Contract Address Details

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { SafeCast } from "@openzeppelin/contracts/utils/math/SafeCast.sol";
import { PacketV1Codec } from "@layerzerolabs/lz-evm-protocol-v2/contracts/messagelib/libs/PacketV1Codec.sol";

import { IUltraLightNode301 } from "./interfaces/IUltraLightNode301.sol";
import { ReceiveLibBaseE1 } from "./ReceiveLibBaseE1.sol";
import { ReceiveUlnBase } from "../ReceiveUlnBase.sol";
import { UlnConfig } from "../UlnBase.sol";

/// @dev ULN301 will be deployed on EndpointV1 and is for backward compatibility with ULN302 on EndpointV2. 301 can talk to both 301 and 302
/// @dev This is a gluing contract. It simply parses the requests and forward to the super.impl() accordingly.
/// @dev In this case, it combines the logic of ReceiveUlnBase and ReceiveLibBaseE1
contract ReceiveUln301 is IUltraLightNode301, ReceiveUlnBase, ReceiveLibBaseE1 {
    using PacketV1Codec for bytes;
    using SafeCast for uint32; // for chain ID uint32 to uint16 conversion

    uint256 internal constant CONFIG_TYPE_EXECUTOR = 1;
    uint256 internal constant CONFIG_TYPE_ULN = 2;

    error LZ_ULN_InvalidConfigType(uint256 configType);

    constructor(address _endpoint, uint32 _localEid) ReceiveLibBaseE1(_endpoint, _localEid) {}

    // ============================ OnlyEndpoint ===================================

    function setConfig(
        uint16 _eid,
        address _oapp,
        uint256 _configType,
        bytes calldata _config
    ) external override onlyEndpoint {
        _assertSupportedEid(_eid);
        if (_configType == CONFIG_TYPE_EXECUTOR) {
            _setExecutor(_eid, _oapp, abi.decode(_config, (address)));
        } else if (_configType == CONFIG_TYPE_ULN) {
            _setUlnConfig(_eid, _oapp, abi.decode(_config, (UlnConfig)));
        } else {
            revert LZ_ULN_InvalidConfigType(_configType);
        }
    }

    // ============================ External ===================================

    /// @dev in 301, this is equivalent to execution as in Endpoint V2
    /// @dev dont need to check endpoint verifiable here to save gas, as it will reverts if not verifiable.
    function commitVerification(bytes calldata _packet, uint256 _gasLimit) external {
        bytes calldata header = _packet.header();
        _assertHeader(header, localEid);

        // cache these values to save gas
        address receiver = _packet.receiverB20();
        uint16 srcEid = _packet.srcEid().toUint16();

        UlnConfig memory config = getUlnConfig(receiver, srcEid);
        _verifyAndReclaimStorage(config, keccak256(header), _packet.payloadHash());

        // endpoint will revert if nonce != ++inboundNonce
        _execute(srcEid, _packet.sender(), receiver, _packet.nonce(), _packet.message(), _gasLimit);
    }

    function verify(bytes calldata _packetHeader, bytes32 _payloadHash, uint64 _confirmations) external {
        _verify(_packetHeader, _payloadHash, _confirmations);
    }

    // ============================ View ===================================

    function getConfig(uint16 _eid, address _oapp, uint256 _configType) external view override returns (bytes memory) {
        if (_configType == CONFIG_TYPE_EXECUTOR) {
            return abi.encode(getExecutor(_oapp, _eid));
        } else if (_configType == CONFIG_TYPE_ULN) {
            return abi.encode(getUlnConfig(_oapp, _eid));
        } else {
            revert LZ_ULN_InvalidConfigType(_configType);
        }
    }

    function version() external pure returns (uint64 major, uint8 minor, uint8 endpointVersion) {
        return (3, 0, 1);
    }
}
        

// SPDX-License-Identifier: BUSL-1.1

pragma solidity >=0.5.0;

interface ILayerZeroUserApplicationConfig {
    // @notice set the configuration of the LayerZero messaging library of the specified version
    // @param _version - messaging library version
    // @param _chainId - the chainId for the pending config change
    // @param _configType - type of configuration. every messaging library has its own convention.
    // @param _config - configuration in the bytes. can encode arbitrary content.
    function setConfig(uint16 _version, uint16 _chainId, uint _configType, bytes calldata _config) external;

    // @notice set the send() LayerZero messaging library version to _version
    // @param _version - new messaging library version
    function setSendVersion(uint16 _version) external;

    // @notice set the lzReceive() LayerZero messaging library version to _version
    // @param _version - new messaging library version
    function setReceiveVersion(uint16 _version) external;

    // @notice Only when the UA needs to resume the message flow in blocking mode and clear the stored payload
    // @param _srcChainId - the chainId of the source chain
    // @param _srcAddress - the contract address of the source contract at the source chain
    function forceResumeReceive(uint16 _srcChainId, bytes calldata _srcAddress) external;
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

import { IMessageLibManager } from "./IMessageLibManager.sol";
import { IMessagingComposer } from "./IMessagingComposer.sol";
import { IMessagingChannel } from "./IMessagingChannel.sol";
import { IMessagingContext } from "./IMessagingContext.sol";

struct MessagingParams {
    uint32 dstEid;
    bytes32 receiver;
    bytes message;
    bytes options;
    bool payInLzToken;
}

struct MessagingReceipt {
    bytes32 guid;
    uint64 nonce;
    MessagingFee fee;
}

struct MessagingFee {
    uint256 nativeFee;
    uint256 lzTokenFee;
}

struct Origin {
    uint32 srcEid;
    bytes32 sender;
    uint64 nonce;
}

interface ILayerZeroEndpointV2 is IMessageLibManager, IMessagingComposer, IMessagingChannel, IMessagingContext {
    event PacketSent(bytes encodedPayload, bytes options, address sendLibrary);

    event PacketVerified(Origin origin, address receiver, bytes32 payloadHash);

    event PacketDelivered(Origin origin, address receiver);

    event LzReceiveAlert(
        address indexed receiver,
        address indexed executor,
        Origin origin,
        bytes32 guid,
        uint256 gas,
        uint256 value,
        bytes message,
        bytes extraData,
        bytes reason
    );

    event LzTokenSet(address token);

    event DelegateSet(address sender, address delegate);

    function quote(MessagingParams calldata _params, address _sender) external view returns (MessagingFee memory);

    function send(
        MessagingParams calldata _params,
        address _refundAddress
    ) external payable returns (MessagingReceipt memory);

    function verify(Origin calldata _origin, address _receiver, bytes32 _payloadHash) external;

    function verifiable(Origin calldata _origin, address _receiver) external view returns (bool);

    function initializable(Origin calldata _origin, address _receiver) external view returns (bool);

    function lzReceive(
        Origin calldata _origin,
        address _receiver,
        bytes32 _guid,
        bytes calldata _message,
        bytes calldata _extraData
    ) external payable;

    // oapp can burn messages partially by calling this function with its own business logic if messages are verified in order
    function clear(address _oapp, Origin calldata _origin, bytes32 _guid, bytes calldata _message) external;

    function setLzToken(address _lzToken) external;

    function lzToken() external view returns (address);

    function nativeToken() external view returns (address);

    function setDelegate(address _delegate) external;
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { Packet } from "../../interfaces/ISendLib.sol";
import { AddressCast } from "../../libs/AddressCast.sol";

library PacketV1Codec {
    using AddressCast for address;
    using AddressCast for bytes32;

    uint8 internal constant PACKET_VERSION = 1;

