feat(protocol): redesign Bridge fee & gasLimit and remove 2-step processing

packages/protocol/contracts/bridge/IBridge.sol

@@ -16,46 +16,34 @@ interface IBridge {
 
     struct Message {
         // Message ID whose value is automatically assigned.
-        uint128 id;
+        uint64 id;
+        // The max processing fee for the relayer. This fee has 3 parts:
+        // - the fee for message calldata.
+        // - the minimal fee reserve for general processing, excluding function call.
+        // - the invocation fee for the function call.
+        // Any unpaid fee will be refunded to the destOwner on the destination chain.
+        // Note that fee must be 0 if gasLimit is 0, or large enough to make the invocation fee
+        // non-zero.
+        uint64 fee;
+        // gasLimit that the processMessage call must have.
+        uint32 gasLimit;
         // The address, EOA or contract, that interacts with this bridge.
         // The value is automatically assigned.
         address from;
         // Source chain ID whose value is automatically assigned.
         uint64 srcChainId;
-        // Destination chain ID where the `to` address lives.
-        uint64 destChainId;
         // The owner of the message on the source chain.
         address srcOwner;
+        // Destination chain ID where the `to` address lives.
+        uint64 destChainId;
         // The owner of the message on the destination chain.
         address destOwner;
         // The destination address on the destination chain.
         address to;
-        // Alternate address to send any refund on the destination chain.
-        // If blank, defaults to destOwner.
-        address refundTo;
         // value to invoke on the destination chain.
         uint256 value;
-        // Processing fee for the relayer.
-        uint256 fee;
-        // gasLimit to invoke on the destination chain. If this value is zero, only destOwner can
-        // process the message. This value will mostly be respected when retrying
-        // (gas > gas_limit) but not when processed by the owner.
-        uint256 gasLimit;
         // callData to invoke on the destination chain.
         bytes data;
-        // Optional memo.
-        string memo;
-    }
-
-    // Note that this struct shall take only 1 slot to minimize gas cost
-    struct ProofReceipt {
-        // The time a message is marked as received on the destination chain
-        uint64 receivedAt;
-        // The address that can execute the message after the invocation delay without an extra
-        // delay.
-        // For a failed message, preferredExecutor's value doesn't matter as only the owner can
-        // invoke the message.
-        address preferredExecutor;
     }
 
     // Struct representing the context of a bridge operation.
@@ -71,44 +59,11 @@ interface IBridge {
     /// @param message The message.
     event MessageSent(bytes32 indexed msgHash, Message message);
 
-    /// @notice Emitted when a message is received.
-    /// @param msgHash The hash of the message.
-    /// @param message The message.
-    /// @param isRecall True if the message is a recall.
-    event MessageReceived(bytes32 indexed msgHash, Message message, bool isRecall);
-
-    /// @notice Emitted when a message is recalled.
-    /// @param msgHash The hash of the message.
-    event MessageRecalled(bytes32 indexed msgHash);
-
-    /// @notice Emitted when a message is executed.
-    /// @param msgHash The hash of the message.
-    event MessageExecuted(bytes32 indexed msgHash);
-
-    /// @notice Emitted when a message is retried.
-    /// @param msgHash The hash of the message.
-    event MessageRetried(bytes32 indexed msgHash);
-
-    /// @notice Emitted when a message is marked failed.
-    /// @param msgHash The hash of the message.
-    event MessageFailed(bytes32 indexed msgHash);
-
     /// @notice Emitted when the status of a message changes.
     /// @param msgHash The hash of the message.
     /// @param status The new status of the message.
     event MessageStatusChanged(bytes32 indexed msgHash, Status status);
 
-    /// @notice Emitted when a message is suspended or unsuspended.
-    /// @param msgHash The hash of the message.
-    /// @param suspended True if the message is suspended.
-    /// @param receivedAt The received-at timestamp, 0 if suspended is true.
-    event MessageSuspended(bytes32 msgHash, bool suspended, uint64 receivedAt);
-
-    /// @notice Emitted when an address is banned or unbanned.
-    /// @param addr The address to ban or unban.
-    /// @param banned True if the address is banned.
-    event AddressBanned(address indexed addr, bool banned);
-
     /// @notice Sends a message to the destination chain and takes custody
     /// of Ether required in this contract.
     /// @param _message The message to be sent.

