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add vif using local interface index instead of IP 

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>
This commit is contained in:
Ilia K 2009-09-16 05:53:07 +00:00 committed by David S. Miller
parent 7bb5fdc2fb
commit ee5e81f000
2 changed files with 20 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/mroute.h
View File

@ -59,13 +59,18 @@ struct vifctl {
unsigned char vifc_flags; /* VIFF_ flags */
unsigned char vifc_threshold; /* ttl limit */
unsigned int vifc_rate_limit; /* Rate limiter values (NI) */
struct in_addr vifc_lcl_addr; /* Our address */
union {
struct in_addr vifc_lcl_addr; /* Local interface address */
int vifc_lcl_ifindex; /* Local interface index */
};
struct in_addr vifc_rmt_addr; /* IPIP tunnel addr */
};
#define VIFF_TUNNEL 0x1 /* IPIP tunnel */
#define VIFF_SRCRT 0x2 /* NI */
#define VIFF_REGISTER 0x4 /* register vif */
#define VIFF_TUNNEL 0x1 /* IPIP tunnel */
#define VIFF_SRCRT 0x2 /* NI */
#define VIFF_REGISTER 0x4 /* register vif */
#define VIFF_USE_IFINDEX 0x8 /* use vifc_lcl_ifindex instead of
vifc_lcl_addr to find an interface */
/*
* Cache manipulation structures for mrouted and PIMd

12
net/ipv4/ipmr.c
View File

@ -469,8 +469,18 @@ static int vif_add(struct net *net, struct vifctl *vifc, int mrtsock)
return err;
}
break;
case VIFF_USE_IFINDEX:
case 0:
dev = ip_dev_find(net, vifc->vifc_lcl_addr.s_addr);
if (vifc->vifc_flags == VIFF_USE_IFINDEX) {
dev = dev_get_by_index(net, vifc->vifc_lcl_ifindex);
if (dev && dev->ip_ptr == NULL) {
dev_put(dev);
return -EADDRNOTAVAIL;
}
} else
dev = ip_dev_find(net, vifc->vifc_lcl_addr.s_addr);
if (!dev)
return -EADDRNOTAVAIL;
err = dev_set_allmulti(dev, 1);