    // header (version + nonce + path)
    // version
    uint256 private constant PACKET_VERSION_OFFSET = 0;
    //    nonce
    uint256 private constant NONCE_OFFSET = 1;
    //    path
    uint256 private constant SRC_EID_OFFSET = 9;
    uint256 private constant SENDER_OFFSET = 13;
    uint256 private constant DST_EID_OFFSET = 45;
    uint256 private constant RECEIVER_OFFSET = 49;
    // payload (guid + message)
    uint256 private constant GUID_OFFSET = 81; // keccak256(nonce + path)
    uint256 private constant MESSAGE_OFFSET = 113;

    function encode(Packet memory _packet) internal pure returns (bytes memory encodedPacket) {
        encodedPacket = abi.encodePacked(
            PACKET_VERSION,
            _packet.nonce,
            _packet.srcEid,
            _packet.sender.toBytes32(),
            _packet.dstEid,
            _packet.receiver,
            _packet.guid,
            _packet.message
        );
    }

    function encodePacketHeader(Packet memory _packet) internal pure returns (bytes memory) {
        return
            abi.encodePacked(
                PACKET_VERSION,
                _packet.nonce,
                _packet.srcEid,
                _packet.sender.toBytes32(),
                _packet.dstEid,
                _packet.receiver
            );
    }

    function encodePayload(Packet memory _packet) internal pure returns (bytes memory) {
        return abi.encodePacked(_packet.guid, _packet.message);
    }

    function header(bytes calldata _packet) internal pure returns (bytes calldata) {
        return _packet[0:GUID_OFFSET];
    }

    function version(bytes calldata _packet) internal pure returns (uint8) {
        return uint8(bytes1(_packet[PACKET_VERSION_OFFSET:NONCE_OFFSET]));
    }

    function nonce(bytes calldata _packet) internal pure returns (uint64) {
        return uint64(bytes8(_packet[NONCE_OFFSET:SRC_EID_OFFSET]));
    }

    function srcEid(bytes calldata _packet) internal pure returns (uint32) {
        return uint32(bytes4(_packet[SRC_EID_OFFSET:SENDER_OFFSET]));
    }

    function sender(bytes calldata _packet) internal pure returns (bytes32) {
        return bytes32(_packet[SENDER_OFFSET:DST_EID_OFFSET]);
    }

    function senderAddressB20(bytes calldata _packet) internal pure returns (address) {
        return sender(_packet).toAddress();
    }

    function dstEid(bytes calldata _packet) internal pure returns (uint32) {
        return uint32(bytes4(_packet[DST_EID_OFFSET:RECEIVER_OFFSET]));
    }

    function receiver(bytes calldata _packet) internal pure returns (bytes32) {
        return bytes32(_packet[RECEIVER_OFFSET:GUID_OFFSET]);
    }

    function receiverB20(bytes calldata _packet) internal pure returns (address) {
        return receiver(_packet).toAddress();
    }

    function guid(bytes calldata _packet) internal pure returns (bytes32) {
        return bytes32(_packet[GUID_OFFSET:MESSAGE_OFFSET]);
    }

    function message(bytes calldata _packet) internal pure returns (bytes calldata) {
        return bytes(_packet[MESSAGE_OFFSET:]);
    }

    function payload(bytes calldata _packet) internal pure returns (bytes calldata) {
        return bytes(_packet[GUID_OFFSET:]);
    }

    function payloadHash(bytes calldata _packet) internal pure returns (bytes32) {
        return keccak256(payload(_packet));
    }
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface IMessagingComposer {
    event ComposeSent(address from, address to, bytes32 guid, uint16 index, bytes message);
    event ComposeDelivered(address from, address to, bytes32 guid, uint16 index);
    event LzComposeAlert(
        address indexed from,
        address indexed to,
        address indexed executor,
        bytes32 guid,
        uint16 index,
        uint256 gas,
        uint256 value,
        bytes message,
        bytes extraData,
        bytes reason
    );

    function composeQueue(
        address _from,
        address _to,
        bytes32 _guid,
        uint16 _index
    ) external view returns (bytes32 messageHash);

    function sendCompose(address _to, bytes32 _guid, uint16 _index, bytes calldata _message) external;

    function lzCompose(
        address _from,
        address _to,
        bytes32 _guid,
        uint16 _index,
        bytes calldata _message,
        bytes calldata _extraData
    ) external payable;
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

struct SetConfigParam {
    uint32 eid;
    uint32 configType;
    bytes config;
}

interface IMessageLibManager {
    struct Timeout {
        address lib;
        uint256 expiry;
    }

    event LibraryRegistered(address newLib);
    event DefaultSendLibrarySet(uint32 eid, address newLib);
    event DefaultReceiveLibrarySet(uint32 eid, address newLib);
    event DefaultReceiveLibraryTimeoutSet(uint32 eid, address oldLib, uint256 expiry);
    event SendLibrarySet(address sender, uint32 eid, address newLib);
    event ReceiveLibrarySet(address receiver, uint32 eid, address newLib);
    event ReceiveLibraryTimeoutSet(address receiver, uint32 eid, address oldLib, uint256 timeout);

    function registerLibrary(address _lib) external;

    function isRegisteredLibrary(address _lib) external view returns (bool);

    function getRegisteredLibraries() external view returns (address[] memory);

    function setDefaultSendLibrary(uint32 _eid, address _newLib) external;

    function defaultSendLibrary(uint32 _eid) external view returns (address);

    function setDefaultReceiveLibrary(uint32 _eid, address _newLib, uint256 _timeout) external;

    function defaultReceiveLibrary(uint32 _eid) external view returns (address);

    function setDefaultReceiveLibraryTimeout(uint32 _eid, address _lib, uint256 _expiry) external;

    function defaultReceiveLibraryTimeout(uint32 _eid) external view returns (address lib, uint256 expiry);

    function isSupportedEid(uint32 _eid) external view returns (bool);

    function isValidReceiveLibrary(address _receiver, uint32 _eid, address _lib) external view returns (bool);

    /// ------------------- OApp interfaces -------------------
    function setSendLibrary(address _oapp, uint32 _eid, address _newLib) external;

    function getSendLibrary(address _sender, uint32 _eid) external view returns (address lib);

    function isDefaultSendLibrary(address _sender, uint32 _eid) external view returns (bool);

    function setReceiveLibrary(address _oapp, uint32 _eid, address _newLib, uint256 _gracePeriod) external;

    function getReceiveLibrary(address _receiver, uint32 _eid) external view returns (address lib, bool isDefault);

    function setReceiveLibraryTimeout(address _oapp, uint32 _eid, address _lib, uint256 _gracePeriod) external;

    function receiveLibraryTimeout(address _receiver, uint32 _eid) external view returns (address lib, uint256 expiry);

    function setConfig(address _oapp, address _lib, SetConfigParam[] calldata _params) external;

    function getConfig(
        address _oapp,
        address _lib,
        uint32 _eid,
        uint32 _configType
    ) external view returns (bytes memory config);
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface IMessagingContext {
    function isSendingMessage() external view returns (bool);

    function getSendContext() external view returns (uint32 dstEid, address sender);
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface IMessagingChannel {
    event InboundNonceSkipped(uint32 srcEid, bytes32 sender, address receiver, uint64 nonce);
    event PacketNilified(uint32 srcEid, bytes32 sender, address receiver, uint64 nonce, bytes32 payloadHash);
    event PacketBurnt(uint32 srcEid, bytes32 sender, address receiver, uint64 nonce, bytes32 payloadHash);

    function eid() external view returns (uint32);

