Both, and fat too. During a strength training workout, fast uptake carbs are the key. Post workout you want to take in both carbs and protein. Fancy shakes and concoctions are not necessary, whole foods will do the same job.
Muscle for life is a good resource for strength training and nutrition. Mike goes a good job of simplifying things and breaking it down. The book is good, but he also breaks most of it down on his website.