TokenBase

TokenBase is the cross chain token contract (cToken). It follows ERC777 standard except the burn function.

Owership and autorities

• Owner of cToken is initially who deployed it (Shuttleflow admin), then the ownership will be transfered to Shuttleflow governance contract. Only owner of the contract is able to mint cToken.
• Only pausers are able to pause/unpause the cToken contract. Initially, the pauser of cToken is Shuttleflow admin.

Contract ABI

TokenBase ABI

Contract Interface

pragma solidity 0.5.11;

interface ITokenBase {
    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external pure returns (uint8);

    function granularity() external pure returns (uint256);

    function totalSupply() external view returns (uint256);

    function balanceOf(address tokenHolder) external view returns (uint256);

    function send(
        address recipient,
        uint256 amount,
        bytes calldata data
    ) external;

    function transfer(address recipient, uint256 amount)
        external
        returns (bool);

    function isOperatorFor(address operator, address tokenHolder)
        external
        view
        returns (bool);

    function authorizeOperator(address operator) external;

    function revokeOperator(address operator) external;

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

    function operatorSend(
        address sender,
        address recipient,
        uint256 amount,
        bytes calldata data,
        bytes calldata operatorData
    ) external;

    function allowance(address holder, address spender)
        external
        view
        returns (uint256);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(
        address holder,
        address recipient,
        uint256 amount
    ) external returns (bool);

    function mint(
        address account,
        uint256 amount,
        address fee_address,
        uint256 fee,
        address defi,
        string calldata tx_id
    ) external returns (bool);

    function burn(
        address user_addr,
        uint256 amount,
        uint256 expected_fee,
        string calldata addr,
        address defi_relayer
    ) external returns (bool);
}

Core Functions

TokenBase implements the functions of ERC777 standard, with a different burn function:

function burn(
        address user_addr, // user conflux address
        uint256 amount, // burn amount
        uint256 expected_fee, // expected burn fee, in 18 decimals
        string memory addr, // external chain receive address
        address defi_relayer // external chain defi relayer address
) public;

Burn cToken from sender's address.

user_addr is used to logging, in case Conflux Defi burn cToken for normal user.

amount should be larger than burn_fee and minimal_burn_value in CustodianCore contract(Note here the decimals of amount is 18 and decimals of burn_fee and minimal_burn_value in CustoidanCore contract is reference token's decimal, the smart contract will do the decimal conversion for comparison). Besides, if the fee is higher than expected_fee, the burn transaction will revert.

addr is a ethereum or bitcoin address, which the reference token will be sent to.

If it is a burnt of eth/erc20 tokens, user can specify a defi_relayer, which will send the eth/erc20 to defi_relayer and logging the user's information. See more in defi relayer.

If user does not want to use defi_relayer, fill it with zero address.

For example,burn(cusdt_address, 1e18, 1e16, user_eth_addr, zero_addr) will burn 1 cUSDT and user is willing to pay no more than 0.01 cUSDT as burn fee to sponsor. The burned usdt will directly sent to user_eth_addr.