Delegator.sol

pragma solidity 0.4.20;


import 'IController.sol';
import 'libraries/DelegationTarget.sol';


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)
            }
        }
    }
}