// File: @openzeppelin/contracts/proxy/ERC1967/ERC1967Upgrade.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.2;

import "../beacon/IBeacon.sol";
import "../../utils/Address.sol";
import "../../utils/StorageSlot.sol";

/**
 * @dev This abstract contract provides getters and event emitting update functions for
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
 *
 * _Available since v4.1._
 *
 * @custom:oz-upgrades-unsafe-allow delegatecall
 */
abstract contract ERC1967Upgrade {
    // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
    bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;

    /**
     * @dev Storage slot with the address of the current implementation.
     * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    /**
     * @dev Emitted when the implementation is upgraded.
     */
    event Upgraded(address indexed implementation);

    /**
     * @dev Returns the current implementation address.
     */
    function _getImplementation() internal view returns (address) {
        return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 implementation slot.
     */
    function _setImplementation(address newImplementation) private {
        require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
    }

    /**
     * @dev Perform implementation upgrade
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }

    /**
     * @dev Perform implementation upgrade with additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        _upgradeTo(newImplementation);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(newImplementation, data);
        }
    }

    /**
     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCallSecure(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        address oldImplementation = _getImplementation();

        // Initial upgrade and setup call
        _setImplementation(newImplementation);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(newImplementation, data);
        }

        // Perform rollback test if not already in progress
        StorageSlot.BooleanSlot storage rollbackTesting = StorageSlot.getBooleanSlot(_ROLLBACK_SLOT);
        if (!rollbackTesting.value) {
            // Trigger rollback using upgradeTo from the new implementation
            rollbackTesting.value = true;
            Address.functionDelegateCall(
                newImplementation,
                abi.encodeWithSignature("upgradeTo(address)", oldImplementation)
            );
            rollbackTesting.value = false;
            // Check rollback was effective
            require(oldImplementation == _getImplementation(), "ERC1967Upgrade: upgrade breaks further upgrades");
            // Finally reset to the new implementation and log the upgrade
            _upgradeTo(newImplementation);
        }
    }

    /**
     * @dev Storage slot with the admin of the contract.
     * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;

    /**
     * @dev Emitted when the admin account has changed.
     */
    event AdminChanged(address previousAdmin, address newAdmin);

    /**
     * @dev Returns the current admin.
     */
    function _getAdmin() internal view returns (address) {
        return StorageSlot.getAddressSlot(_ADMIN_SLOT).value;
    }

    /**
     * @dev Stores a new address in the EIP1967 admin slot.
     */
    function _setAdmin(address newAdmin) private {
        require(newAdmin != address(0), "ERC1967: new admin is the zero address");
        StorageSlot.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
    }

    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     */
    function _changeAdmin(address newAdmin) internal {
        emit AdminChanged(_getAdmin(), newAdmin);
        _setAdmin(newAdmin);
    }

    /**
     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
     */
    bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;

    /**
     * @dev Emitted when the beacon is upgraded.
     */
    event BeaconUpgraded(address indexed beacon);

    /**
     * @dev Returns the current beacon.
     */
    function _getBeacon() internal view returns (address) {
        return StorageSlot.getAddressSlot(_BEACON_SLOT).value;
    }

    /**
     * @dev Stores a new beacon in the EIP1967 beacon slot.
     */
    function _setBeacon(address newBeacon) private {
        require(Address.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            Address.isContract(IBeacon(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlot.getAddressSlot(_BEACON_SLOT).value = newBeacon;
    }

    /**
     * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
     * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
     *
     * Emits a {BeaconUpgraded} event.
     */
    function _upgradeBeaconToAndCall(
        address newBeacon,
        bytes memory data,
        bool forceCall
    ) internal {
        _setBeacon(newBeacon);
        emit BeaconUpgraded(newBeacon);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(IBeacon(newBeacon).implementation(), data);
        }
    }
}

// File: @openzeppelin/contracts/proxy/beacon/IBeacon.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev This is the interface that {BeaconProxy} expects of its beacon.
 */
interface IBeacon {
    /**
     * @dev Must return an address that can be used as a delegate call target.
     *
     * {BeaconProxy} will check that this address is a contract.
     */
    function implementation() external view returns (address);
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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);
            }
        }
    }
}

