GasFeePricingUpgradeable

contracts/messaging/MessageBusSenderUpgradeable.sol

@@ -45,7 +45,7 @@ contract MessageBusSenderUpgradeable is OwnableUpgradeable, PausableUpgradeable
         return keccak256(abi.encode(_srcAddress, _srcChainId, _dstAddress, _dstChainId, _srcNonce, _message));
     }
 
-    function estimateFee(uint256 _dstChainId, bytes calldata _options) public returns (uint256) {
+    function estimateFee(uint256 _dstChainId, bytes calldata _options) public view returns (uint256) {
         uint256 fee = IGasFeePricing(gasFeePricing).estimateGasFee(_dstChainId, _options);
         require(fee != 0, "Fee not set");
         return fee;

contracts/messaging/framework/SynMessagingReceiverUpgradeable.sol

@@ -44,30 +44,76 @@ abstract contract SynMessagingReceiverUpgradeable is ISynMessagingReceiver, Owna
         address _executor
     ) internal virtual;
 
+    // Send a message using full msg.value as fees, refund extra to msg.sender
     function _send(
         bytes32 _receiver,
         uint256 _dstChainId,
         bytes memory _message,
         bytes memory _options
     ) internal virtual {
-        _send(_receiver, _dstChainId, _message, _options, payable(msg.sender));
+        _send(_receiver, _dstChainId, _message, _options, msg.value, payable(msg.sender));
     }
 
+    // Send a message using full msg.value as fees, refund extra to specified address
     function _send(
         bytes32 _receiver,
         uint256 _dstChainId,
         bytes memory _message,
         bytes memory _options,
         address payable _refundAddress
     ) internal virtual {
-        require(trustedRemoteLookup[_dstChainId] != bytes32(0), "Receiver not trusted remote");
-        IMessageBus(messageBus).sendMessage{value: msg.value}(
-            _receiver,
-            _dstChainId,
-            _message,
-            _options,
-            _refundAddress
+        _send(_receiver, _dstChainId, _message, _options, msg.value, _refundAddress);
+    }
+
+    // Send a message to a bunch of chains, refund extra fees to specified address
+    function _send(
+        bytes32[] memory _receivers,
+        uint256[] memory _dstChainIds,
+        bytes memory _message,
+        bytes[] memory _options,
+        uint256[] memory _fees,
+        address payable _refundAddress
+    ) internal {
+        require(
+            _receivers.length == _fees.length && _dstChainIds.length == _fees.length && _options.length == _fees.length,
+            "!arrays"
+        );
+        for (uint256 i = 0; i < _fees.length; ++i) {
+            _send(_receivers[i], _dstChainIds[i], _message, _options[i], _fees[i], _refundAddress);
+        }
+    }
+
+    // Send a bunch of messages to a bunch of chains, refund extra fees to specified address
+    function _send(
+        bytes32[] memory _receivers,
+        uint256[] memory _dstChainIds,
+        bytes[] memory _messages,
+        bytes[] memory _options,
+        uint256[] memory _fees,
+        address payable _refundAddress
+    ) internal {
+        require(
+            _receivers.length == _fees.length &&
+                _dstChainIds.length == _fees.length &&
+                _messages.length == _fees.length &&
+                _options.length == _fees.length,
+            "!arrays"
         );
+        for (uint256 i = 0; i < _fees.length; ++i) {
+            _send(_receivers[i], _dstChainIds[i], _messages[i], _options[i], _fees[i], _refundAddress);
+        }
+    }
+
+    function _send(
+        bytes32 _receiver,
+        uint256 _dstChainId,
+        bytes memory _message,
+        bytes memory _options,
+        uint256 _fee,
+        address payable _refundAddress
+    ) internal {
+        require(trustedRemoteLookup[_dstChainId] != bytes32(0), "Receiver not trusted remote");
+        IMessageBus(messageBus).sendMessage{value: _fee}(_receiver, _dstChainId, _message, _options, _refundAddress);
     }
 
     //** Config Functions */

contracts/messaging/interfaces/IGasFeePricing.sol

@@ -24,5 +24,5 @@ interface IGasFeePricing {
      * @notice Returns srcGasToken fee to charge in wei for the cross-chain message based on the gas limit
      * @param _options Versioned struct used to instruct relayer on how to proceed with gas limits. Contains data on gas limit to submit tx with.
      */
-    function estimateGasFee(uint256 _dstChainId, bytes calldata _options) external returns (uint256);
+    function estimateGasFee(uint256 _dstChainId, bytes calldata _options) external view returns (uint256);
 }

contracts/messaging/libraries/Options.sol

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+library Options {
+    enum TxType {
+        UNKNOWN,
+        DEFAULT,
+        GASDROP
+    }
+
+    function encode(uint256 _gasLimit) internal pure returns (bytes memory) {
+        return abi.encodePacked(uint16(TxType.DEFAULT), _gasLimit);
+    }
+
+    function encode(
+        uint256 _gasLimit,
+        uint256 _gasDropAmount,
+        bytes32 _dstReceiver
+    ) internal pure returns (bytes memory) {
+        return abi.encodePacked(uint16(TxType.GASDROP), _gasLimit, _gasDropAmount, _dstReceiver);
+    }
+
+    function decode(bytes memory _options)
+        internal
+        pure
+        returns (
+            uint256 gasLimit,
+            uint256 gasDropAmount,
+            bytes32 dstReceiver
+        )
+    {
+        require(_options.length == 2 + 32 || _options.length == 2 + 32 * 3, "Wrong _options size");
+        uint16 txType;
+        // solhint-disable-next-line
+        assembly {
+            txType := mload(add(_options, 2))
+            gasLimit := mload(add(_options, 34))
+        }
+
+        if (txType == uint16(TxType.GASDROP)) {
+            // solhint-disable-next-line
+            assembly {
+                gasDropAmount := mload(add(_options, 66))
+                dstReceiver := mload(add(_options, 98))
+            }
+            require(gasDropAmount != 0, "gasDropAmount empty");
+            require(dstReceiver != bytes32(0), "dstReceiver empty");
+        }
+    }
+}

