├── .github └── workflows │ └── test.yml ├── .gitignore ├── .gitmodules ├── LICENSE ├── README.md ├── foundry.toml ├── src ├── DestinationSettler.sol ├── DestinationSettler2.sol ├── DestinationSettler3.sol ├── ERC7683.sol ├── ERC7683Permit2Lib.sol ├── IPermit2.sol ├── OriginSettler.sol ├── ResolvedCrossChainOrderLib.sol └── Structs.sol └── test ├── DestinationSettler.t.sol └── OriginSettler.t.sol /.github/workflows/test.yml: -------------------------------------------------------------------------------- 1 | name: CI 2 | 3 | on: 4 | push: 5 | pull_request: 6 | workflow_dispatch: 7 | 8 | env: 9 | FOUNDRY_PROFILE: ci 10 | 11 | jobs: 12 | check: 13 | strategy: 14 | fail-fast: true 15 | 16 | name: Foundry project 17 | runs-on: ubuntu-latest 18 | steps: 19 | - uses: actions/checkout@v4 20 | with: 21 | submodules: recursive 22 | 23 | - name: Install Foundry 24 | uses: foundry-rs/foundry-toolchain@v1 25 | with: 26 | version: nightly 27 | 28 | - name: Show Forge version 29 | run: | 30 | forge --version 31 | 32 | - name: Run Forge fmt 33 | run: | 34 | forge fmt --check 35 | id: fmt 36 | 37 | - name: Run Forge build 38 | run: | 39 | forge build --sizes 40 | id: build 41 | 42 | - name: Run Forge tests 43 | run: | 44 | forge test -vvv 45 | id: test 46 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Compiler files 2 | cache/ 3 | out/ 4 | 5 | # Ignores development broadcast logs 6 | !/broadcast 7 | /broadcast/*/31337/ 8 | /broadcast/**/dry-run/ 9 | 10 | # Docs 11 | docs/ 12 | 13 | # Dotenv file 14 | .env 15 | -------------------------------------------------------------------------------- /.gitmodules: -------------------------------------------------------------------------------- 1 | [submodule "lib/forge-std"] 2 | path = lib/forge-std 3 | url = https://github.com/foundry-rs/forge-std 4 | [submodule "lib/openzeppelin-contracts"] 5 | path = lib/openzeppelin-contracts 6 | url = https://github.com/openzeppelin/openzeppelin-contracts 7 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU AFFERO GENERAL PUBLIC LICENSE 2 | Version 3, 19 November 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU Affero General Public License is a free, copyleft license for 11 | software and other kinds of works, specifically designed to ensure 12 | cooperation with the community in the case of network server software. 13 | 14 | The licenses for most software and other practical works are designed 15 | to take away your freedom to share and change the works. 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It is safest 628 | to attach them to the start of each source file to most effectively 629 | state the exclusion of warranty; and each file should have at least 630 | the "copyright" line and a pointer to where the full notice is found. 631 | 632 | 633 | Copyright (C) 634 | 635 | This program is free software: you can redistribute it and/or modify 636 | it under the terms of the GNU Affero General Public License as published 637 | by the Free Software Foundation, either version 3 of the License, or 638 | (at your option) any later version. 639 | 640 | This program is distributed in the hope that it will be useful, 641 | but WITHOUT ANY WARRANTY; without even the implied warranty of 642 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 643 | GNU Affero General Public License for more details. 644 | 645 | You should have received a copy of the GNU Affero General Public License 646 | along with this program. If not, see . 647 | 648 | Also add information on how to contact you by electronic and paper mail. 649 | 650 | If your software can interact with users remotely through a computer 651 | network, you should also make sure that it provides a way for users to 652 | get its source. For example, if your program is a web application, its 653 | interface could display a "Source" link that leads users to an archive 654 | of the code. There are many ways you could offer source, and different 655 | solutions will be better for different programs; see section 13 for the 656 | specific requirements. 657 | 658 | You should also get your employer (if you work as a programmer) or school, 659 | if any, to sign a "copyright disclaimer" for the program, if necessary. 660 | For more information on this, and how to apply and follow the GNU AGPL, see 661 | . 662 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Motivation 2 | 3 | This repository demonstrates how EIP7702 can allow a user to delegate a cross chain action via an ERC7683 order. 4 | 5 | ## Summary 6 | 7 | [ERC7683](https://eips.ethereum.org/EIPS/eip-7683) generally supports a cross-chain user flow where the user can create an intent on an origin chain containing call data to be executed on a destination chain. This destination chain execution should be funded by assets deposited on the origin chain. 8 | 9 | This 7683 intent can be combined with an [EIP7702](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-7702.md)-compatible smart contract wallet deployed on the destination chain to allow the destination chain calldata execution to look like it was sent from the user's EOA, instead of from the smart contract wallet address. 10 | 11 | This repository contains contracts and scripts demonstrating this flow. 12 | 13 | ## Intended cross-chain flow 14 | 15 | 1. User signs destination UserOp (`UserOp = [{calldata, target},{},...]`). 16 | 2. (optional) User signs destination 7702 delegation. 17 | 3. User creates 7683 order containing 1 & 2. 18 | 4. User sends `open` transaction on origin chain `OriginSettler` 19 | 5. Relayer sees 7683 order 20 | 6. Relayer sends fill on destination chain `DestinationSettler` 21 | 7. (optional) If fill requires user delegation to be set up, relayer must include this in their fill txn, which should be a type 4 txn. 22 | 8. Fill pulls funds from filler's account to the user’s EOA and then calls `XAccount.xExecute` on user’s EOA with the UserOp 23 | 10. **`XAccount` now executes UserOp within the context of the user's EOA** where the `msg.sender` is now set to the user's EOA and the `code` is set to the `XAccount` 24 | 11. If fill is submitted successfully and as user ordered in 7683 order, filler can get refund 25 | 26 | ## On-chain Components 27 | 28 | - `OriginSettler`: Origin chain contract that user interacts with to open an ERC7683 cross-chain intent. The `open` function helps the user to form an ERC7683 intent correctly containing the `calldata` that the user wants to delegate to a filler to execute on the destination chain. `openFor` can be used to help a user pass their signed order to a filler off-chain and subsequently allows the filler to create the 7683 order on the user's behalf. Therefore, `openFor` allows the user to experience a totally gas-free experience from origin to destination chain. 29 | - The `open` functionality also optionally lets the user include a 7702 authorization that the user wants the filler to submit on-chain on their behalf. This can be used to allow the user to set the `code` of their destination chain EOA to the `XAccount` contract. 30 | - The 7683 order contains the destination chain calldata in a [`FillInstruction`](https://eips.ethereum.org/EIPS/eip-7683#fillerdata). If the 7702 delegation is a prerequisite for executing this calldata on the destination chain, then the filler should get the delegation data from the `OriginSettler` events. 