static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff,
unsigned int dataoff,
const char **dptr, unsigned int *datalen,
unsigned int matchoff, unsigned int matchlen,
const char *buffer, unsigned int buflen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
struct tcphdr *th;
unsigned int baseoff;
if (nf_ct_protonum(ct) == IPPROTO_TCP) {
th = (struct tcphdr *)(skb->data + protoff);
baseoff = protoff + th->doff * 4;
matchoff += dataoff - baseoff;
if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
protoff, matchoff, matchlen,
buffer, buflen, false))
return 0;
} else {
baseoff = protoff + sizeof(struct udphdr);
matchoff += dataoff - baseoff;
if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
protoff, matchoff, matchlen,
buffer, buflen))
return 0;
}
/* Reload data pointer and adjust datalen value */
*dptr = skb->data + dataoff;
*datalen += buflen - matchlen;
return 1;
}
/* Generic function for mangling variable-length address changes inside
* NATed TCP connections (like the PORT XXX,XXX,XXX,XXX,XXX,XXX
* command in FTP).
*
* Takes care about all the nasty sequence number changes, checksumming,
* skb enlargement, ...
*
* */
int nf_nat_mangle_tcp_packet(struct sk_buff **skb,
struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
unsigned int match_offset,
unsigned int match_len,
const char *rep_buffer,
unsigned int rep_len)
{
return __nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
match_offset, match_len,
rep_buffer, rep_len, true);
}
