Hm.. [IPV4]: Be more verbose about invalid ICMPs sent to broadcast.

[=?ISO-8859-2?Q?Krzysztof_Ol=EAdzki?=]

Hello,

I have just changed kernel on one of my servers from 2.4.21-rc6 into
2.4.22-pre3. One host in my network has some problems with so IP stack
implementation so I get used to read a lot of error messages from kernel
about invalid ICMP error.

I noticed that old, well known message:
Jul  9 18:27:46 mac kernel: 192.168.0.108 sent an invalid ICMP error to a broadcast.

suddenly chaned into:
Jul  9 18:36:28 mac kernel: 192.168.0.230 sent an invalid ICMP type 3, code 0 error to a broadcast:192.168.3.255 on eth0

As you can see the sender is different. If you look at the patch you can
see that NIPQUAD(skb->nh.iph->saddr) was chaned into NIPQUAD(iph->saddr):

--- 1.16/net/ipv4/icmp.c        Mon Feb 24 03:17:59 2003
+++ 1.17/net/ipv4/icmp.c        Mon Jun 23 13:16:17 2003
@@ -595,8 +595,11 @@
                if (inet_addr_type(iph->daddr) == RTN_BROADCAST)
                {
                        if (net_ratelimit())
-                               printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP error to a broadcast.\n",
-                               NIPQUAD(skb->nh.iph->saddr)); <- THIS ONE
+                               printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP type %u, code %u error to a broadcast: %u.%u.%u.%u on %s\n",
+                                       NIPQUAD(iph->saddr),  <- THIS ONE
+                                       icmph->type, icmph->code,
+                                       NIPQUAD(iph->daddr),
+                                       skb->dev->name);
                        goto out;
                }
        }

There is a line:
  iph = (struct iphdr *) skb->data;"
so AFAIK this line:
  ((struct iphdr*) skb->data)->saddr
is not the same like this one:
   skb->nh.iph->saddr
or am I wrong? Any other reason why this message has now different sender
address?

Best Regards,

			Krzysztof Oledzki