rt6_get_dflt_router
struct fib6_info *rt6_get_dflt_router(struct net *net,
rt = rt6_get_dflt_router(net, &ipv6_hdr(skb)->saddr, skb->dev);
rt = rt6_get_dflt_router(net, gwaddr, dev);
return rt6_get_dflt_router(net, gwaddr, dev);