31 | - `DestinationSettler`: Destination chain contract that filler interacts with to fulfill a ERC7683 cross-chain intent. The `fill` function is used by the `filler` to credit the user's EOA with any assets that they had deposited on the `OriginSettler` when initiating the 7683 intent and subsequently execute any `calldata` on behalf of the user that was included in the 7683 intent. 32 | - The `fill` function will delegate execution of `calldata` to the `XAccount` 7702-compatible proxy contract so it is a prerequisite that the user has already set their destination chain EOA's `code` to `XAccount` via a 7702 transaction. The authorization should submitted by the user or delegated 33 | to the filler to set. 34 | - As stated above, the `OriginSettler#open` function can be used by the user to include a 7702 authorization to be submitted by the filler on the destination chain. This way the user can complete the prerequisite 7702 transaction and delegate the `calldata` execution in the same 7683 intent. 35 | - `XAccount`: Destination chain proxy contract that users should set as their `code` via a 7702 type 4 transaction. Verifies that any calldata execution delegated to it was signed by the expected user. 36 | 37 | ## Differences between DestinationSettler.sol variants 38 | 39 | This repository contains multiple DestinationSettler{2,3}.sol contracts that demonstrate different ways of setting up the `XAccount` smart contract wallet and how they interact with the `DestinationSettler` contract. 40 | 41 | The `DestinationSettler.sol` contract delegates all signature and UserOp verification to the `XAccount` wallet so that users need to only trust the `XAccount` contract and can use this wallet with any settlement system. 42 | 43 | The `DestinationSettler2.sol` performs all signature and UserOp verification and only uses the `XAccount` wallet as a Multicaller or Multisender contract to execute the calls. This reduces gas costs compared to `DestinationSettler.sol` but it means the user needs to trust the `DestinationSettler2.sol`. There are reasons not to combine the escrow logic with the verification logic so this is offered as an alternative to `DestinationSettler.sol` which separates the concerns. 44 | 45 | The `DestinationSettler3.sol` offers similar UX to the `DestinationSettler2.sol` in that the user must trust the settlement contract to perform verification, but this contract also performs the Multicaller duties. Its even more gas efficient than `DestinationSettler2.sol` because there is no `XAccount` contract to call. 46 | 47 | ## Off-chain components 48 | 49 | - Relayer that will pick up 7683 order and fill it on destination. 50 | 51 | ## Security 52 | 53 | The main architecture decision we made was whether to place the destination chain signature verification logic in the `DestinationSettler` or the `XAccount` contract. By placing this in the latter, we are implicitly encouraging there to be many different types of destination chain settlement contracts, that offer different fulfillment guarantees and features to fillers, that all delegate UserOp execution to a singleton `XAccount` contract. The user needs to trust that `XAccount` will do what its supposed to do. 54 | 55 | The alternative would be to instead encourage that the `DestinationSettler` contract is a singleton contract that should be trusted by users. Any UserOp verification logic enforced in the settlement contract would be shared across all users. This would make the `XAccount` contract much simpler. We decided against this as the default option because we believe there are opinionated settlement contract features that would greatly improve user and filler UX but that we didn't want to include in a singleton contract. 56 | 57 | For example, the settlement contract should ideally protect against duplicate fulfillment of the same 7683 order and simultaneously allow the user to protect fillers from colliding fill transactions. These features would require the `fill` function on the settlement contract to include parameters like `exclusiveRelayer` and enforce logic like checking if `fillStatuses[fillHash] = true`. But, we believe there are strong arguments for why these features are opinionated and do not belong in a generalized `DestinationSettler` contract. 58 | 59 | We also think its better for users if they only need to designate a smart contract wallet they trust that can work with any settlement system, rather than have to trust each settlement system they interact with. This assumes there will be multiple settlement systems offered to users eventually. 60 | 61 | ## EIP7702 resources 62 | 63 | [This best-practices document](https://hackmd.io/@rimeissner/eip7702-best-practices) was very useful in guiding design of `XAccount` 64 | -------------------------------------------------------------------------------- /foundry.toml: -------------------------------------------------------------------------------- 1 | [profile.default] 2 | src = "src" 3 | out = "out" 4 | libs = ["lib"] 5 | remappings = [ 6 | "@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/" 7 | ] 8 | optimizer_runs = 1_000_000 9 | 10 | # See more config options https://github.com/foundry-rs/foundry/blob/master/crates/config/README.md#all-options 11 | -------------------------------------------------------------------------------- /src/DestinationSettler.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol"; 4 | import {SignatureChecker} from "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol"; 5 | import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; 6 | import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; 7 | import {GaslessCrossChainOrder} from "./ERC7683.sol"; 8 | import {CallByUser, Call} from "./Structs.sol"; 9 | import {ResolvedCrossChainOrderLib} from "./ResolvedCrossChainOrderLib.sol"; 10 | 11 | /** 12 | * @notice Destination chain entrypoint contract for fillers relaying cross chain message containing delegated 13 | * calldata. 14 | * @dev This is a simple escrow contract that is encouraged to be modified by different xchain settlement systems 15 | * that might want to add features such as exclusive filling, deadlines, fee-collection, etc. 16 | * @dev This could be replaced by the Across SpokePool, for example, which gives fillers many features with which 17 | * to protect themselves from malicious users and moreover allows them to provide transparent pricing to users. 18 | * However, this contract could be bypassed almost completely by lightweight settlement systems that could essentially 19 | * combine its logic with the XAccount contract to avoid the extra transferFrom and approve steps required in a more 20 | * complex escrow system. 21 | */ 22 | contract DestinationSettler is ReentrancyGuard { 23 | using SafeERC20 for IERC20; 24 | 25 | /// @notice Store unique orders to prevent duplicate fills for the same order. 26 | mapping(bytes32 => bool) public fillStatuses; 27 | 28 | error InvalidOrderId(); 29 | error DuplicateFill(); 30 | 31 | // Called by filler, who sees ERC7683 intent emitted on origin chain 32 | // containing the callsByUser data to be executed following a 7702 delegation. 33 | // @dev We don't use the last parameter `fillerData` in this function. 34 | function fill(bytes32 orderId, bytes calldata originData, bytes calldata) external nonReentrant { 35 | (CallByUser memory callsByUser) = abi.decode(originData, (CallByUser)); 36 | if (ResolvedCrossChainOrderLib.getOrderId(callsByUser) != orderId) revert InvalidOrderId(); 37 | 38 | // Protect against duplicate fills. 