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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 | /* Redirect. Simple mapping which alters dst to a local IP address. */
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/netdevice.h>
#include <linux/if.h>
#include <linux/inetdevice.h>
#include <net/protocol.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* FIXME: Take multiple ranges --RR */
static int
redirect_check(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const struct ip_nat_multi_range *mr = targinfo;
if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
DEBUGP("redirect_check: size %u.\n", targinfosize);
return 0;
}
if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) {
DEBUGP("redirect_check: bad hooks %x.\n", hook_mask);
return 0;
}
if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
DEBUGP("redirect_check: bad MAP_IPS.\n");
return 0;
}
if (mr->rangesize != 1) {
DEBUGP("redirect_check: bad rangesize %u.\n", mr->rangesize);
return 0;
}
return 1;
}
static unsigned int
redirect_target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
u_int32_t newdst;
const struct ip_nat_multi_range *mr = targinfo;
struct ip_nat_multi_range newrange;
IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
|| hooknum == NF_IP_LOCAL_OUT);
ct = ip_conntrack_get(*pskb, &ctinfo);
IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
/* Local packets: make them go to loopback */
if (hooknum == NF_IP_LOCAL_OUT)
newdst = htonl(0x7F000001);
else
/* Grab first address on interface. */
newdst = (((struct in_device *)(*pskb)->dev->ip_ptr)
->ifa_list->ifa_local);
/* Transfer from original range. */
newrange = ((struct ip_nat_multi_range)
{ 1, { { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
newdst, newdst,
mr->range[0].min, mr->range[0].max } } });
/* Hand modified range to generic setup. */
return ip_nat_setup_info(ct, &newrange, hooknum);
}
static struct ipt_target redirect_reg
= { { NULL, NULL }, "REDIRECT", redirect_target, redirect_check, NULL,
THIS_MODULE };
static int __init init(void)
{
return ipt_register_target(&redirect_reg);
}
static void __exit fini(void)
{
ipt_unregister_target(&redirect_reg);
}
module_init(init);
module_exit(fini);
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