Extending the length of the stop to wait for a drug dog isn't legal. The key phrases include "am I being detained", "am I free to go", "what is your reasonable articulable suspicion of a crime", and "what is your name and badge number". Record everything.

Of course they'll be more than happy to break the law themselves. They'll investigate themselves and find no wrongdoing. And I'm sure the officer will claim they smelled something giving them reasonable suspicion.