39 | if (fillStatuses[orderId]) revert DuplicateFill(); 40 | fillStatuses[orderId] = true; 41 | 42 | // TODO: Protect fillers from collisions with other fillers. Requires letting user set an exclusive relayer. 43 | 44 | // Pull funds into this settlement contract and perform any steps necessary to ensure that filler 45 | // receives a refund of their assets. 46 | _fundAndApproveXAccount(callsByUser); 47 | 48 | // The following call will only succeed if the user has set a 7702 authorization to set its code 49 | // equal to the XAccount contract. The filler should have seen any auth data emitted in an OriginSettler 50 | // event on the sending chain. 51 | XAccount(payable(callsByUser.user)).xExecute(orderId, callsByUser); 52 | 53 | // Perform any final steps required to prove that filler has successfully filled the ERC7683 intent. 54 | // For example, we could emit an event containing a unique hash of the fill that could be proved 55 | // on the origin chain via a receipt proof + RIP7755. 56 | // e.g. emit Executed(orderId) 57 | } 58 | 59 | // Pull funds into this settlement contract as escrow and use to execute user's calldata. Escrowed 60 | // funds will be paid back to filler after this contract successfully verifies the settled intent. 61 | // This step could be skipped by lightweight escrow systems that don't need to perform additional 62 | // validation on the filler's actions. 63 | function _fundAndApproveXAccount(CallByUser memory call) internal { 64 | IERC20(call.asset.token).safeTransferFrom(msg.sender, address(this), call.asset.amount); 65 | IERC20(call.asset.token).forceApprove(call.user, call.asset.amount); 66 | } 67 | } 68 | 69 | // TODO: Move to separate file once we are more confident in architecture. For now keep here for readability. 70 | 71 | /** 72 | * @notice Singleton contract used by all users who want to sign data on origin chain and delegate execution of 73 | * their calldata on this chain to this contract. 74 | */ 75 | contract XAccount is ReentrancyGuard { 76 | using SafeERC20 for IERC20; 77 | 78 | error CallReverted(uint256 index, Call[] calls); 79 | error InvalidCall(uint256 index, Call[] calls); 80 | error DuplicateExecution(); 81 | error InvalidExecutionChainId(); 82 | error InvalidUserSignature(); 83 | 84 | /// @notice Store unique user ops to prevent duplicate executions. 85 | mapping(bytes32 => bool) public executionStatuses; 86 | 87 | /** 88 | * @notice Entrypoint function to be called by DestinationSettler contract on this chain. Should pull funds 89 | * to user's EOA and then execute calldata. 90 | * @dev Assume user has 7702-delegated code already to this contract. 91 | * @dev All calldata and 7702 authorization data is assumed to have been emitted on the origin chain in am ERC7683 92 | * intent creation event. 93 | */ 94 | function xExecute(bytes32 orderId, CallByUser memory userCalls) external nonReentrant { 95 | if (executionStatuses[orderId]) revert DuplicateExecution(); 96 | executionStatuses[orderId] = true; 97 | 98 | // Verify that the user signed the data blob. 99 | _verifyCalls(userCalls); 100 | // Verify that any included 7702 authorization data is as expected. 101 | _verify7702Delegation(); 102 | _fundUser(userCalls); 103 | 104 | // TODO: Should we allow user to handle case where the calls fail and they want to specify 105 | // a fallback recipient? This might not be neccessary since the user will have pulled funds 106 | // into their account so worst case they'll still have access to those funds. 107 | _attemptCalls(userCalls.calls); 108 | } 109 | 110 | function _verifyCalls(CallByUser memory userCalls) internal view { 111 | if (userCalls.chainId != block.chainid) revert InvalidExecutionChainId(); 112 | // @dev address(this) should be the userCall.user's EOA. 113 | // TODO: Make the blob to sign EIP712-compatible (i.e. instead of keccak256(abi.encode(...)) set 114 | // this to SigningLib.getTypedDataHash(...) 115 | if ( 116 | !SignatureChecker.isValidSignatureNow( 117 | address(this), keccak256(abi.encode(userCalls.calls, userCalls.nonce)), userCalls.signature 118 | ) 119 | ) revert InvalidUserSignature(); 120 | } 121 | 122 | function _verify7702Delegation() internal { 123 | // TODO: We might not need this function at all, because if the authorization data requires that this contract 124 | // is set as the delegation code, then xExecute would fail if the auth data is not submitted by the filler. 125 | // However, it might still be useful to verify that the delegate is set correctly, like checking EXTCODEHASH. 126 | } 127 | 128 | function _attemptCalls(Call[] memory calls) internal { 129 | for (uint256 i = 0; i < calls.length; ++i) { 130 | Call memory call = calls[i]; 131 | 132 | // If we are calling an EOA with calldata, assume target was incorrectly specified and revert. 133 | if (call.callData.length > 0 && call.target.code.length == 0) { 134 | revert InvalidCall(i, calls); 135 | } 136 | 137 | (bool success,) = call.target.call{value: call.value}(call.callData); 138 | if (!success) revert CallReverted(i, calls); 139 | } 140 | } 141 | 142 | function _fundUser(CallByUser memory call) internal { 143 | IERC20(call.asset.token).safeTransferFrom(msg.sender, call.user, call.asset.amount); 144 | } 145 | 146 | // Used if the caller is trying to unwrap the native token to this contract. 147 | receive() external payable {} 148 | } 149 | -------------------------------------------------------------------------------- /src/DestinationSettler2.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol"; 4 | import {SignatureChecker} from "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol"; 5 | import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; 6 | import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; 7 | import {GaslessCrossChainOrder} from "./ERC7683.sol"; 8 | import {CallByUser, Call} from "./Structs.sol"; 9 | import {ResolvedCrossChainOrderLib} from "./ResolvedCrossChainOrderLib.sol"; 10 | 11 | /** 12 | * @notice Destination chain entrypoint contract for fillers relaying cross chain message containing delegated 13 | * calldata. 14 | * @dev The difference between this contract and the DestinationSettler.sol contract is that this contract 15 | * performs all the CallByUser signature verification rather than having the XAccount contract do it. This reduces 16 | * gas costs in the `fill()` function but it does mean that all users must trust the DestinationSettler 17 | * contract since it performs the signature verification. Unlike this contract, the DestinationSettler.sol contract 18 | * can be swapped out for another settlement contract because the XAccount provides the signature verification 19 | * protection for the user. As a result, the XAccount smart contract wallet used by this settler is much more 20 | * lightweight than the one used by the DestinationSettler.sol contract. 21 | */ 22 | contract DestinationSettler2 is ReentrancyGuard { 23 | using SafeERC20 for IERC20; 24 | 25 | /// @notice Store unique orders to prevent duplicate fills for the same order. 26 | mapping(bytes32 => bool) public fillStatuses; 27 | 28 | error InvalidOrderId(); 29 | error DuplicateFill(); 30 | error InvalidUserSignature(); 31 | error InvalidExecutionChainId(); 32 | 33 | // Called by filler, who sees ERC7683 intent emitted on origin chain 34 | // containing the callsByUser data to be executed following a 7702 delegation. 