Add fee multiplier to protocol

contracts/src/DeployScript.sol

@@ -80,7 +80,8 @@ contract DeployScript is Script {
             assetHubAgentID: assetHubAgentID,
             assetHubCreateAssetFee: uint128(vm.envUint("CREATE_ASSET_FEE")),
             assetHubReserveTransferFee: uint128(vm.envUint("RESERVE_TRANSFER_FEE")),
-            exchangeRate: ud60x18(vm.envUint("EXCHANGE_RATE"))
+            exchangeRate: ud60x18(vm.envUint("EXCHANGE_RATE")),
+            multiplier: ud60x18(vm.envUint("FEE_MULTIPLIER"))
         });
 
         GatewayProxy gateway = new GatewayProxy(address(gatewayLogic), abi.encode(config));

contracts/src/Gateway.sol

@@ -390,6 +390,7 @@ contract Gateway is IGateway, IInitializable {
         SetPricingParametersParams memory params = abi.decode(data, (SetPricingParametersParams));
         pricing.exchangeRate = params.exchangeRate;
         pricing.deliveryCost = params.deliveryCost;
+        pricing.multiplier = params.multiplier;
         emit PricingParametersChanged();
     }
 
@@ -462,19 +463,22 @@ contract Gateway is IGateway, IInitializable {
     }
 
     // Convert foreign currency to native currency (ROC/KSM/DOT -> ETH)
-    function _convertToNative(UD60x18 exchangeRate, uint256 amount) internal view returns (uint256) {
-        UD60x18 amountFP = convert(amount);
+    function _convertToNative(UD60x18 exchangeRate, UD60x18 multiplier, UD60x18 amount)
+        internal
+        view
+        returns (uint256)
+    {
         UD60x18 ethDecimals = convert(1e18);
         UD60x18 foreignDecimals = convert(10).pow(convert(uint256(FOREIGN_TOKEN_DECIMALS)));
-        UD60x18 nativeAmountFP = amountFP.mul(exchangeRate).div(foreignDecimals).mul(ethDecimals);
-        uint256 nativeAmount = convert(nativeAmountFP);
-        return nativeAmount;
+        UD60x18 nativeAmount = multiplier.mul(amount).mul(exchangeRate).div(foreignDecimals).mul(ethDecimals);
+        return convert(nativeAmount);
     }
 
     // Calculate the fee for accepting an outbound message
     function _calculateFee(Costs memory costs) internal view returns (uint256) {
         PricingStorage.Layout storage pricing = PricingStorage.layout();
-        return costs.native + _convertToNative(pricing.exchangeRate, pricing.deliveryCost + costs.foreign);
+        UD60x18 amount = convert(pricing.deliveryCost + costs.foreign);
+        return costs.native + _convertToNative(pricing.exchangeRate, pricing.multiplier, amount);
     }
 
     // Submit an outbound message to Polkadot, after taking fees
@@ -569,24 +573,26 @@ contract Gateway is IGateway, IInitializable {
         uint128 assetHubReserveTransferFee;
         /// @dev extra fee to discourage spamming
         uint256 registerTokenFee;
+        /// @dev Fee multiplier
+        UD60x18 multiplier;
     }
 
     /// @dev Initialize storage in the gateway
     /// NOTE: This is not externally accessible as this function selector is overshadowed in the proxy
-    function initialize(bytes calldata data) external {
+    function initialize(bytes calldata data) external virtual {
         // Prevent initialization of storage in implementation contract
         if (ERC1967.load() == address(0)) {
             revert Unauthorized();
         }
 
-        Config memory config = abi.decode(data, (Config));
-
         CoreStorage.Layout storage core = CoreStorage.layout();
 
         if (core.channels[PRIMARY_GOVERNANCE_CHANNEL_ID].agent != address(0)) {
             revert AlreadyInitialized();
         }
 
+        Config memory config = abi.decode(data, (Config));
+
         core.mode = config.mode;
 
         // Initialize agent for BridgeHub
@@ -613,6 +619,7 @@ contract Gateway is IGateway, IInitializable {
         PricingStorage.Layout storage pricing = PricingStorage.layout();
         pricing.exchangeRate = config.exchangeRate;
         pricing.deliveryCost = config.deliveryCost;
+        pricing.multiplier = config.multiplier;
 
         // Initialize assets storage
         AssetsStorage.Layout storage assets = AssetsStorage.layout();

contracts/src/Params.sol

@@ -79,4 +79,6 @@ struct SetPricingParametersParams {
     UD60x18 exchangeRate;
     /// @dev The cost of delivering messages to BridgeHub in DOT
     uint128 deliveryCost;
+    /// @dev Fee multiplier
+    UD60x18 multiplier;
 }

contracts/src/storage/PricingStorage.sol

@@ -10,6 +10,8 @@ library PricingStorage {
         UD60x18 exchangeRate;
         /// @dev The cost of delivering messages to BridgeHub in DOT
         uint128 deliveryCost;
+        /// @dev Fee multiplier
+        UD60x18 multiplier;
     }
 
     bytes32 internal constant SLOT = keccak256("org.snowbridge.storage.pricing");