    // this is an emergency function if a message cannot be verified for some reasons
    // required to provide _nextNonce to avoid race condition
    function skip(address _oapp, uint32 _srcEid, bytes32 _sender, uint64 _nonce) external;

    function nilify(address _oapp, uint32 _srcEid, bytes32 _sender, uint64 _nonce, bytes32 _payloadHash) external;

    function burn(address _oapp, uint32 _srcEid, bytes32 _sender, uint64 _nonce, bytes32 _payloadHash) external;

    function nextGuid(address _sender, uint32 _dstEid, bytes32 _receiver) external view returns (bytes32);

    function inboundNonce(address _receiver, uint32 _srcEid, bytes32 _sender) external view returns (uint64);

    function outboundNonce(address _sender, uint32 _dstEid, bytes32 _receiver) external view returns (uint64);

    function inboundPayloadHash(
        address _receiver,
        uint32 _srcEid,
        bytes32 _sender,
        uint64 _nonce
    ) external view returns (bytes32);

    function lazyInboundNonce(address _receiver, uint32 _srcEid, bytes32 _sender) external view returns (uint64);
}
          

// SPDX-License-Identifier: BUSL-1.1

pragma solidity >=0.5.0;

import "./ILayerZeroUserApplicationConfig.sol";

interface ILayerZeroEndpoint is ILayerZeroUserApplicationConfig {
    // @notice send a LayerZero message to the specified address at a LayerZero endpoint.
    // @param _dstChainId - the destination chain identifier
    // @param _destination - the address on destination chain (in bytes). address length/format may vary by chains
    // @param _payload - a custom bytes payload to send to the destination contract
    // @param _refundAddress - if the source transaction is cheaper than the amount of value passed, refund the additional amount to this address
    // @param _zroPaymentAddress - the address of the ZRO token holder who would pay for the transaction
    // @param _adapterParams - parameters for custom functionality. e.g. receive airdropped native gas from the relayer on destination
    function send(
        uint16 _dstChainId,
        bytes calldata _destination,
        bytes calldata _payload,
        address payable _refundAddress,
        address _zroPaymentAddress,
        bytes calldata _adapterParams
    ) external payable;

    // @notice used by the messaging library to publish verified payload
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source contract (as bytes) at the source chain
    // @param _dstAddress - the address on destination chain
    // @param _nonce - the unbound message ordering nonce
    // @param _gasLimit - the gas limit for external contract execution
    // @param _payload - verified payload to send to the destination contract
    function receivePayload(
        uint16 _srcChainId,
        bytes calldata _srcAddress,
        address _dstAddress,
        uint64 _nonce,
        uint _gasLimit,
        bytes calldata _payload
    ) external;

    // @notice get the inboundNonce of a receiver from a source chain which could be EVM or non-EVM chain
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    function getInboundNonce(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (uint64);

    // @notice get the outboundNonce from this source chain which, consequently, is always an EVM
    // @param _srcAddress - the source chain contract address
    function getOutboundNonce(uint16 _dstChainId, address _srcAddress) external view returns (uint64);

    // @notice gets a quote in source native gas, for the amount that send() requires to pay for message delivery
    // @param _dstChainId - the destination chain identifier
    // @param _userApplication - the user app address on this EVM chain
    // @param _payload - the custom message to send over LayerZero
    // @param _payInZRO - if false, user app pays the protocol fee in native token
    // @param _adapterParam - parameters for the adapter service, e.g. send some dust native token to dstChain
    function estimateFees(
        uint16 _dstChainId,
        address _userApplication,
        bytes calldata _payload,
        bool _payInZRO,
        bytes calldata _adapterParam
    ) external view returns (uint nativeFee, uint zroFee);

    // @notice get this Endpoint's immutable source identifier
    function getChainId() external view returns (uint16);

    // @notice the interface to retry failed message on this Endpoint destination
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    // @param _payload - the payload to be retried
    function retryPayload(uint16 _srcChainId, bytes calldata _srcAddress, bytes calldata _payload) external;

    // @notice query if any STORED payload (message blocking) at the endpoint.
    // @param _srcChainId - the source chain identifier
    // @param _srcAddress - the source chain contract address
    function hasStoredPayload(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (bool);

    // @notice query if the _libraryAddress is valid for sending msgs.
    // @param _userApplication - the user app address on this EVM chain
    function getSendLibraryAddress(address _userApplication) external view returns (address);

    // @notice query if the _libraryAddress is valid for receiving msgs.
    // @param _userApplication - the user app address on this EVM chain
    function getReceiveLibraryAddress(address _userApplication) external view returns (address);

    // @notice query if the non-reentrancy guard for send() is on
    // @return true if the guard is on. false otherwise
    function isSendingPayload() external view returns (bool);

    // @notice query if the non-reentrancy guard for receive() is on
    // @return true if the guard is on. false otherwise
    function isReceivingPayload() external view returns (bool);

    // @notice get the configuration of the LayerZero messaging library of the specified version
    // @param _version - messaging library version
    // @param _chainId - the chainId for the pending config change
    // @param _userApplication - the contract address of the user application
    // @param _configType - type of configuration. every messaging library has its own convention.
    function getConfig(
        uint16 _version,
        uint16 _chainId,
        address _userApplication,
        uint _configType
    ) external view returns (bytes memory);

    // @notice get the send() LayerZero messaging library version
    // @param _userApplication - the contract address of the user application
    function getSendVersion(address _userApplication) external view returns (uint16);

    // @notice get the lzReceive() LayerZero messaging library version
    // @param _userApplication - the contract address of the user application
    function getReceiveVersion(address _userApplication) external view returns (uint16);
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

import { IERC165 } from "@openzeppelin/contracts/utils/introspection/IERC165.sol";

import { SetConfigParam } from "./IMessageLibManager.sol";

enum MessageLibType {
    Send,
    Receive,
    SendAndReceive
}

interface IMessageLib is IERC165 {
    function setConfig(address _oapp, SetConfigParam[] calldata _config) external;

    function getConfig(uint32 _eid, address _oapp, uint32 _configType) external view returns (bytes memory config);

    function isSupportedEid(uint32 _eid) external view returns (bool);

    // message libs of same major version are compatible
    function version() external view returns (uint64 major, uint8 minor, uint8 endpointVersion);

    function messageLibType() external view returns (MessageLibType);
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

import { MessagingFee } from "./ILayerZeroEndpointV2.sol";
import { IMessageLib } from "./IMessageLib.sol";

struct Packet {
    uint64 nonce;
    uint32 srcEid;
    address sender;
    uint32 dstEid;
    bytes32 receiver;
    bytes32 guid;
    bytes message;
}

interface ISendLib is IMessageLib {
    function send(
        Packet calldata _packet,
        bytes calldata _options,
        bool _payInLzToken
    ) external returns (MessagingFee memory, bytes memory encodedPacket);

    function quote(
        Packet calldata _packet,
        bytes calldata _options,
        bool _payInLzToken
    ) external view returns (MessagingFee memory);

    function setTreasury(address _treasury) external;

    function withdrawFee(address _to, uint256 _amount) external;

    function withdrawLzTokenFee(address _lzToken, address _to, uint256 _amount) external;
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

library AddressCast {
    error AddressCast_InvalidSizeForAddress();
    error AddressCast_InvalidAddress();

    function toBytes32(bytes calldata _addressBytes) internal pure returns (bytes32 result) {
        if (_addressBytes.length > 32) revert AddressCast_InvalidAddress();
        result = bytes32(_addressBytes);
        unchecked {
            uint256 offset = 32 - _addressBytes.length;
            result = result >> (offset * 8);
        }
    }

    function toBytes32(address _address) internal pure returns (bytes32 result) {
        result = bytes32(uint256(uint160(_address)));
    }

    function toBytes(bytes32 _addressBytes32, uint256 _size) internal pure returns (bytes memory result) {
        if (_size == 0 || _size > 32) revert AddressCast_InvalidSizeForAddress();
        result = new bytes(_size);
        unchecked {
            uint256 offset = 256 - _size * 8;
            assembly {
                mstore(add(result, 32), shl(offset, _addressBytes32))
            }
        }
    }

    function toAddress(bytes32 _addressBytes32) internal pure returns (address result) {
        result = address(uint160(uint256(_addressBytes32)));
    }

    function toAddress(bytes calldata _addressBytes) internal pure returns (address result) {
        if (_addressBytes.length != 20) revert AddressCast_InvalidAddress();
        result = address(bytes20(_addressBytes));
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
          

// SPDX-License-Identifier: MIT

pragma solidity >=0.8.0;

interface IUltraLightNode301 {
    function commitVerification(bytes calldata _packet, uint256 _gasLimit) external;
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SafeCast.sol)
// This file was procedurally generated from scripts/generate/templates/SafeCast.js.

