iptables: handle cidr notation more sanely (Phil Oester <kernel@linuxace.com>)

iptables: handle cidr notation more sanely (Phil Oester <kernel@linuxace.com>)

At present, a command such as

iptables -A foo -s 10.10/16

will interpret 10.10/16 as 10.0.0.10/16, and after applying the mask end
up with 10.0.0.0/16, which likely isn't what the user intended.  Yet
some people do expect 10.10 (without the cidr notation) to end up as
10.0.0.10.

The below patch should satisfy all parties.  It zero pads the missing
octets only in the cidr case, leaving the IP untouched otherwise.

This resolves bug #422