You are probably much more informed and/or astute when it comes to Russia/Iran relationships. I've haven't follow them that closely but have a difficult time thinking that Russian leadership (whoever that is now) actually wants Iran to have the bomb. Russia doesn't think highly of Islamists after the Chechnya Beslan school massacre.
I don't see an upside for Russia even though they trade with Iran. I don't see an upside for any nation to want Iran or the Norks to have atomic weapons. I also don't think that China wants anymore competition as a wannabe world power, either. They are working too hard to be the regional power and that takes a lot of focus and resources.
Doubt that North Korea is still a China protectorate. If they were, China would have put a halt to the Nork missle/nuclear program some years back. Why? Because China is enjoying growth (GDP) we can only dream about. Why would they allow NK to kill their golden goose who buys their products? Why would they want to kill off the country that owes them so much in Bonds?
China may have long term goals to be THE world power, but they won't needlessly attack us. Plus, their citizens are getting more prosperous by the day. Big plus for the leadership.
Again, as for Russia, yes many what the Soviet Union back and all the power that projected. However, their economy is a wreck and they are not enamored with Muslims. They get it.