Traveling India Via Canada From USA

[sanndsu]

Hi,

I'm traveling to India this Dec 24th Via Canada. My itinerary looks like this.

Minneapolis, USA -> Toranto, Canada -> Frankfurt, Germany -> Chennai, India

My Return Flight (SAME ROUTE)

Chennai, India -> Frankfurt, Germany -> Toronto, Canada -> Minneapolis, USA

My question, do I need a transit visa in Canada. even If I'm staying inside the airport?. (I know I don't need transit visa in Frankfurt).

Please, advise. If I need a transit visa, then I need to change my ininerary.

Thanks