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint248 from uint256, reverting on
     * overflow (when the input is greater than largest uint248).
     *
     * Counterpart to Solidity's `uint248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toUint248(uint256 value) internal pure returns (uint248) {
        require(value <= type(uint248).max, "SafeCast: value doesn't fit in 248 bits");
        return uint248(value);
    }

    /**
     * @dev Returns the downcasted uint240 from uint256, reverting on
     * overflow (when the input is greater than largest uint240).
     *
     * Counterpart to Solidity's `uint240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toUint240(uint256 value) internal pure returns (uint240) {
        require(value <= type(uint240).max, "SafeCast: value doesn't fit in 240 bits");
        return uint240(value);
    }

    /**
     * @dev Returns the downcasted uint232 from uint256, reverting on
     * overflow (when the input is greater than largest uint232).
     *
     * Counterpart to Solidity's `uint232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toUint232(uint256 value) internal pure returns (uint232) {
        require(value <= type(uint232).max, "SafeCast: value doesn't fit in 232 bits");
        return uint232(value);
    }

    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.2._
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint216 from uint256, reverting on
     * overflow (when the input is greater than largest uint216).
     *
     * Counterpart to Solidity's `uint216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toUint216(uint256 value) internal pure returns (uint216) {
        require(value <= type(uint216).max, "SafeCast: value doesn't fit in 216 bits");
        return uint216(value);
    }

    /**
     * @dev Returns the downcasted uint208 from uint256, reverting on
     * overflow (when the input is greater than largest uint208).
     *
     * Counterpart to Solidity's `uint208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toUint208(uint256 value) internal pure returns (uint208) {
        require(value <= type(uint208).max, "SafeCast: value doesn't fit in 208 bits");
        return uint208(value);
    }

    /**
     * @dev Returns the downcasted uint200 from uint256, reverting on
     * overflow (when the input is greater than largest uint200).
     *
     * Counterpart to Solidity's `uint200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toUint200(uint256 value) internal pure returns (uint200) {
        require(value <= type(uint200).max, "SafeCast: value doesn't fit in 200 bits");
        return uint200(value);
    }

    /**
     * @dev Returns the downcasted uint192 from uint256, reverting on
     * overflow (when the input is greater than largest uint192).
     *
     * Counterpart to Solidity's `uint192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toUint192(uint256 value) internal pure returns (uint192) {
        require(value <= type(uint192).max, "SafeCast: value doesn't fit in 192 bits");
        return uint192(value);
    }

    /**
     * @dev Returns the downcasted uint184 from uint256, reverting on
     * overflow (when the input is greater than largest uint184).
     *
     * Counterpart to Solidity's `uint184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toUint184(uint256 value) internal pure returns (uint184) {
        require(value <= type(uint184).max, "SafeCast: value doesn't fit in 184 bits");
        return uint184(value);
    }

    /**
     * @dev Returns the downcasted uint176 from uint256, reverting on
     * overflow (when the input is greater than largest uint176).
     *
     * Counterpart to Solidity's `uint176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toUint176(uint256 value) internal pure returns (uint176) {
        require(value <= type(uint176).max, "SafeCast: value doesn't fit in 176 bits");
        return uint176(value);
    }

    /**
     * @dev Returns the downcasted uint168 from uint256, reverting on
     * overflow (when the input is greater than largest uint168).
     *
     * Counterpart to Solidity's `uint168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toUint168(uint256 value) internal pure returns (uint168) {
        require(value <= type(uint168).max, "SafeCast: value doesn't fit in 168 bits");
        return uint168(value);
    }

    /**
     * @dev Returns the downcasted uint160 from uint256, reverting on
     * overflow (when the input is greater than largest uint160).
     *
     * Counterpart to Solidity's `uint160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toUint160(uint256 value) internal pure returns (uint160) {
        require(value <= type(uint160).max, "SafeCast: value doesn't fit in 160 bits");
        return uint160(value);
    }

    /**
     * @dev Returns the downcasted uint152 from uint256, reverting on
     * overflow (when the input is greater than largest uint152).
     *
     * Counterpart to Solidity's `uint152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toUint152(uint256 value) internal pure returns (uint152) {
        require(value <= type(uint152).max, "SafeCast: value doesn't fit in 152 bits");
        return uint152(value);
    }

    /**
     * @dev Returns the downcasted uint144 from uint256, reverting on
     * overflow (when the input is greater than largest uint144).
     *
     * Counterpart to Solidity's `uint144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toUint144(uint256 value) internal pure returns (uint144) {
        require(value <= type(uint144).max, "SafeCast: value doesn't fit in 144 bits");
        return uint144(value);
    }

    /**
     * @dev Returns the downcasted uint136 from uint256, reverting on
     * overflow (when the input is greater than largest uint136).
     *
     * Counterpart to Solidity's `uint136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toUint136(uint256 value) internal pure returns (uint136) {
        require(value <= type(uint136).max, "SafeCast: value doesn't fit in 136 bits");
        return uint136(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v2.5._
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint120 from uint256, reverting on
     * overflow (when the input is greater than largest uint120).
     *
     * Counterpart to Solidity's `uint120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toUint120(uint256 value) internal pure returns (uint120) {
        require(value <= type(uint120).max, "SafeCast: value doesn't fit in 120 bits");
        return uint120(value);
    }

    /**
     * @dev Returns the downcasted uint112 from uint256, reverting on
     * overflow (when the input is greater than largest uint112).
     *
     * Counterpart to Solidity's `uint112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toUint112(uint256 value) internal pure returns (uint112) {
        require(value <= type(uint112).max, "SafeCast: value doesn't fit in 112 bits");
        return uint112(value);
    }

    /**
     * @dev Returns the downcasted uint104 from uint256, reverting on
     * overflow (when the input is greater than largest uint104).
     *
     * Counterpart to Solidity's `uint104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toUint104(uint256 value) internal pure returns (uint104) {
        require(value <= type(uint104).max, "SafeCast: value doesn't fit in 104 bits");
        return uint104(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.2._
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint88 from uint256, reverting on
     * overflow (when the input is greater than largest uint88).
     *
     * Counterpart to Solidity's `uint88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toUint88(uint256 value) internal pure returns (uint88) {
        require(value <= type(uint88).max, "SafeCast: value doesn't fit in 88 bits");
        return uint88(value);
    }

    /**
     * @dev Returns the downcasted uint80 from uint256, reverting on
     * overflow (when the input is greater than largest uint80).
     *
     * Counterpart to Solidity's `uint80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toUint80(uint256 value) internal pure returns (uint80) {
        require(value <= type(uint80).max, "SafeCast: value doesn't fit in 80 bits");
        return uint80(value);
    }

