Fee for Gateway.sendToken should cover all costs (#1015)

Co-authored-by: ron <[email protected]>

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "contracts/lib/canonical-weth"]
 	path = contracts/lib/canonical-weth
 	url = https://github.com/Snowfork/canonical-weth
+[submodule "contracts/lib/prb-math"]
+	path = contracts/lib/prb-math
+	url = https://github.com/PaulRBerg/prb-math

contracts/remappings.txt

@@ -3,3 +3,4 @@ ds-test/=lib/ds-test/src/
 forge-std/=lib/forge-std/src/
 openzeppelin-contracts/=lib/openzeppelin-contracts/
 openzeppelin/=lib/openzeppelin-contracts/contracts/
+prb/math/=lib/prb-math/

contracts/src/AgentExecutor.sol

@@ -17,8 +17,7 @@ contract AgentExecutor {
     /// @dev Execute a message which originated from the Polkadot side of the bridge. In other terms,
     /// the `data` parameter is constructed by the BridgeHub parachain.
     ///
-    /// NOTE: There are no authorization checks here. Since this contract is only used for its code.
-    function execute(address, bytes memory data) external {
+    function execute(bytes memory data) external {
         (AgentExecuteCommand command, bytes memory params) = abi.decode(data, (AgentExecuteCommand, bytes));
         if (command == AgentExecuteCommand.TransferToken) {
             (address token, address recipient, uint128 amount) = abi.decode(params, (address, address, uint128));
@@ -29,7 +28,6 @@ contract AgentExecutor {
     /// @dev Transfer ether to `recipient`. Unlike `_transferToken` This logic is not nested within `execute`,
     /// as the gateway needs to control an agent's ether balance directly.
     ///
-    /// NOTE: There are no authorization checks here. Since this contract is only used for its code.
     function transferNative(address payable recipient, uint256 amount) external {
         recipient.safeNativeTransfer(amount);
     }

contracts/src/Assets.sol

@@ -9,7 +9,7 @@ import {SafeTokenTransferFrom} from "./utils/SafeTransfer.sol";
 
 import {AssetsStorage} from "./storage/AssetsStorage.sol";
 import {SubstrateTypes} from "./SubstrateTypes.sol";
-import {ParaID, MultiAddress} from "./Types.sol";
+import {ParaID, MultiAddress, Ticket, Costs} from "./Types.sol";
 import {Address} from "./utils/Address.sol";
 
 /// @title Library for implementing Ethereum->Polkadot ERC20 transfers.
@@ -23,14 +23,6 @@ library Assets {
     error InvalidDestination();
     error Unsupported();
 
-    // This library requires state which must be initialized in the gateway's storage.
-    function initialize(uint256 registerTokenFee, uint256 sendTokenFee) external {
-        AssetsStorage.Layout storage $ = AssetsStorage.layout();
-
-        $.registerTokenFee = registerTokenFee;
-        $.sendTokenFee = sendTokenFee;
-    }
-
     /// @dev transfer tokens from the sender to the specified
     function _transferToAgent(address assetHubAgent, address token, address sender, uint128 amount) internal {
         if (!token.isContract()) {
@@ -44,54 +36,100 @@ library Assets {
         IERC20(token).safeTransferFrom(sender, assetHubAgent, amount);
     }
 
+    function sendTokenCosts(ParaID assetHubParaID, ParaID destinationChain, uint128 destinationChainFee)
+        external
+        view
+        returns (Costs memory costs)
+    {
+        return _sendTokenCosts(assetHubParaID, destinationChain, destinationChainFee);
+    }
+
+    function _sendTokenCosts(ParaID assetHubParaID, ParaID destinationChain, uint128 destinationChainFee)
+        internal
+        view
+        returns (Costs memory costs)
+    {
+        AssetsStorage.Layout storage $ = AssetsStorage.layout();
+        if (assetHubParaID == destinationChain) {
+            costs.foreign = $.assetHubReserveTransferFee;
+        } else {
+            // If the final destination chain is not AssetHub, then the fee needs to additionally
+            // include the cost of executing an XCM on the final destination parachain.
+            costs.foreign = $.assetHubReserveTransferFee + destinationChainFee;
+        }
+        costs.native = 0;
+    }
+
     function sendToken(
         ParaID assetHubParaID,
         address assetHubAgent,
         address token,
         address sender,
         ParaID destinationChain,
         MultiAddress calldata destinationAddress,
+        uint128 destinationChainFee,
         uint128 amount
-    ) external returns (bytes memory payload, uint256 extraFee) {
+    ) external returns (Ticket memory ticket) {
         AssetsStorage.Layout storage $ = AssetsStorage.layout();
 
