int
nf_nat_seq_adjust(struct sk_buff *skb,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct tcphdr *tcph;
int dir;
__be32 newseq, newack;
s16 seqoff, ackoff;
struct nf_conn_nat *nat = nfct_nat(ct);
struct nf_nat_seq *this_way, *other_way;
dir = CTINFO2DIR(ctinfo);
this_way = &nat->seq[dir];
other_way = &nat->seq[!dir];
#ifdef CONFIG_HTC_NETWORK_MODIFY
if (IS_ERR(this_way) || (!this_way))
printk(KERN_ERR "[NET] this_way is NULL in %s!\n", __func__);
#endif
if (!skb_make_writable(skb, ip_hdrlen(skb) + sizeof(*tcph)))
return 0;
tcph = (void *)skb->data + ip_hdrlen(skb);
if (after(ntohl(tcph->seq), this_way->correction_pos))
seqoff = this_way->offset_after;
else
seqoff = this_way->offset_before;
if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
other_way->correction_pos))
ackoff = other_way->offset_after;
else
ackoff = other_way->offset_before;
newseq = htonl(ntohl(tcph->seq) + seqoff);
newack = htonl(ntohl(tcph->ack_seq) - ackoff);
inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, 0);
inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, 0);
pr_debug("Adjusting sequence number from %u->%u, ack from %u->%u\n",
ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
ntohl(newack));
tcph->seq = newseq;
tcph->ack_seq = newack;
return nf_nat_sack_adjust(skb, tcph, ct, ctinfo);
}
/* TCP sequence number adjustment. Returns 1 on success, 0 on failure */
int
nf_nat_seq_adjust(struct sk_buff **pskb,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
struct tcphdr *tcph;
int dir;
__be32 newseq, newack;
struct nf_conn_nat *nat = nfct_nat(ct);
struct nf_nat_seq *this_way, *other_way;
dir = CTINFO2DIR(ctinfo);
this_way = &nat->info.seq[dir];
other_way = &nat->info.seq[!dir];
if (!skb_make_writable(pskb, (*pskb)->nh.iph->ihl*4+sizeof(*tcph)))
return 0;
tcph = (void *)(*pskb)->data + (*pskb)->nh.iph->ihl*4;
if (after(ntohl(tcph->seq), this_way->correction_pos))
newseq = htonl(ntohl(tcph->seq) + this_way->offset_after);
else
newseq = htonl(ntohl(tcph->seq) + this_way->offset_before);
if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
other_way->correction_pos))
newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_after);
else
newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_before);
nf_proto_csum_replace4(&tcph->check, *pskb, tcph->seq, newseq, 0);
nf_proto_csum_replace4(&tcph->check, *pskb, tcph->ack_seq, newack, 0);
DEBUGP("Adjusting sequence number from %u->%u, ack from %u->%u\n",
ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
ntohl(newack));
tcph->seq = newseq;
tcph->ack_seq = newack;
if (!nf_nat_sack_adjust(pskb, tcph, ct, ctinfo))
return 0;
nf_conntrack_tcp_update(*pskb, (*pskb)->nh.iph->ihl*4, ct, dir);
return 1;
}