// File: @openzeppelin/contracts/utils/StorageSlot.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC1967 implementation slot:
 * ```
 * contract ERC1967 {
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
 */
library StorageSlot {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        assembly {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        assembly {
            r.slot := slot
        }
    }
}

// File: /contracts/Getters.sol



// contracts/Getters.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

import "./State.sol";

contract Getters is State {
    function getGuardianSet(uint32 index) public view returns (Structs.GuardianSet memory) {
        return _state.guardianSets[index];
    }

    function getCurrentGuardianSetIndex() public view returns (uint32) {
        return _state.guardianSetIndex;
    }

    function getGuardianSetExpiry() public view returns (uint32) {
        return _state.guardianSetExpiry;
    }

    function governanceActionIsConsumed(bytes32 hash) public view returns (bool) {
        return _state.consumedGovernanceActions[hash];
    }

    function isInitialized(address impl) public view returns (bool) {
        return _state.initializedImplementations[impl];
    }

    function chainId() public view returns (uint16) {
        return _state.provider.chainId;
    }

    function evmChainId() public view returns (uint256) {
        return _state.evmChainId;
    }

    function isFork() public view returns (bool) {
        return evmChainId() != block.chainid;
    }

    function governanceChainId() public view returns (uint16){
        return _state.provider.governanceChainId;
    }

    function governanceContract() public view returns (bytes32){
        return _state.provider.governanceContract;
    }

    function messageFee() public view returns (uint256) {
        return _state.messageFee;
    }

    function nextSequence(address emitter) public view returns (uint64) {
        return _state.sequences[emitter];
    }
}
// File: /contracts/Governance.sol



// contracts/Governance.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

import "./Structs.sol";
import "./GovernanceStructs.sol";
import "./Messages.sol";
import "./Setters.sol";

import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Upgrade.sol";

/**
 * @dev `Governance` defines a means to enacting changes to the core bridge contract,
 * guardianSets, message fees, and transfer fees
 */
abstract contract Governance is GovernanceStructs, Messages, Setters, ERC1967Upgrade {
    event ContractUpgraded(address indexed oldContract, address indexed newContract);
    event GuardianSetAdded(uint32 indexed index);

    // "Core" (left padded)
    bytes32 constant module = 0x00000000000000000000000000000000000000000000000000000000436f7265;

    /**
     * @dev Upgrades a contract via Governance VAA/VM
     */
    function submitContractUpgrade(bytes memory _vm) public {
        require(!isFork(), "invalid fork");

        Structs.VM memory vm = parseVM(_vm);

        // Verify the VAA is valid before processing it
        (bool isValid, string memory reason) = verifyGovernanceVM(vm);
        require(isValid, reason);

        GovernanceStructs.ContractUpgrade memory upgrade = parseContractUpgrade(vm.payload);

        // Verify the VAA is for this module
        require(upgrade.module == module, "Invalid Module");

        // Verify the VAA is for this chain
        require(upgrade.chain == chainId(), "Invalid Chain");

        // Record the governance action as consumed
        setGovernanceActionConsumed(vm.hash);

        // Upgrades the implementation to the new contract
        upgradeImplementation(upgrade.newContract);
    }

    /**
     * @dev Sets a `messageFee` via Governance VAA/VM
     */
    function submitSetMessageFee(bytes memory _vm) public {
        Structs.VM memory vm = parseVM(_vm);

        // Verify the VAA is valid before processing it
        (bool isValid, string memory reason) = verifyGovernanceVM(vm);
        require(isValid, reason);

        GovernanceStructs.SetMessageFee memory upgrade = parseSetMessageFee(vm.payload);

        // Verify the VAA is for this module
        require(upgrade.module == module, "Invalid Module");

        // Verify the VAA is for this chain
        require(upgrade.chain == chainId() && !isFork(), "Invalid Chain");

        // Record the governance action as consumed to prevent reentry
        setGovernanceActionConsumed(vm.hash);

        // Updates the messageFee
        setMessageFee(upgrade.messageFee);
    }

    /**
     * @dev Deploys a new `guardianSet` via Governance VAA/VM
     */
    function submitNewGuardianSet(bytes memory _vm) public {
        Structs.VM memory vm = parseVM(_vm);

        // Verify the VAA is valid before processing it
        (bool isValid, string memory reason) = verifyGovernanceVM(vm);
        require(isValid, reason);

        GovernanceStructs.GuardianSetUpgrade memory upgrade = parseGuardianSetUpgrade(vm.payload);

        // Verify the VAA is for this module
        require(upgrade.module == module, "invalid Module");

        // Verify the VAA is for this chain
        require((upgrade.chain == chainId() && !isFork()) || upgrade.chain == 0, "invalid Chain");

        // Verify the Guardian Set keys are not empty, this guards
        // against the accidential upgrade to an empty GuardianSet
        require(upgrade.newGuardianSet.keys.length > 0, "new guardian set is empty");

        // Verify that the index is incrementing via a predictable +1 pattern
        require(upgrade.newGuardianSetIndex == getCurrentGuardianSetIndex() + 1, "index must increase in steps of 1");

        // Record the governance action as consumed to prevent reentry
        setGovernanceActionConsumed(vm.hash);

        // Trigger a time-based expiry of current guardianSet
        expireGuardianSet(getCurrentGuardianSetIndex());

        // Add the new guardianSet to guardianSets
        storeGuardianSet(upgrade.newGuardianSet, upgrade.newGuardianSetIndex);

        // Makes the new guardianSet effective
        updateGuardianSetIndex(upgrade.newGuardianSetIndex);
    }

    /**
     * @dev Submits transfer fees to the recipient via Governance VAA/VM
     */
    function submitTransferFees(bytes memory _vm) public {
        Structs.VM memory vm = parseVM(_vm);

        // Verify the VAA is valid before processing it
        (bool isValid, string memory reason) = verifyGovernanceVM(vm);
        require(isValid, reason);

        // Obtains the transfer from the VAA payload
        GovernanceStructs.TransferFees memory transfer = parseTransferFees(vm.payload);

        // Verify the VAA is for this module
        require(transfer.module == module, "invalid Module");

