 What the speaker really wants is to get the salt.It is a request, or call for action as opposed to information, thus making the sentence allofunctional (note that adding a word like 'please' at the end would tend to make this point clearer, and when posed as a question, this request is perceived as being more polite than if it were simply in the natural imperative).Therefore, what at first may come off as an interrogative sentence upon initial delivery, the listener must almost immediately reinterpret as an imperative and respond accordingly.