    /**
     * @dev Returns the downcasted uint72 from uint256, reverting on
     * overflow (when the input is greater than largest uint72).
     *
     * Counterpart to Solidity's `uint72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toUint72(uint256 value) internal pure returns (uint72) {
        require(value <= type(uint72).max, "SafeCast: value doesn't fit in 72 bits");
        return uint72(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v2.5._
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint56 from uint256, reverting on
     * overflow (when the input is greater than largest uint56).
     *
     * Counterpart to Solidity's `uint56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toUint56(uint256 value) internal pure returns (uint56) {
        require(value <= type(uint56).max, "SafeCast: value doesn't fit in 56 bits");
        return uint56(value);
    }

    /**
     * @dev Returns the downcasted uint48 from uint256, reverting on
     * overflow (when the input is greater than largest uint48).
     *
     * Counterpart to Solidity's `uint48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toUint48(uint256 value) internal pure returns (uint48) {
        require(value <= type(uint48).max, "SafeCast: value doesn't fit in 48 bits");
        return uint48(value);
    }

    /**
     * @dev Returns the downcasted uint40 from uint256, reverting on
     * overflow (when the input is greater than largest uint40).
     *
     * Counterpart to Solidity's `uint40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toUint40(uint256 value) internal pure returns (uint40) {
        require(value <= type(uint40).max, "SafeCast: value doesn't fit in 40 bits");
        return uint40(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v2.5._
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint24 from uint256, reverting on
     * overflow (when the input is greater than largest uint24).
     *
     * Counterpart to Solidity's `uint24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toUint24(uint256 value) internal pure returns (uint24) {
        require(value <= type(uint24).max, "SafeCast: value doesn't fit in 24 bits");
        return uint24(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v2.5._
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v2.5._
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     *
     * _Available since v3.0._
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int248 from int256, reverting on
     * overflow (when the input is less than smallest int248 or
     * greater than largest int248).
     *
     * Counterpart to Solidity's `int248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toInt248(int256 value) internal pure returns (int248 downcasted) {
        downcasted = int248(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 248 bits");
    }

    /**
     * @dev Returns the downcasted int240 from int256, reverting on
     * overflow (when the input is less than smallest int240 or
     * greater than largest int240).
     *
     * Counterpart to Solidity's `int240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toInt240(int256 value) internal pure returns (int240 downcasted) {
        downcasted = int240(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 240 bits");
    }

    /**
     * @dev Returns the downcasted int232 from int256, reverting on
     * overflow (when the input is less than smallest int232 or
     * greater than largest int232).
     *
     * Counterpart to Solidity's `int232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toInt232(int256 value) internal pure returns (int232 downcasted) {
        downcasted = int232(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 232 bits");
    }

    /**
     * @dev Returns the downcasted int224 from int256, reverting on
     * overflow (when the input is less than smallest int224 or
     * greater than largest int224).
     *
     * Counterpart to Solidity's `int224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.7._
     */
    function toInt224(int256 value) internal pure returns (int224 downcasted) {
        downcasted = int224(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 224 bits");
    }

    /**
     * @dev Returns the downcasted int216 from int256, reverting on
     * overflow (when the input is less than smallest int216 or
     * greater than largest int216).
     *
     * Counterpart to Solidity's `int216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toInt216(int256 value) internal pure returns (int216 downcasted) {
        downcasted = int216(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 216 bits");
    }

    /**
     * @dev Returns the downcasted int208 from int256, reverting on
     * overflow (when the input is less than smallest int208 or
     * greater than largest int208).
     *
     * Counterpart to Solidity's `int208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toInt208(int256 value) internal pure returns (int208 downcasted) {
        downcasted = int208(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 208 bits");
    }

    /**
     * @dev Returns the downcasted int200 from int256, reverting on
     * overflow (when the input is less than smallest int200 or
     * greater than largest int200).
     *
     * Counterpart to Solidity's `int200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toInt200(int256 value) internal pure returns (int200 downcasted) {
        downcasted = int200(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 200 bits");
    }

    /**
     * @dev Returns the downcasted int192 from int256, reverting on
     * overflow (when the input is less than smallest int192 or
     * greater than largest int192).
     *
     * Counterpart to Solidity's `int192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toInt192(int256 value) internal pure returns (int192 downcasted) {
        downcasted = int192(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 192 bits");
    }

    /**
     * @dev Returns the downcasted int184 from int256, reverting on
     * overflow (when the input is less than smallest int184 or
     * greater than largest int184).
     *
     * Counterpart to Solidity's `int184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toInt184(int256 value) internal pure returns (int184 downcasted) {
        downcasted = int184(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 184 bits");
    }

    /**
     * @dev Returns the downcasted int176 from int256, reverting on
     * overflow (when the input is less than smallest int176 or
     * greater than largest int176).
     *
     * Counterpart to Solidity's `int176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toInt176(int256 value) internal pure returns (int176 downcasted) {
        downcasted = int176(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 176 bits");
    }

    /**
     * @dev Returns the downcasted int168 from int256, reverting on
     * overflow (when the input is less than smallest int168 or
     * greater than largest int168).
     *
     * Counterpart to Solidity's `int168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toInt168(int256 value) internal pure returns (int168 downcasted) {
        downcasted = int168(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 168 bits");
    }

    /**
     * @dev Returns the downcasted int160 from int256, reverting on
     * overflow (when the input is less than smallest int160 or
     * greater than largest int160).
     *
     * Counterpart to Solidity's `int160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toInt160(int256 value) internal pure returns (int160 downcasted) {
        downcasted = int160(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 160 bits");
    }

    /**
     * @dev Returns the downcasted int152 from int256, reverting on
     * overflow (when the input is less than smallest int152 or
     * greater than largest int152).
     *
     * Counterpart to Solidity's `int152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toInt152(int256 value) internal pure returns (int152 downcasted) {
        downcasted = int152(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 152 bits");
    }

    /**
     * @dev Returns the downcasted int144 from int256, reverting on
     * overflow (when the input is less than smallest int144 or
     * greater than largest int144).
     *
     * Counterpart to Solidity's `int144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toInt144(int256 value) internal pure returns (int144 downcasted) {
        downcasted = int144(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 144 bits");
    }

    /**
     * @dev Returns the downcasted int136 from int256, reverting on
     * overflow (when the input is less than smallest int136 or
     * greater than largest int136).
     *
     * Counterpart to Solidity's `int136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toInt136(int256 value) internal pure returns (int136 downcasted) {
        downcasted = int136(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 136 bits");
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128 downcasted) {
        downcasted = int128(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 128 bits");
    }

    /**
     * @dev Returns the downcasted int120 from int256, reverting on
     * overflow (when the input is less than smallest int120 or
     * greater than largest int120).
     *
     * Counterpart to Solidity's `int120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toInt120(int256 value) internal pure returns (int120 downcasted) {
        downcasted = int120(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 120 bits");
    }

    /**
     * @dev Returns the downcasted int112 from int256, reverting on
     * overflow (when the input is less than smallest int112 or
     * greater than largest int112).
     *
     * Counterpart to Solidity's `int112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toInt112(int256 value) internal pure returns (int112 downcasted) {
        downcasted = int112(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 112 bits");
    }

    /**
     * @dev Returns the downcasted int104 from int256, reverting on
     * overflow (when the input is less than smallest int104 or
     * greater than largest int104).
     *
     * Counterpart to Solidity's `int104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toInt104(int256 value) internal pure returns (int104 downcasted) {
        downcasted = int104(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 104 bits");
    }

    /**
     * @dev Returns the downcasted int96 from int256, reverting on
     * overflow (when the input is less than smallest int96 or
     * greater than largest int96).
     *
     * Counterpart to Solidity's `int96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.7._
     */
    function toInt96(int256 value) internal pure returns (int96 downcasted) {
        downcasted = int96(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 96 bits");
    }

