libnetlink: introduce rta_nest and u8, u16, u64 helpers for nesting within rtattr

This patch introduces two new api's rta_nest and rta_nest_end to
nest attributes inside a rta attribute represented by 'struct rtattr'
as required to construct a nexthop. Also adds rta_addattr* variants
for u8, u16 and u64 as needed to support encapsulation.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Jiri Benc <jbenc@redhat.com>
2 files changed