pay contract: pay axelar gas using native token

packages/contract/Makefile

@@ -12,12 +12,11 @@ full:
 	make build
 
 test:
-	# $(eval BASE_MAINNET_RPC ?= $(or $(BASE_MAINNET_RPC),https://base-rpc.publicnode.com)) # Use environment variable if set, otherwise use default
-	# @echo Running tests with RPC: $(BASE_MAINNET_RPC)
-	# forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --no-match-path "test/uniswap/*"
-	# forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --fork-block-number 14513720 --match-path "test/uniswap/*" --no-match-path "test/uniswap/Quoter.t.sol"
-	# forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --fork-block-number 15950101 --match-path "test/uniswap/Quoter.t.sol"
-	forge test -vvv --match-path "test/DaimoPay.t.sol"
+	$(eval BASE_MAINNET_RPC ?= $(or $(BASE_MAINNET_RPC),https://base-rpc.publicnode.com)) # Use environment variable if set, otherwise use default
+	@echo Running tests with RPC: $(BASE_MAINNET_RPC)
+	forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --no-match-path "test/uniswap/*"
+	forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --fork-block-number 14513720 --match-path "test/uniswap/*" --no-match-path "test/uniswap/Quoter.t.sol"
+	forge test -vvv --fork-url "$(BASE_MAINNET_RPC)" --fork-block-number 15950101 --match-path "test/uniswap/Quoter.t.sol"
 
 coverage:
 	$(eval BASE_MAINNET_RPC ?= $(or $(BASE_MAINNET_RPC),https://base-rpc.publicnode.com)) # Use environment variable if set, otherwise use default

packages/contract/script/pay/DeployDaimoPayAxelarBridger.s.sol

@@ -5,7 +5,6 @@ import "forge-std/Script.sol";
 import "openzeppelin-contracts/contracts/proxy/ERC1967/ERC1967Proxy.sol";
 
 import "../../src/pay/DaimoPayAxelarBridger.sol";
-import "../../src/pay/DaimoPayAxelarReceiver.sol";
 import "../Constants.s.sol";
 
 contract DeployDaimoPayAxelarBridger is Script {
@@ -24,7 +23,7 @@ contract DeployDaimoPayAxelarBridger is Script {
         address initOwner = msg.sender;
 
         address bridger = CREATE3.deploy(
-            keccak256("DaimoPayAxelarBridger-test3"),
+            keccak256("DaimoPayAxelarBridger-new2"),
             abi.encodePacked(
                 type(DaimoPayAxelarBridger).creationCode,
                 abi.encode(
@@ -54,7 +53,7 @@ contract DeployDaimoPayAxelarBridger is Script {
     {
         address axelarReceiver = CREATE3.getDeployed(
             msg.sender,
-            keccak256("DaimoPayAxelarReceiver-test3")
+            keccak256("DaimoPayAxelarBridger-new2")
         );
 
         bool testnet = _isTestnet(block.chainid);
@@ -76,12 +75,11 @@ contract DeployDaimoPayAxelarBridger is Script {
             block.chainid == OP_MAINNET ||
             block.chainid == POLYGON_MAINNET
         ) {
-            chainIds = new uint256[](2);
-            toTokens = new address[](2);
-            bridgeRoutes = new DaimoPayAxelarBridger.AxelarBridgeRoute[](2);
+            chainIds = new uint256[](1);
+            toTokens = new address[](1);
+            bridgeRoutes = new DaimoPayAxelarBridger.AxelarBridgeRoute[](1);
 
             chainIds[0] = BNB_MAINNET;
-            chainIds[1] = OP_MAINNET;
 
             for (uint32 i = 0; i < chainIds.length; ++i) {
                 toTokens[i] = _getAxlUSDCAddress(chainIds[i]);
@@ -90,7 +88,7 @@ contract DeployDaimoPayAxelarBridger is Script {
                     tokenSymbol: "axlUSDC",
                     localTokenAddr: _getAxlUSDCAddress(block.chainid),
                     receiverContract: axelarReceiver,
-                    fee: 1_000_000 // 1 USDC
+                    fee: 300000000000000 // 0.0003 ETH
                 });
             }
         } else if (block.chainid == BNB_MAINNET) {
@@ -112,7 +110,7 @@ contract DeployDaimoPayAxelarBridger is Script {
                     tokenSymbol: "axlUSDC",
                     localTokenAddr: _getAxlUSDCAddress(block.chainid),
                     receiverContract: axelarReceiver,
-                    fee: 1_000_000 // 1 USDC
+                    fee: 300000000000000 // 0.0003 ETH
                 });
             }
         } else {

