The number of valid octets should be 4, not simply >0. It's fine to return 4 rather than 'true', but it is not fine to return 1 or 2 or 3. The number of the counting shall be 4.
"First shalt thou take out the Holy Pin, then shalt thou count to three, no more, no less. Three shall be the number thou shalt count, and the number of the counting shall be three. Four shalt thou not count, neither count thou two, excepting that thou then proceed to three. Five is right out. Once the number three, being the third number, be reached, then lobbest thou thy Holy Hand Grenade of Antioch towards thy foe, who being naughty in My sight, shall snuff it."
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)