Draft contract change for no native billing in data streams

contracts/scripts/native_solc_compile_all_llo-feeds

@@ -31,6 +31,7 @@ compileContract () {
 compileContract llo-feeds/Verifier.sol
 compileContract llo-feeds/VerifierProxy.sol
 compileContract llo-feeds/FeeManager.sol
+compileContract llo-feeds/FeeManagerNoNative.sol
 compileContract llo-feeds/RewardManager.sol
 
 

contracts/src/v0.8/llo-feeds/FeeManager.sol

@@ -173,7 +173,7 @@ contract FeeManager is IFeeManager, ConfirmedOwner, TypeAndVersionInterface {
     bytes calldata payload,
     bytes calldata parameterPayload,
     address subscriber
-  ) external payable override onlyProxy {
+  ) external payable virtual override onlyProxy {
     (Common.Asset memory fee, Common.Asset memory reward, uint256 appliedDiscount) = _processFee(
       payload,
       parameterPayload,
@@ -200,7 +200,7 @@ contract FeeManager is IFeeManager, ConfirmedOwner, TypeAndVersionInterface {
     bytes[] calldata payloads,
     bytes calldata parameterPayload,
     address subscriber
-  ) external payable override onlyProxy {
+  ) external payable virtual override onlyProxy {
     FeeAndReward[] memory feesAndRewards = new IFeeManager.FeeAndReward[](payloads.length);
 
     //keep track of the number of fees to prevent over initialising the FeePayment array within _convertToLinkAndNativeFees

contracts/src/v0.8/llo-feeds/FeeManagerNoNative.sol

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.19;
+
+import {IFeeManager} from "./interfaces/IFeeManager.sol";
+import {Common} from "./libraries/Common.sol";
+import {IERC20} from "../vendor/openzeppelin-solidity/v4.8.3/contracts/interfaces/IERC20.sol";
+import {SafeERC20} from "../vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/utils/SafeERC20.sol";
+import {FeeManager} from "./FeeManager.sol";
+
+/**
+ * @title FeeManagerNoNative
+ * @author Michael Fletcher
+ * @author Austin Born
+ * @author TJ Cunha
+ * @notice This contract is a variation of the FeeManager contract, and adds a modifier blocks native billing to fee handling functions
+ */
+contract FeeManagerNoNative is FeeManager {
+  using SafeERC20 for IERC20;
+
+  /// @notice thrown when trying to pay nativeFee with native, which is disallowed when we force wETH billing for nativeFee
+  error NativeBillingDisallowed();
+
+  modifier blockNativeBilling() {
+    if (msg.value != 0) revert NativeBillingDisallowed();
+    _;
+  }
+  constructor(
+    address _linkAddress,
+    address _nativeAddress,
+    address _proxyAddress,
+    address _rewardManagerAddress
+  ) FeeManager(_linkAddress, _nativeAddress, _proxyAddress, _rewardManagerAddress) {}
+
+  /// @inheritdoc FeeManager
+  function processFee(
+    bytes calldata payload,
+    bytes calldata parameterPayload,
+    address subscriber
+  ) external payable override onlyProxy blockNativeBilling {
+    (Common.Asset memory fee, Common.Asset memory reward, uint256 appliedDiscount) = _processFee(
+      payload,
+      parameterPayload,
+      subscriber
+    );
+
+    IFeeManager.FeeAndReward[] memory feeAndReward = new IFeeManager.FeeAndReward[](1);
+    feeAndReward[0] = IFeeManager.FeeAndReward(bytes32(payload), fee, reward, appliedDiscount);
+
+    if (fee.assetAddress == i_linkAddress) {
+      _handleFeesAndRewards(subscriber, feeAndReward, 1, 0);
+    } else {
+      _handleFeesAndRewards(subscriber, feeAndReward, 0, 1);
+    }
+  }
+
+  /// @inheritdoc FeeManager
+  function processFeeBulk(
+    bytes[] calldata payloads,
+    bytes calldata parameterPayload,
+    address subscriber
+  ) external payable override onlyProxy blockNativeBilling {
+    FeeAndReward[] memory feesAndRewards = new IFeeManager.FeeAndReward[](payloads.length);
+
+    //keep track of the number of fees to prevent over initialising the FeePayment array within _convertToLinkAndNativeFees
+    uint256 numberOfLinkFees;
+    uint256 numberOfNativeFees;
+
+    uint256 feesAndRewardsIndex;
+    for (uint256 i; i < payloads.length; ++i) {
+      (Common.Asset memory fee, Common.Asset memory reward, uint256 appliedDiscount) = _processFee(
+        payloads[i],
+        parameterPayload,
+        subscriber
+      );
+
+      if (fee.amount != 0) {
+        feesAndRewards[feesAndRewardsIndex++] = IFeeManager.FeeAndReward(
+          bytes32(payloads[i]),
+          fee,
+          reward,
+          appliedDiscount
+        );
+
+        unchecked {
+          //keep track of some tallys to make downstream calculations more efficient
+          if (fee.assetAddress == i_linkAddress) {
+            ++numberOfLinkFees;
+          } else {
+            ++numberOfNativeFees;
+          }
+        }
+      }
+    }
+
+    if (numberOfLinkFees != 0 || numberOfNativeFees != 0) {
+      _handleFeesAndRewards(subscriber, feesAndRewards, numberOfLinkFees, numberOfNativeFees);
+    }
+  }
+}