35 | // @dev We don't use the last parameter `fillerData` in this function. 36 | function fill(bytes32 orderId, bytes calldata originData, bytes calldata) external nonReentrant { 37 | (CallByUser memory callsByUser) = abi.decode(originData, (CallByUser)); 38 | if (ResolvedCrossChainOrderLib.getOrderId(callsByUser) != orderId) revert InvalidOrderId(); 39 | 40 | // Protect against duplicate fills. 41 | if (fillStatuses[orderId]) revert DuplicateFill(); 42 | fillStatuses[orderId] = true; 43 | 44 | // TODO: Protect fillers from collisions with other fillers. Requires letting user set an exclusive relayer. 45 | 46 | // Pull funds into this settlement contract and perform any steps necessary to ensure that filler 47 | // receives a refund of their assets. 48 | _fundUser(callsByUser); 49 | 50 | _verifyCalls(callsByUser); 51 | _verify7702Delegation(); 52 | 53 | // The following call will only succeed if the user has set a 7702 authorization to set its code 54 | // equal to the XAccount contract. The filler should have seen any auth data emitted in an OriginSettler 55 | // event on the sending chain. 56 | XAccount(payable(callsByUser.user)).xExecute(callsByUser); 57 | 58 | // Perform any final steps required to prove that filler has successfully filled the ERC7683 intent. 59 | // For example, we could emit an event containing a unique hash of the fill that could be proved 60 | // on the origin chain via a receipt proof + RIP7755. 61 | // e.g. emit Executed(orderId) 62 | } 63 | 64 | // Pull funds into this settlement contract as escrow and use to execute user's calldata. Escrowed 65 | // funds will be paid back to filler after this contract successfully verifies the settled intent. 66 | // This step could be skipped by lightweight escrow systems that don't need to perform additional 67 | // validation on the filler's actions. 68 | function _fundUser(CallByUser memory call) internal { 69 | IERC20(call.asset.token).safeTransferFrom(msg.sender, call.user, call.asset.amount); 70 | } 71 | 72 | function _verifyCalls(CallByUser memory userCalls) internal view { 73 | if (userCalls.chainId != block.chainid) revert InvalidExecutionChainId(); 74 | // TODO: Make the blob to sign EIP712-compatible (i.e. instead of keccak256(abi.encode(...)) set 75 | // this to SigningLib.getTypedDataHash(...) 76 | if ( 77 | !SignatureChecker.isValidSignatureNow( 78 | userCalls.user, keccak256(abi.encode(userCalls.calls, userCalls.nonce)), userCalls.signature 79 | ) 80 | ) revert InvalidUserSignature(); 81 | } 82 | 83 | function _verify7702Delegation() internal { 84 | // TODO: We might not need this function at all, because if the authorization data requires that this contract 85 | // is set as the delegation code, then xExecute would fail if the auth data is not submitted by the filler. 86 | // However, it might still be useful to verify that the delegate is set correctly, like checking EXTCODEHASH. 87 | } 88 | } 89 | 90 | // TODO: Move to separate file once we are more confident in architecture. For now keep here for readability. 91 | 92 | /** 93 | * @notice Singleton contract used by all users who want to sign data on origin chain and delegate execution of 94 | * their calldata on this chain to this contract. 95 | */ 96 | contract XAccount is ReentrancyGuard { 97 | /// @notice Address of settlement contract that can delegate user ops to this smart contract wallet. 98 | address public constant DESTINATION_SETTLER = address(0xf00d); 99 | 100 | error NotCalledByDestinationSettler(); 101 | error CallReverted(uint256 index, Call[] calls); 102 | error InvalidCall(uint256 index, Call[] calls); 103 | 104 | // Entrypoint function to be called by DestinationSettler contract on this chain. 105 | // Assume user has 7702-delegated code already to this contract. 106 | // All calldata and 7702 authorization data is assumed to have been emitted on the origin chain in am ERC7683 107 | // intent creation event. 108 | function xExecute(CallByUser memory userCalls) external nonReentrant { 109 | if (msg.sender != DESTINATION_SETTLER) revert NotCalledByDestinationSettler(); 110 | _attemptCalls(userCalls.calls); 111 | } 112 | 113 | function _attemptCalls(Call[] memory calls) internal { 114 | for (uint256 i = 0; i < calls.length; ++i) { 115 | Call memory call = calls[i]; 116 | 117 | // If we are calling an EOA with calldata, assume target was incorrectly specified and revert. 118 | if (call.callData.length > 0 && call.target.code.length == 0) { 119 | revert InvalidCall(i, calls); 120 | } 121 | 122 | (bool success,) = call.target.call{value: call.value}(call.callData); 123 | if (!success) revert CallReverted(i, calls); 124 | } 125 | } 126 | 127 | // Used if the caller is trying to unwrap the native token to this contract. 128 | receive() external payable {} 129 | } 130 | -------------------------------------------------------------------------------- /src/DestinationSettler3.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol"; 4 | import {SignatureChecker} from "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol"; 5 | import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; 6 | import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; 7 | import {GaslessCrossChainOrder} from "./ERC7683.sol"; 8 | import {CallByUser, Call} from "./Structs.sol"; 9 | import {ResolvedCrossChainOrderLib} from "./ResolvedCrossChainOrderLib.sol"; 10 | 11 | /** 12 | * @notice Destination chain entrypoint contract for fillers relaying cross chain message containing delegated 13 | * calldata. 14 | * @dev The difference between this contract and the DestinationSettler.sol contract is that this contract 15 | * performs all the CallByUser signature verification AND executes the user's calldata, rather than having 16 | * the XAccount contract do it. This reduces gas costs in the `fill()` function but it does mean that all users 17 | * must trust the DestinationSettler contract since it performs the signature verification. This contract is different 18 | * from DestinationSettler2.sol because it collapses the XAccount and the DestinationSettler2 contracts into one. 19 | */ 20 | contract DestinationSettler3 is ReentrancyGuard { 21 | using SafeERC20 for IERC20; 22 | 23 | /// @notice Store unique orders to prevent duplicate fills for the same order. 24 | mapping(bytes32 => bool) public fillStatuses; 25 | 26 | error CallReverted(uint256 index, Call[] calls); 27 | error InvalidCall(uint256 index, Call[] calls); 28 | error InvalidOrderId(); 29 | error DuplicateFill(); 30 | error InvalidUserSignature(); 31 | error InvalidExecutionChainId(); 32 | 33 | // Called by filler, who sees ERC7683 intent emitted on origin chain 34 | // containing the callsByUser data to be executed following a 7702 delegation. 35 | // @dev We don't use the last parameter `fillerData` in this function. 36 | function fill(bytes32 orderId, bytes calldata originData, bytes calldata) external nonReentrant { 37 | (CallByUser memory callsByUser) = abi.decode(originData, (CallByUser)); 38 | if (ResolvedCrossChainOrderLib.getOrderId(callsByUser) != orderId) revert InvalidOrderId(); 39 | 40 | // Protect against duplicate fills. 41 | if (fillStatuses[orderId]) revert DuplicateFill(); 42 | fillStatuses[orderId] = true; 43 | 44 | // TODO: Protect fillers from collisions with other fillers. Requires letting user set an exclusive relayer. 