VISA Question

Hi There

I am Canadian, flying into Hanoi and staying 3 days, then flying to Siem Reap for 3 days, and then flying back into Ho Chi Minh for 3 days. Since I will be flying in and out of Vietnam, I had the following questions:

1) Do I need a VISA given my duration in total is less than 15 days (in and out)
2) If I do need a VISA, what type of VISA do I need ?

Thanks
Ernest