When routing daemon wants to enable forwarding of multicast traffic it
performs something like:
struct vifctl vc = {
.vifc_vifi = 1,
.vifc_flags = 0,
.vifc_threshold = 1,
.vifc_rate_limit = 0,
.vifc_lcl_addr = ip, /* <--- ip address of physical
interface, e.g. eth0 */
.vifc_rmt_addr.s_addr = htonl(INADDR_ANY),
};
setsockopt(fd, IPPROTO_IP, MRT_ADD_VIF, &vc, sizeof(vc));
This leads (in the kernel) to calling vif_add() function call which
search the (physical) device using assigned IP address:
dev = ip_dev_find(net, vifc->vifc_lcl_addr.s_addr);
The current API (struct vifctl) does not allow to specify an
interface other way than using it's IP, and if there are more than a
single interface with specified IP only the first one will be found.
The attached patch (against 2.6.30.4) allows to specify an interface
by its index, instead of IP address:
struct vifctl vc = {
.vifc_vifi = 1,
.vifc_flags = VIFF_USE_IFINDEX, /* NEW */
.vifc_threshold = 1,
.vifc_rate_limit = 0,
.vifc_lcl_ifindex = if_nametoindex("eth0"), /* NEW */
.vifc_rmt_addr.s_addr = htonl(INADDR_ANY),
};
setsockopt(fd, IPPROTO_IP, MRT_ADD_VIF, &vc, sizeof(vc));
Signed-off-by: Ilia K. <mail4ilia@gmail.com>
=== modified file 'include/linux/mroute.h'
Signed-off-by: David S. Miller <davem@davemloft.net>
ee5e81f000