Contract Address Details

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "../libraries/PbBridge.sol";
import "./Pool.sol";

/**
 * @title The liquidity-pool based bridge.
 */
contract Bridge is Pool {
    using SafeERC20 for IERC20;

    // liquidity events
    event Send(
        bytes32 transferId,
        address sender,
        address receiver,
        address token,
        uint256 amount,
        uint64 dstChainId,
        uint64 nonce,
        uint32 maxSlippage
    );
    event Relay(
        bytes32 transferId,
        address sender,
        address receiver,
        address token,
        uint256 amount,
        uint64 srcChainId,
        bytes32 srcTransferId
    );
    // gov events
    event MinSendUpdated(address token, uint256 amount);
    event MaxSendUpdated(address token, uint256 amount);

    mapping(bytes32 => bool) public transfers;
    mapping(address => uint256) public minSend; // send _amount must > minSend
    mapping(address => uint256) public maxSend;

    // min allowed max slippage uint32 value is slippage * 1M, eg. 0.5% -> 5000
    uint32 public minimalMaxSlippage;

    /**
     * @notice Send a cross-chain transfer via the liquidity pool-based bridge.
     * NOTE: This function DOES NOT SUPPORT fee-on-transfer / rebasing tokens.
     * @param _receiver The address of the receiver.
     * @param _token The address of the token.
     * @param _amount The amount of the transfer.
     * @param _dstChainId The destination chain ID.
     * @param _nonce A number input to guarantee uniqueness of transferId. Can be timestamp in practice.
     * @param _maxSlippage The max slippage accepted, given as percentage in point (pip). Eg. 5000 means 0.5%.
     * Must be greater than minimalMaxSlippage. Receiver is guaranteed to receive at least (100% - max slippage percentage) * amount or the
     * transfer can be refunded.
     */
    function send(
        address _receiver,
        address _token,
        uint256 _amount,
        uint64 _dstChainId,
        uint64 _nonce,
        uint32 _maxSlippage // slippage * 1M, eg. 0.5% -> 5000
    ) external nonReentrant whenNotPaused {
        bytes32 transferId = _send(_receiver, _token, _amount, _dstChainId, _nonce, _maxSlippage);
        IERC20(_token).safeTransferFrom(msg.sender, address(this), _amount);
        emit Send(transferId, msg.sender, _receiver, _token, _amount, _dstChainId, _nonce, _maxSlippage);
    }

    /**
     * @notice Send a cross-chain transfer via the liquidity pool-based bridge using the native token.
     * @param _receiver The address of the receiver.
     * @param _amount The amount of the transfer.
     * @param _dstChainId The destination chain ID.
     * @param _nonce A unique number. Can be timestamp in practice.
     * @param _maxSlippage The max slippage accepted, given as percentage in point (pip). Eg. 5000 means 0.5%.
     * Must be greater than minimalMaxSlippage. Receiver is guaranteed to receive at least (100% - max slippage percentage) * amount or the
     * transfer can be refunded.
     */
    function sendNative(
        address _receiver,
        uint256 _amount,
        uint64 _dstChainId,
        uint64 _nonce,
        uint32 _maxSlippage
    ) external payable nonReentrant whenNotPaused {
        require(msg.value == _amount, "Amount mismatch");
        require(nativeWrap != address(0), "Native wrap not set");
        bytes32 transferId = _send(_receiver, nativeWrap, _amount, _dstChainId, _nonce, _maxSlippage);
        IWETH(nativeWrap).deposit{value: _amount}();
        emit Send(transferId, msg.sender, _receiver, nativeWrap, _amount, _dstChainId, _nonce, _maxSlippage);
    }

    function _send(
        address _receiver,
        address _token,
        uint256 _amount,
        uint64 _dstChainId,
        uint64 _nonce,
        uint32 _maxSlippage
    ) private returns (bytes32) {
        require(_amount > minSend[_token], "amount too small");
        require(maxSend[_token] == 0 || _amount <= maxSend[_token], "amount too large");
        require(_maxSlippage > minimalMaxSlippage, "max slippage too small");
        bytes32 transferId = keccak256(
            // uint64(block.chainid) for consistency as entire system uses uint64 for chain id
            // len = 20 + 20 + 20 + 32 + 8 + 8 + 8 = 116
            abi.encodePacked(msg.sender, _receiver, _token, _amount, _dstChainId, _nonce, uint64(block.chainid))
        );
        require(transfers[transferId] == false, "transfer exists");
        transfers[transferId] = true;
        return transferId;
    }

