NL_RTA_MULTIPATH
{ .type = NL_RTA_MULTIPATH, .off = _OUT(rta_multipath), .cb = nlattr_get_multipath },
#define RTA_MULTIPATH NL_RTA_MULTIPATH
int off = nlattr_add_nested(nw, NL_RTA_MULTIPATH);
{ .type = NL_RTA_MULTIPATH, .off = _OUT(rta_multipath), .cb = nlattr_get_multipath },