remappings.txt

@@ -1,2 +1,4 @@
 ds-test=lib/ds-test/src
-forge-std=lib/forge-std/src
+forge-std=lib/forge-std/src
+
+src-messaging=contracts/messaging

test/dfk/HeroBridgeTest.sol

@@ -3,19 +3,19 @@ pragma solidity 0.8.13;
 import "forge-std/Test.sol";
 import {Utilities} from "../utils/Utilities.sol";
 
-import "../../contracts/messaging/dfk/types/HeroTypes.sol";
-
-import "../../contracts/messaging/dfk/bridge/HeroBridgeUpgradeable.sol";
-import "../../contracts/messaging/dfk/random/RandomGenerator.sol";
-import "../../contracts/messaging/dfk/auctions/AssistingAuctionUpgradeable.sol";
-import "../../contracts/messaging/dfk/StatScienceUpgradeable.sol";
-import "../../contracts/messaging/dfk/HeroCoreUpgradeable.sol";
-
-import "../../contracts/messaging/MessageBusUpgradeable.sol";
-import "../../contracts/messaging/GasFeePricing.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
-import "../../contracts/messaging/apps/PingPong.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
+import "src-messaging/dfk/types/HeroTypes.sol";
+
+import "src-messaging/dfk/bridge/HeroBridgeUpgradeable.sol";
+import "src-messaging/dfk/random/RandomGenerator.sol";
+import "src-messaging/dfk/auctions/AssistingAuctionUpgradeable.sol";
+import "src-messaging/dfk/StatScienceUpgradeable.sol";
+import "src-messaging/dfk/HeroCoreUpgradeable.sol";
+
+import "src-messaging/MessageBusUpgradeable.sol";
+import "src-messaging/GasFeePricing.sol";
+import "src-messaging/AuthVerifier.sol";
+import "src-messaging/apps/PingPong.sol";
+import "src-messaging/AuthVerifier.sol";
 
 contract HeroBridgeUpgradeableTest is Test {
     Utilities internal utils;

test/dfk/HeroEncoding.t.sol

@@ -1,7 +1,7 @@
 pragma solidity 0.8.13;
 
 import "forge-std/Test.sol";
-import "../../contracts/messaging/dfk/types/HeroTypes.sol";
+import "src-messaging/dfk/types/HeroTypes.sol";
 
 contract HeroEncodingTest is Test {
     function testHeroStruct() public {

test/dfk/TearBridge.t.sol

@@ -3,12 +3,12 @@ pragma solidity 0.8.13;
 import "forge-std/Test.sol";
 import {Utilities} from "../utils/Utilities.sol";
 
-import "../../contracts/messaging/dfk/bridge/TearBridge.sol";
-import "../../contracts/messaging/dfk/inventory/GaiaTears.sol";
+import "src-messaging/dfk/bridge/TearBridge.sol";
+import "src-messaging/dfk/inventory/GaiaTears.sol";
 
-import "../../contracts/messaging/MessageBusUpgradeable.sol";
-import "../../contracts/messaging/GasFeePricing.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
+import "src-messaging/MessageBusUpgradeable.sol";
+import "src-messaging/GasFeePricing.sol";
+import "src-messaging/AuthVerifier.sol";
 
 contract TearBridgeTest is Test {
     Utilities internal utils;

test/messaging/AuthVerifier.t.sol

@@ -1,7 +1,7 @@
 pragma solidity 0.8.13;
 
 import "forge-std/Test.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
+import "src-messaging/AuthVerifier.sol";
 
 contract AuthVerifierTest is Test {
     AuthVerifier public authVerifier;

test/messaging/BatchMessageSender.t.sol

@@ -2,11 +2,11 @@ pragma solidity 0.8.13;
 
 import "forge-std/Test.sol";
 import {Utilities} from "../utils/Utilities.sol";
-import "../../contracts/messaging/MessageBusUpgradeable.sol";
-import "../../contracts/messaging/GasFeePricing.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
-import "../../contracts/messaging/apps/BatchMessageSender.sol";
-import "../../contracts/messaging/AuthVerifier.sol";
+import "src-messaging/MessageBusUpgradeable.sol";
+import "src-messaging/GasFeePricing.sol";
+import "src-messaging/AuthVerifier.sol";
+import "src-messaging/apps/BatchMessageSender.sol";
+import "src-messaging/AuthVerifier.sol";
 
 contract BatchMessageSenderTest is Test {
     Utilities internal utils;

test/messaging/GasFeePricing.t.sol

@@ -2,7 +2,7 @@ pragma solidity 0.8.13;
 
 import "forge-std/Test.sol";
 
-import "../../contracts/messaging/GasFeePricing.sol";
+import "src-messaging/GasFeePricing.sol";
 
 contract GasFeePricingTest is Test {
     GasFeePricing public gasFeePricing;