You are correct that cocaine "fills the tunnel" (the pharmacology terminology is that it "blocks the transporter"). But it is not an autoreceptor, so the reuptake transporter does not send a stop signal, it just removed neurotransmitter from the cleft. But once you've blocked it with cocaine, neurotransmitter is not being removed from the cleft so it has a ...
Cocaine binds competitively to DAT, though not in precisely the same binding site, rather there is overlap, and many of the same amino acids are involved in binding of each.
Amphetamine and benztropines also bind in the same region.
Beuming, T., Kniazeff, J., Bergmann, M. L., Shi, L., Gracia, L., Raniszewska, K., ... & Loland, C. J. (2008). The binding ...
The following paper answers your question in detail:
It seems like the following aa are responsible for the binding, but please refer to the paper for more details:
You can easily google for this question and find plenty of disreputable sources, but this is another case where Wikipedia does an okay job. There are some misleading and erroneous sentences, but this one basically sums it up:
Compared to ingestion, the faster absorption of insufflated cocaine results in quicker attainment of maximum drug effects.