/* manipulate a GRE packet according to maniptype */
static int
gre_manip_pkt(struct sk_buff **pskb,
unsigned int iphdroff,
const struct ip_conntrack_tuple *tuple,
enum ip_nat_manip_type maniptype)
{
struct gre_hdr *greh;
struct gre_hdr_pptp *pgreh;
struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff);
unsigned int hdroff = iphdroff + iph->ihl*4;
/* pgreh includes two optional 32bit fields which are not required
* to be there. That's where the magic '8' comes from */
if (!skb_make_writable(pskb, hdroff + sizeof(*pgreh)-8))
return 0;
greh = (void *)(*pskb)->data + hdroff;
pgreh = (struct gre_hdr_pptp *) greh;
/* we only have destination manip of a packet, since 'source key'
* is not present in the packet itself */
if (maniptype == IP_NAT_MANIP_DST) {
/* key manipulation is always dest */
switch (greh->version) {
case 0:
if (!greh->key) {
DEBUGP("can't nat GRE w/o key\n");
break;
}
if (greh->csum) {
/* FIXME: Never tested this code... */
*(gre_csum(greh)) =
nf_proto_csum_update(*pskb,
~*(gre_key(greh)),
tuple->dst.u.gre.key,
*(gre_csum(greh)), 0);
}
*(gre_key(greh)) = tuple->dst.u.gre.key;
break;
case GRE_VERSION_PPTP:
DEBUGP("call_id -> 0x%04x\n",
ntohs(tuple->dst.u.gre.key));
pgreh->call_id = tuple->dst.u.gre.key;
break;
default:
DEBUGP("can't nat unknown GRE version\n");
return 0;
break;
}
}
return 1;
}
/* manipulate a GRE packet according to maniptype */
static void
gre_manip_pkt(struct iphdr *iph, size_t len,
const struct ip_conntrack_manip *manip,
enum ip_nat_manip_type maniptype)
{
struct gre_hdr *greh = (struct gre_hdr *)((u_int32_t *)iph+iph->ihl);
struct gre_hdr_pptp *pgreh = (struct gre_hdr_pptp *) greh;
/* we only have destination manip of a packet, since 'source key'
* is not present in the packet itself */
if (maniptype == IP_NAT_MANIP_DST) {
/* key manipulation is always dest */
switch (greh->version) {
case 0:
if (!greh->key) {
DEBUGP("can't nat GRE w/o key\n");
break;
}
if (greh->csum) {
/* FIXME: Never tested this code... */
*(gre_csum(greh)) =
ip_nat_cheat_check(~*(gre_key(greh)),
manip->u.gre.key,
*(gre_csum(greh)));
}
*(gre_key(greh)) = manip->u.gre.key;
break;
case GRE_VERSION_PPTP:
DEBUGP("call_id -> 0x%04x\n",
ntohl(manip->u.gre.key));
pgreh->call_id = htons(ntohl(manip->u.gre.key));
break;
default:
DEBUGP("can't nat unknown GRE version\n");
break;
}
}
}