45 | 46 | // Pull funds into this settlement contract and perform any steps necessary to ensure that filler 47 | // receives a refund of their assets. 48 | _fundUser(callsByUser); 49 | 50 | _verifyCalls(callsByUser); 51 | _verify7702Delegation(); 52 | 53 | // The following call might fail if the user has not set a 7702 authorization to set its code 54 | // equal to this contract. Without this authorization, the msg.sender will not be the userCalls.user. 55 | // The filler should have seen any auth data emitted in an OriginSettler event on the sending chain. 56 | _attemptCalls(callsByUser.calls); 57 | 58 | // Perform any final steps required to prove that filler has successfully filled the ERC7683 intent. 59 | // For example, we could emit an event containing a unique hash of the fill that could be proved 60 | // on the origin chain via a receipt proof + RIP7755. 61 | // e.g. emit Executed(orderId) 62 | } 63 | 64 | // Pull funds into this settlement contract as escrow and use to execute user's calldata. Escrowed 65 | // funds will be paid back to filler after this contract successfully verifies the settled intent. 66 | // This step could be skipped by lightweight escrow systems that don't need to perform additional 67 | // validation on the filler's actions. 68 | function _fundUser(CallByUser memory call) internal { 69 | IERC20(call.asset.token).safeTransferFrom(msg.sender, call.user, call.asset.amount); 70 | } 71 | 72 | function _verifyCalls(CallByUser memory userCalls) internal view { 73 | if (userCalls.chainId != block.chainid) revert InvalidExecutionChainId(); 74 | // TODO: Make the blob to sign EIP712-compatible (i.e. instead of keccak256(abi.encode(...)) set 75 | // this to SigningLib.getTypedDataHash(...) 76 | if ( 77 | !SignatureChecker.isValidSignatureNow( 78 | userCalls.user, keccak256(abi.encode(userCalls.calls, userCalls.nonce)), userCalls.signature 79 | ) 80 | ) revert InvalidUserSignature(); 81 | } 82 | 83 | function _verify7702Delegation() internal { 84 | // TODO: We might not need this function at all, because if the authorization data requires that this contract 85 | // is set as the delegation code, then xExecute would fail if the auth data is not submitted by the filler. 86 | // However, it might still be useful to verify that the delegate is set correctly, like checking EXTCODEHASH. 87 | } 88 | 89 | function _attemptCalls(Call[] memory calls) internal { 90 | for (uint256 i = 0; i < calls.length; ++i) { 91 | Call memory call = calls[i]; 92 | 93 | // If we are calling an EOA with calldata, assume target was incorrectly specified and revert. 94 | if (call.callData.length > 0 && call.target.code.length == 0) { 95 | revert InvalidCall(i, calls); 96 | } 97 | 98 | (bool success,) = call.target.call{value: call.value}(call.callData); 99 | if (!success) revert CallReverted(i, calls); 100 | } 101 | } 102 | 103 | // Used if the caller is trying to unwrap the native token to this contract. 104 | receive() external payable {} 105 | } 106 | -------------------------------------------------------------------------------- /src/ERC7683.sol: -------------------------------------------------------------------------------- 1 | // SPDX-License-Identifier: GPL-3.0-or-later 2 | pragma solidity ^0.8.0; 3 | 4 | /// @title GaslessCrossChainOrder CrossChainOrder type 5 | /// @notice Standard order struct to be signed by users, disseminated to fillers, and submitted to origin settler contracts 6 | struct GaslessCrossChainOrder { 7 | /// @dev The contract address that the order is meant to be settled by. 8 | /// Fillers send this order to this contract address on the origin chain 9 | address originSettler; 10 | /// @dev The address of the user who is initiating the swap, 11 | /// whose input tokens will be taken and escrowed 12 | address user; 13 | /// @dev Nonce to be used as replay protection for the order 14 | uint256 nonce; 15 | /// @dev The chainId of the origin chain 16 | uint256 originChainId; 17 | /// @dev The timestamp by which the order must be opened 18 | uint32 openDeadline; 19 | /// @dev The timestamp by which the order must be filled on the destination chain 20 | uint32 fillDeadline; 21 | /// @dev Type identifier for the order data. This is an EIP-712 typehash. 22 | bytes32 orderDataType; 23 | /// @dev Arbitrary implementation-specific data 24 | /// Can be used to define tokens, amounts, destination chains, fees, settlement parameters, 25 | /// or any other order-type specific information 26 | bytes orderData; 27 | } 28 | 29 | /// @title OnchainCrossChainOrder CrossChainOrder type 30 | /// @notice Standard order struct for user-opened orders, where the user is the msg.sender. 31 | struct OnchainCrossChainOrder { 32 | /// @dev The timestamp by which the order must be filled on the destination chain 33 | uint32 fillDeadline; 34 | /// @dev Type identifier for the order data. This is an EIP-712 typehash. 35 | bytes32 orderDataType; 36 | /// @dev Arbitrary implementation-specific data 37 | /// Can be used to define tokens, amounts, destination chains, fees, settlement parameters, 38 | /// or any other order-type specific information 39 | bytes orderData; 40 | } 41 | 42 | /// @title ResolvedCrossChainOrder type 43 | /// @notice An implementation-generic representation of an order intended for filler consumption 44 | /// @dev Defines all requirements for filling an order by unbundling the implementation-specific orderData. 45 | /// @dev Intended to improve integration generalization by allowing fillers to compute the exact input and output information of any order 46 | struct ResolvedCrossChainOrder { 47 | /// @dev The address of the user who is initiating the transfer 48 | address user; 49 | /// @dev The chainId of the origin chain 50 | uint256 originChainId; 51 | /// @dev The timestamp by which the order must be opened 52 | uint32 openDeadline; 53 | /// @dev The timestamp by which the order must be filled on the destination chain(s) 54 | uint32 fillDeadline; 55 | /// @dev The unique identifier for this order within this settlement system 56 | bytes32 orderId; 57 | /// @dev The max outputs that the filler will send. It's possible the actual amount depends on the state of the destination 58 | /// chain (destination dutch auction, for instance), so these outputs should be considered a cap on filler liabilities. 59 | Output[] maxSpent; 60 | /// @dev The minimum outputs that must to be given to the filler as part of order settlement. Similar to maxSpent, it's possible 61 | /// that special order types may not be able to guarantee the exact amount at open time, so this should be considered 62 | /// a floor on filler receipts. 63 | Output[] minReceived; 64 | /// @dev Each instruction in this array is parameterizes a single leg of the fill. This provides the filler with the information 65 | /// necessary to perform the fill on the destination(s). 