packages/protocol/contracts/bridge/README.md

@@ -24,33 +24,34 @@ If user wants to bridge ether, he/she will initiate a bridge transaction with `s
 ```
     struct Message {
         // Message ID whose value is automatically assigned.
-        uint128 id;
+        uint64 id;
+        // The max processing fee for the relayer. This fee has 3 parts:
+        // - the fee for message calldata.
+        // - the minimal fee reserve for general processing, excluding function call.
+        // - the invocation fee for the function call.
+        // Any unpaid fee will be refunded to the destOwner on the destination chain.
+        // Note that fee must be 0 if gasLimit is 0, or large enough to make the invocation fee
+        // non-zero.
+        uint64 fee;
+        // gasLimit that the processMessage call must have.
+        uint32 gasLimit;
         // The address, EOA or contract, that interacts with this bridge.
         // The value is automatically assigned.
         address from;
         // Source chain ID whose value is automatically assigned.
         uint64 srcChainId;
-        // Destination chain ID where the `to` address lives.
-        uint64 destChainId;
         // The owner of the message on the source chain.
         address srcOwner;
+        // Destination chain ID where the `to` address lives.
+        uint64 destChainId;
         // The owner of the message on the destination chain.
         address destOwner;
         // The destination address on the destination chain.
         address to;
-        // Alternate address to send any refund on the destination chain.
-        // If blank, defaults to destOwner.
-        address refundTo;
         // value to invoke on the destination chain.
         uint256 value;
-        // Processing fee for the relayer.
-        uint256 fee;
-        // gasLimit to invoke on the destination chain. If this value is zero, only destOwner can process the message.
-        uint256 gasLimit;
         // callData to invoke on the destination chain.
         bytes data;
-        // Optional memo.
-        string memo;
     }
 ```
 
@@ -66,31 +67,29 @@ If user wants to bridge other tokens (`ERC20`, `ERC1155` or `ERC721`.) he/she wi
 In case of ERC20 the transaction can be initiated by initializing a struct (below) and calling `sendToken`:
 
 ```
-    struct BridgeTransferOp {
-        uint256 destChainId;
+  struct BridgeTransferOp {
+        uint64 destChainId;
+        address destOwner;
         address to;
+        uint64 fee;
         address token;
+        uint32 gasLimit;
         uint256 amount;
-        uint256 gasLimit;
-        uint256 fee;
-        address refundTo;
-        string memo;
     }
 ```
 
 In case of `ERC1155` or `ERC721`, the mechanism is the same but struct looks like this:
 
 ```
-struct BridgeTransferOp {
-        uint256 destChainId;
+    struct BridgeTransferOp {
+        uint64 destChainId;
+        address destOwner;
         address to;
+        uint64 fee;
         address token;
+        uint32 gasLimit;
         uint256[] tokenIds;
         uint256[] amounts;
-        uint256 gasLimit;
-        uint256 fee;
-        address refundTo;
-        string memo;
     }
 ```
 

packages/protocol/contracts/signal/ISignalService.sol

@@ -98,13 +98,15 @@ interface ISignalService {
     /// @param _signal The signal (message) to send.
     /// @param _proof Merkle proof that the signal was persisted on the
     /// source chain.
+    /// @return numCacheOps_ The number of newly cached items.
     function proveSignalReceived(
         uint64 _chainId,
         address _app,
         bytes32 _signal,
         bytes calldata _proof
     )
-        external;
+        external
+        returns (uint256 numCacheOps_);
 
     /// @notice Verifies if a signal has been received on the target chain.
     /// This is the "readonly" version of proveSignalReceived.

packages/protocol/contracts/signal/SignalService.sol

@@ -100,12 +100,13 @@ contract SignalService is EssentialContract, ISignalService {
         virtual
         whenNotPaused
         nonReentrant
+        returns (uint256 numCacheOps_)
     {
         CacheAction[] memory actions = // actions for caching
          _verifySignalReceived(_chainId, _app, _signal, _proof, true);
 
         for (uint256 i; i < actions.length; ++i) {
-            _cache(actions[i]);
+            numCacheOps_ += _cache(actions[i]);
         }
     }
 
@@ -259,12 +260,13 @@ contract SignalService is EssentialContract, ISignalService {
         emit SignalSent(_app, _signal, slot_, _value);
     }
 
-    function _cache(CacheAction memory _action) private {
+    function _cache(CacheAction memory _action) private returns (uint256 numCacheOps_) {
         // cache state root
         bool cacheStateRoot = _action.option == CacheOption.CACHE_BOTH
             || _action.option == CacheOption.CACHE_STATE_ROOT;
 
         if (cacheStateRoot && _action.isFullProof && !_action.isLastHop) {
+            numCacheOps_ = 1;
             _syncChainData(
                 _action.chainId, LibStrings.H_STATE_ROOT, _action.blockId, _action.rootHash
             );
@@ -275,6 +277,7 @@ contract SignalService is EssentialContract, ISignalService {
             || _action.option == CacheOption.CACHE_SIGNAL_ROOT;
 
         if (cacheSignalRoot && (_action.isFullProof || !_action.isLastHop)) {
+            numCacheOps_ += 1;
             _syncChainData(
                 _action.chainId, LibStrings.H_SIGNAL_ROOT, _action.blockId, _action.signalRoot
             );

packages/protocol/contracts/tokenvault/BaseNFTVault.sol

@@ -19,28 +19,17 @@ abstract contract BaseNFTVault is BaseVault {
         string name;
     }
 
