f_flower: Treat port 0 as valid

f_flower: Treat port 0 as valid

It is not currently possible to add a filter matching on port 0 despite
it being a valid port number. This is caused by cited commit which
treats a value of 0 as an indication that the port was not specified.

Instead of inferring that a port range was specified by checking that both
the minimum and the maximum ports are non-zero, simply add a boolean
argument to parse_range() and set it after parsing a port range.

Before:

 # tc filter add dev swp1 ingress pref 1 proto ip flower ip_proto udp src_port 0 action pass
 Illegal "src_port"

 # tc filter add dev swp1 ingress pref 2 proto ip flower ip_proto udp dst_port 0 action pass
 Illegal "dst_port"

 # tc filter add dev swp1 ingress pref 3 proto ip flower ip_proto udp src_port 0-100 action pass
 Illegal "src_port"

 # tc filter add dev swp1 ingress pref 4 proto ip flower ip_proto udp dst_port 0-100 action pass
 Illegal "dst_port"

After:

 # tc filter add dev swp1 ingress pref 1 proto ip flower ip_proto udp src_port 0 action pass

 # tc filter add dev swp1 ingress pref 2 proto ip flower ip_proto udp dst_port 0 action pass

 # tc filter add dev swp1 ingress pref 3 proto ip flower ip_proto udp src_port 0-100 action pass

 # tc filter add dev swp1 ingress pref 4 proto ip flower ip_proto udp dst_port 0-100 action pass

 # tc filter show dev swp1 ingress | grep _port
   src_port 0
   dst_port 0
   src_port 0-100
   dst_port 0-100

Fixes: 767b6fd620dd ("tc: flower: fix port value truncation")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>