deployed on the correct address
+    ETHBridge::deploy(provider, signal_service, trusted_publisher, counterpart).await?;
+
+    let contract =
+        ETHBridge::deploy(provider, signal_service, trusted_publisher, counterpart).await?;
+
     Ok(contract)
 }
 

src/libs/LibSignal.sol

@@ -12,66 +12,57 @@ library LibSignal {
     using SlotDerivation for string;
     using SafeCast for uint256;
 
-    bytes32 constant SIGNAL_NAMESPACE = keccak256("generic-signal");
-
     /// @dev A `value` was signaled at a namespaced slot for the current `msg.sender`.
     function signaled(bytes32 value) internal view returns (bool) {
-        return signaled(value, SIGNAL_NAMESPACE);
-    }
-
-    /// @dev A `value` was signaled at a namespaced slot for the current `msg.sender` and
-    /// namespace.
-    function signaled(bytes32 value, bytes32 namespace) internal view returns (bool) {
-        return signaled(value, msg.sender, namespace);
+        return signaled(value, msg.sender);
     }
 
     /// @dev A `value` was signaled at a namespaced slot. See `deriveSlot`.
-    function signaled(bytes32 value, address account, bytes32 namespace) internal view returns (bool) {
-        bytes32 slot = deriveSlot(value, account, namespace);
+    function signaled(bytes32 value, address account) internal view returns (bool) {
+        bytes32 slot = deriveSlot(value, account);
         return slot.getBooleanSlot().value == true;
     }
 
-    /// @dev Signal a `value` at a namespaced slot for the current `msg.sender` and namespace.
+    /// @dev Signal a `value` at a namespaced slot for the current `msg.sender`.
     function signal(bytes32 value) internal returns (bytes32) {
-        return signal(value, msg.sender, SIGNAL_NAMESPACE);
+        return signal(value, msg.sender);
     }
 
     /// @dev Signal a `value` at a namespaced slot. See `deriveSlot`.
-    function signal(bytes32 value, address account, bytes32 namespace) internal returns (bytes32) {
-        bytes32 slot = deriveSlot(value, account, namespace);
+    function signal(bytes32 value, address account) internal returns (bytes32) {
+        bytes32 slot = deriveSlot(value, account);
         slot.getBooleanSlot().value = true;
         return slot;
     }
 
-    /// @dev Returns the storage slot for a signal. Namespaced to the msg.sender, value and namespace.
-    function deriveSlot(bytes32 value, bytes32 namespace) internal view returns (bytes32) {
-        return deriveSlot(value, msg.sender, namespace);
+    /// @dev Returns the storage slot for a signal. Namespaced to the msg.sender and value
+    function deriveSlot(bytes32 value) internal view returns (bytes32) {
+        return deriveSlot(value, msg.sender);
     }
 
-    /// @dev Returns the storage slot for a signal. Namespaced to the current account and value and namespace.
-    function deriveSlot(bytes32 value, address account, bytes32 namespace) internal pure returns (bytes32) {
-        return string(abi.encodePacked(value, account, namespace)).erc7201Slot();
+    /// @dev Returns the storage slot for a signal. Namespaced to the current account and value.
+    function deriveSlot(bytes32 value, address account) internal pure returns (bytes32) {
+        return string(abi.encodePacked(value, account)).erc7201Slot();
     }
 
     /// @dev Performs a storage proof verification for a signal stored on the contract using this library
     /// @param value The signal value to verify
-    /// @param namespace The namespace of the signal
     /// @param sender The address that originally sent the signal on the source chain
-    /// @param root The state root or storage root from the source chain to verify against
-    /// @param accountProof Merkle proof for the contract's account against the state root. Empty if we are using a
-    /// storage root.
-    /// @param storageProof Merkle proof for the derived storage slot against the account's storage root
+    /// @param root The state root from the source chain to verify against
+    /// @param accountProof Merkle proof for the SignalService account against the state root.
+    /// @param storageProof Merkle proof for the derived storage slot against the SignalService's storage root
+    /// @dev We can use `address(this)` as the SignalService address, even when `root` refers to a different chain,
+    /// because we assume the SignalService is deployed at the same address on every chain.
     function verifySignal(
         bytes32 value,
-        bytes32 namespace,
         address sender,
         bytes32 root,
         bytes[] memory accountProof,
         bytes[] memory storageProof
-    ) internal pure {
+    ) internal view {
         bytes32 encodedBool = bytes32(uint256(1));
         LibTrieProof.verifyMerkleProof(
-            root, sender, deriveSlot(value, sender, namespace), encodedBool, accountProof, storageProof
+            root, address(this), deriveSlot(value, sender), encodedBool, accountProof, storageProof
         );
     }
 }

src/protocol/ETHBridge.sol

@@ -2,62 +2,78 @@
 pragma solidity ^0.8.28;
 
 import {IETHBridge} from "./IETHBridge.sol";
+import {ISignalService} from "./ISignalService.sol";
+import {ReentrancyGuardTransient} from "@openzeppelin/contracts/utils/ReentrancyGuardTransient.sol";
 