        // Verify the VAA is for this chain
        require((transfer.chain == chainId() && !isFork()) || transfer.chain == 0, "invalid Chain");

        // Record the governance action as consumed to prevent reentry
        setGovernanceActionConsumed(vm.hash);

        // Obtains the recipient address to be paid transfer fees
        address payable recipient = payable(address(uint160(uint256(transfer.recipient))));

        // Transfers transfer fees to the recipient
        recipient.transfer(transfer.amount);
    }

    /**
    * @dev Updates the `chainId` and `evmChainId` on a forked chain via Governance VAA/VM
    */
    function submitRecoverChainId(bytes memory _vm) public {
        require(isFork(), "not a fork");

        Structs.VM memory vm = parseVM(_vm);

        // Verify the VAA is valid before processing it
        (bool isValid, string memory reason) = verifyGovernanceVM(vm);
        require(isValid, reason);

        GovernanceStructs.RecoverChainId memory rci = parseRecoverChainId(vm.payload);

        // Verify the VAA is for this module
        require(rci.module == module, "invalid Module");

        // Verify the VAA is for this chain
        require(rci.evmChainId == block.chainid, "invalid EVM Chain");

        // Record the governance action as consumed to prevent reentry
        setGovernanceActionConsumed(vm.hash);

        // Update the chainIds
        setEvmChainId(rci.evmChainId);
        setChainId(rci.newChainId);
    }

    /**
     * @dev Upgrades the `currentImplementation` with a `newImplementation`
     */
    function upgradeImplementation(address newImplementation) internal {
        address currentImplementation = _getImplementation();

        _upgradeTo(newImplementation);

        // Call initialize function of the new implementation
        (bool success, bytes memory reason) = newImplementation.delegatecall(abi.encodeWithSignature("initialize()"));

        require(success, string(reason));

        emit ContractUpgraded(currentImplementation, newImplementation);
    }

    /**
     * @dev Verifies a Governance VAA/VM is valid
     */
    function verifyGovernanceVM(Structs.VM memory vm) internal view returns (bool, string memory){
        // Verify the VAA is valid
        (bool isValid, string memory reason) = verifyVM(vm);
        if (!isValid){
            return (false, reason);
        }

        // only current guardianset can sign governance packets
        if (vm.guardianSetIndex != getCurrentGuardianSetIndex()) {
            return (false, "not signed by current guardian set");
        }

        // Verify the VAA is from the governance chain (Solana)
        if (uint16(vm.emitterChainId) != governanceChainId()) {
            return (false, "wrong governance chain");
        }

        // Verify the emitter contract is the governance contract (0x4 left padded)
        if (vm.emitterAddress != governanceContract()) {
            return (false, "wrong governance contract");
        }

        // Verify this governance action hasn't already been
        // consumed to prevent reentry and replay
        if (governanceActionIsConsumed(vm.hash)){
            return (false, "governance action already consumed");
        }

        // Confirm the governance VAA/VM is valid
        return (true, "");
    }
}
// File: /contracts/GovernanceStructs.sol



// contracts/GovernanceStructs.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

import "./libraries/external/BytesLib.sol";
import "./Structs.sol";

/**
 * @dev `GovernanceStructs` defines a set of structs and parsing functions
 * for minimal struct validation
 */
contract GovernanceStructs {
    using BytesLib for bytes;

    enum GovernanceAction {
        UpgradeContract,
        UpgradeGuardianset
    }

    struct ContractUpgrade {
        bytes32 module;
        uint8 action;
        uint16 chain;

        address newContract;
    }

    struct GuardianSetUpgrade {
        bytes32 module;
        uint8 action;
        uint16 chain;

        Structs.GuardianSet newGuardianSet;
        uint32 newGuardianSetIndex;
    }

    struct SetMessageFee {
        bytes32 module;
        uint8 action;
        uint16 chain;

        uint256 messageFee;
    }

    struct TransferFees {
        bytes32 module;
        uint8 action;
        uint16 chain;

        uint256 amount;
        bytes32 recipient;
    }

    struct RecoverChainId {
        bytes32 module;
        uint8 action;

        uint256 evmChainId;
        uint16 newChainId;
    }

    /// @dev Parse a contract upgrade (action 1) with minimal validation
    function parseContractUpgrade(bytes memory encodedUpgrade) public pure returns (ContractUpgrade memory cu) {
        uint index = 0;

        cu.module = encodedUpgrade.toBytes32(index);
        index += 32;

        cu.action = encodedUpgrade.toUint8(index);
        index += 1;

        require(cu.action == 1, "invalid ContractUpgrade");

        cu.chain = encodedUpgrade.toUint16(index);
        index += 2;

        cu.newContract = address(uint160(uint256(encodedUpgrade.toBytes32(index))));
        index += 32;

        require(encodedUpgrade.length == index, "invalid ContractUpgrade");
    }

    /// @dev Parse a guardianSet upgrade (action 2) with minimal validation
    function parseGuardianSetUpgrade(bytes memory encodedUpgrade) public pure returns (GuardianSetUpgrade memory gsu) {
        uint index = 0;

        gsu.module = encodedUpgrade.toBytes32(index);
        index += 32;

        gsu.action = encodedUpgrade.toUint8(index);
        index += 1;

        require(gsu.action == 2, "invalid GuardianSetUpgrade");

        gsu.chain = encodedUpgrade.toUint16(index);
        index += 2;

        gsu.newGuardianSetIndex = encodedUpgrade.toUint32(index);
        index += 4;

        uint8 guardianLength = encodedUpgrade.toUint8(index);
        index += 1;

        gsu.newGuardianSet = Structs.GuardianSet({
            keys : new address[](guardianLength),
            expirationTime : 0
        });

        for(uint i = 0; i < guardianLength; i++) {
            gsu.newGuardianSet.keys[i] = encodedUpgrade.toAddress(index);
            index += 20;
        }

        require(encodedUpgrade.length == index, "invalid GuardianSetUpgrade");
    }

    /// @dev Parse a setMessageFee (action 3) with minimal validation
    function parseSetMessageFee(bytes memory encodedSetMessageFee) public pure returns (SetMessageFee memory smf) {
        uint index = 0;

        smf.module = encodedSetMessageFee.toBytes32(index);
        index += 32;

        smf.action = encodedSetMessageFee.toUint8(index);
        index += 1;

        require(smf.action == 3, "invalid SetMessageFee");

        smf.chain = encodedSetMessageFee.toUint16(index);
