Commit ee5e81f0 authored Sep 16, 2009 by Ilia K Committed by David S. Miller Oct 07, 2009

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>

parent 7bb5fdc2

include/linux/mroute.h

+9 −4

Original line number	Diff line number	Diff line
		@@ -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_USE_IFINDEX 0x8 /* use vifc_lcl_ifindex instead of
		vifc_lcl_addr to find an interface */

		/*
		* Cache manipulation structures for mrouted and PIMd

net/ipv4/ipmr.c

+11 −1

Original line number	Diff line number	Diff line
		@@ -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:
		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);