Delegator

// Submitted by EthereumHistory (ethereumhistory.com)
pragma solidity 0.4.20;


contract IController {
    function assertIsWhitelisted(address _target) public view returns(bool);
    function lookup(bytes32 _key) public view returns(address);
    function stopInEmergency() public view returns(bool);
    function onlyInEmergency() public view returns(bool);
    function getTimestamp() public view returns (uint256);
    function emergencyStop() public returns (bool);
}


contract IControlled {
    function getController() public view returns (IController);
    function setController(IController _controller) public returns(bool);
}


contract Controlled is IControlled {
    IController internal controller;

    modifier onlyWhitelistedCallers {
        require(controller.assertIsWhitelisted(msg.sender));
        _;
    }

    modifier onlyCaller(bytes32 _key) {
        require(msg.sender == controller.lookup(_key));
        _;
    }

    modifier onlyControllerCaller {
        require(IController(msg.sender) == controller);
        _;
    }

    modifier onlyInGoodTimes {
        require(controller.stopInEmergency());
        _;
    }

    modifier onlyInBadTimes {
        require(controller.onlyInEmergency());
        _;
    }

    function Controlled() public {
        controller = IController(msg.sender);
    }

    function getController() public view returns(IController) {
        return controller;
    }

    function setController(IController _controller) public onlyControllerCaller returns(bool) {
        controller = _controller;
        return true;
    }
}


contract DelegationTarget is Controlled {
    bytes32 public controllerLookupName;
}


contract Delegator is DelegationTarget {
    function Delegator(IController _controller, bytes32 _controllerLookupName) public {
        controller = _controller;
        controllerLookupName = _controllerLookupName;
    }

    function() external payable {
        // Do nothing if we haven't properly set up the delegator to delegate calls
        if (controllerLookupName == 0) {
            return;
        }

        // Get the delegation target contract
        address _target = controller.lookup(controllerLookupName);

        assembly {
            //0x40 is the address where the next free memory slot is stored in Solidity
            let _calldataMemoryOffset := mload(0x40)
            // new "memory end" including padding. The bitwise operations here ensure we get rounded up to the nearest 32 byte boundary
            let _size := and(add(calldatasize, 0x1f), not(0x1f))
            // Update the pointer at 0x40 to point at new free memory location so any theoretical allocation doesn't stomp our memory in this call
            mstore(0x40, add(_calldataMemoryOffset, _size))
            // Copy method signature and parameters of this call into memory
            calldatacopy(_calldataMemoryOffset, 0x0, calldatasize)
            // Call the actual method via delegation
            let _retval := delegatecall(gas, _target, _calldataMemoryOffset, calldatasize, 0, 0)
            switch _retval
            case 0 {
                // 0 == it threw, so we revert
                revert(0,0)
            } default {
                // If the call succeeded return the return data from the delegate call
                let _returndataMemoryOffset := mload(0x40)
                // Update the pointer at 0x40 again to point at new free memory location so any theoretical allocation doesn't stomp our memory in this call
                mstore(0x40, add(_returndataMemoryOffset, returndatasize))
                returndatacopy(_returndataMemoryOffset, 0x0, returndatasize)
                return(_returndataMemoryOffset, returndatasize)
            }
        }
    }
}