-    // Struct representing the details of a bridged token transfer operation.
+    /// @devStruct representing the details of a bridged token transfer operation.
+    /// 5 slots
     struct BridgeTransferOp {
-        // Destination chain ID.
         uint64 destChainId;
-        // The owner of the bridge message on the destination chain.
         address destOwner;
-        // Recipient address.
         address to;
-        // Address of the token.
+        uint64 fee;
         address token;
-        // IDs of the tokens to transfer.
+        uint32 gasLimit;
         uint256[] tokenIds;
-        // Amounts of tokens to transfer.
         uint256[] amounts;
-        // Gas limit for the operation.
-        uint256 gasLimit;
-        // Processing fee for the relayer.
-        uint256 fee;
-        // Address for refund, if needed.
-        address refundTo;
-        // Optional memo.
-        string memo;
     }
 
     /// @notice ERC1155 interface ID.

packages/protocol/contracts/tokenvault/ERC1155Vault.sol

@@ -43,7 +43,7 @@ contract ERC1155Vault is BaseNFTVault, ERC1155ReceiverUpgradeable {
     /// @param _op Option for sending the ERC1155 token.
     /// @return message_ The constructed message.
 
-    function sendToken(BridgeTransferOp memory _op)
+    function sendToken(BridgeTransferOp calldata _op)
         external
         payable
         whenNotPaused
@@ -70,12 +70,10 @@ contract ERC1155Vault is BaseNFTVault, ERC1155ReceiverUpgradeable {
             srcOwner: msg.sender,
             destOwner: _op.destOwner != address(0) ? _op.destOwner : msg.sender,
             to: resolve(_op.destChainId, name(), false),
-            refundTo: _op.refundTo,
             value: msg.value - _op.fee,
             fee: _op.fee,
             gasLimit: _op.gasLimit,
-            data: data,
-            memo: _op.memo
+            data: data
         });
 
         // Send the message and obtain the message hash

packages/protocol/contracts/tokenvault/ERC20Vault.sol

@@ -28,16 +28,15 @@ contract ERC20Vault is BaseVault {
     }
 
     /// @dev Represents an operation to send tokens to another chain.
+    /// 4 slots
     struct BridgeTransferOp {
         uint64 destChainId;
         address destOwner;
         address to;
+        uint64 fee;
         address token;
+        uint32 gasLimit;
         uint256 amount;
-        uint256 gasLimit;
-        uint256 fee;
-        address refundTo;
-        string memo;
     }
 
     /// @notice Mappings from bridged tokens to their canonical tokens.
@@ -232,12 +231,10 @@ contract ERC20Vault is BaseVault {
             srcOwner: msg.sender,
             destOwner: _op.destOwner != address(0) ? _op.destOwner : msg.sender,
             to: resolve(_op.destChainId, name(), false),
-            refundTo: _op.refundTo,
             value: msg.value - _op.fee,
             fee: _op.fee,
             gasLimit: _op.gasLimit,
-            data: data,
-            memo: _op.memo
+            data: data
         });
 
         bytes32 msgHash;

packages/protocol/contracts/tokenvault/ERC721Vault.sol

@@ -29,7 +29,7 @@ contract ERC721Vault is BaseNFTVault, IERC721Receiver {
     /// by invoking the message call.
     /// @param _op Option for sending the ERC721 token.
     /// @return message_ The constructed message.
-    function sendToken(BridgeTransferOp memory _op)
+    function sendToken(BridgeTransferOp calldata _op)
         external
         payable
         whenNotPaused
@@ -55,12 +55,10 @@ contract ERC721Vault is BaseNFTVault, IERC721Receiver {
             srcOwner: msg.sender,
             destOwner: _op.destOwner != address(0) ? _op.destOwner : msg.sender,
             to: resolve(_op.destChainId, name(), false),
-            refundTo: _op.refundTo,
             value: msg.value - _op.fee,
             fee: _op.fee,
             gasLimit: _op.gasLimit,
-            data: data,
-            memo: _op.memo
+            data: data
         });
 
         bytes32 msgHash;

packages/protocol/genesis/GenerateGenesis.g.sol

@@ -154,7 +154,7 @@ contract TestGenerateGenesis is Test, AddressResolver {
 
         assertEq(ownerSecurityCouncil, bridgeProxy.owner());
 
-        vm.expectRevert(Bridge.B_NOT_RECEIVED.selector);
+        vm.expectRevert(Bridge.B_PERMISSION_DENIED.selector);
         bridgeProxy.processMessage(
             IBridge.Message({
                 id: 0,
@@ -164,12 +164,10 @@ contract TestGenerateGenesis is Test, AddressResolver {
                 srcOwner: address(0),
                 destOwner: address(0),
                 to: address(0),
-                refundTo: address(0),
                 value: 0,
                 fee: 0,
                 gasLimit: 0,
-                data: "",
-                memo: ""
+                data: ""
             }),
             ""
         );
@@ -190,12 +188,10 @@ contract TestGenerateGenesis is Test, AddressResolver {
                 srcOwner: address(0),
                 destOwner: address(0),
                 to: address(0),
-                refundTo: address(0),
                 value: 0,
                 fee: 0,
                 gasLimit: 0,
-                data: "",
-                memo: ""
+                data: ""
             }),
             ""
         );