static int
tcp_dnat_handler(struct sk_buff *skb,
struct dispatcher_protocol *pp, struct dispatcher_service *svc)
{
struct tcphdr *tcph;
unsigned int tcphoff;
int oldlen;
struct dispatcher_dest *dest = svc->dest;
__be16 localport;
localport = htons(GET_REAL_PORT(htons(dest->port), svc));
#ifdef CONFIG_DISPATCHER_IPV6
if (dest->af == AF_INET6)
tcphoff = sizeof(struct ipv6hdr);
else
#endif
tcphoff = ip_hdrlen(skb);
oldlen = skb->len - tcphoff;
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph))) {
return 0;
}
tcph = (void *)skb_network_header(skb) + tcphoff;
tcph->dest = localport;
/*
* Adjust TCP checksums
*/
if (skb->ip_summed == CHECKSUM_PARTIAL) {
tcp_partial_csum_update(dest->af, tcph, &svc->addr, &dest->addr,
htons(oldlen),
htons(skb->len - tcphoff));
} else {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(dest->af, tcph, &svc->addr, &dest->addr,
svc->port, localport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
}
return 1;
}
static int
tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
{
struct tcphdr *tcph;
unsigned int tcphoff = iph->len;
int oldlen;
int payload_csum = 0;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6 && iph->fragoffs)
return 1;
#endif
oldlen = skb->len - tcphoff;
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
return 0;
if (unlikely(cp->app != NULL)) {
int ret;
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
/*
* Attempt ip_vs_app call.
* It will fix ip_vs_conn and iph ack_seq stuff
*/
if (!(ret = ip_vs_app_pkt_in(cp, skb)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - tcphoff;
else
payload_csum = 1;
}
tcph = (void *)skb_network_header(skb) + tcphoff;
tcph->dest = cp->dport;
/*
* Adjust TCP checksums
*/
if (skb->ip_summed == CHECKSUM_PARTIAL) {
tcp_partial_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
htons(oldlen),
htons(skb->len - tcphoff));
} else if (!payload_csum) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
cp->vport, cp->dport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = (cp->app && pp->csum_check) ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
tcph->check = csum_ipv6_magic(&cp->caddr.in6,
&cp->daddr.in6,
skb->len - tcphoff,
cp->protocol, skb->csum);
else
#endif
tcph->check = csum_tcpudp_magic(cp->caddr.ip,
cp->daddr.ip,
skb->len - tcphoff,
cp->protocol,
skb->csum);
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return 1;
}
static int
tcp_fnat_out_handler(struct sk_buff *skb,
struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
{
struct tcphdr *tcph;
unsigned int tcphoff;
int oldlen;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
tcphoff = sizeof(struct ipv6hdr);
else
#endif
tcphoff = ip_hdrlen(skb);
oldlen = skb->len - tcphoff;
/* csum_check requires unshared skb */
if (!skb_make_writable(skb, tcphoff + sizeof(*tcph)))
return 0;
if (unlikely(cp->app != NULL)) {
/* Some checks before mangling */
if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
return 0;
/* Call application helper if needed */
if (!ip_vs_app_pkt_out(cp, skb))
return 0;
}
tcph = (void *)skb_network_header(skb) + tcphoff;
tcp_save_out_seq(skb, cp, tcph, tcphoff);
tcph->source = cp->vport;
tcph->dest = cp->cport;
/*
* for syn_ack
* 1. adjust tcp opt mss in rs->client
*/
if (tcph->syn && tcph->ack) {
tcp_opt_adjust_mss(cp->af, tcph);
}
/* adjust tcp ack/sack sequence */
if (tcp_out_adjust_seq(cp, tcph) == 0) {
return 0;
}
/*
* for syn_ack
* 2. init sequence
*/
if (tcph->syn && tcph->ack) {
tcp_out_init_seq(cp, tcph);
}
/* do csum later */
if (sysctl_ip_vs_csum_offload) {
skb->csum_start = skb_network_header(skb) -
skb->head + (ip_hdr(skb)->ihl << 2);
skb->csum_offset = offsetof(struct tcphdr, check);
skb->ip_summed = CHECKSUM_PARTIAL;
}
/* Adjust TCP checksums */
if (skb->ip_summed == CHECKSUM_PARTIAL) {
tcp_partial_csum_reset(cp->af, (skb->len - tcphoff),
tcph, &cp->vaddr, &cp->caddr);
} else if (!cp->app) {
/* Only port and addr are changed, do fast csum update */
tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
cp->dport, cp->vport);
tcp_fast_csum_update(cp->af, tcph, &cp->laddr, &cp->caddr,
cp->lport, cp->cport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = CHECKSUM_NONE;
} else {
/* full checksum calculation */
tcph->check = 0;
skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
tcph->check = csum_ipv6_magic(&cp->vaddr.in6,
&cp->caddr.in6,
skb->len - tcphoff,
cp->protocol, skb->csum);
else
#endif
tcph->check = csum_tcpudp_magic(cp->vaddr.ip,
cp->caddr.ip,
skb->len - tcphoff,
cp->protocol, skb->csum);
IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
pp->name, tcph->check,
(char *)&(tcph->check) - (char *)tcph);
}
return 1;
}