        index += 2;

        smf.messageFee = encodedSetMessageFee.toUint256(index);
        index += 32;

        require(encodedSetMessageFee.length == index, "invalid SetMessageFee");
    }

    /// @dev Parse a transferFees (action 4) with minimal validation
    function parseTransferFees(bytes memory encodedTransferFees) public pure returns (TransferFees memory tf) {
        uint index = 0;

        tf.module = encodedTransferFees.toBytes32(index);
        index += 32;

        tf.action = encodedTransferFees.toUint8(index);
        index += 1;

        require(tf.action == 4, "invalid TransferFees");

        tf.chain = encodedTransferFees.toUint16(index);
        index += 2;

        tf.amount = encodedTransferFees.toUint256(index);
        index += 32;

        tf.recipient = encodedTransferFees.toBytes32(index);
        index += 32;

        require(encodedTransferFees.length == index, "invalid TransferFees");
    }

    /// @dev Parse a recoverChainId (action 5) with minimal validation
    function parseRecoverChainId(bytes memory encodedRecoverChainId) public pure returns (RecoverChainId memory rci) {
        uint index = 0;

        rci.module = encodedRecoverChainId.toBytes32(index);
        index += 32;

        rci.action = encodedRecoverChainId.toUint8(index);
        index += 1;

        require(rci.action == 5, "invalid RecoverChainId");

        rci.evmChainId = encodedRecoverChainId.toUint256(index);
        index += 32;

        rci.newChainId = encodedRecoverChainId.toUint16(index);
        index += 2;

        require(encodedRecoverChainId.length == index, "invalid RecoverChainId");
    }
}
// File: /contracts/Implementation.sol



// contracts/Implementation.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "./Governance.sol";

import "@openzeppelin/contracts/proxy/ERC1967/ERC1967Upgrade.sol";

contract Implementation is Governance {
    event LogMessagePublished(address indexed sender, uint64 sequence, uint32 nonce, bytes payload, uint8 consistencyLevel);

    // Publish a message to be attested by the Wormhole network
    function publishMessage(
        uint32 nonce,
        bytes memory payload,
        uint8 consistencyLevel
    ) public payable returns (uint64 sequence) {
        // check fee
        require(msg.value == messageFee(), "invalid fee");

        sequence = useSequence(msg.sender);
        // emit log
        emit LogMessagePublished(msg.sender, sequence, nonce, payload, consistencyLevel);
    }

    function useSequence(address emitter) internal returns (uint64 sequence) {
        sequence = nextSequence(emitter);
        setNextSequence(emitter, sequence + 1);
    }

    function initialize() initializer public virtual {
        // this function needs to be exposed for an upgrade to pass
        uint256 evmChainId;
        uint16 chain = chainId();

        // Wormhole chain ids explicitly enumerated
        if        (chain == 2)  { evmChainId = 1;          // ethereum
        } else if (chain == 4)  { evmChainId = 56;         // bsc
        } else if (chain == 5)  { evmChainId = 137;        // polygon
        } else if (chain == 6)  { evmChainId = 43114;      // avalanche
        } else if (chain == 7)  { evmChainId = 42262;      // oasis
        } else if (chain == 9)  { evmChainId = 1313161554; // aurora
        } else if (chain == 10) { evmChainId = 250;        // fantom
        } else if (chain == 11) { evmChainId = 686;        // karura
        } else if (chain == 12) { evmChainId = 787;        // acala
        } else if (chain == 13) { evmChainId = 8217;       // klaytn
        } else if (chain == 14) { evmChainId = 42220;      // celo
        } else if (chain == 16) { evmChainId = 1284;       // moonbeam
        } else if (chain == 17) { evmChainId = 245022934;  // neon
        } else if (chain == 23) { evmChainId = 42161;      // arbitrum
        } else if (chain == 24) { evmChainId = 10;         // optimism
        } else if (chain == 25) { evmChainId = 100;        // gnosis
        } else {
            revert("Unknown chain id.");
        }

        setEvmChainId(evmChainId);
    }

    modifier initializer() {
        address implementation = ERC1967Upgrade._getImplementation();

        require(
            !isInitialized(implementation),
            "already initialized"
        );

        setInitialized(implementation);

        _;
    }

    fallback() external payable {revert("unsupported");}

    receive() external payable {revert("the Wormhole contract does not accept assets");}
}

// File: /contracts/Messages.sol



// contracts/Messages.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "./Getters.sol";
import "./Structs.sol";
import "./libraries/external/BytesLib.sol";


contract Messages is Getters {
    using BytesLib for bytes;

    /// @dev parseAndVerifyVM serves to parse an encodedVM and wholy validate it for consumption
    function parseAndVerifyVM(bytes calldata encodedVM) public view returns (Structs.VM memory vm, bool valid, string memory reason) {
        vm = parseVM(encodedVM);
        (valid, reason) = verifyVM(vm);
    }

   /**
    * @dev `verifyVM` serves to validate an arbitrary vm against a valid Guardian set
    *  - it aims to make sure the VM is for a known guardianSet
    *  - it aims to ensure the guardianSet is not expired
    *  - it aims to ensure the VM has reached quorum
    *  - it aims to verify the signatures provided against the guardianSet
    */
    function verifyVM(Structs.VM memory vm) public view returns (bool valid, string memory reason) {
        /// @dev Obtain the current guardianSet for the guardianSetIndex provided
        Structs.GuardianSet memory guardianSet = getGuardianSet(vm.guardianSetIndex);

       /**
        * @dev Checks whether the guardianSet has zero keys
        * WARNING: This keys check is critical to ensure the guardianSet has keys present AND to ensure
        * that guardianSet key size doesn't fall to zero and negatively impact quorum assessment.  If guardianSet
        * key length is 0 and vm.signatures length is 0, this could compromise the integrity of both vm and
        * signature verification.
        */
        if(guardianSet.keys.length == 0){
            return (false, "invalid guardian set");
        }

        /// @dev Checks if VM guardian set index matches the current index (unless the current set is expired).
        if(vm.guardianSetIndex != getCurrentGuardianSetIndex() && guardianSet.expirationTime < block.timestamp){
            return (false, "guardian set has expired");
        }

       /**
        * @dev We're using a fixed point number transformation with 1 decimal to deal with rounding.
        *   WARNING: This quorum check is critical to assessing whether we have enough Guardian signatures to validate a VM