    /**
     * @dev Returns the downcasted int88 from int256, reverting on
     * overflow (when the input is less than smallest int88 or
     * greater than largest int88).
     *
     * Counterpart to Solidity's `int88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toInt88(int256 value) internal pure returns (int88 downcasted) {
        downcasted = int88(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 88 bits");
    }

    /**
     * @dev Returns the downcasted int80 from int256, reverting on
     * overflow (when the input is less than smallest int80 or
     * greater than largest int80).
     *
     * Counterpart to Solidity's `int80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toInt80(int256 value) internal pure returns (int80 downcasted) {
        downcasted = int80(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 80 bits");
    }

    /**
     * @dev Returns the downcasted int72 from int256, reverting on
     * overflow (when the input is less than smallest int72 or
     * greater than largest int72).
     *
     * Counterpart to Solidity's `int72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toInt72(int256 value) internal pure returns (int72 downcasted) {
        downcasted = int72(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 72 bits");
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64 downcasted) {
        downcasted = int64(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 64 bits");
    }

    /**
     * @dev Returns the downcasted int56 from int256, reverting on
     * overflow (when the input is less than smallest int56 or
     * greater than largest int56).
     *
     * Counterpart to Solidity's `int56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toInt56(int256 value) internal pure returns (int56 downcasted) {
        downcasted = int56(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 56 bits");
    }

    /**
     * @dev Returns the downcasted int48 from int256, reverting on
     * overflow (when the input is less than smallest int48 or
     * greater than largest int48).
     *
     * Counterpart to Solidity's `int48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toInt48(int256 value) internal pure returns (int48 downcasted) {
        downcasted = int48(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 48 bits");
    }

    /**
     * @dev Returns the downcasted int40 from int256, reverting on
     * overflow (when the input is less than smallest int40 or
     * greater than largest int40).
     *
     * Counterpart to Solidity's `int40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toInt40(int256 value) internal pure returns (int40 downcasted) {
        downcasted = int40(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 40 bits");
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32 downcasted) {
        downcasted = int32(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 32 bits");
    }

    /**
     * @dev Returns the downcasted int24 from int256, reverting on
     * overflow (when the input is less than smallest int24 or
     * greater than largest int24).
     *
     * Counterpart to Solidity's `int24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toInt24(int256 value) internal pure returns (int24 downcasted) {
        downcasted = int24(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 24 bits");
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16 downcasted) {
        downcasted = int16(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 16 bits");
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8 downcasted) {
        downcasted = int8(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 8 bits");
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     *
     * _Available since v3.0._
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";

abstract contract AddressSizeConfig is Ownable {
    // EndpointV1 is using bytes as address. this map is for address length assertion
    mapping(uint32 dstEid => uint256 size) public addressSizes;

    event AddressSizeSet(uint16 eid, uint256 size);

    error AddressSizeConfig_InvalidAddressSize();
    error AddressSizeConfig_AddressSizeAlreadySet();

    function setAddressSize(uint16 _eid, uint256 _size) external onlyOwner {
        if (_size > 32) revert AddressSizeConfig_InvalidAddressSize();
        if (addressSizes[_eid] != 0) revert AddressSizeConfig_AddressSizeAlreadySet();
        addressSizes[_eid] = _size;
        emit AddressSizeSet(_eid, _size);
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { Origin } from "@layerzerolabs/lz-evm-protocol-v2/contracts/interfaces/ILayerZeroEndpointV2.sol";
import { ILayerZeroEndpoint } from "@layerzerolabs/lz-evm-v1-0.7/contracts/interfaces/ILayerZeroEndpoint.sol";
import { AddressCast } from "@layerzerolabs/lz-evm-protocol-v2/contracts/libs/AddressCast.sol";

import { AddressSizeConfig } from "./AddressSizeConfig.sol";
import { MessageLibBase } from "../../MessageLibBase.sol";

// only receiver function from "@layerzerolabs/lz-evm-v1-0.7/contracts/interfaces/ILayerZeroMessagingLibrary.sol"
// because we are separating the send and receive libraries
interface ILayerZeroReceiveLibrary {
    // setConfig / getConfig are User Application (UA) functions to specify Oracle, Relayer, blockConfirmations, libraryVersion
    function setConfig(uint16 _chainId, address _userApplication, uint256 _configType, bytes calldata _config) external;

    function getConfig(
        uint16 _chainId,
        address _userApplication,
        uint256 _configType
    ) external view returns (bytes memory);
}

struct SetDefaultExecutorParam {
    uint32 eid;
    address executor;
}

/// @dev receive-side message library base contract on endpoint v1.
/// design:
/// 1/ it provides an internal execute function that calls the endpoint. It enforces the path definition on V1.
/// 2/ it provides interfaces to configure executors that is whitelisted to execute the msg to prevent grieving
abstract contract ReceiveLibBaseE1 is MessageLibBase, AddressSizeConfig, ILayerZeroReceiveLibrary {
    using AddressCast for bytes32;

    mapping(address oapp => mapping(uint32 eid => address executor)) public executors;
    mapping(uint32 eid => address executor) public defaultExecutors;

    // this event is the same as the PacketDelivered event on EndpointV2
    event PacketDelivered(Origin origin, address receiver);
    event InvalidDst(
        uint16 indexed srcChainId,
        bytes32 srcAddress,
        address indexed dstAddress,
        uint64 nonce,
        bytes32 payloadHash
    );
    event DefaultExecutorsSet(SetDefaultExecutorParam[] params);
    event ExecutorSet(address oapp, uint32 eid, address executor);

    error LZ_MessageLib_InvalidExecutor();
    error LZ_MessageLib_OnlyExecutor();

    constructor(address _endpoint, uint32 _localEid) MessageLibBase(_endpoint, _localEid) {}

    function setDefaultExecutors(SetDefaultExecutorParam[] calldata _params) external onlyOwner {
        for (uint256 i = 0; i < _params.length; ++i) {
            SetDefaultExecutorParam calldata param = _params[i];
            if (param.executor == address(0x0)) revert LZ_MessageLib_InvalidExecutor();
            defaultExecutors[param.eid] = param.executor;
        }
        emit DefaultExecutorsSet(_params);
    }

    function getExecutor(address _oapp, uint32 _remoteEid) public view returns (address) {
        address executor = executors[_oapp][_remoteEid];
        return executor != address(0x0) ? executor : defaultExecutors[_remoteEid];
    }

    function _setExecutor(uint32 _remoteEid, address _oapp, address _executor) internal {
        executors[_oapp][_remoteEid] = _executor;
        emit ExecutorSet(_oapp, _remoteEid, _executor);
    }

    /// @dev this function change pack the path as required for EndpointV1
    function _execute(
        uint16 _srcEid,
        bytes32 _sender,
        address _receiver,
        uint64 _nonce,
        bytes memory _message,
        uint256 _gasLimit
    ) internal {
        // if the executor is malicious, it can make the msg as a storedPayload or fail in the nonBlockingApp
        // which might result in unintended behaviour and risks, like grieving.
        // to err on the safe side, we should assert the executor here.
        if (msg.sender != getExecutor(_receiver, _srcEid)) revert LZ_MessageLib_OnlyExecutor();

        if (_receiver.code.length == 0) {
            /// on chains where EOA has no codes, it will early return and emit InvalidDst event
            // on chains where all address have codes, this will be skipped
            emit InvalidDst(_srcEid, _sender, _receiver, _nonce, keccak256(_message));
            return;
        }

        bytes memory pathData = abi.encodePacked(_sender.toBytes(addressSizes[_srcEid]), _receiver);
        ILayerZeroEndpoint(endpoint).receivePayload(_srcEid, pathData, _receiver, _nonce, _gasLimit, _message);