    /**
     * @notice Relay a cross-chain transfer sent from a liquidity pool-based bridge on another chain.
     * @param _relayRequest The serialized Relay protobuf.
     * @param _sigs The list of signatures sorted by signing addresses in ascending order. A relay must be signed-off by
     * +2/3 of the bridge's current signing power to be delivered.
     * @param _signers The sorted list of signers.
     * @param _powers The signing powers of the signers.
     */
    function relay(
        bytes calldata _relayRequest,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) external whenNotPaused {
        bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "Relay"));
        verifySigs(abi.encodePacked(domain, _relayRequest), _sigs, _signers, _powers);
        PbBridge.Relay memory request = PbBridge.decRelay(_relayRequest);
        // len = 20 + 20 + 20 + 32 + 8 + 8 + 32 = 140
        bytes32 transferId = keccak256(
            abi.encodePacked(
                request.sender,
                request.receiver,
                request.token,
                request.amount,
                request.srcChainId,
                request.dstChainId,
                request.srcTransferId
            )
        );
        require(transfers[transferId] == false, "transfer exists");
        transfers[transferId] = true;
        _updateVolume(request.token, request.amount);
        uint256 delayThreshold = delayThresholds[request.token];
        if (delayThreshold > 0 && request.amount > delayThreshold) {
            _addDelayedTransfer(transferId, request.receiver, request.token, request.amount);
        } else {
            _sendToken(request.receiver, request.token, request.amount);
        }

        emit Relay(
            transferId,
            request.sender,
            request.receiver,
            request.token,
            request.amount,
            request.srcChainId,
            request.srcTransferId
        );
    }

    function setMinSend(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
        require(_tokens.length == _amounts.length, "length mismatch");
        for (uint256 i = 0; i < _tokens.length; i++) {
            minSend[_tokens[i]] = _amounts[i];
            emit MinSendUpdated(_tokens[i], _amounts[i]);
        }
    }

    function setMaxSend(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
        require(_tokens.length == _amounts.length, "length mismatch");
        for (uint256 i = 0; i < _tokens.length; i++) {
            maxSend[_tokens[i]] = _amounts[i];
            emit MaxSendUpdated(_tokens[i], _amounts[i]);
        }
    }

    function setMinimalMaxSlippage(uint32 _minimalMaxSlippage) external onlyGovernor {
        minimalMaxSlippage = _minimalMaxSlippage;
    }

    // This is needed to receive ETH when calling `IWETH.withdraw`
    receive() external payable {}
}
        

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.8.0;

interface ISigsVerifier {
    /**
     * @notice Verifies that a message is signed by a quorum among the signers.
     * @param _msg signed message
     * @param _sigs list of signatures sorted by signer addresses in ascending order
     * @param _signers sorted list of current signers
     * @param _powers powers of current signers
     */
    function verifySigs(
        bytes memory _msg,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) external view;
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.8.0;

interface IWETH {
    function deposit() external payable;

    function withdraw(uint256) external;
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

// runtime proto sol library
library Pb {
    enum WireType {
        Varint,
        Fixed64,
        LengthDelim,
        StartGroup,
        EndGroup,
        Fixed32
    }

    struct Buffer {
        uint256 idx; // the start index of next read. when idx=b.length, we're done
        bytes b; // hold serialized proto msg, readonly
    }

    // create a new in-memory Buffer object from raw msg bytes
    function fromBytes(bytes memory raw) internal pure returns (Buffer memory buf) {
        buf.b = raw;
        buf.idx = 0;
    }

    // whether there are unread bytes
    function hasMore(Buffer memory buf) internal pure returns (bool) {
        return buf.idx < buf.b.length;
    }

    // decode current field number and wiretype
    function decKey(Buffer memory buf) internal pure returns (uint256 tag, WireType wiretype) {
        uint256 v = decVarint(buf);
        tag = v / 8;
        wiretype = WireType(v & 7);
    }

