iproute2 fwmark feature request

[Nguyen Dinh Nam <64vn@xxxxxxxxxx>]

Hello netdev,
There are 2^32 values for fwmark, it's a hugh number.
netfilter deal with it better than iproute2, particularly, there is an 
optional mask to apply to the fwmark before comparing it with some value 
(mark module of iptables). It's very helpful because we can use that 32 
bits to store several sub values at the same time.
So it'll be cool if the syntax is
SELECTOR := [ from PREFIX ] [ to PREFIX ] [ tos TOS ] [ fwmark 
FWMARK[/MASK] ]
Regards,
Nam