        Origin memory origin = Origin(_srcEid, _sender, _nonce);
        emit PacketDelivered(origin, _receiver);
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { PacketV1Codec } from "@layerzerolabs/lz-evm-protocol-v2/contracts/messagelib/libs/PacketV1Codec.sol";

import { UlnBase, UlnConfig } from "./UlnBase.sol";

struct Verification {
    bool submitted;
    uint64 confirmations;
}

/// @dev includes the utility functions for checking ULN states and logics
abstract contract ReceiveUlnBase is UlnBase {
    using PacketV1Codec for bytes;

    mapping(bytes32 headerHash => mapping(bytes32 payloadHash => mapping(address dvn => Verification)))
        public hashLookup;

    event PayloadVerified(address dvn, bytes header, uint256 confirmations, bytes32 proofHash);

    error LZ_ULN_InvalidPacketHeader();
    error LZ_ULN_InvalidPacketVersion();
    error LZ_ULN_InvalidEid();
    error LZ_ULN_Verifying();

    // ============================ External ===================================
    function verifiable(
        UlnConfig memory _config,
        bytes32 _headerHash,
        bytes32 _payloadHash
    ) external view returns (bool) {
        return _checkVerifiable(_config, _headerHash, _payloadHash);
    }

    function assertHeader(bytes calldata _packetHeader, uint32 _localEid) external pure {
        _assertHeader(_packetHeader, _localEid);
    }

    // ============================ Internal ===================================
    /// @dev per DVN signing function
    function _verify(bytes calldata _packetHeader, bytes32 _payloadHash, uint64 _confirmations) internal {
        hashLookup[keccak256(_packetHeader)][_payloadHash][msg.sender] = Verification(true, _confirmations);
        emit PayloadVerified(msg.sender, _packetHeader, _confirmations, _payloadHash);
    }

    function _verified(
        address _dvn,
        bytes32 _headerHash,
        bytes32 _payloadHash,
        uint64 _requiredConfirmation
    ) internal view returns (bool verified) {
        Verification memory verification = hashLookup[_headerHash][_payloadHash][_dvn];
        // return true if the dvn has signed enough confirmations
        verified = verification.submitted && verification.confirmations >= _requiredConfirmation;
    }

    function _verifyAndReclaimStorage(UlnConfig memory _config, bytes32 _headerHash, bytes32 _payloadHash) internal {
        if (!_checkVerifiable(_config, _headerHash, _payloadHash)) {
            revert LZ_ULN_Verifying();
        }

        // iterate the required DVNs
        if (_config.requiredDVNCount > 0) {
            for (uint8 i = 0; i < _config.requiredDVNCount; ++i) {
                delete hashLookup[_headerHash][_payloadHash][_config.requiredDVNs[i]];
            }
        }

        // iterate the optional DVNs
        if (_config.optionalDVNCount > 0) {
            for (uint8 i = 0; i < _config.optionalDVNCount; ++i) {
                delete hashLookup[_headerHash][_payloadHash][_config.optionalDVNs[i]];
            }
        }
    }

    function _assertHeader(bytes calldata _packetHeader, uint32 _localEid) internal pure {
        // assert packet header is of right size 81
        if (_packetHeader.length != 81) revert LZ_ULN_InvalidPacketHeader();
        // assert packet header version is the same as ULN
        if (_packetHeader.version() != PacketV1Codec.PACKET_VERSION) revert LZ_ULN_InvalidPacketVersion();
        // assert the packet is for this endpoint
        if (_packetHeader.dstEid() != _localEid) revert LZ_ULN_InvalidEid();
    }

    /// @dev for verifiable view function
    /// @dev checks if this verification is ready to be committed to the endpoint
    function _checkVerifiable(
        UlnConfig memory _config,
        bytes32 _headerHash,
        bytes32 _payloadHash
    ) internal view returns (bool) {
        // iterate the required DVNs
        if (_config.requiredDVNCount > 0) {
            for (uint8 i = 0; i < _config.requiredDVNCount; ++i) {
                if (!_verified(_config.requiredDVNs[i], _headerHash, _payloadHash, _config.confirmations)) {
                    // return if any of the required DVNs haven't signed
                    return false;
                }
            }
            if (_config.optionalDVNCount == 0) {
                // returns early if all required DVNs have signed and there are no optional DVNs
                return true;
            }
        }

        // then it must require optional validations
        uint8 threshold = _config.optionalDVNThreshold;
        for (uint8 i = 0; i < _config.optionalDVNCount; ++i) {
            if (_verified(_config.optionalDVNs[i], _headerHash, _payloadHash, _config.confirmations)) {
                // increment the optional count if the optional DVN has signed
                threshold--;
                if (threshold == 0) {
                    // early return if the optional threshold has hit
                    return true;
                }
            }
        }

        // return false as a catch-all
        return false;
    }
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

/// @dev simply a container of endpoint address and local eid
abstract contract MessageLibBase {
    address internal immutable endpoint;
    uint32 internal immutable localEid;

    error LZ_MessageLib_OnlyEndpoint();

    modifier onlyEndpoint() {
        if (endpoint != msg.sender) revert LZ_MessageLib_OnlyEndpoint();
        _;
    }

    constructor(address _endpoint, uint32 _localEid) {
        endpoint = _endpoint;
        localEid = _localEid;
    }
}
          

// SPDX-License-Identifier: LZBL-1.2

pragma solidity ^0.8.20;

import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";

// the formal properties are documented in the setter functions
struct UlnConfig {
    uint64 confirmations;
    // we store the length of required DVNs and optional DVNs instead of using DVN.length directly to save gas
    uint8 requiredDVNCount; // 0 indicate DEFAULT, NIL_DVN_COUNT indicate NONE (to override the value of default)
    uint8 optionalDVNCount; // 0 indicate DEFAULT, NIL_DVN_COUNT indicate NONE (to override the value of default)
    uint8 optionalDVNThreshold; // (0, optionalDVNCount]
    address[] requiredDVNs; // no duplicates. sorted an an ascending order. allowed overlap with optionalDVNs
    address[] optionalDVNs; // no duplicates. sorted an an ascending order. allowed overlap with requiredDVNs
}

struct SetDefaultUlnConfigParam {
    uint32 eid;
    UlnConfig config;
}

/// @dev includes the utility functions for checking ULN states and logics
abstract contract UlnBase is Ownable {
    address private constant DEFAULT_CONFIG = address(0);
    // reserved values for
    uint8 internal constant DEFAULT = 0;
    uint8 internal constant NIL_DVN_COUNT = type(uint8).max;
    uint64 internal constant NIL_CONFIRMATIONS = type(uint64).max;
    // 127 to prevent total number of DVNs (127 * 2) exceeding uint8.max (255)
    // by limiting the total size, it would help constraint the design of DVNOptions
    uint8 private constant MAX_COUNT = (type(uint8).max - 1) / 2;

    mapping(address oapp => mapping(uint32 eid => UlnConfig)) internal ulnConfigs;

    error LZ_ULN_Unsorted();
    error LZ_ULN_InvalidRequiredDVNCount();
    error LZ_ULN_InvalidOptionalDVNCount();
    error LZ_ULN_AtLeastOneDVN();
    error LZ_ULN_InvalidOptionalDVNThreshold();
    error LZ_ULN_InvalidConfirmations();
    error LZ_ULN_UnsupportedEid(uint32 eid);

    event DefaultUlnConfigsSet(SetDefaultUlnConfigParam[] params);
    event UlnConfigSet(address oapp, uint32 eid, UlnConfig config);