packages/contract/script/pay/DeployDaimoPayRelayer.s.sol

@@ -14,7 +14,7 @@ contract DeployDaimoPayRelayer is Script {
         vm.startBroadcast();
 
         address daimoPayRelayer = CREATE3.deploy(
-            keccak256("DaimoPayRelayer-test11"),
+            keccak256("DaimoPayRelayer-new2"),
             abi.encodePacked(
                 type(DaimoPayRelayer).creationCode,
                 abi.encode(owner)

packages/contract/src/pay/DaimoPayAxelarBridger.sol

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pragma solidity ^0.8.12;
 
+import {AxelarExpressExecutableWithToken} from "@axelar-network/contracts/express/AxelarExpressExecutableWithToken.sol";
 import {IAxelarGatewayWithToken} from "@axelar-network/contracts/interfaces/IAxelarGatewayWithToken.sol";
 import {IAxelarGasService} from "@axelar-network/contracts/interfaces/IAxelarGasService.sol";
 import "@openzeppelin/contracts/utils/Strings.sol";
@@ -17,7 +18,11 @@ import "../interfaces/IDaimoPayBridger.sol";
 /// @dev Bridges assets from to a destination chain using Axelar Protocol. Makes
 /// the assumption that the local token is an ERC20 token and has a 1 to 1 price
 /// with the corresponding destination token.
-contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
+contract DaimoPayAxelarBridger is
+    IDaimoPayBridger,
+    AxelarExpressExecutableWithToken,
+    Ownable2Step
+{
     using SafeERC20 for IERC20;
     using Strings for address;
 
@@ -26,6 +31,7 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
         string tokenSymbol;
         address localTokenAddr;
         address receiverContract;
+        // Fee to be paid in native token for Axelar's bridging gas fee
         uint256 fee;
     }
 
@@ -66,7 +72,10 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
         uint256[] memory _toChainIds,
         address[] memory _toTokens,
         AxelarBridgeRoute[] memory _bridgeRoutes
-    ) Ownable(_owner) {
+    )
+        Ownable(_owner)
+        AxelarExpressExecutableWithToken(address(_axelarGateway))
+    {
         axelarGateway = _axelarGateway;
         axelarGasService = _axelarGasService;
 
@@ -135,11 +144,40 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
         });
     }
 
+    // ----- AXELAR EXECUTABLE FUNCTIONS -----
+
+    /// Part of the AxelarExpressExecutableWithToken interface. Used to make
+    /// a contract call on the destination chain without tokens. Not supported
+    /// by this implementation because we will always be bridging tokens.
+    function _execute(
+        bytes32 /* commandId */,
+        string calldata /* sourceChain */,
+        string calldata /* sourceAddress */,
+        bytes calldata /* payload */
+    ) internal pure override {
+        revert("DPAxB: _execute not supported");
+    }
+
+    /// Part of the AxelarExpressExecutableWithToken interface. Used to make
+    /// a contract call on the destination chain with tokens. Will always be
+    /// used to transfer tokens to the intent address on the destination chain.
+    function _executeWithToken(
+        bytes32 /* commandId */,
+        string calldata /* sourceChain */,
+        string calldata /* sourceAddress */,
+        bytes calldata payload,
+        string calldata tokenSymbol,
+        uint256 amount
+    ) internal override {
+        address recipient = abi.decode(payload, (address));
+        address tokenAddress = axelarGateway.tokenAddresses(tokenSymbol);
+
+        IERC20(tokenAddress).safeTransfer(recipient, amount);
+    }
+
     // ----- BRIDGING FUNCTIONS -----
 