-/// @dev Abstract ETH bridging contract to send native ETH between L1 <-> L2 using storage proofs.
+/// @dev ETH bridging contract to send native ETH between L1 <-> L2 using storage proofs.
 ///
 /// IMPORTANT: No recovery mechanism is implemented in case an account creates a deposit that can't be claimed.
-contract ETHBridge is IETHBridge {
+contract ETHBridge is IETHBridge, ReentrancyGuardTransient {
     mapping(bytes32 id => bool claimed) private _claimed;
 
     /// Incremental nonce to generate unique deposit IDs.
     uint256 private _globalDepositNonce;
 
-    /// Namespace for the ETH bridge.
-    bytes32 internal constant ETH_BRIDGE_NAMESPACE = keccak256("eth-bridge");
+    ISignalService public immutable signalService;
+
+    /// @dev Trusted source of commitments in the `CommitmentStore` that the bridge will use to validate withdrawals
+    /// @dev This is the Anchor on L2 and the Checkpoint Tracker on the L1
+    address public immutable trustedCommitmentPublisher;
+
+    /// @dev The counterpart bridge contract on the other chain.
+    /// This is used to locate deposit signals inside the other chain's state root.
+    /// WARN: This address has no significance (and may be untrustworthy) on this chain.
+    address public immutable counterpart;
+
+    constructor(address _signalService, address _trustedCommitmentPublisher, address _counterpart) {
+        require(_signalService != address(0), "Empty signal service");
+        require(_trustedCommitmentPublisher != address(0), "Empty trusted publisher");
+
+        signalService = ISignalService(_signalService);
+        trustedCommitmentPublisher = _trustedCommitmentPublisher;
+        counterpart = _counterpart;
+    }
 
     /// @inheritdoc IETHBridge
-    function claimed(bytes32 id) public view virtual returns (bool) {
+    function claimed(bytes32 id) public view returns (bool) {
         return _claimed[id];
     }
 
     /// @inheritdoc IETHBridge
-    function getDepositId(ETHDeposit memory ethDeposit) public view virtual returns (bytes32 id) {
+    function getDepositId(ETHDeposit memory ethDeposit) public pure returns (bytes32 id) {
         return _generateId(ethDeposit);
     }
 
     /// @inheritdoc IETHBridge
-    function deposit(address to, bytes memory data) public payable virtual returns (bytes32 id) {
+    function deposit(address to, bytes memory data) public payable returns (bytes32 id) {
         ETHDeposit memory ethDeposit = ETHDeposit(_globalDepositNonce, msg.sender, to, msg.value, data);
         id = _generateId(ethDeposit);
         unchecked {
             ++_globalDepositNonce;
         }
+
+        signalService.sendSignal(id);
         emit DepositMade(id, ethDeposit);
     }
 
     /// @inheritdoc IETHBridge
-    function claimDeposit(ETHDeposit memory ethDeposit, uint256 height, bytes memory proof)
-        external
-        returns (bytes32 id)
-    {
-        id = _generateId(ethDeposit);
-    }
-
-    /// @dev Processes deposit claim by id.
-    /// @param id Identifier of the deposit
-    /// @param ethDeposit Deposit to process
-    function _processClaimDepositWithId(bytes32 id, ETHDeposit memory ethDeposit) internal virtual {
+    function claimDeposit(ETHDeposit memory ethDeposit, uint256 height, bytes memory proof) external nonReentrant {
+        bytes32 id = _generateId(ethDeposit);
         require(!claimed(id), AlreadyClaimed());
+
+        signalService.verifySignal(height, trustedCommitmentPublisher, counterpart, id, proof);
+
         _claimed[id] = true;
         _sendETH(ethDeposit.to, ethDeposit.amount, ethDeposit.data);
+
         emit DepositClaimed(id, ethDeposit);
     }
 
     /// @dev Function to transfer ETH to the receiver but ignoring the returndata.
     /// @param to Address to send the ETH to
     /// @param value Amount of ETH to send
     /// @param data Data to send to the receiver
-    function _sendETH(address to, uint256 value, bytes memory data) internal virtual {
+    function _sendETH(address to, uint256 value, bytes memory data) internal {
         (bool success,) = to.call{value: value}(data);
         require(success, FailedClaim());
     }