On Fri, May 04, 2007 at 01:48:48PM +0100, David Howells ([EMAIL PROTECTED])
wrote:
>
> Hi,
Hi David.
> I would like to determine through which interface packets sent to a particular
> UDP destination will go through, and so determine the MTU size for that
> interface. Can anyone suggest a good way of doing this from within the
> kernel?
I used following code in netchannels:
static int netchannel_ip_route_output_flow(struct rtable **rp, struct flowi
*flp, int flags)
{
int err;
err = __ip_route_output_key(rp, flp);
if (err)
return err;
if (flp->proto) {
if (!flp->fl4_src)
flp->fl4_src = (*rp)->rt_src;
if (!flp->fl4_dst)
flp->fl4_dst = (*rp)->rt_dst;
}
return 0;
}
struct dst_entry *route_get_raw(u32 saddr, u32 daddr, u16 sport, u16 dport, u8
proto)
{
struct rtable *rt;
struct flowi fl = { .oif = 0,
.nl_u = { .ip4_u =
{ .saddr = saddr,
.daddr = daddr,
.tos = 0 } },
.proto = proto,
.uli_u = { .ports =
{ .sport = sport,
.dport = dport } } };
if (netchannel_ip_route_output_flow(&rt, &fl, 0))
goto no_route;
return dst_clone(&rt->u.dst);
no_route:
return NULL;
}
This is basically a copied input route code.
dst entry, obtained from route_get_raw() holds a pointer to network device.
--
Evgeniy Polyakov
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