Contract Source Code:

// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeApprove: approve failed'
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeTransfer: transfer failed'
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::transferFrom: transferFrom failed'
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');
    }
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.0;

import "@uniswap/lib/contracts/libraries/TransferHelper.sol";

/**
 * @title MetaRouterGateway
 * @notice During the `metaRoute` transaction `MetaRouter` (only) claims user's tokens
 * from `MetaRoutetGateway` contract and then operates with them.
 */
contract MetaRouterGateway {
    address public immutable metaRouter;

    modifier onlyMetarouter() {
        require(metaRouter == msg.sender, "Symb: caller is not the metarouter");
        _;
    }

    constructor(address _metaRouter) {
        metaRouter = _metaRouter;
    }

    function claimTokens(
        address _token,
        address _from,
        uint256 _amount
    ) external onlyMetarouter {
        TransferHelper.safeTransferFrom(_token, _from, metaRouter, _amount);
    }
}