netlink: implement nla_put_in_addr and nla_put_in6_addr

IP addresses are often stored in netlink attributes. Add generic functions
to do that.

For nla_put_in_addr, it would be nicer to pass struct in_addr but this is
not used universally throughout the kernel, in way too many places __be32 is
used to store IPv4 address.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_vti.c

@@ -505,8 +505,8 @@ static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	nla_put_u32(skb, IFLA_VTI_LINK, p->link);
 	nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key);
 	nla_put_be32(skb, IFLA_VTI_OKEY, p->o_key);
-	nla_put_be32(skb, IFLA_VTI_LOCAL, p->iph.saddr);
-	nla_put_be32(skb, IFLA_VTI_REMOTE, p->iph.daddr);
+	nla_put_in_addr(skb, IFLA_VTI_LOCAL, p->iph.saddr);
+	nla_put_in_addr(skb, IFLA_VTI_REMOTE, p->iph.daddr);
 
 	return 0;
 }