Commit 8741b2bf authored by Hideaki Yoshifuji's avatar Hideaki Yoshifuji Committed by David S. Miller

[IPv6]: Rework default router selection.

parent ce7d8f9d
......@@ -13,6 +13,17 @@
* 2 of the License, or (at your option) any later version.
*/
/* Changes:
*
* YOSHIFUJI Hideaki @USAGI
* reworked default router selection.
* - respect outgoing interface
* - select from (probably) reachable routers (i.e.
* routers in REACHABLE, STALE, DELAY or PROBE states).
* - always select the same router if it is (probably)
* reachable. otherwise, round-robin the list.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
......@@ -168,6 +179,7 @@ static __inline__ struct rt6_info *rt6_device_match(struct rt6_info *rt,
static struct rt6_info *rt6_dflt_pointer = NULL;
static spinlock_t rt6_dflt_lock = SPIN_LOCK_UNLOCKED;
/* Default Router Selection (RFC 2461 6.3.6) */
static struct rt6_info *rt6_best_dflt(struct rt6_info *rt, int oif)
{
struct rt6_info *match = NULL;
......@@ -176,63 +188,117 @@ static struct rt6_info *rt6_best_dflt(struct rt6_info *rt, int oif)
for (sprt = rt; sprt; sprt = sprt->u.next) {
struct neighbour *neigh;
int m = 0;
if ((neigh = sprt->rt6i_nexthop) != NULL) {
int m = -1;
if (!oif ||
(sprt->rt6i_dev &&
sprt->rt6i_dev->ifindex == oif))
m += 8;
if (sprt == rt6_dflt_pointer)
m += 4;
if ((neigh = sprt->rt6i_nexthop) != NULL) {
read_lock_bh(&neigh->lock);
switch (neigh->nud_state) {
case NUD_REACHABLE:
if (sprt != rt6_dflt_pointer) {
rt = sprt;
goto out;
}
m = 2;
m += 3;
break;
case NUD_STALE:
case NUD_DELAY:
m = 1;
case NUD_PROBE:
m += 2;
break;
case NUD_STALE:
m = 1;
case NUD_NOARP:
case NUD_PERMANENT:
m += 1;
break;
};
if (oif && sprt->rt6i_dev->ifindex == oif) {
m += 2;
case NUD_INCOMPLETE:
default:
read_unlock_bh(&neigh->lock);
continue;
}
read_unlock_bh(&neigh->lock);
} else {
continue;
}
if (m >= mpri) {
mpri = m;
if (m > mpri || m >= 12) {
match = sprt;
mpri = m;
if (m >= 12) {
/* we choose the lastest default router if it
* is in (probably) reachable state.
* If route changed, we should do pmtu
* discovery. --yoshfuji
*/
break;
}
}
}
if (match) {
rt = match;
} else {
spin_lock(&rt6_dflt_lock);
if (!match) {
/*
* No default routers are known to be reachable.
* SHOULD round robin
*/
spin_lock(&rt6_dflt_lock);
if (rt6_dflt_pointer) {
struct rt6_info *next;
for (sprt = rt6_dflt_pointer->u.next;
sprt; sprt = sprt->u.next) {
if (sprt->u.dst.obsolete <= 0 &&
sprt->u.dst.error == 0) {
match = sprt;
break;
}
}
for (sprt = rt;
!match && sprt && sprt != rt6_dflt_pointer;
sprt = sprt->u.next) {
if (sprt->u.dst.obsolete <= 0 &&
sprt->u.dst.error == 0) {
match = sprt;
break;
}
}
}
}
if ((next = rt6_dflt_pointer->u.next) != NULL &&
next->u.dst.obsolete <= 0 &&
next->u.dst.error == 0)
rt = next;
if (match) {
if (rt6_dflt_pointer != match)
RT6_TRACE1(KERN_INFO
"changed default router: %p->%p\n",
rt6_dflt_pointer, match);
rt6_dflt_pointer = match;
}
spin_unlock(&rt6_dflt_lock);
if (!match) {
/*
* Last Resort: if no default routers found,
* use addrconf default route.
* We don't record this route.
*/
for (sprt = ip6_routing_table.leaf;
sprt; sprt = sprt->u.next) {
if ((sprt->rt6i_flags & RTF_DEFAULT) &&
(!oif ||
(sprt->rt6i_dev &&
sprt->rt6i_dev->ifindex == oif))) {
match = sprt;
break;
}
}
if (!match) {
/* no default route. give up. */
match = &ip6_null_entry;
}
}
out:
spin_lock(&rt6_dflt_lock);
rt6_dflt_pointer = rt;
spin_unlock(&rt6_dflt_lock);
return rt;
return match;
}
struct rt6_info *rt6_lookup(struct in6_addr *daddr, struct in6_addr *saddr,
......
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