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/*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/types.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/sctp.h>
#include <net/sctp/checksum.h>
#include <net/netfilter/nf_nat_protocol.h>
static u_int16_t nf_sctp_port_rover;
static void
sctp_unique_tuple(struct nf_conntrack_tuple *tuple,
const struct nf_nat_range *range,
enum nf_nat_manip_type maniptype,
const struct nf_conn *ct)
{
nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
&nf_sctp_port_rover);
}
static bool
sctp_manip_pkt(struct sk_buff *skb,
unsigned int iphdroff,
const struct nf_conntrack_tuple *tuple,
enum nf_nat_manip_type maniptype)
{
const struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
struct sk_buff *frag;
sctp_sctphdr_t *hdr;
unsigned int hdroff = iphdroff + iph->ihl*4;
__be32 oldip, newip;
__be32 crc32;
if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
return false;
iph = (struct iphdr *)(skb->data + iphdroff);
hdr = (struct sctphdr *)(skb->data + hdroff);
if (maniptype == IP_NAT_MANIP_SRC) {
/* Get rid of src ip and src pt */
oldip = iph->saddr;
newip = tuple->src.u3.ip;
hdr->source = tuple->src.u.sctp.port;
} else {
/* Get rid of dst ip and dst pt */
oldip = iph->daddr;
newip = tuple->dst.u3.ip;
hdr->dest = tuple->dst.u.sctp.port;
}
crc32 = sctp_start_cksum((u8 *)hdr, skb_headlen(skb) - hdroff);
skb_walk_frags(skb, frag)
crc32 = sctp_update_cksum((u8 *)frag->data, skb_headlen(frag),
crc32);
crc32 = sctp_end_cksum(crc32);
hdr->checksum = crc32;
return true;
}
static const struct nf_nat_protocol nf_nat_protocol_sctp = {
.protonum = IPPROTO_SCTP,
.me = THIS_MODULE,
.manip_pkt = sctp_manip_pkt,
.in_range = nf_nat_proto_in_range,
.unique_tuple = sctp_unique_tuple,
#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
.range_to_nlattr = nf_nat_proto_range_to_nlattr,
.nlattr_to_range = nf_nat_proto_nlattr_to_range,
#endif
};
static int __init nf_nat_proto_sctp_init(void)
{
return nf_nat_protocol_register(&nf_nat_protocol_sctp);
}
static void __exit nf_nat_proto_sctp_exit(void)
{
nf_nat_protocol_unregister(&nf_nat_protocol_sctp);
}
module_init(nf_nat_proto_sctp_init);
module_exit(nf_nat_proto_sctp_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SCTP NAT protocol helper");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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