    // ============================ OnlyOwner ===================================

    /// @dev about the DEFAULT ULN config
    /// 1) its values are all LITERAL (e.g. 0 is 0). whereas in the oapp ULN config, 0 (default value) points to the default ULN config
    ///     this design enables the oapp to point to DEFAULT config without explicitly setting the config
    /// 2) its configuration is more restrictive than the oapp ULN config that
    ///     a) it must not use NIL value, where NIL is used only by oapps to indicate the LITERAL 0
    ///     b) it must have at least one DVN
    function setDefaultUlnConfigs(SetDefaultUlnConfigParam[] calldata _params) external onlyOwner {
        for (uint256 i = 0; i < _params.length; ++i) {
            SetDefaultUlnConfigParam calldata param = _params[i];

            // 2.a must not use NIL
            if (param.config.requiredDVNCount == NIL_DVN_COUNT) revert LZ_ULN_InvalidRequiredDVNCount();
            if (param.config.optionalDVNCount == NIL_DVN_COUNT) revert LZ_ULN_InvalidOptionalDVNCount();
            if (param.config.confirmations == NIL_CONFIRMATIONS) revert LZ_ULN_InvalidConfirmations();

            // 2.b must have at least one dvn
            _assertAtLeastOneDVN(param.config);

            _setConfig(DEFAULT_CONFIG, param.eid, param.config);
        }
        emit DefaultUlnConfigsSet(_params);
    }

    // ============================ View ===================================
    // @dev assuming most oapps use default, we get default as memory and custom as storage to save gas
    function getUlnConfig(address _oapp, uint32 _remoteEid) public view returns (UlnConfig memory rtnConfig) {
        UlnConfig storage defaultConfig = ulnConfigs[DEFAULT_CONFIG][_remoteEid];
        UlnConfig storage customConfig = ulnConfigs[_oapp][_remoteEid];

        // if confirmations is 0, use default
        uint64 confirmations = customConfig.confirmations;
        if (confirmations == DEFAULT) {
            rtnConfig.confirmations = defaultConfig.confirmations;
        } else if (confirmations != NIL_CONFIRMATIONS) {
            // if confirmations is uint64.max, no block confirmations required
            rtnConfig.confirmations = confirmations;
        } // else do nothing, rtnConfig.confirmation is 0

        if (customConfig.requiredDVNCount == DEFAULT) {
            if (defaultConfig.requiredDVNCount > 0) {
                // copy only if count > 0. save gas
                rtnConfig.requiredDVNs = defaultConfig.requiredDVNs;
                rtnConfig.requiredDVNCount = defaultConfig.requiredDVNCount;
            } // else, do nothing
        } else {
            if (customConfig.requiredDVNCount != NIL_DVN_COUNT) {
                rtnConfig.requiredDVNs = customConfig.requiredDVNs;
                rtnConfig.requiredDVNCount = customConfig.requiredDVNCount;
            } // else, do nothing
        }

        if (customConfig.optionalDVNCount == DEFAULT) {
            if (defaultConfig.optionalDVNCount > 0) {
                // copy only if count > 0. save gas
                rtnConfig.optionalDVNs = defaultConfig.optionalDVNs;
                rtnConfig.optionalDVNCount = defaultConfig.optionalDVNCount;
                rtnConfig.optionalDVNThreshold = defaultConfig.optionalDVNThreshold;
            }
        } else {
            if (customConfig.optionalDVNCount != NIL_DVN_COUNT) {
                rtnConfig.optionalDVNs = customConfig.optionalDVNs;
                rtnConfig.optionalDVNCount = customConfig.optionalDVNCount;
                rtnConfig.optionalDVNThreshold = customConfig.optionalDVNThreshold;
            }
        }

        // the final value must have at least one dvn
        // it is possible that some default config result into 0 dvns
        _assertAtLeastOneDVN(rtnConfig);
    }

    /// @dev Get the uln config without the default config for the given remoteEid.
    function getAppUlnConfig(address _oapp, uint32 _remoteEid) external view returns (UlnConfig memory) {
        return ulnConfigs[_oapp][_remoteEid];
    }

    // ============================ Internal ===================================
    function _setUlnConfig(uint32 _remoteEid, address _oapp, UlnConfig memory _param) internal {
        _setConfig(_oapp, _remoteEid, _param);

        // get ULN config again as a catch all to ensure the config is valid
        getUlnConfig(_oapp, _remoteEid);
        emit UlnConfigSet(_oapp, _remoteEid, _param);
    }

    /// @dev a supported Eid must have a valid default uln config, which has at least one dvn
    function _isSupportedEid(uint32 _remoteEid) internal view returns (bool) {
        UlnConfig storage defaultConfig = ulnConfigs[DEFAULT_CONFIG][_remoteEid];
        return defaultConfig.requiredDVNCount > 0 || defaultConfig.optionalDVNThreshold > 0;
    }

    function _assertSupportedEid(uint32 _remoteEid) internal view {
        if (!_isSupportedEid(_remoteEid)) revert LZ_ULN_UnsupportedEid(_remoteEid);
    }

    // ============================ Private ===================================

    function _assertAtLeastOneDVN(UlnConfig memory _config) private pure {
        if (_config.requiredDVNCount == 0 && _config.optionalDVNThreshold == 0) revert LZ_ULN_AtLeastOneDVN();
    }

    /// @dev this private function is used in both setDefaultUlnConfigs and setUlnConfig
    function _setConfig(address _oapp, uint32 _eid, UlnConfig memory _param) private {
        // @dev required dvns
        // if dvnCount == NONE, dvns list must be empty
        // if dvnCount == DEFAULT, dvn list must be empty
        // otherwise, dvnList.length == dvnCount and assert the list is valid
        if (_param.requiredDVNCount == NIL_DVN_COUNT || _param.requiredDVNCount == DEFAULT) {
            if (_param.requiredDVNs.length != 0) revert LZ_ULN_InvalidRequiredDVNCount();
        } else {
            if (_param.requiredDVNs.length != _param.requiredDVNCount || _param.requiredDVNCount > MAX_COUNT)
                revert LZ_ULN_InvalidRequiredDVNCount();
            _assertNoDuplicates(_param.requiredDVNs);
        }

        // @dev optional dvns
        // if optionalDVNCount == NONE, optionalDVNs list must be empty and threshold must be 0
        // if optionalDVNCount == DEFAULT, optionalDVNs list must be empty and threshold must be 0
        // otherwise, optionalDVNs.length == optionalDVNCount, threshold > 0 && threshold <= optionalDVNCount and assert the list is valid

        // example use case: an oapp uses the DEFAULT 'required' but
        //     a) use a custom 1/1 dvn (practically a required dvn), or
        //     b) use a custom 2/3 dvn
        if (_param.optionalDVNCount == NIL_DVN_COUNT || _param.optionalDVNCount == DEFAULT) {
            if (_param.optionalDVNs.length != 0) revert LZ_ULN_InvalidOptionalDVNCount();
            if (_param.optionalDVNThreshold != 0) revert LZ_ULN_InvalidOptionalDVNThreshold();
        } else {
            if (_param.optionalDVNs.length != _param.optionalDVNCount || _param.optionalDVNCount > MAX_COUNT)
                revert LZ_ULN_InvalidOptionalDVNCount();
            if (_param.optionalDVNThreshold == 0 || _param.optionalDVNThreshold > _param.optionalDVNCount)
                revert LZ_ULN_InvalidOptionalDVNThreshold();
            _assertNoDuplicates(_param.optionalDVNs);
        }
        // don't assert valid count here, as it needs to be validated along side default config

        ulnConfigs[_oapp][_eid] = _param;
    }

    function _assertNoDuplicates(address[] memory _dvns) private pure {
        address lastDVN = address(0);
        for (uint256 i = 0; i < _dvns.length; i++) {
            address dvn = _dvns[i];
            if (dvn <= lastDVN) revert LZ_ULN_Unsorted(); // to ensure no duplicates
            lastDVN = dvn;
        }
    }
}