-    /// Get the local token that corresponds to the destination token. Get the
-    /// minimum input amount for a given output amount. The input amount must
-    /// cover the max of the percentage fee and the flat fee.
+    /// Get the local token that corresponds to the destination token.
     function getInputTokenAmount(
         uint256 toChainId,
         address toToken,
@@ -148,20 +186,22 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
         AxelarBridgeRoute memory bridgeRoute = bridgeRouteMapping[toChainId][
             toToken
         ];
-        return (bridgeRoute.localTokenAddr, toAmount + bridgeRoute.fee);
+        return (bridgeRoute.localTokenAddr, toAmount);
     }
 
-    /// Initiate a bridge to a destination chain using Across Protocol.
+    /// Initiate a bridge to a destination chain using Axelar Protocol.
     function sendToChain(
         uint256 toChainId,
         address toAddress,
         address toToken,
         uint256 toAmount,
-        bytes calldata /* extraData */
+        bytes calldata extraData
     ) public {
         require(toChainId != block.chainid, "DPAxB: same chain");
         require(toAmount > 0, "DPAxB: zero amount");
 
+        address refundAddress = abi.decode(extraData, (address));
+
         // Get the local token that corresponds to the destination token.
         (address inputToken, uint256 inputAmount) = getInputTokenAmount({
             toChainId: toChainId,
@@ -173,36 +213,40 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
             toToken
         ];
 
-        // Move input token from caller to this contract and approve the
-        // AxelarGateway contract.
+        // Move input token from caller to this contract
         IERC20(inputToken).safeTransferFrom({
             from: msg.sender,
             to: address(this),
             value: inputAmount
         });
-        IERC20(inputToken).forceApprove({
-            spender: address(axelarGateway),
-            value: inputAmount
-        });
 
-        axelarGasService.payGasForExpressCallWithToken(
-            msg.sender,
+        // Pay for Axelar's bridging gas fee.
+        axelarGasService.payNativeGasForContractCallWithToken{
+            value: bridgeRoute.fee
+        }(
+            address(this),
             bridgeRoute.destChainName,
             bridgeRoute.receiverContract.toHexString(),
             abi.encode(toAddress),
             bridgeRoute.tokenSymbol,
-            inputAmount,
-            inputToken,
-            bridgeRoute.fee,
-            msg.sender
+            toAmount,
+            refundAddress
         );
 
+        // Approve the AxelarGateway contract and initiate the bridge. Send the
+        // tokens to the DaimoPayAxelarBridger on the destination chain. The
+        // _executeWithToken function will be called on the destination chain
+        // to transfer the tokens to the toAddress.
+        IERC20(inputToken).forceApprove({
+            spender: address(axelarGateway),
+            value: toAmount
+        });
         axelarGateway.callContractWithToken(
             bridgeRoute.destChainName,
             bridgeRoute.receiverContract.toHexString(),
             abi.encode(toAddress),
             bridgeRoute.tokenSymbol,
-            inputAmount
+            toAmount
         );
 
         emit BridgeInitiated({
@@ -215,4 +259,6 @@ contract DaimoPayAxelarBridger is IDaimoPayBridger, Ownable2Step {
             toAmount: toAmount
         });
     }
+
+    receive() external payable {}
 }

packages/contract/src/pay/DaimoPayRelayer.sol

@@ -117,6 +117,26 @@ contract DaimoPayRelayer is Ownable2Step {
         );
     }
 
+    function startIntent(
+        DaimoPay dp,
+        PayIntent calldata intent,
+        Call[] calldata calls,
+        bytes calldata bridgeExtraData,
+        uint256 bridgeGasFee
+    ) public onlyOwner {
+        // We use Axelar when bridging to/from BSC. Axelar requries a native token
+        // payment for the gas fee.
+        if (block.chainid == 56 || intent.toChainId == 56) {
+            DaimoPayBridger bridger = dp.bridger();
+            IDaimoPayBridger axelarBridger = bridger.chainIdToBridger(56);
+            (bool success, ) = address(axelarBridger).call{value: bridgeGasFee}(
+                ""
+            );
+            require(success, "DPR: axelar fee transfer failed");
+        }
+        dp.startIntent(intent, calls, bridgeExtraData);
+    }
+
     function fastFinish(
         DaimoPay dp,
         PayIntent calldata intent,