No officer or employee of the department shall receive directly, or indirectly, any compensation for his services other than that prescribed or authorized by law or the director; nor shall he receive any compensation whatever, directly or indirectly, for any act or service which he may do or perform for or on behalf of any contractor, or agent, or employee of a contractor. For any violation of the provisions of this section the officer or employee shall be discharged from his office or service; and every contractor, or employee, or agent of a contractor engaged therein, shall be expelled from the prison grounds, and not again permitted within the same as a contractor, agent, or employee.