Canadian travelling to India with two layovers on China

I am travelling from Vancouver, Canada to Kolkata, India. The airline (China Eastern) stops in two places in China -- 2 hours in Nanjing and then 4 hours and 15 minutes in Kunming. On the return, the stopover in Kunming is 3 hours and 10 minutes and then 1 hour and 40 minutes in Nanjing. I am not technically going to leave the Airport but since it involves two stops in China, I am a little apprehensive to book tickets only to find out I need to pay hefty sums of money for visas. If that's the case, I will go through Hong Kong or Dubai where I don't need visas to transit or even leave the airport.

Any help in this regards is greatly appreciated. I will most likely book something next week.