IPredicate.sol

pragma solidity ^0.5.2;

import {RLPReader} from "solidity-rlp/contracts/RLPReader.sol";

import {Common} from "../../common/lib/Common.sol";
import {RLPEncode} from "../../common/lib/RLPEncode.sol";

import {IWithdrawManager} from "../withdrawManager/IWithdrawManager.sol";
import {IDepositManager} from "../depositManager/IDepositManager.sol";
import {
    ExitsDataStructure
} from "../withdrawManager/WithdrawManagerStorage.sol";
import {ChainIdMixin} from "../../common/mixin/ChainIdMixin.sol";

interface IPredicate {
    /**
   * @notice Verify the deprecation of a state update
   * @param exit ABI encoded PlasmaExit data
   * @param inputUtxo ABI encoded Input UTXO data
   * @param challengeData RLP encoded data of the challenge reference tx that encodes the following fields
   * headerNumber Header block number of which the reference tx was a part of
   * blockProof Proof that the block header (in the child chain) is a leaf in the submitted merkle root
   * blockNumber Block number of which the reference tx is a part of
   * blockTime Reference tx block time
   * blocktxRoot Transactions root of block
   * blockReceiptsRoot Receipts root of block
   * receipt Receipt of the reference transaction
   * receiptProof Merkle proof of the reference receipt
   * branchMask Merkle proof branchMask for the receipt
   * logIndex Log Index to read from the receipt
   * tx Challenge transaction
   * txProof Merkle proof of the challenge tx
   * @return Whether or not the state is deprecated
   */
    function verifyDeprecation(
        bytes calldata exit,
        bytes calldata inputUtxo,
        bytes calldata challengeData
    ) external returns (bool);

    function interpretStateUpdate(bytes calldata state)
        external
        view
        returns (bytes memory);
    function onFinalizeExit(bytes calldata data) external;
}

contract PredicateUtils is ExitsDataStructure, ChainIdMixin {
    using RLPReader for RLPReader.RLPItem;

    // Bonded exits collaterized at 0.1 ETH
    uint256 private constant BOND_AMOUNT = 10**17;

    IWithdrawManager internal withdrawManager;
    IDepositManager internal depositManager;

    modifier onlyWithdrawManager() {
        require(
            msg.sender == address(withdrawManager),
            "ONLY_WITHDRAW_MANAGER"
        );
        _;
    }

    modifier isBondProvided() {
        require(msg.value == BOND_AMOUNT, "Invalid Bond amount");
        _;
    }

    function onFinalizeExit(bytes calldata data) external onlyWithdrawManager {
        (, address token, address exitor, uint256 tokenId) = decodeExitForProcessExit(
            data
        );
        depositManager.transferAssets(token, exitor, tokenId);
    }

    function sendBond() internal {
        address(uint160(address(withdrawManager))).transfer(BOND_AMOUNT);
    }

    function getAddressFromTx(RLPReader.RLPItem[] memory txList)
        internal
        pure
        returns (address signer, bytes32 txHash)
    {
        bytes[] memory rawTx = new bytes[](9);
        for (uint8 i = 0; i <= 5; i++) {
            rawTx[i] = txList[i].toBytes();
        }
        rawTx[6] = networkId;
        rawTx[7] = hex""; // [7] and [8] have something to do with v, r, s values
        rawTx[8] = hex"";

        txHash = keccak256(RLPEncode.encodeList(rawTx));
        signer = ecrecover(
            txHash,
            Common.getV(txList[6].toBytes(), Common.toUint16(networkId)),
            bytes32(txList[7].toUint()),
            bytes32(txList[8].toUint())
        );
    }

    function decodeExit(bytes memory data)
        internal
        pure
        returns (PlasmaExit memory)
    {
        (address owner, address token, uint256 amountOrTokenId, bytes32 txHash, bool isRegularExit) = abi
            .decode(data, (address, address, uint256, bytes32, bool));
        return
            PlasmaExit(
                amountOrTokenId,
                txHash,
                owner,
                token,
                isRegularExit,
                address(0) /* predicate value is not required */
            );
    }

    function decodeExitForProcessExit(bytes memory data)
        internal
        pure
        returns (uint256 exitId, address token, address exitor, uint256 tokenId)
    {
        (exitId, token, exitor, tokenId) = abi.decode(
            data,
            (uint256, address, address, uint256)
        );
    }

    function decodeInputUtxo(bytes memory data)
        internal
        pure
        returns (uint256 age, address signer, address predicate, address token)
    {
        (age, signer, predicate, token) = abi.decode(
            data,
            (uint256, address, address, address)
        );
    }

}

contract IErcPredicate is IPredicate, PredicateUtils {
    enum ExitType {Invalid, OutgoingTransfer, IncomingTransfer, Burnt}

    struct ExitTxData {
        uint256 amountOrToken;
        bytes32 txHash;
        address childToken;
        address signer;
        ExitType exitType;
    }

    struct ReferenceTxData {
        uint256 closingBalance;
        uint256 age;
        address childToken;
        address rootToken;
    }

    uint256 internal constant MAX_LOGS = 10;

    constructor(address _withdrawManager, address _depositManager) public {
        withdrawManager = IWithdrawManager(_withdrawManager);
        depositManager = IDepositManager(_depositManager);
    }
}