    // count tag occurrences, return an array due to no memory map support
    // have to create array for (maxtag+1) size. cnts[tag] = occurrences
    // should keep buf.idx unchanged because this is only a count function
    function cntTags(Buffer memory buf, uint256 maxtag) internal pure returns (uint256[] memory cnts) {
        uint256 originalIdx = buf.idx;
        cnts = new uint256[](maxtag + 1); // protobuf's tags are from 1 rather than 0
        uint256 tag;
        WireType wire;
        while (hasMore(buf)) {
            (tag, wire) = decKey(buf);
            cnts[tag] += 1;
            skipValue(buf, wire);
        }
        buf.idx = originalIdx;
    }

    // read varint from current buf idx, move buf.idx to next read, return the int value
    function decVarint(Buffer memory buf) internal pure returns (uint256 v) {
        bytes10 tmp; // proto int is at most 10 bytes (7 bits can be used per byte)
        bytes memory bb = buf.b; // get buf.b mem addr to use in assembly
        v = buf.idx; // use v to save one additional uint variable
        assembly {
            tmp := mload(add(add(bb, 32), v)) // load 10 bytes from buf.b[buf.idx] to tmp
        }
        uint256 b; // store current byte content
        v = 0; // reset to 0 for return value
        for (uint256 i = 0; i < 10; i++) {
            assembly {
                b := byte(i, tmp) // don't use tmp[i] because it does bound check and costs extra
            }
            v |= (b & 0x7F) << (i * 7);
            if (b & 0x80 == 0) {
                buf.idx += i + 1;
                return v;
            }
        }
        revert(); // i=10, invalid varint stream
    }

    // read length delimited field and return bytes
    function decBytes(Buffer memory buf) internal pure returns (bytes memory b) {
        uint256 len = decVarint(buf);
        uint256 end = buf.idx + len;
        require(end <= buf.b.length); // avoid overflow
        b = new bytes(len);
        bytes memory bufB = buf.b; // get buf.b mem addr to use in assembly
        uint256 bStart;
        uint256 bufBStart = buf.idx;
        assembly {
            bStart := add(b, 32)
            bufBStart := add(add(bufB, 32), bufBStart)
        }
        for (uint256 i = 0; i < len; i += 32) {
            assembly {
                mstore(add(bStart, i), mload(add(bufBStart, i)))
            }
        }
        buf.idx = end;
    }

    // return packed ints
    function decPacked(Buffer memory buf) internal pure returns (uint256[] memory t) {
        uint256 len = decVarint(buf);
        uint256 end = buf.idx + len;
        require(end <= buf.b.length); // avoid overflow
        // array in memory must be init w/ known length
        // so we have to create a tmp array w/ max possible len first
        uint256[] memory tmp = new uint256[](len);
        uint256 i = 0; // count how many ints are there
        while (buf.idx < end) {
            tmp[i] = decVarint(buf);
            i++;
        }
        t = new uint256[](i); // init t with correct length
        for (uint256 j = 0; j < i; j++) {
            t[j] = tmp[j];
        }
        return t;
    }

    // move idx pass current value field, to beginning of next tag or msg end
    function skipValue(Buffer memory buf, WireType wire) internal pure {
        if (wire == WireType.Varint) {
            decVarint(buf);
        } else if (wire == WireType.LengthDelim) {
            uint256 len = decVarint(buf);
            buf.idx += len; // skip len bytes value data
            require(buf.idx <= buf.b.length); // avoid overflow
        } else {
            revert();
        } // unsupported wiretype
    }

    // type conversion help utils
    function _bool(uint256 x) internal pure returns (bool v) {
        return x != 0;
    }

    function _uint256(bytes memory b) internal pure returns (uint256 v) {
        require(b.length <= 32); // b's length must be smaller than or equal to 32
        assembly {
            v := mload(add(b, 32))
        } // load all 32bytes to v
        v = v >> (8 * (32 - b.length)); // only first b.length is valid
    }

    function _address(bytes memory b) internal pure returns (address v) {
        v = _addressPayable(b);
    }

    function _addressPayable(bytes memory b) internal pure returns (address payable v) {
        require(b.length == 20);
        //load 32bytes then shift right 12 bytes
        assembly {
            v := div(mload(add(b, 32)), 0x1000000000000000000000000)
        }
    }

    function _bytes32(bytes memory b) internal pure returns (bytes32 v) {
        require(b.length == 32);
        assembly {
            v := mload(add(b, 32))
        }
    }

