static void icmp_redirect(struct icmphdr *icmph, struct sk_buff *skb, int len)
{
struct iphdr *iph;
unsigned long ip;
if (len < sizeof(struct iphdr)) {
icmp_statistics.IcmpInErrors++;
return;
}
/*
* Get the copied header of the packet that caused the redirect
*/
iph = (struct iphdr *) (icmph + 1);
ip = iph->daddr;
switch(icmph->code & 7) {
case ICMP_REDIR_NET:
case ICMP_REDIR_NETTOS:
/*
* As per RFC recommendations now handle it as
* a host redirect.
*/
case ICMP_REDIR_HOST:
case ICMP_REDIR_HOSTTOS:
ip_rt_redirect(skb->nh.iph->saddr, ip, icmph->un.gateway, iph->saddr, iph->tos, skb->dev);
break;
default:
break;
}
}
static void icmp_redirect(struct icmphdr *icmph, struct sk_buff *skb, struct device *dev, __u32 source, __u32 daddr, int len)
{
struct iphdr *iph;
unsigned long ip;
/*
* Get the copied header of the packet that caused the redirect
*/
if(len<=sizeof(struct iphdr))
goto flush_it;
iph = (struct iphdr *) (icmph + 1);
ip = iph->daddr;
/*
* If we are a router and we run a routing protocol, we MUST NOT follow redirects.
* When using no routing protocol, we MAY follow redirects. (RFC 1812, 5.2.7.2)
*/
#if !defined(CONFIG_IP_DUMB_ROUTER)
if (sysctl_ip_forward) {
NETDEBUG(printk(KERN_INFO "icmp: ICMP redirect ignored. dest = %lX, "
"orig gw = %lX, \"new\" gw = %lX, device = %s.\n", ntohl(ip),
ntohl(source), ntohl(icmph->un.gateway), dev->name));
goto flush_it;
}
#endif
switch(icmph->code & 7)
{
case ICMP_REDIR_NET:
/*
* This causes a problem with subnetted networks. What we should do
* is use ICMP_ADDRESS to get the subnet mask of the problem route
* and set both. But we don't.. [RFC1812 says routers MUST NOT
* generate Network Redirects]
*/
#ifdef not_a_good_idea
ip_rt_add((RTF_DYNAMIC | RTF_MODIFIED | RTF_GATEWAY),
ip, 0, icmph->un.gateway, dev,0, 0, 0);
#endif
/*
* As per RFC recommendations now handle it as
* a host redirect.
*/
case ICMP_REDIR_HOST:
/*
* Add better route to host.
* But first check that the redirect
* comes from the old gateway..
* And make sure it's an ok host address
* (not some confused thing sending our
* address)
*/
NETDEBUG(printk(KERN_INFO "ICMP redirect from %s\n", in_ntoa(source)));
ip_rt_redirect(source, ip, icmph->un.gateway, dev);
break;
case ICMP_REDIR_NETTOS:
case ICMP_REDIR_HOSTTOS:
NETDEBUG(printk(KERN_INFO "ICMP: cannot handle TOS redirects yet!\n"));
break;
default:
break;
}
/*
* Discard the original packet
*/
flush_it:
kfree_skb(skb, FREE_READ);
}
