Re: [RFC][2.4 PATCH] source address selection for ARP requests

[Willy Tarreau <willy@w.ods.org>]

On Wed, Aug 20, 2003 at 02:47:11PM -0700, David S. Miller wrote:
> On Wed, 20 Aug 2003 23:34:43 +0200
> Willy Tarreau <willy@w.ods.org> wrote:
> 
> > +	if (in_dev == NULL)
> > +		return;
> 
> A NULL in_dev is what you'll see if no addresses are
> assigned to the interface, therefore you must treat
> this case similarly.

OK, that's fine. It is what I wanted to test with in_dev->ifa_list==NULL. I
don't know if I must keep the test or not (anyway, it doesn't hurt, this isn't
a fast path).

Better this way ?

Cheers,
Willy

--------

patch 1 :

diff -urN linux-2.4.22-rc2/net/ipv4/arp.c linux-2.4.22-rc2-arp/net/ipv4/arp.c
--- linux-2.4.22-rc2/net/ipv4/arp.c	Fri Aug  1 23:06:29 2003
+++ linux-2.4.22-rc2-arp/net/ipv4/arp.c	Thu Aug 21 00:20:19 2003
@@ -320,13 +320,20 @@
 	u32 saddr;
 	u8  *dst_ha = NULL;
 	struct net_device *dev = neigh->dev;
+	struct in_device *in_dev = in_dev_get(dev);
 	u32 target = *(u32*)neigh->primary_key;
 	int probes = atomic_read(&neigh->probes);
 
-	if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL)
+	if (in_dev == NULL || in_dev->ifa_list == NULL ||
+	    (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL &&
+	    (IN_DEV_SHARED_MEDIA(in_dev) ||
+	    inet_addr_onlink(in_dev, skb->nh.iph->saddr, 0))))
 		saddr = skb->nh.iph->saddr;
 	else
 		saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
+
+	if (in_dev == NULL)
+		in_dev_put(in_dev);
 
 	if ((probes -= neigh->parms->ucast_probes) < 0) {
 		if (!(neigh->nud_state&NUD_VALID))

---------

patch 2 :


diff -urN linux-2.4.22-rc2/net/ipv4/arp.c linux-2.4.22-rc2-arp2/net/ipv4/arp.c
--- linux-2.4.22-rc2/net/ipv4/arp.c	Fri Aug  1 23:06:29 2003
+++ linux-2.4.22-rc2-arp2/net/ipv4/arp.c	Thu Aug 21 00:24:25 2003
@@ -320,13 +320,19 @@
 	u32 saddr;
 	u8  *dst_ha = NULL;
 	struct net_device *dev = neigh->dev;
+	struct in_device *in_dev = in_dev_get(dev);
 	u32 target = *(u32*)neigh->primary_key;
 	int probes = atomic_read(&neigh->probes);
 
-	if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL)
-		saddr = skb->nh.iph->saddr;
+	if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL &&
+	    (in_dev == NULL || IN_DEV_SHARED_MEDIA(in_dev) ||
+	     (saddr = inet_select_addr(dev, target, RT_SCOPE_LINK)) == 0))
+			saddr = skb->nh.iph->saddr;
 	else
 		saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
+
+	if (in_dev == NULL)
+		in_dev_put(in_dev);
 
 	if ((probes -= neigh->parms->ucast_probes) < 0) {
 		if (!(neigh->nud_state&NUD_VALID))