    // uint[] to uint8[]
    function uint8s(uint256[] memory arr) internal pure returns (uint8[] memory t) {
        t = new uint8[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint8(arr[i]);
        }
    }

    function uint32s(uint256[] memory arr) internal pure returns (uint32[] memory t) {
        t = new uint32[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint32(arr[i]);
        }
    }

    function uint64s(uint256[] memory arr) internal pure returns (uint64[] memory t) {
        t = new uint64[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint64(arr[i]);
        }
    }

    function bools(uint256[] memory arr) internal pure returns (bool[] memory t) {
        t = new bool[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = arr[i] != 0;
        }
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

// Code generated by protoc-gen-sol. DO NOT EDIT.
// source: bridge.proto
pragma solidity 0.8.9;
import "./Pb.sol";

library PbBridge {
    using Pb for Pb.Buffer; // so we can call Pb funcs on Buffer obj

    struct Relay {
        address sender; // tag: 1
        address receiver; // tag: 2
        address token; // tag: 3
        uint256 amount; // tag: 4
        uint64 srcChainId; // tag: 5
        uint64 dstChainId; // tag: 6
        bytes32 srcTransferId; // tag: 7
    } // end struct Relay

    function decRelay(bytes memory raw) internal pure returns (Relay memory m) {
        Pb.Buffer memory buf = Pb.fromBytes(raw);

        uint256 tag;
        Pb.WireType wire;
        while (buf.hasMore()) {
            (tag, wire) = buf.decKey();
            if (false) {}
            // solidity has no switch/case
            else if (tag == 1) {
                m.sender = Pb._address(buf.decBytes());
            } else if (tag == 2) {
                m.receiver = Pb._address(buf.decBytes());
            } else if (tag == 3) {
                m.token = Pb._address(buf.decBytes());
            } else if (tag == 4) {
                m.amount = Pb._uint256(buf.decBytes());
            } else if (tag == 5) {
                m.srcChainId = uint64(buf.decVarint());
            } else if (tag == 6) {
                m.dstChainId = uint64(buf.decVarint());
            } else if (tag == 7) {
                m.srcTransferId = Pb._bytes32(buf.decBytes());
            } else {
                buf.skipValue(wire);
            } // skip value of unknown tag
        }
    } // end decoder Relay
}
          

// SPDX-License-Identifier: GPL-3.0-only

// Code generated by protoc-gen-sol. DO NOT EDIT.
// source: contracts/libraries/proto/pool.proto
pragma solidity 0.8.9;
import "./Pb.sol";

library PbPool {
    using Pb for Pb.Buffer; // so we can call Pb funcs on Buffer obj

    struct WithdrawMsg {
        uint64 chainid; // tag: 1
        uint64 seqnum; // tag: 2
        address receiver; // tag: 3
        address token; // tag: 4
        uint256 amount; // tag: 5
        bytes32 refid; // tag: 6
    } // end struct WithdrawMsg

    function decWithdrawMsg(bytes memory raw) internal pure returns (WithdrawMsg memory m) {
        Pb.Buffer memory buf = Pb.fromBytes(raw);

        uint256 tag;
        Pb.WireType wire;
        while (buf.hasMore()) {
            (tag, wire) = buf.decKey();
            if (false) {}
            // solidity has no switch/case
            else if (tag == 1) {
                m.chainid = uint64(buf.decVarint());
            } else if (tag == 2) {
                m.seqnum = uint64(buf.decVarint());
            } else if (tag == 3) {
                m.receiver = Pb._address(buf.decBytes());
            } else if (tag == 4) {
                m.token = Pb._address(buf.decBytes());
            } else if (tag == 5) {
                m.amount = Pb._uint256(buf.decBytes());
            } else if (tag == 6) {
                m.refid = Pb._bytes32(buf.decBytes());
            } else {
                buf.skipValue(wire);
            } // skip value of unknown tag
        }
    } // end decoder WithdrawMsg
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "../interfaces/IWETH.sol";
import "../libraries/PbPool.sol";
import "../safeguard/Pauser.sol";
import "../safeguard/VolumeControl.sol";
import "../safeguard/DelayedTransfer.sol";
import "./Signers.sol";