66 | FillInstruction[] fillInstructions; 67 | } 68 | 69 | /// @notice Tokens that must be receive for a valid order fulfillment 70 | struct Output { 71 | /// @dev The address of the ERC20 token on the destination chain 72 | /// @dev address(0) used as a sentinel for the native token 73 | bytes32 token; 74 | /// @dev The amount of the token to be sent 75 | uint256 amount; 76 | /// @dev The address to receive the output tokens 77 | bytes32 recipient; 78 | /// @dev The destination chain for this output 79 | uint256 chainId; 80 | } 81 | 82 | /// @title FillInstruction type 83 | /// @notice Instructions to parameterize each leg of the fill 84 | /// @dev Provides all the origin-generated information required to produce a valid fill leg 85 | struct FillInstruction { 86 | /// @dev The contract address that the order is meant to be settled by 87 | uint64 destinationChainId; 88 | /// @dev The contract address that the order is meant to be filled on 89 | bytes32 destinationSettler; 90 | /// @dev The data generated on the origin chain needed by the destinationSettler to process the fill 91 | bytes originData; 92 | } 93 | 94 | /// @title IOriginSettler 95 | /// @notice Standard interface for settlement contracts on the origin chain 96 | interface IOriginSettler { 97 | /// @notice Signals that an order has been opened 98 | /// @param orderId a unique order identifier within this settlement system 99 | /// @param resolvedOrder resolved order that would be returned by resolve if called instead of Open 100 | event Open(bytes32 indexed orderId, ResolvedCrossChainOrder resolvedOrder); 101 | 102 | /// @notice Opens a gasless cross-chain order on behalf of a user. 103 | /// @dev To be called by the filler. 104 | /// @dev This method must emit the Open event 105 | /// @param order The GaslessCrossChainOrder definition 106 | /// @param signature The user's signature over the order 107 | /// @param originFillerData Any filler-defined data required by the settler 108 | function openFor(GaslessCrossChainOrder calldata order, bytes calldata signature, bytes calldata originFillerData) 109 | external; 110 | 111 | /// @notice Opens a cross-chain order 112 | /// @dev To be called by the user 113 | /// @dev This method must emit the Open event 114 | /// @param order The OnchainCrossChainOrder definition 115 | function open(OnchainCrossChainOrder calldata order) external; 116 | 117 | /// @notice Resolves a specific GaslessCrossChainOrder into a generic ResolvedCrossChainOrder 118 | /// @dev Intended to improve standardized integration of various order types and settlement contracts 119 | /// @param order The GaslessCrossChainOrder definition 120 | /// @param originFillerData Any filler-defined data required by the settler 121 | /// @return ResolvedCrossChainOrder hydrated order data including the inputs and outputs of the order 122 | function resolveFor(GaslessCrossChainOrder calldata order, bytes calldata originFillerData) 123 | external 124 | view 125 | returns (ResolvedCrossChainOrder memory); 126 | 127 | /// @notice Resolves a specific OnchainCrossChainOrder into a generic ResolvedCrossChainOrder 128 | /// @dev Intended to improve standardized integration of various order types and settlement contracts 129 | /// @param order The OnchainCrossChainOrder definition 130 | /// @return ResolvedCrossChainOrder hydrated order data including the inputs and outputs of the order 131 | function resolve(OnchainCrossChainOrder calldata order) external view returns (ResolvedCrossChainOrder memory); 132 | } 133 | 134 | /// @title IDestinationSettler 135 | /// @notice Standard interface for settlement contracts on the destination chain 136 | interface IDestinationSettler { 137 | /// @notice Fills a single leg of a particular order on the destination chain 138 | /// @param orderId Unique order identifier for this order 139 | /// @param originData Data emitted on the origin to parameterize the fill 140 | /// @param fillerData Data provided by the filler to inform the fill or express their preferences 141 | function fill(bytes32 orderId, bytes calldata originData, bytes calldata fillerData) external; 142 | } 143 | -------------------------------------------------------------------------------- /src/ERC7683Permit2Lib.sol: -------------------------------------------------------------------------------- 1 | // SPDX-License-Identifier: UNLICENSED 2 | pragma solidity ^0.8.0; 3 | 4 | import {CallByUser, EIP7702AuthData} from "./Structs.sol"; 5 | import {GaslessCrossChainOrder} from "./ERC7683.sol"; 6 | 7 | bytes constant CALL_BY_USER_TYPE = abi.encodePacked( 8 | "CallByUser(", 9 | "address user,", 10 | "uint256 nonce", 11 | "Asset asset,", 12 | "uint64 chainId,", 13 | "bytes signature,", 14 | "Call[] calls)" 15 | ); 16 | 17 | bytes constant CALL_TYPE = abi.encodePacked("Call(", "address target,", "bytes callData,", "uint256 value)"); 18 | 19 | bytes constant ASSET_TYPE = abi.encodePacked("Asset(", "address token,", "uint256 amount)"); 20 | 21 | bytes constant AUTHORIZATION_TYPE = 22 | abi.encodePacked("Authorization(", "uint256 chainId", "address codeAddress", "uint256 nonce", "bytes signature)"); 23 | 24 | bytes constant EIP7702_AUTH_DATA_TYPE = abi.encodePacked("EIP7702AuthData(", "Authorization[] authlist)"); 25 | 26 | bytes32 constant CALL_BY_USER_TYPE_HASH = keccak256(CALL_BY_USER_TYPE); 27 | 28 | library ERC7683Permit2Lib { 29 | bytes internal constant GASLESS_CROSS_CHAIN_ORDER_TYPE = abi.encodePacked( 30 | "GaslessCrossChainOrder(", 31 | "address originSettler,", 32 | "address user,", 33 | "uint256 nonce,", 34 | "uint256 originChainId,", 35 | "uint32 openDeadline,", 36 | "uint32 fillDeadline,", 37 | "bytes32 orderDataType,", 38 | "CallByUser orderData)" 39 | ); 40 | 41 | bytes internal constant GASLESS_CROSS_CHAIN_ORDER_EIP712_TYPE = abi.encodePacked( 42 | GASLESS_CROSS_CHAIN_ORDER_TYPE, CALL_BY_USER_TYPE, CALL_TYPE, ASSET_TYPE, EIP7702_AUTH_DATA_TYPE 43 | ); 44 | bytes32 internal constant GASLESS_CROSS_CHAIN_ORDER_TYPE_HASH = keccak256(GASLESS_CROSS_CHAIN_ORDER_EIP712_TYPE); 45 | 46 | string private constant TOKEN_PERMISSIONS_TYPE = "TokenPermissions(address token,uint256 amount)"; 47 | string internal constant PERMIT2_ORDER_TYPE = string( 48 | abi.encodePacked( 49 | "GaslessCrossChainOrder witness)", 50 | AUTHORIZATION_TYPE, 51 | EIP7702_AUTH_DATA_TYPE, 52 | CALL_BY_USER_TYPE, 53 | GASLESS_CROSS_CHAIN_ORDER_TYPE, 54 | TOKEN_PERMISSIONS_TYPE 55 | ) 56 | ); 57 | 58 | // Hashes an order to get an order hash. Needed for permit2. 59 | function hashOrder(GaslessCrossChainOrder memory order, bytes32 userCallDataHash, bytes32 authDataHash) 60 | internal 61 | pure 62 | returns (bytes32) 63 | { 64 | return keccak256( 65 | abi.encode( 66 | GASLESS_CROSS_CHAIN_ORDER_TYPE_HASH, 67 | order.originSettler, 68 | order.user, 69 | order.nonce, 70 | order.originChainId, 71 | order.openDeadline, 72 | order.fillDeadline, 73 | order.orderDataType, 74 | userCallDataHash, 75 | authDataHash 76 | ) 77 | ); 78 | } 79 | 80 | function hashUserCallData(CallByUser memory userCallData) internal pure returns (bytes32) { 81 | return keccak256( 82 | abi.encode( 83 | CALL_BY_USER_TYPE_HASH, 84 | userCallData.user, 85 | userCallData.nonce, 86 | userCallData.asset, 87 | userCallData.chainId, 88 | userCallData.signature, 89 | userCallData.calls 90 | ) 91 | ); 92 | } 93 | 94 | function hashAuthData(EIP7702AuthData memory authData) internal pure returns (bytes32) { 95 | return keccak256(abi.encode(EIP7702_AUTH_DATA_TYPE, authData.authlist, AUTHORIZATION_TYPE)); 96 | } 97 | } 98 | -------------------------------------------------------------------------------- /src/IPermit2.