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/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* 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/netfilter.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/if.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
static int
icmp_in_range(const struct ip_conntrack_tuple *tuple,
enum ip_nat_manip_type maniptype,
const union ip_conntrack_manip_proto *min,
const union ip_conntrack_manip_proto *max)
{
return (tuple->src.u.icmp.id >= min->icmp.id
&& tuple->src.u.icmp.id <= max->icmp.id);
}
static int
icmp_unique_tuple(struct ip_conntrack_tuple *tuple,
const struct ip_nat_range *range,
enum ip_nat_manip_type maniptype,
const struct ip_conntrack *conntrack)
{
static u_int16_t id;
unsigned int range_size;
unsigned int i;
range_size = ntohs(range->max.icmp.id) - ntohs(range->min.icmp.id) + 1;
/* If no range specified... */
if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
range_size = 0xFFFF;
for (i = 0; i < range_size; i++, id++) {
tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) +
(id % range_size));
if (!ip_nat_used_tuple(tuple, conntrack))
return 1;
}
return 0;
}
static int
icmp_manip_pkt(struct sk_buff **pskb,
unsigned int iphdroff,
const struct ip_conntrack_tuple *tuple,
enum ip_nat_manip_type maniptype)
{
struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff);
struct icmphdr *hdr;
unsigned int hdroff = iphdroff + iph->ihl*4;
if (!skb_make_writable(pskb, hdroff + sizeof(*hdr)))
return 0;
hdr = (struct icmphdr *)((*pskb)->data + hdroff);
hdr->checksum = nf_proto_csum_update(*pskb,
hdr->un.echo.id ^ 0xFFFF,
tuple->src.u.icmp.id,
hdr->checksum, 0);
hdr->un.echo.id = tuple->src.u.icmp.id;
return 1;
}
struct ip_nat_protocol ip_nat_protocol_icmp = {
.name = "ICMP",
.protonum = IPPROTO_ICMP,
.me = THIS_MODULE,
.manip_pkt = icmp_manip_pkt,
.in_range = icmp_in_range,
.unique_tuple = icmp_unique_tuple,
#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
.range_to_nfattr = ip_nat_port_range_to_nfattr,
.nfattr_to_range = ip_nat_port_nfattr_to_range,
#endif
};
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