/**
 * @title Liquidity pool functions for {Bridge}.
 */
contract Pool is Signers, ReentrancyGuard, Pauser, VolumeControl, DelayedTransfer {
    using SafeERC20 for IERC20;

    uint64 public addseq; // ensure unique LiquidityAdded event, start from 1
    mapping(address => uint256) public minAdd; // add _amount must > minAdd

    // map of successful withdraws, if true means already withdrew money or added to delayedTransfers
    mapping(bytes32 => bool) public withdraws;

    // erc20 wrap of gas token of this chain, eg. WETH, when relay ie. pay out,
    // if request.token equals this, will withdraw and send native token to receiver
    // note we don't check whether it's zero address. when this isn't set, and request.token
    // is all 0 address, guarantee fail
    address public nativeWrap;

    // liquidity events
    event LiquidityAdded(
        uint64 seqnum,
        address provider,
        address token,
        uint256 amount // how many tokens were added
    );
    event WithdrawDone(
        bytes32 withdrawId,
        uint64 seqnum,
        address receiver,
        address token,
        uint256 amount,
        bytes32 refid
    );
    event MinAddUpdated(address token, uint256 amount);

    /**
     * @notice Add liquidity to the pool-based bridge.
     * NOTE: This function DOES NOT SUPPORT fee-on-transfer / rebasing tokens.
     * NOTE: ONLY call this from an EOA. DO NOT call from a contract address.
     * @param _token The address of the token.
     * @param _amount The amount to add.
     */
    function addLiquidity(address _token, uint256 _amount) external nonReentrant whenNotPaused {
        require(_amount > minAdd[_token], "amount too small");
        addseq += 1;
        IERC20(_token).safeTransferFrom(msg.sender, address(this), _amount);
        emit LiquidityAdded(addseq, msg.sender, _token, _amount);
    }

    /**
     * @notice Add native token liquidity to the pool-based bridge.
     * NOTE: ONLY call this from an EOA. DO NOT call from a contract address.
     * @param _amount The amount to add.
     */
    function addNativeLiquidity(uint256 _amount) external payable nonReentrant whenNotPaused {
        require(msg.value == _amount, "Amount mismatch");
        require(nativeWrap != address(0), "Native wrap not set");
        require(_amount > minAdd[nativeWrap], "amount too small");
        addseq += 1;
        IWETH(nativeWrap).deposit{value: _amount}();
        emit LiquidityAdded(addseq, msg.sender, nativeWrap, _amount);
    }

    /**
     * @notice Withdraw funds from the bridge pool.
     * @param _wdmsg The serialized Withdraw protobuf.
     * @param _sigs The list of signatures sorted by signing addresses in ascending order. A withdrawal must be
     * signed-off by +2/3 of the bridge's current signing power to be delivered.
     * @param _signers The sorted list of signers.
     * @param _powers The signing powers of the signers.
     */
    function withdraw(
        bytes calldata _wdmsg,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) external whenNotPaused {
        bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "WithdrawMsg"));
        verifySigs(abi.encodePacked(domain, _wdmsg), _sigs, _signers, _powers);
        // decode and check wdmsg
        PbPool.WithdrawMsg memory wdmsg = PbPool.decWithdrawMsg(_wdmsg);
        // len = 8 + 8 + 20 + 20 + 32 = 88
        bytes32 wdId = keccak256(
            abi.encodePacked(wdmsg.chainid, wdmsg.seqnum, wdmsg.receiver, wdmsg.token, wdmsg.amount)
        );
        require(withdraws[wdId] == false, "withdraw already succeeded");
        withdraws[wdId] = true;
        _updateVolume(wdmsg.token, wdmsg.amount);
        uint256 delayThreshold = delayThresholds[wdmsg.token];
        if (delayThreshold > 0 && wdmsg.amount > delayThreshold) {
            _addDelayedTransfer(wdId, wdmsg.receiver, wdmsg.token, wdmsg.amount);
        } else {
            _sendToken(wdmsg.receiver, wdmsg.token, wdmsg.amount);
        }
        emit WithdrawDone(wdId, wdmsg.seqnum, wdmsg.receiver, wdmsg.token, wdmsg.amount, wdmsg.refid);
    }