         _transferToAgent(assetHubAgent, token, sender, amount);
+        ticket.costs = _sendTokenCosts(assetHubParaID, destinationChain, destinationChainFee);
 
         if (destinationChain == assetHubParaID) {
             if (destinationAddress.isAddress32()) {
-                payload = SubstrateTypes.SendTokenToAssetHubAddress32(token, destinationAddress.asAddress32(), amount);
+                ticket.payload = SubstrateTypes.SendTokenToAssetHubAddress32(
+                    token, destinationAddress.asAddress32(), $.assetHubReserveTransferFee, amount
+                );
             } else {
+                // AssetHub does not support 20-byte account IDs
                 revert Unsupported();
             }
         } else {
             if (destinationAddress.isAddress32()) {
-                payload = SubstrateTypes.SendTokenToAddress32(
-                    token, destinationChain, destinationAddress.asAddress32(), amount
+                ticket.payload = SubstrateTypes.SendTokenToAddress32(
+                    token,
+                    destinationChain,
+                    destinationAddress.asAddress32(),
+                    $.assetHubReserveTransferFee,
+                    destinationChainFee,
+                    amount
                 );
             } else if (destinationAddress.isAddress20()) {
-                payload = SubstrateTypes.SendTokenToAddress20(
-                    token, destinationChain, destinationAddress.asAddress20(), amount
+                ticket.payload = SubstrateTypes.SendTokenToAddress20(
+                    token,
+                    destinationChain,
+                    destinationAddress.asAddress20(),
+                    $.assetHubReserveTransferFee,
+                    destinationChainFee,
+                    amount
                 );
             } else {
                 revert Unsupported();
             }
         }
-        extraFee = $.sendTokenFee;
-
         emit IGateway.TokenSent(sender, token, destinationChain, destinationAddress, amount);
     }
 
-    /// @dev Enqueues a create native token message to substrate.
-    /// @param token The ERC20 token address.
-    function registerToken(address token) external returns (bytes memory payload, uint256 extraFee) {
+    function registerTokenCosts() external view returns (Costs memory costs) {
+        return _registerTokenCosts();
+    }
+
+    function _registerTokenCosts() internal view returns (Costs memory costs) {
         AssetsStorage.Layout storage $ = AssetsStorage.layout();
+        costs.foreign = $.assetHubCreateAssetFee;
+        costs.native = $.registerTokenFee;
+    }
 
+    /// @dev Enqueues a create native token message to substrate.
+    /// @param token The ERC20 token address.
+    function registerToken(address token) external returns (Ticket memory ticket) {
         if (!token.isContract()) {
             revert InvalidToken();
         }
 
-        payload = SubstrateTypes.RegisterToken(token);
-        extraFee = $.registerTokenFee;
+        AssetsStorage.Layout storage $ = AssetsStorage.layout();
+        ticket.costs = _registerTokenCosts();
+        ticket.payload = SubstrateTypes.RegisterToken(token, $.assetHubCreateAssetFee);
 
         emit IGateway.TokenRegistrationSent(token);
     }

contracts/src/DeployScript.sol

@@ -15,6 +15,7 @@ import {AgentExecutor} from "./AgentExecutor.sol";
 import {ChannelID, ParaID, OperatingMode} from "./Types.sol";
 import {SafeNativeTransfer} from "./utils/SafeTransfer.sol";
 import {stdJson} from "forge-std/StdJson.sol";
+import {UD60x18, ud60x18} from "prb/math/src/UD60x18.sol";
 
 contract DeployScript is Script {
     using SafeNativeTransfer for address payable;
@@ -56,14 +57,17 @@ contract DeployScript is Script {
         ParaID assetHubParaID = ParaID.wrap(uint32(vm.envUint("ASSET_HUB_PARAID")));
         bytes32 assetHubAgentID = vm.envBytes32("ASSET_HUB_AGENT_ID");
 
+        uint8 foreignTokenDecimals = uint8(vm.envUint("FOREIGN_TOKEN_DECIMALS"));
+
         AgentExecutor executor = new AgentExecutor();
         Gateway gatewayLogic = new Gateway(
             address(beefyClient),
             address(executor),
             bridgeHubParaID,
             bridgeHubAgentID,
             assetHubParaID,
-            assetHubAgentID
+            assetHubAgentID,
+            foreignTokenDecimals
         );
 
         bool rejectOutboundMessages = vm.envBool("REJECT_OUTBOUND_MESSAGES");
@@ -76,9 +80,11 @@ contract DeployScript is Script {
 
         Gateway.Config memory config = Gateway.Config({
             mode: defaultOperatingMode,
-            outboundFee: vm.envUint("DEFAULT_FEE"),
-            registerTokenFee: vm.envUint("REGISTER_NATIVE_TOKEN_FEE"),
-            sendTokenFee: vm.envUint("SEND_NATIVE_TOKEN_FEE")
+            deliveryCost: uint128(vm.envUint("DELIVERY_COST")),
+            registerTokenFee: uint128(vm.envUint("REGISTER_TOKEN_FEE")),
+            assetHubCreateAssetFee: uint128(vm.envUint("CREATE_ASSET_FEE")),
+            assetHubReserveTransferFee: uint128(vm.envUint("RESERVE_TRANSFER_FEE")),
+            exchangeRate: ud60x18(vm.envUint("EXCHANGE_RATE"))
         });
 
         GatewayProxy gateway = new GatewayProxy(address(gatewayLogic), abi.encode(config));