        *   if making any changes to this, obtain additional peer review. If guardianSet key length is 0 and
        *   vm.signatures length is 0, this could compromise the integrity of both vm and signature verification.
        */
        if (vm.signatures.length < quorum(guardianSet.keys.length)){
            return (false, "no quorum");
        }

        /// @dev Verify the proposed vm.signatures against the guardianSet
        (bool signaturesValid, string memory invalidReason) = verifySignatures(vm.hash, vm.signatures, guardianSet);
        if(!signaturesValid){
            return (false, invalidReason);
        }

        /// If we are here, we've validated the VM is a valid multi-sig that matches the guardianSet.
        return (true, "");
    }

    /**
     * @dev verifySignatures serves to validate arbitrary sigatures against an arbitrary guardianSet
     *  - it intentionally does not solve for expectations within guardianSet (you should use verifyVM if you need these protections)
     *  - it intentioanlly does not solve for quorum (you should use verifyVM if you need these protections)
     *  - it intentionally returns true when signatures is an empty set (you should use verifyVM if you need these protections)
     */
    function verifySignatures(bytes32 hash, Structs.Signature[] memory signatures, Structs.GuardianSet memory guardianSet) public pure returns (bool valid, string memory reason) {
        uint8 lastIndex = 0;
        uint256 guardianCount = guardianSet.keys.length;
        for (uint i = 0; i < signatures.length; i++) {
            Structs.Signature memory sig = signatures[i];

            /// Ensure that provided signature indices are ascending only
            require(i == 0 || sig.guardianIndex > lastIndex, "signature indices must be ascending");
            lastIndex = sig.guardianIndex;

            /// @dev Ensure that the provided signature index is within the
            /// bounds of the guardianSet. This is implicitly checked by the array
            /// index operation below, so this check is technically redundant.
            /// However, reverting explicitly here ensures that a bug is not
            /// introduced accidentally later due to the nontrivial storage
            /// semantics of solidity.
            require(sig.guardianIndex < guardianCount, "guardian index out of bounds");

            /// Check to see if the signer of the signature does not match a specific Guardian key at the provided index
            if(ecrecover(hash, sig.v, sig.r, sig.s) != guardianSet.keys[sig.guardianIndex]){
                return (false, "VM signature invalid");
            }
        }

        /// If we are here, we've validated that the provided signatures are valid for the provided guardianSet
        return (true, "");
    }

    /**
     * @dev parseVM serves to parse an encodedVM into a vm struct
     *  - it intentionally performs no validation functions, it simply parses raw into a struct
     */
    function parseVM(bytes memory encodedVM) public pure virtual returns (Structs.VM memory vm) {
        uint index = 0;

        vm.version = encodedVM.toUint8(index);
        index += 1;
        // SECURITY: Note that currently the VM.version is not part of the hash 
        // and for reasons described below it cannot be made part of the hash. 
        // This means that this field's integrity is not protected and cannot be trusted. 
        // This is not a problem today since there is only one accepted version, but it 
        // could be a problem if we wanted to allow other versions in the future. 
        require(vm.version == 1, "VM version incompatible"); 

        vm.guardianSetIndex = encodedVM.toUint32(index);
        index += 4;

        // Parse Signatures
        uint256 signersLen = encodedVM.toUint8(index);
        index += 1;
        vm.signatures = new Structs.Signature[](signersLen);
        for (uint i = 0; i < signersLen; i++) {
            vm.signatures[i].guardianIndex = encodedVM.toUint8(index);
            index += 1;

            vm.signatures[i].r = encodedVM.toBytes32(index);
            index += 32;
            vm.signatures[i].s = encodedVM.toBytes32(index);
            index += 32;
            vm.signatures[i].v = encodedVM.toUint8(index) + 27;
            index += 1;
        }

        /*
        Hash the body

        SECURITY: Do not change the way the hash of a VM is computed! 
        Changing it could result into two different hashes for the same observation. 
        But xDapps rely on the hash of an observation for replay protection.
        */
        bytes memory body = encodedVM.slice(index, encodedVM.length - index);
        vm.hash = keccak256(abi.encodePacked(keccak256(body)));

        // Parse the body
        vm.timestamp = encodedVM.toUint32(index);
        index += 4;

        vm.nonce = encodedVM.toUint32(index);
        index += 4;

        vm.emitterChainId = encodedVM.toUint16(index);
        index += 2;

        vm.emitterAddress = encodedVM.toBytes32(index);
        index += 32;

        vm.sequence = encodedVM.toUint64(index);
        index += 8;

        vm.consistencyLevel = encodedVM.toUint8(index);
        index += 1;

        vm.payload = encodedVM.slice(index, encodedVM.length - index);
    }

    /**
     * @dev quorum serves solely to determine the number of signatures required to acheive quorum
     */
    function quorum(uint numGuardians) public pure virtual returns (uint numSignaturesRequiredForQuorum) {
        // The max number of guardians is 255
        require(numGuardians < 256, "too many guardians");
        return ((numGuardians * 2) / 3) + 1;
    }
}

// File: /contracts/Setters.sol



// contracts/Setters.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

import "./State.sol";

contract Setters is State {
    function updateGuardianSetIndex(uint32 newIndex) internal {
        _state.guardianSetIndex = newIndex;
    }

    function expireGuardianSet(uint32 index) internal {
        _state.guardianSets[index].expirationTime = uint32(block.timestamp) + 86400;
    }

    function storeGuardianSet(Structs.GuardianSet memory set, uint32 index) internal {
        _state.guardianSets[index] = set;
    }

    function setInitialized(address implementatiom) internal {
        _state.initializedImplementations[implementatiom] = true;
    }

    function setGovernanceActionConsumed(bytes32 hash) internal {
        _state.consumedGovernanceActions[hash] = true;
    }

    function setChainId(uint16 chainId) internal {
        _state.provider.chainId = chainId;
    }

    function setGovernanceChainId(uint16 chainId) internal {
        _state.provider.governanceChainId = chainId;
    }