contracts/src/upgrades/rococo/GatewayV2.sol

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2023 Snowfork <[email protected]>
+pragma solidity 0.8.23;
+
+import "../../Gateway.sol";
+
+import {UD60x18, convert} from "prb/math/src/UD60x18.sol";
+import {PricingStorage} from "../../storage/PricingStorage.sol";
+
+contract GatewayV2 is Gateway {
+    constructor(
+        address beefyClient,
+        address agentExecutor,
+        ParaID bridgeHubParaID,
+        bytes32 bridgeHubAgentID,
+        uint8 foreignTokenDecimals
+    ) Gateway(beefyClient, agentExecutor, bridgeHubParaID, bridgeHubAgentID, foreignTokenDecimals) {}
+
+    function initialize(bytes memory data) external override {
+        // Prevent initialization of storage in implementation contract
+        if (ERC1967.load() == address(0)) {
+            revert Unauthorized();
+        }
+
+        PricingStorage.Layout storage pricing = PricingStorage.layout();
+
+        if (pricing.multiplier != convert(0)) {
+            revert AlreadyInitialized();
+        }
+
+        pricing.multiplier = abi.decode(data, (UD60x18));
+    }
+}

contracts/test/Gateway.t.sol

@@ -90,6 +90,7 @@ contract GatewayTest is Test {
 
     // ETH/DOT exchange rate
     UD60x18 public exchangeRate = ud60x18(0.0025e18);
+    UD60x18 public multiplier = ud60x18(1e18);
 
     function setUp() public {
         AgentExecutor executor = new AgentExecutor();
@@ -103,7 +104,8 @@ contract GatewayTest is Test {
             assetHubAgentID: assetHubAgentID,
             assetHubCreateAssetFee: createTokenFee,
             assetHubReserveTransferFee: sendTokenFee,
-            exchangeRate: exchangeRate
+            exchangeRate: exchangeRate,
+            multiplier: multiplier
         });
         gateway = new GatewayProxy(address(gatewayLogic), abi.encode(config));
         GatewayMock(address(gateway)).setCommitmentsAreVerified(true);
@@ -483,7 +485,7 @@ contract GatewayTest is Test {
         assertEq(GatewayV2(address(gateway)).getValue(), 42);
     }
 
-    function testUgradeInitializerRunsOnlyOnce() public {
+    function testUpgradeInitializerRunsOnlyOnce() public {
         // Upgrade to this current logic contract
         AgentExecutor executor = new AgentExecutor();
         GatewayMock currentLogic =
@@ -497,7 +499,8 @@ contract GatewayTest is Test {
             assetHubAgentID: assetHubAgentID,
             assetHubCreateAssetFee: createTokenFee,
             assetHubReserveTransferFee: sendTokenFee,
-            exchangeRate: exchangeRate
+            exchangeRate: exchangeRate,
+            multiplier: multiplier
         });
 
         UpgradeParams memory params = UpgradeParams({
@@ -516,7 +519,7 @@ contract GatewayTest is Test {
 
         testSetPricingParameters();
         uint256 fee = IGateway(address(gateway)).quoteRegisterTokenFee();
-        assertEq(fee, 10000000000000000);
+        assertEq(fee, 20000000000000001);
 
         testCreateAgent();
         assertNotEq(GatewayMock(address(gateway)).agentOf(agentID), address(0));
@@ -538,7 +541,7 @@ contract GatewayTest is Test {
 
         // Verify that storage was not overwritten
         fee = IGateway(address(gateway)).quoteRegisterTokenFee();
-        assertEq(fee, 10000000000000000);
+        assertEq(fee, 20000000000000001);
         assertNotEq(GatewayMock(address(gateway)).agentOf(agentID), address(0));
     }
 
@@ -875,14 +878,19 @@ contract GatewayTest is Test {
     function testSetPricingParameters() public {
         uint256 fee = IGateway(address(gateway)).quoteRegisterTokenFee();
         assertEq(fee, 5000000000000000);
-        // Double the exchangeRate
+        // Double both the exchangeRate and multiplier. Should lead to an 4x fee increase
         GatewayMock(address(gateway)).setPricingParametersPublic(
             abi.encode(
-                SetPricingParametersParams({exchangeRate: exchangeRate.mul(convert(2)), deliveryCost: outboundFee})
+                SetPricingParametersParams({
+                    exchangeRate: exchangeRate.mul(convert(2)),
+                    multiplier: multiplier.mul(convert(2)),
+                    deliveryCost: outboundFee
+                })
             )
         );
+        // Should expect 4x fee increase
         fee = IGateway(address(gateway)).quoteRegisterTokenFee();
-        assertEq(fee, 10000000000000000);
+        assertEq(fee, 20000000000000001);
     }
 
     function testSendTokenToForeignDestWithInvalidFee() public {

web/packages/test/scripts/set-env.sh

@@ -94,12 +94,13 @@ export REJECT_OUTBOUND_MESSAGES="${REJECT_OUTBOUND_MESSAGES:-false}"
 
 ## Fee
 export REGISTER_TOKEN_FEE="${REGISTER_TOKEN_FEE:-200000000000000000}"
-export DELIVERY_COST="${DELIVERY_COST:-10000000000}"
 export CREATE_ASSET_FEE="${CREATE_ASSET_FEE:-10000000000}"
 export RESERVE_TRANSFER_FEE="${RESERVE_TRANSFER_FEE:-10000000000}"
 
-## Price
+## Pricing Parameters
 export EXCHANGE_RATE="${EXCHANGE_RATE:-2500000000000000}"
+export DELIVERY_COST="${DELIVERY_COST:-10000000000}"
+export FEE_MULTIPLIER="${FEE_MULTIPLIER:-1000000000000000000}"
 export FEE_PER_GAS="${FEE_PER_GAS:-20000000000}"
 
 ## Reward