add ipv6_is_multicast

Signed-off-by: Etienne Basset <etienne.basset@ensta.org>
add copy_route helper

Signed-off-by: Etienne Basset <etienne.basset@ensta.org>
replace memcpy with copy_subnet or copy_route

Signed-off-by: Etienne Basset <etienne.basset@ensta.org>
correct ident error

Signed-off-by: Etienne Basset <etienne.basset@ensta.org>