    function setGovernanceContract(bytes32 governanceContract) internal {
        _state.provider.governanceContract = governanceContract;
    }

    function setMessageFee(uint256 newFee) internal {
        _state.messageFee = newFee;
    }

    function setNextSequence(address emitter, uint64 sequence) internal {
        _state.sequences[emitter] = sequence;
    }

    function setEvmChainId(uint256 evmChainId) internal {
        require(evmChainId == block.chainid, "invalid evmChainId");
        _state.evmChainId = evmChainId;
    }
}
// File: /contracts/State.sol



// contracts/State.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

import "./Structs.sol";

contract Events {
    event LogGuardianSetChanged(
        uint32 oldGuardianIndex,
        uint32 newGuardianIndex
    );

    event LogMessagePublished(
        address emitter_address,
        uint32 nonce,
        bytes payload
    );
}

contract Storage {
    struct WormholeState {
        Structs.Provider provider;

        // Mapping of guardian_set_index => guardian set
        mapping(uint32 => Structs.GuardianSet) guardianSets;

        // Current active guardian set index
        uint32 guardianSetIndex;

        // Period for which a guardian set stays active after it has been replaced
        uint32 guardianSetExpiry;

        // Sequence numbers per emitter
        mapping(address => uint64) sequences;

        // Mapping of consumed governance actions
        mapping(bytes32 => bool) consumedGovernanceActions;

        // Mapping of initialized implementations
        mapping(address => bool) initializedImplementations;

        uint256 messageFee;

        // EIP-155 Chain ID
        uint256 evmChainId;
    }
}

contract State {
    Storage.WormholeState _state;
}

// File: /contracts/Structs.sol



// contracts/Structs.sol
// SPDX-License-Identifier: Apache 2

pragma solidity ^0.8.0;

interface Structs {
	struct Provider {
		uint16 chainId;
		uint16 governanceChainId;
		bytes32 governanceContract;
	}

	struct GuardianSet {
		address[] keys;
		uint32 expirationTime;
	}

	struct Signature {
		bytes32 r;
		bytes32 s;
		uint8 v;
		uint8 guardianIndex;
	}

	struct VM {
		uint8 version;
		uint32 timestamp;
		uint32 nonce;
		uint16 emitterChainId;
		bytes32 emitterAddress;
		uint64 sequence;
		uint8 consistencyLevel;
		bytes payload;

		uint32 guardianSetIndex;
		Signature[] signatures;

		bytes32 hash;
	}
}

// File: /contracts/libraries/external/BytesLib.sol



// SPDX-License-Identifier: Unlicense
/*
 * @title Solidity Bytes Arrays Utils
 * @author Gonçalo Sá <goncalo.sa@consensys.net>
 *
 * @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
 *      The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
 */
pragma solidity >=0.8.0 <0.9.0;


library BytesLib {
    function concat(
        bytes memory _preBytes,
        bytes memory _postBytes
    )
        internal
        pure
        returns (bytes memory)
    {
        bytes memory tempBytes;

        assembly {
            // Get a location of some free memory and store it in tempBytes as
            // Solidity does for memory variables.
            tempBytes := mload(0x40)

            // Store the length of the first bytes array at the beginning of
            // the memory for tempBytes.
            let length := mload(_preBytes)
            mstore(tempBytes, length)

            // Maintain a memory counter for the current write location in the
            // temp bytes array by adding the 32 bytes for the array length to
            // the starting location.
            let mc := add(tempBytes, 0x20)
            // Stop copying when the memory counter reaches the length of the
            // first bytes array.
            let end := add(mc, length)

            for {
                // Initialize a copy counter to the start of the _preBytes data,
                // 32 bytes into its memory.
                let cc := add(_preBytes, 0x20)
            } lt(mc, end) {
                // Increase both counters by 32 bytes each iteration.
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                // Write the _preBytes data into the tempBytes memory 32 bytes
                // at a time.
                mstore(mc, mload(cc))
            }

            // Add the length of _postBytes to the current length of tempBytes
            // and store it as the new length in the first 32 bytes of the
            // tempBytes memory.
            length := mload(_postBytes)
            mstore(tempBytes, add(length, mload(tempBytes)))

            // Move the memory counter back from a multiple of 0x20 to the
            // actual end of the _preBytes data.
            mc := end
            // Stop copying when the memory counter reaches the new combined
            // length of the arrays.
            end := add(mc, length)

            for {
                let cc := add(_postBytes, 0x20)
            } lt(mc, end) {
                mc := add(mc, 0x20)
                cc := add(cc, 0x20)
            } {
                mstore(mc, mload(cc))
            }

            // Update the free-memory pointer by padding our last write location
            // to 32 bytes: add 31 bytes to the end of tempBytes to move to the
            // next 32 byte block, then round down to the nearest multiple of
            // 32. If the sum of the length of the two arrays is zero then add
            // one before rounding down to leave a blank 32 bytes (the length block with 0).
            mstore(0x40, and(
              add(add(end, iszero(add(length, mload(_preBytes)))), 31),
              not(31) // Round down to the nearest 32 bytes.
            ))
        }

        return tempBytes;
    }

    function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
        assembly {
            // Read the first 32 bytes of _preBytes storage, which is the length
            // of the array. (We don't need to use the offset into the slot
            // because arrays use the entire slot.)
            let fslot := sload(_preBytes.slot)
            // Arrays of 31 bytes or less have an even value in their slot,
            // while longer arrays have an odd value. The actual length is
            // the slot divided by two for odd values, and the lowest order
            // byte divided by two for even values.
            // If the slot is even, bitwise and the slot with 255 and divide by
            // two to get the length. If the slot is odd, bitwise and the slot
            // with -1 and divide by two.
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)
            let newlength := add(slength, mlength)
            // slength can contain both the length and contents of the array
            // if length < 32 bytes so let's prepare for that
            // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
            switch add(lt(slength, 32), lt(newlength, 32))
            case 2 {
                // Since the new array still fits in the slot, we just need to
                // update the contents of the slot.
                // uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
                sstore(
                    _preBytes.slot,
                    // all the modifications to the slot are inside this
                    // next block
                    add(
                        // we can just add to the slot contents because the
                        // bytes we want to change are the LSBs
                        fslot,
                        add(
                            mul(
                                div(
                                    // load the bytes from memory
                                    mload(add(_postBytes, 0x20)),
                                    // zero all bytes to the right
                                    exp(0x100, sub(32, mlength))
                                ),
                                // and now shift left the number of bytes to
                                // leave space for the length in the slot
                                exp(0x100, sub(32, newlength))
                            ),
                            // increase length by the double of the memory
                            // bytes length
                            mul(mlength, 2)
                        )
                    )
                )
            }
            case 1 {
                // The stored value fits in the slot, but the combined value
                // will exceed it.
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

                // The contents of the _postBytes array start 32 bytes into
                // the structure. Our first read should obtain the `submod`
                // bytes that can fit into the unused space in the last word
                // of the stored array. To get this, we read 32 bytes starting
                // from `submod`, so the data we read overlaps with the array
                // contents by `submod` bytes. Masking the lowest-order
                // `submod` bytes allows us to add that value directly to the
                // stored value.

                let submod := sub(32, slength)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(
                    sc,
                    add(
                        and(
                            fslot,
                            0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00
                        ),
                        and(mload(mc), mask)
                    )
                )

                for {
                    mc := add(mc, 0x20)
                    sc := add(sc, 1)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
            default {
                // get the keccak hash to get the contents of the array
                mstore(0x0, _preBytes.slot)
                // Start copying to the last used word of the stored array.
                let sc := add(keccak256(0x0, 0x20), div(slength, 32))

                // save new length
                sstore(_preBytes.slot, add(mul(newlength, 2), 1))

                // Copy over the first `submod` bytes of the new data as in
                // case 1 above.
                let slengthmod := mod(slength, 32)
                let mlengthmod := mod(mlength, 32)
                let submod := sub(32, slengthmod)
                let mc := add(_postBytes, submod)
                let end := add(_postBytes, mlength)
                let mask := sub(exp(0x100, submod), 1)

                sstore(sc, add(sload(sc), and(mload(mc), mask)))

                for {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } lt(mc, end) {
                    sc := add(sc, 1)
                    mc := add(mc, 0x20)
                } {
                    sstore(sc, mload(mc))
                }

                mask := exp(0x100, sub(mc, end))

                sstore(sc, mul(div(mload(mc), mask), mask))
            }
        }
    }

    function slice(
        bytes memory _bytes,
        uint256 _start,
        uint256 _length
    )
        internal
        pure
        returns (bytes memory)
    {
        require(_length + 31 >= _length, "slice_overflow");
        require(_bytes.length >= _start + _length, "slice_outOfBounds");

        bytes memory tempBytes;

        assembly {
            switch iszero(_length)
            case 0 {
                // Get a location of some free memory and store it in tempBytes as
                // Solidity does for memory variables.
                tempBytes := mload(0x40)

                // The first word of the slice result is potentially a partial
                // word read from the original array. To read it, we calculate
                // the length of that partial word and start copying that many
                // bytes into the array. The first word we copy will start with
                // data we don't care about, but the last `lengthmod` bytes will
                // land at the beginning of the contents of the new array. When
                // we're done copying, we overwrite the full first word with
                // the actual length of the slice.
                let lengthmod := and(_length, 31)

                // The multiplication in the next line is necessary
                // because when slicing multiples of 32 bytes (lengthmod == 0)
                // the following copy loop was copying the origin's length
                // and then ending prematurely not copying everything it should.
                let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod)))
                let end := add(mc, _length)

                for {
                    // The multiplication in the next line has the same exact purpose
                    // as the one above.
                    let cc := add(add(add(_bytes, lengthmod), mul(0x20, iszero(lengthmod))), _start)
                } lt(mc, end) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    mstore(mc, mload(cc))
                }

                mstore(tempBytes, _length)

                //update free-memory pointer
                //allocating the array padded to 32 bytes like the compiler does now
                mstore(0x40, and(add(mc, 31), not(31)))
            }
            //if we want a zero-length slice let's just return a zero-length array
            default {
                tempBytes := mload(0x40)
                //zero out the 32 bytes slice we are about to return
                //we need to do it because Solidity does not garbage collect