    function executeDelayedTransfer(bytes32 id) external whenNotPaused {
        delayedTransfer memory transfer = _executeDelayedTransfer(id);
        _sendToken(transfer.receiver, transfer.token, transfer.amount);
    }

    function setMinAdd(address[] calldata _tokens, uint256[] calldata _amounts) external onlyGovernor {
        require(_tokens.length == _amounts.length, "length mismatch");
        for (uint256 i = 0; i < _tokens.length; i++) {
            minAdd[_tokens[i]] = _amounts[i];
            emit MinAddUpdated(_tokens[i], _amounts[i]);
        }
    }

    function _sendToken(
        address _receiver,
        address _token,
        uint256 _amount
    ) internal {
        if (_token == nativeWrap) {
            // withdraw then transfer native to receiver
            IWETH(nativeWrap).withdraw(_amount);
            (bool sent, ) = _receiver.call{value: _amount, gas: 50000}("");
            require(sent, "failed to send native token");
        } else {
            IERC20(_token).safeTransfer(_receiver, _amount);
        }
    }

    // set nativeWrap, for relay requests, if token == nativeWrap, will withdraw first then transfer native to receiver
    function setWrap(address _weth) external onlyOwner {
        nativeWrap = _weth;
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "../interfaces/ISigsVerifier.sol";

/**
 * @title Multi-sig verification and management functions for {Bridge}.
 */
contract Signers is Ownable, ISigsVerifier {
    using ECDSA for bytes32;

    bytes32 public ssHash;
    uint256 public triggerTime; // timestamp when last update was triggered

    // reset can be called by the owner address for emergency recovery
    uint256 public resetTime;
    uint256 public noticePeriod; // advance notice period as seconds for reset
    uint256 constant MAX_INT = 2**256 - 1;

    event SignersUpdated(address[] _signers, uint256[] _powers);

    event ResetNotification(uint256 resetTime);

    /**
     * @notice Verifies that a message is signed by a quorum among the signers
     * The sigs must be sorted by signer addresses in ascending order.
     * @param _msg signed message
     * @param _sigs list of signatures sorted by signer addresses in ascending order
     * @param _signers sorted list of current signers
     * @param _powers powers of current signers
     */
    function verifySigs(
        bytes memory _msg,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) public view override {
        bytes32 h = keccak256(abi.encodePacked(_signers, _powers));
        require(ssHash == h, "Mismatch current signers");
        _verifySignedPowers(keccak256(_msg).toEthSignedMessageHash(), _sigs, _signers, _powers);
    }

    /**
     * @notice Update new signers.
     * @param _newSigners sorted list of new signers
     * @param _curPowers powers of new signers
     * @param _sigs list of signatures sorted by signer addresses in ascending order
     * @param _curSigners sorted list of current signers
     * @param _curPowers powers of current signers
     */
    function updateSigners(
        uint256 _triggerTime,
        address[] calldata _newSigners,
        uint256[] calldata _newPowers,
        bytes[] calldata _sigs,
        address[] calldata _curSigners,
        uint256[] calldata _curPowers
    ) external {
        // use trigger time for nonce protection, must be ascending
        require(_triggerTime > triggerTime, "Trigger time is not increasing");
        // make sure triggerTime is not too large, as it cannot be decreased once set
        require(_triggerTime < block.timestamp + 3600, "Trigger time is too large");
        bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "UpdateSigners"));
        verifySigs(abi.encodePacked(domain, _triggerTime, _newSigners, _newPowers), _sigs, _curSigners, _curPowers);
        _updateSigners(_newSigners, _newPowers);
        triggerTime = _triggerTime;
    }