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | interface IPermit2 { 4 | struct TokenPermissions { 5 | address token; 6 | uint256 amount; 7 | } 8 | 9 | struct PermitTransferFrom { 10 | TokenPermissions permitted; 11 | uint256 nonce; 12 | uint256 deadline; 13 | } 14 | 15 | struct SignatureTransferDetails { 16 | address to; 17 | uint256 requestedAmount; 18 | } 19 | 20 | function permitWitnessTransferFrom( 21 | PermitTransferFrom memory permit, 22 | SignatureTransferDetails calldata transferDetails, 23 | address owner, 24 | bytes32 witness, 25 | string calldata witnessTypeString, 26 | bytes calldata signature 27 | ) external; 28 | 29 | function transferFrom(address from, address to, uint160 amount, address token) external; 30 | } 31 | -------------------------------------------------------------------------------- /src/OriginSettler.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol"; 4 | import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol"; 5 | import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol"; 6 | import { 7 | OnchainCrossChainOrder, 8 | GaslessCrossChainOrder, 9 | ResolvedCrossChainOrder, 10 | IOriginSettler, 11 | Output, 12 | FillInstruction 13 | } from "./ERC7683.sol"; 14 | import {EIP7702AuthData, CallByUser, Call, Asset} from "./Structs.sol"; 15 | import {IPermit2} from "./IPermit2.sol"; 16 | import {ERC7683Permit2Lib} from "./ERC7683Permit2Lib.sol"; 17 | import {ResolvedCrossChainOrderLib} from "./ResolvedCrossChainOrderLib.sol"; 18 | 19 | contract OriginSettler is ReentrancyGuard { 20 | using SafeERC20 for IERC20; 21 | 22 | IPermit2 public immutable PERMIT2 = IPermit2(address(0xf00d)); 23 | 24 | error WrongSettlementContract(); 25 | error WrongChainId(); 26 | error WrongOrderDataType(); 27 | error WrongExclusiveRelayer(); 28 | 29 | event Requested7702Delegation(EIP7702AuthData authData); 30 | 31 | bytes32 immutable ORDER_DATA_TYPE_HASH = keccak256("TODO"); 32 | 33 | mapping(bytes32 => Asset) public pendingOrders; 34 | 35 | /// @notice Opens a cross-chain order 36 | /// @dev To be called by the user 37 | /// @dev This method must emit the Open event 38 | /// @param order The OnchainCrossChainOrder definition 39 | function open(OnchainCrossChainOrder calldata order) external nonReentrant { 40 | (ResolvedCrossChainOrder memory resolvedOrder,, EIP7702AuthData memory authData, Asset memory inputAsset) = 41 | _resolve(order); 42 | 43 | require(pendingOrders[resolvedOrder.orderId].amount > 0, "Order already pending"); 44 | pendingOrders[resolvedOrder.orderId] = inputAsset; 45 | 46 | // TODO: Assets should only be releaseable to the filler 47 | // on this chain once a proof of fill is submitted in a separate function. Ideally we can use RIP7755 48 | // to implement the storage proof escrow system. 49 | IERC20(inputAsset.token).safeTransferFrom(msg.sender, address(this), inputAsset.amount); 50 | 51 | // If a 7702 delegation is a prerequisite to executing the user's calldata on the destination chain, 52 | // emit the authData here. 53 | if (authData.authlist.length > 0) { 54 | emit Requested7702Delegation(authData); 55 | } 56 | 57 | // The OpenEvent contains originData which is required to make the destination chain fill, so we only 58 | // emit the user calls. 59 | emit IOriginSettler.Open(keccak256(resolvedOrder.fillInstructions[0].originData), resolvedOrder); 60 | } 61 | 62 | /// @notice Opens a gasless cross-chain order on behalf of a user. 63 | /// @dev To be called by the filler. 64 | /// @dev This method must emit the Open event 65 | /// @param order The GaslessCrossChainOrder definition 66 | /// @param permit2Signature The user's signature over the order plus any permit 2 witness data 67 | // @dev We don't use the last parameter `originFillerData` in this function. 68 | function openFor(GaslessCrossChainOrder calldata order, bytes calldata permit2Signature, bytes calldata) 69 | external 70 | nonReentrant 71 | { 72 | ( 73 | ResolvedCrossChainOrder memory resolvedOrder, 74 | CallByUser memory calls, 75 | EIP7702AuthData memory authData, 76 | Asset memory inputAsset 77 | ) = _resolveFor(order); 78 | 79 | // TODO: Permit2 will pull assets into this contract, and they should only be releaseable to the filler 80 | // on this chain once a proof of fill is submitted in a separate function. Ideally we can use RIP7755 81 | // to implement the storage proof escrow system. 82 | require(pendingOrders[resolvedOrder.orderId].amount > 0, "Order already pending"); 83 | pendingOrders[resolvedOrder.orderId] = inputAsset; 84 | 85 | // Verify Permit2 signature and pull user funds into this contract. The signature should include 86 | // the UserOp and any prerequisite EIP7702 delegation authorizations as witness data so we will doubly 87 | // verify the user signed the data to be emitted as originData. 88 | _processPermit2Order(order, calls, authData, inputAsset, permit2Signature); 89 | 90 | // If a 7702 delegation is a prerequisite to executing the user's calldata on the destination chain, 91 | // emit the authData here. 92 | if (authData.authlist.length > 0) { 93 | emit Requested7702Delegation(authData); 94 | } 95 | 96 | // The OpenEvent contains originData which is required to make the destination chain fill, so we only 97 | // emit the user calls. 98 | emit IOriginSettler.Open(keccak256(resolvedOrder.fillInstructions[0].originData), resolvedOrder); 99 | } 100 | 101 | function repayFiller(bytes32 orderId, address filler, bytes calldata proof) external nonReentrant { 102 | // Note: this flow could be made simpler if there were an ext-sload opcode we could use 103 | // to read state from DestinationSettler on remote chain. This would allow us to ask the 104 | // node directly to run a storage proof attesting to existence of some remote chain state, 105 | // rather than us submitting the proof here. 106 | 107 | // Verify proof of destination chain fill for `orderId`: 108 | // - orderId was filled on DestinationSettler 109 | // - filler was EOA who called `fill()` and should be repaid. 110 | 111 | // Repay filler 112 | Asset memory asset = pendingOrders[orderId]; 113 | require(asset.amount > 0, "Order not found or already repaid"); 114 | delete pendingOrders[orderId]; 115 | IERC20(asset.token).safeTransfer(filler, asset.amount); 116 | 117 | // Emit some event to help Filler track their refund. 118 | } 119 | 120 | function decode7683OrderData(bytes memory orderData) 121 | public 122 | pure 123 | returns (CallByUser memory calls, EIP7702AuthData memory authData, Asset memory asset) 124 | { 125 | return (abi.decode(orderData, (CallByUser, EIP7702AuthData, Asset))); 126 | } 127 | 128 | function _resolve(OnchainCrossChainOrder calldata order) 129 | internal 130 | view 131 | returns ( 132 | ResolvedCrossChainOrder memory resolvedOrder, 133 | CallByUser memory calls, 134 | EIP7702AuthData memory authData, 135 | Asset memory inputAsset 136 | ) 137 | { 138 | if (order.orderDataType != ORDER_DATA_TYPE_HASH) { 139 | revert WrongOrderDataType(); 140 | } 141 | 142 | (calls, authData, inputAsset) = decode7683OrderData(order.orderData); 143 | 144 | (Output[] memory maxSpent, Output[] memory minReceived, FillInstruction[] memory fillInstructions) = 145 | _resolveCommonStructs(calls, inputAsset); 146 | 147 | resolvedOrder = ResolvedCrossChainOrder({ 148 | user: msg.sender, 149 | originChainId: block.chainid, 150 | openDeadline: type(uint32).max, // no deadline since user is msg.sender 151 | fillDeadline: order.fillDeadline, 152 | minReceived: minReceived, 153 | maxSpent: maxSpent, 154 | fillInstructions: fillInstructions, 155 | orderId: ResolvedCrossChainOrderLib.getOrderId(calls) 156 | }); 157 | } 158 | 159 | function _resolveFor(GaslessCrossChainOrder calldata order) 160 | internal 161 | view 162 | returns ( 163 | ResolvedCrossChainOrder memory resolvedOrder, 