                mstore(tempBytes, 0)

                mstore(0x40, add(tempBytes, 0x20))
            }
        }

        return tempBytes;
    }

    function toAddress(bytes memory _bytes, uint256 _start) internal pure returns (address) {
        require(_bytes.length >= _start + 20, "toAddress_outOfBounds");
        address tempAddress;

        assembly {
            tempAddress := div(mload(add(add(_bytes, 0x20), _start)), 0x1000000000000000000000000)
        }

        return tempAddress;
    }

    function toUint8(bytes memory _bytes, uint256 _start) internal pure returns (uint8) {
        require(_bytes.length >= _start + 1 , "toUint8_outOfBounds");
        uint8 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x1), _start))
        }

        return tempUint;
    }

    function toUint16(bytes memory _bytes, uint256 _start) internal pure returns (uint16) {
        require(_bytes.length >= _start + 2, "toUint16_outOfBounds");
        uint16 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x2), _start))
        }

        return tempUint;
    }

    function toUint32(bytes memory _bytes, uint256 _start) internal pure returns (uint32) {
        require(_bytes.length >= _start + 4, "toUint32_outOfBounds");
        uint32 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x4), _start))
        }

        return tempUint;
    }

    function toUint64(bytes memory _bytes, uint256 _start) internal pure returns (uint64) {
        require(_bytes.length >= _start + 8, "toUint64_outOfBounds");
        uint64 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x8), _start))
        }

        return tempUint;
    }

    function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
        require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
        uint96 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0xc), _start))
        }

        return tempUint;
    }

    function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
        require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
        uint128 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x10), _start))
        }

        return tempUint;
    }

    function toUint256(bytes memory _bytes, uint256 _start) internal pure returns (uint256) {
        require(_bytes.length >= _start + 32, "toUint256_outOfBounds");
        uint256 tempUint;

        assembly {
            tempUint := mload(add(add(_bytes, 0x20), _start))
        }

        return tempUint;
    }

    function toBytes32(bytes memory _bytes, uint256 _start) internal pure returns (bytes32) {
        require(_bytes.length >= _start + 32, "toBytes32_outOfBounds");
        bytes32 tempBytes32;

        assembly {
            tempBytes32 := mload(add(add(_bytes, 0x20), _start))
        }

        return tempBytes32;
    }

    function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
        bool success = true;

        assembly {
            let length := mload(_preBytes)

            // if lengths don't match the arrays are not equal
            switch eq(length, mload(_postBytes))
            case 1 {
                // cb is a circuit breaker in the for loop since there's
                //  no said feature for inline assembly loops
                // cb = 1 - don't breaker
                // cb = 0 - break
                let cb := 1

                let mc := add(_preBytes, 0x20)
                let end := add(mc, length)

                for {
                    let cc := add(_postBytes, 0x20)
                // the next line is the loop condition:
                // while(uint256(mc < end) + cb == 2)
                } eq(add(lt(mc, end), cb), 2) {
                    mc := add(mc, 0x20)
                    cc := add(cc, 0x20)
                } {
                    // if any of these checks fails then arrays are not equal
                    if iszero(eq(mload(mc), mload(cc))) {
                        // unsuccess:
                        success := 0
                        cb := 0
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }

        return success;
    }

    function equalStorage(
        bytes storage _preBytes,
        bytes memory _postBytes
    )
        internal
        view
        returns (bool)
    {
        bool success = true;

        assembly {
            // we know _preBytes_offset is 0
            let fslot := sload(_preBytes.slot)
            // Decode the length of the stored array like in concatStorage().
            let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
            let mlength := mload(_postBytes)

            // if lengths don't match the arrays are not equal
            switch eq(slength, mlength)
            case 1 {
                // slength can contain both the length and contents of the array
                // if length < 32 bytes so let's prepare for that
                // v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
                if iszero(iszero(slength)) {
                    switch lt(slength, 32)
                    case 1 {
                        // blank the last byte which is the length
                        fslot := mul(div(fslot, 0x100), 0x100)

                        if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
                            // unsuccess:
                            success := 0
                        }
                    }
                    default {
                        // cb is a circuit breaker in the for loop since there's
                        //  no said feature for inline assembly loops
                        // cb = 1 - don't breaker
                        // cb = 0 - break
                        let cb := 1

                        // get the keccak hash to get the contents of the array
                        mstore(0x0, _preBytes.slot)
                        let sc := keccak256(0x0, 0x20)

                        let mc := add(_postBytes, 0x20)
                        let end := add(mc, mlength)

                        // the next line is the loop condition:
                        // while(uint256(mc < end) + cb == 2)
                        for {} eq(add(lt(mc, end), cb), 2) {
                            sc := add(sc, 1)
                            mc := add(mc, 0x20)
                        } {
                            if iszero(eq(sload(sc), mload(mc))) {
                                // unsuccess:
                                success := 0
                                cb := 0
                            }
                        }
                    }
                }
            }
            default {
                // unsuccess:
                success := 0
            }
        }

        return success;
    }
}