contract TokenTransferProxy is Ownable {

    /// @dev Only authorized addresses can invoke functions with this modifier.
    modifier onlyAuthorized {
        require(authorized[msg.sender]);
        _;
    }

    modifier targetAuthorized(address target) {
        require(authorized[target]);
        _;
    }

    modifier targetNotAuthorized(address target) {
        require(!authorized[target]);
        _;
    }

    mapping (address => bool) public authorized;
    address[] public authorities;

    event LogAuthorizedAddressAdded(address indexed target, address indexed caller);
    event LogAuthorizedAddressRemoved(address indexed target, address indexed caller);

    /*
     * Public functions
     */

    /// @dev Authorizes an address.
    /// @param target Address to authorize.
    function addAuthorizedAddress(address target)
        public
        onlyOwner
        targetNotAuthorized(target)
    {
        authorized[target] = true;
        authorities.push(target);
        LogAuthorizedAddressAdded(target, msg.sender);
    }

    /// @dev Removes authorizion of an address.
    /// @param target Address to remove authorization from.
    function removeAuthorizedAddress(address target)
        public
        onlyOwner
        targetAuthorized(target)
    {
        delete authorized[target];
        for (uint i = 0; i < authorities.length; i++) {
            if (authorities[i] == target) {
                authorities[i] = authorities[authorities.length - 1];
                authorities.length -= 1;
                break;
            }
        }
        LogAuthorizedAddressRemoved(target, msg.sender);
    }

    /// @dev Calls into ERC20 Token contract, invoking transferFrom.
    /// @param token Address of token to transfer.
    /// @param from Address to transfer token from.
    /// @param to Address to transfer token to.
    /// @param value Amount of token to transfer.
    /// @return Success of transfer.
    function transferFrom(
        address token,
        address from,
        address to,
        uint value)
        public
        onlyAuthorized
        returns (bool)
    {
        return Token(token).transferFrom(from, to, value);
    }

    /*
     * Public constant functions
     */

    /// @dev Gets all authorized addresses.
    /// @return Array of authorized addresses.
    function getAuthorizedAddresses()
        public
        constant
        returns (address[])
    {
        return authorities;
    }
}
/// @title TokenTransferProxy - Transfers tokens on behalf of contracts that have been approved via decentralized governance.
/// @author Amir Bandeali - <amir@0xProject.com>, Will Warren - <will@0xProject.com>
function transferFrom(
    address token,
    address from,
    address to,
    uint value)
    public
    onlyAuthorized
    returns (bool)
{
    return Token(token).transferFrom(from, to, value);
}

/// @dev Calls into ERC20 Token contract, invoking transferFrom.
/// @param token Address of token to transfer.
/// @param from Address to transfer token from.
/// @param to Address to transfer token to.
/// @param value Amount of token to transfer.
/// @return Success of transfer.