static bool
xt_cluster_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
struct sk_buff *pskb = (struct sk_buff *)skb;
const struct xt_cluster_match_info *info = par->matchinfo;
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
unsigned long hash;
if (!xt_cluster_is_multicast_addr(skb, par->family) &&
skb->pkt_type == PACKET_MULTICAST) {
pskb->pkt_type = PACKET_HOST;
}
ct = nf_ct_get(skb, &ctinfo);
if (ct == NULL)
return false;
if (ct == &nf_conntrack_untracked)
return false;
if (ct->master)
hash = xt_cluster_hash(ct->master, info);
else
hash = xt_cluster_hash(ct, info);
return !!((1 << hash) & info->node_mask) ^
!!(info->flags & XT_CLUSTER_F_INV);
}
static bool
xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
struct sk_buff *pskb = (struct sk_buff *)skb;
const struct xt_cluster_match_info *info = par->matchinfo;
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
unsigned long hash;
/* This match assumes that all nodes see the same packets. This can be
* achieved if the switch that connects the cluster nodes support some
* sort of 'port mirroring'. However, if your switch does not support
* this, your cluster nodes can reply ARP request using a multicast MAC
* address. Thus, your switch will flood the same packets to the
* cluster nodes with the same multicast MAC address. Using a multicast
* link address is a RFC 1812 (section 3.3.2) violation, but this works
* fine in practise.
*
* Unfortunately, if you use the multicast MAC address, the link layer
* sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted
* by TCP and others for packets coming to this node. For that reason,
* this match mangles skbuff's pkt_type if it detects a packet
* addressed to a unicast address but using PACKET_MULTICAST. Yes, I
* know, matches should not alter packets, but we are doing this here
* because we would need to add a PKTTYPE target for this sole purpose.
*/
if (!xt_cluster_is_multicast_addr(skb, par->family) &&
skb->pkt_type == PACKET_MULTICAST) {
pskb->pkt_type = PACKET_HOST;
}
ct = nf_ct_get(skb, &ctinfo);
if (ct == NULL)
return false;
if (nf_ct_is_untracked(ct))
return false;
if (ct->master)
hash = xt_cluster_hash(ct->master, info);
else
hash = xt_cluster_hash(ct, info);
return !!((1 << hash) & info->node_mask) ^
!!(info->flags & XT_CLUSTER_F_INV);
}
