[PATCH] add vif using local interface index instead of IP

[PATCH] add vif using local interface index instead of IP

[Ilia K.]

[-- Attachment #1: Type: text/plain, Size: 1426 bytes --]

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>

[-- Attachment #2: vif_add.patch --]
[-- Type: text/x-diff, Size: 1634 bytes --]

=== modified file 'include/linux/mroute.h'
--- old/include/linux/mroute.h	2009-08-10 11:17:32 +0000
+++ new/include/linux/mroute.h	2009-09-08 06:58:46 +0000
@@ -59,13 +59,18 @@
 	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

=== modified file 'net/ipv4/ipmr.c'
--- old/net/ipv4/ipmr.c	2009-08-10 11:17:32 +0000
+++ new/net/ipv4/ipmr.c	2009-09-08 06:34:21 +0000
@@ -470,8 +470,18 @@
 			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);

Re: [PATCH] add vif using local interface index instead of IP

[David Miller]

From: "Ilia K." <mail4ilia@gmail.com>
Date: Wed, 16 Sep 2009 18:53:07 +0300

> When routing daemon wants to enable forwarding of multicast traffic it
> performs something like:
 ...
> 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:
...
> Signed-off-by: Ilia K. <mail4ilia@gmail.com>

Applied, thank you.