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ipv4: Adjust semantics of rt->rt_gateway.

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In order to allow prefixed routes, we have to adjust how rt_gateway
is set and interpreted.

The new interpretation is:

1) rt_gateway == 0, destination is on-link, nexthop is iph->daddr

2) rt_gateway != 0, destination requires a nexthop gateway

Abstract the fetching of the proper nexthop value using a new
inline helper, rt_nexthop(), as suggested by Joe Perches.

Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Vijay Subramanian <subramanian.vijay@gmail.com>
This commit is contained in:
David S. Miller 2012-07-13 05:03:45 -07:00
parent f1ce3062c5
commit f8126f1d51
8 changed files with 25 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

17
net/ipv4/route.c
View file

@ -1085,8 +1085,9 @@ void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
else
src = inet_select_addr(rt->dst.dev, rt->rt_gateway,
RT_SCOPE_UNIVERSE);
src = inet_select_addr(rt->dst.dev,
rt_nexthop(rt, iph->daddr),
RT_SCOPE_UNIVERSE);
rcu_read_unlock();
}
memcpy(addr, &src, 4);
@ -1132,7 +1133,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst)
mtu = dst->dev->mtu;
if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
if (rt->rt_gateway != 0 && mtu > 576)
if (rt->rt_gateway && mtu > 576)
mtu = 576;
}
@ -1274,7 +1275,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
rth->rt_iif = dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
rth->rt_gateway = daddr;
rth->rt_gateway = 0;
rth->fi = NULL;
if (our) {
rth->dst.input= ip_local_deliver;
@ -1392,7 +1393,7 @@ static int __mkroute_input(struct sk_buff *skb,
rth->rt_iif = in_dev->dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
rth->rt_gateway = daddr;
rth->rt_gateway = 0;
rth->fi = NULL;
rth->dst.input = ip_forward;
@ -1557,7 +1558,7 @@ local_input:
rth->rt_iif = dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
rth->rt_gateway = daddr;
rth->rt_gateway = 0;
rth->fi = NULL;
if (res.type == RTN_UNREACHABLE) {
rth->dst.input= ip_error;
@ -1707,7 +1708,7 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
rth->rt_iif = orig_oif ? : dev_out->ifindex;
rth->rt_oif = orig_oif;
rth->rt_pmtu = 0;
rth->rt_gateway = fl4->daddr;
rth->rt_gateway = 0;
rth->fi = NULL;
RT_CACHE_STAT_INC(out_slow_tot);
@ -2070,7 +2071,7 @@ static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
if (nla_put_be32(skb, RTA_PREFSRC, fl4->saddr))
goto nla_put_failure;
}
if (fl4->daddr != rt->rt_gateway &&
if (rt->rt_gateway &&
nla_put_be32(skb, RTA_GATEWAY, rt->rt_gateway))
goto nla_put_failure;