Is transit visa required

Dear sir

I am travelling from Kolkata to Sanfransisco and Then returning back from sab fransisco to kolkta. While returing i will reach at shanghai pudding airport on 7th jan 6.20 pm and then have a conneting flight to kumming on 7th jan 9.00 pm and it will reach kumming at 1.00 am on 8th jan . The final destination which is kolkta, flight from kumming to kolkata is at 11.50 pm on 8th jan. I dont wish to go out of any airport and want to be inside the airport only do i require transit G type