164 | CallByUser memory calls, 165 | EIP7702AuthData memory authData, 166 | Asset memory inputAsset 167 | ) 168 | { 169 | if (order.originSettler != address(this)) { 170 | revert WrongSettlementContract(); 171 | } 172 | 173 | if (order.originChainId != block.chainid) { 174 | revert WrongChainId(); 175 | } 176 | 177 | if (order.orderDataType != ORDER_DATA_TYPE_HASH) { 178 | revert WrongOrderDataType(); 179 | } 180 | 181 | (calls, authData, inputAsset) = decode7683OrderData(order.orderData); 182 | 183 | (Output[] memory maxSpent, Output[] memory minReceived, FillInstruction[] memory fillInstructions) = 184 | _resolveCommonStructs(calls, inputAsset); 185 | 186 | resolvedOrder = ResolvedCrossChainOrder({ 187 | user: order.user, 188 | originChainId: order.originChainId, 189 | openDeadline: order.openDeadline, 190 | fillDeadline: order.fillDeadline, 191 | minReceived: minReceived, 192 | maxSpent: maxSpent, 193 | fillInstructions: fillInstructions, 194 | orderId: ResolvedCrossChainOrderLib.getOrderId(calls) 195 | }); 196 | } 197 | 198 | function _resolveCommonStructs(CallByUser memory calls, Asset memory inputAsset) 199 | internal 200 | view 201 | returns (Output[] memory maxSpent, Output[] memory minReceived, FillInstruction[] memory fillInstructions) 202 | { 203 | // Max outputs that filler should spend on destination chain. 204 | maxSpent = new Output[](1); 205 | maxSpent[0] = Output({ 206 | token: _toBytes32(calls.asset.token), 207 | amount: calls.asset.amount, 208 | recipient: _toBytes32(calls.user), 209 | chainId: calls.chainId 210 | }); 211 | 212 | // Minimum outputs that are returned to filler on this chain 213 | // The filler can call `repayFiller` to get their funds back by submitting a proof of their fill. 214 | minReceived = new Output[](1); 215 | minReceived[0] = Output({ 216 | token: _toBytes32(inputAsset.token), 217 | amount: inputAsset.amount, 218 | recipient: _toBytes32(address(0)), // We don't know who will be the filler on the destination chain, so set 219 | // to default zero address to indicate that the funds should be returned to whoever the filler ends up being 220 | chainId: block.chainid // repay filler on this chain 221 | }); 222 | 223 | fillInstructions = new FillInstruction[](1); 224 | 225 | // OriginData will be included on destination chain fill() and it should contain the data needed to execute the 226 | // user's intended call. We don't include the authData here as the calldata execution will revert if the 227 | // authData isn't submitted as a prerequisite to delegate the user's code. Instead, we emit the authData 228 | // in this contract so that the filler submitting the destination chain calldata can use it. 229 | bytes memory originData = abi.encode(calls); 230 | fillInstructions[0] = FillInstruction({ 231 | destinationChainId: calls.chainId, 232 | destinationSettler: _toBytes32(address(123)), // TODO: Should be address of destination settler for destination chain. 233 | originData: originData 234 | }); 235 | } 236 | 237 | function _processPermit2Order( 238 | GaslessCrossChainOrder memory order, 239 | CallByUser memory calls, 240 | EIP7702AuthData memory authData, 241 | Asset memory inputAsset, 242 | bytes memory signature 243 | ) internal { 244 | IPermit2.PermitTransferFrom memory permit = IPermit2.PermitTransferFrom({ 245 | permitted: IPermit2.TokenPermissions({token: inputAsset.token, amount: inputAsset.amount}), 246 | nonce: order.nonce, 247 | deadline: order.openDeadline 248 | }); 249 | 250 | IPermit2.SignatureTransferDetails memory signatureTransferDetails = 251 | IPermit2.SignatureTransferDetails({to: address(this), requestedAmount: inputAsset.amount}); 252 | 253 | // Pull user funds into this contract. 254 | PERMIT2.permitWitnessTransferFrom( 255 | permit, 256 | signatureTransferDetails, 257 | order.user, 258 | // User should have signed a permit2 blob including the destination chain UserOp and any prerequisite 259 | // EIP7702 delegation authorizations. 260 | ERC7683Permit2Lib.hashOrder( 261 | order, ERC7683Permit2Lib.hashUserCallData(calls), ERC7683Permit2Lib.hashAuthData(authData) 262 | ), // witness data hash 263 | ERC7683Permit2Lib.PERMIT2_ORDER_TYPE, // witness data type string 264 | signature 265 | ); 266 | } 267 | 268 | function _toBytes32(address input) internal pure returns (bytes32) { 269 | return bytes32(uint256(uint160(input))); 270 | } 271 | } 272 | -------------------------------------------------------------------------------- /src/ResolvedCrossChainOrderLib.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {CallByUser} from "./Structs.sol"; 4 | 5 | /** 6 | * @notice Contains common functions used by Destination and Origin settler 7 | * to encode and decode an ERC7683 ResolvedCrossChainOrder. 8 | */ 9 | library ResolvedCrossChainOrderLib { 10 | // Returns a unique representation of the ERC7683 resolved cross chain order. The resolved cross chain order's 11 | // originData contains a CallByUser struct which contains a nonce, so the user can guarantee t 12 | // his order is unique by using the nonce+user combination. 13 | function getOrderId(CallByUser memory calls) internal pure returns (bytes32) { 14 | return keccak256(abi.encode(calls)); 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /src/Structs.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | struct Authorization { 4 | uint256 chainId; 5 | address codeAddress; 6 | uint256 nonce; 7 | bytes signature; 8 | } 9 | 10 | struct EIP7702AuthData { 11 | Authorization[] authlist; 12 | } 13 | 14 | struct Asset { 15 | address token; 16 | uint256 amount; 17 | } 18 | 19 | struct Call { 20 | address target; 21 | bytes callData; 22 | uint256 value; 23 | } 24 | 25 | struct CallByUser { 26 | address user; // User who delegated calldata and funded assets on origin chain. 27 | uint256 nonce; // Unique nonce for this user call to prevent replay. Set by user on origin chain so 28 | // there is no re-org risk to this value. 29 | Asset asset; // token & amount, used to fund execution of calldata 30 | uint64 chainId; // should match chain id where calls are to be executed 31 | bytes signature; // Signed calldata, to be used by the XAccount contract to verify the user's ordered the calldata. 32 | Call[] calls; // calldata to execute 33 | } 34 | -------------------------------------------------------------------------------- /test/DestinationSettler.t.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {Test, console} from "forge-std/Test.sol"; 4 | import {DestinationSettler} from "../src/DestinationSettler.sol"; 5 | 6 | contract DestinationSettlerTest is Test { 7 | DestinationSettler public destinationSettler; 8 | 9 | function setUp() public { 10 | destinationSettler = new DestinationSettler(); 11 | } 12 | 13 | function test_fill() public { 14 | // TODO 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /test/OriginSettler.t.sol: -------------------------------------------------------------------------------- 1 | pragma solidity ^0.8.0; 2 | 3 | import {Test, console} from "forge-std/Test.sol"; 4 | import {OriginSettler} from "../src/OriginSettler.sol"; 5 | 6 | contract OriginSettlerTest is Test { 7 | OriginSettler public originSettler; 8 | 9 | function setUp() public { 10 | originSettler = new OriginSettler(); 11 | } 12 | 13 | function test_openFor() public { 14 | // TODO test gas-less Permit2 path 15 | } 16 | } 17 | --------------------------------------------------------------------------------