    /**
     * @notice reset signers, only used for init setup and emergency recovery
     */
    function resetSigners(address[] calldata _signers, uint256[] calldata _powers) external onlyOwner {
        require(block.timestamp > resetTime, "not reach reset time");
        resetTime = MAX_INT;
        _updateSigners(_signers, _powers);
    }

    function notifyResetSigners() external onlyOwner {
        resetTime = block.timestamp + noticePeriod;
        emit ResetNotification(resetTime);
    }

    function increaseNoticePeriod(uint256 period) external onlyOwner {
        require(period > noticePeriod, "notice period can only be increased");
        noticePeriod = period;
    }

    // separate from verifySigs func to avoid "stack too deep" issue
    function _verifySignedPowers(
        bytes32 _hash,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) private pure {
        require(_signers.length == _powers.length, "signers and powers length not match");
        uint256 totalPower; // sum of all signer.power
        for (uint256 i = 0; i < _signers.length; i++) {
            totalPower += _powers[i];
        }
        uint256 quorum = (totalPower * 2) / 3 + 1;

        uint256 signedPower; // sum of signer powers who are in sigs
        address prev = address(0);
        uint256 index = 0;
        for (uint256 i = 0; i < _sigs.length; i++) {
            address signer = _hash.recover(_sigs[i]);
            require(signer > prev, "signers not in ascending order");
            prev = signer;
            // now find match signer add its power
            while (signer > _signers[index]) {
                index += 1;
                require(index < _signers.length, "signer not found");
            }
            if (signer == _signers[index]) {
                signedPower += _powers[index];
            }
            if (signedPower >= quorum) {
                // return early to save gas
                return;
            }
        }
        revert("quorum not reached");
    }

    function _updateSigners(address[] calldata _signers, uint256[] calldata _powers) private {
        require(_signers.length == _powers.length, "signers and powers length not match");
        address prev = address(0);
        for (uint256 i = 0; i < _signers.length; i++) {
            require(_signers[i] > prev, "New signers not in ascending order");
            prev = _signers[i];
        }
        ssHash = keccak256(abi.encodePacked(_signers, _powers));
        emit SignersUpdated(_signers, _powers);
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "./Governor.sol";

abstract contract DelayedTransfer is Governor {
    struct delayedTransfer {
        address receiver;
        address token;
        uint256 amount;
        uint256 timestamp;
    }
    mapping(bytes32 => delayedTransfer) public delayedTransfers;
    mapping(address => uint256) public delayThresholds;
    uint256 public delayPeriod; // in seconds

    event DelayedTransferAdded(bytes32 id);
    event DelayedTransferExecuted(bytes32 id, address receiver, address token, uint256 amount);

    event DelayPeriodUpdated(uint256 period);
    event DelayThresholdUpdated(address token, uint256 threshold);

    function setDelayThresholds(address[] calldata _tokens, uint256[] calldata _thresholds) external onlyGovernor {
        require(_tokens.length == _thresholds.length, "length mismatch");
        for (uint256 i = 0; i < _tokens.length; i++) {
            delayThresholds[_tokens[i]] = _thresholds[i];
            emit DelayThresholdUpdated(_tokens[i], _thresholds[i]);
        }
    }

    function setDelayPeriod(uint256 _period) external onlyGovernor {
        delayPeriod = _period;
        emit DelayPeriodUpdated(_period);
    }

    function _addDelayedTransfer(
        bytes32 id,
        address receiver,
        address token,
        uint256 amount
    ) internal {
        require(delayedTransfers[id].timestamp == 0, "delayed transfer already exists");
        delayedTransfers[id] = delayedTransfer({
            receiver: receiver,
            token: token,
            amount: amount,
            timestamp: block.timestamp
        });
        emit DelayedTransferAdded(id);
    }

    // caller needs to do the actual token transfer
    function _executeDelayedTransfer(bytes32 id) internal returns (delayedTransfer memory) {
        delayedTransfer memory transfer = delayedTransfers[id];
        require(transfer.timestamp > 0, "delayed transfer not exist");
        require(block.timestamp > transfer.timestamp + delayPeriod, "delayed transfer still locked");
        delete delayedTransfers[id];
        emit DelayedTransferExecuted(id, transfer.receiver, transfer.token, transfer.amount);
        return transfer;
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "@openzeppelin/contracts/access/Ownable.sol";

abstract contract Governor is Ownable {
    mapping(address => bool) public governors;

    event GovernorAdded(address account);
    event GovernorRemoved(address account);

    modifier onlyGovernor() {
        require(isGovernor(msg.sender), "Caller is not governor");
        _;
    }

    constructor() {
        _addGovernor(msg.sender);
    }

    function isGovernor(address _account) public view returns (bool) {
        return governors[_account];
    }

    function addGovernor(address _account) public onlyOwner {
        _addGovernor(_account);
    }

    function removeGovernor(address _account) public onlyOwner {
        _removeGovernor(_account);
    }

    function renounceGovernor() public {
        _removeGovernor(msg.sender);
    }

    function _addGovernor(address _account) private {
        require(!isGovernor(_account), "Account is already governor");
        governors[_account] = true;
        emit GovernorAdded(_account);
    }

    function _removeGovernor(address _account) private {
        require(isGovernor(_account), "Account is not governor");
        governors[_account] = false;
        emit GovernorRemoved(_account);
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

abstract contract Pauser is Ownable, Pausable {
    mapping(address => bool) public pausers;

    event PauserAdded(address account);
    event PauserRemoved(address account);

    constructor() {
        _addPauser(msg.sender);
    }

    modifier onlyPauser() {
        require(isPauser(msg.sender), "Caller is not pauser");
        _;
    }

    function pause() public onlyPauser {
        _pause();
    }

    function unpause() public onlyPauser {
        _unpause();
    }

    function isPauser(address account) public view returns (bool) {
        return pausers[account];
    }

    function addPauser(address account) public onlyOwner {
        _addPauser(account);
    }

    function removePauser(address account) public onlyOwner {
        _removePauser(account);
    }

    function renouncePauser() public {
        _removePauser(msg.sender);
    }

    function _addPauser(address account) private {
        require(!isPauser(account), "Account is already pauser");
        pausers[account] = true;
        emit PauserAdded(account);
    }

    function _removePauser(address account) private {
        require(isPauser(account), "Account is not pauser");
        pausers[account] = false;
        emit PauserRemoved(account);
    }
}
          

// SPDX-License-Identifier: GPL-3.0-only

pragma solidity 0.8.9;

import "./Governor.sol";

abstract contract VolumeControl is Governor {
    uint256 public epochLength; // seconds
    mapping(address => uint256) public epochVolumes; // key is token
    mapping(address => uint256) public epochVolumeCaps; // key is token
    mapping(address => uint256) public lastOpTimestamps; // key is token

    event EpochLengthUpdated(uint256 length);
    event EpochVolumeUpdated(address token, uint256 cap);

    function setEpochLength(uint256 _length) external onlyGovernor {
        epochLength = _length;
        emit EpochLengthUpdated(_length);
    }

    function setEpochVolumeCaps(address[] calldata _tokens, uint256[] calldata _caps) external onlyGovernor {
        require(_tokens.length == _caps.length, "length mismatch");
        for (uint256 i = 0; i < _tokens.length; i++) {
            epochVolumeCaps[_tokens[i]] = _caps[i];
            emit EpochVolumeUpdated(_tokens[i], _caps[i]);
        }
    }

    function _updateVolume(address _token, uint256 _amount) internal {
        if (epochLength == 0) {
            return;
        }
        uint256 cap = epochVolumeCaps[_token];
        if (cap == 0) {
            return;
        }
        uint256 volume = epochVolumes[_token];
        uint256 timestamp = block.timestamp;
        uint256 epochStartTime = (timestamp / epochLength) * epochLength;
        if (lastOpTimestamps[_token] < epochStartTime) {
            volume = _amount;
        } else {
            volume += _amount;
        }
        require(volume <= cap, "volume exceeds cap");
        epochVolumes[_token] = volume;
        lastOpTimestamps[_token] = timestamp;
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing 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: MIT
// OpenZeppelin Contracts v4.4.1 (security/Pausable.sol)

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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;
    }
}
          

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

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

import "../Strings.sol";

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        // Check the signature length
        // - case 65: r,s,v signature (standard)
        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else if (signature.length == 64) {
            bytes32 r;
            bytes32 vs;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            assembly {
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
            }
            return tryRecover(hash, r, vs);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }
        if (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}