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/* Shared library add-on to iptables to add simple non load-balancing SNAT support. */
#include <stdbool.h>
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <net/netfilter/nf_nat.h>
/* For 64bit kernel / 32bit userspace */
#include <linux/netfilter_ipv4/ipt_SAME.h>
static void SAME_help(void)
{
printf(
"SAME target options:\n"
" --to <ipaddr>-<ipaddr>\n"
" Addresses to map source to.\n"
" May be specified more than\n"
" once for multiple ranges.\n"
" --nodst\n"
" Don't use destination-ip in\n"
" source selection\n"
" --random\n"
" Randomize source port\n");
}
static const struct option SAME_opts[] = {
{.name = "to", .has_arg = true, .val = '1'},
{.name = "nodst", .has_arg = false, .val = '2'},
{.name = "random", .has_arg = false, .val = '3'},
XT_GETOPT_TABLEEND,
};
/* Parses range of IPs */
static void
parse_to(char *arg, struct nf_nat_range *range)
{
char *dash;
const struct in_addr *ip;
range->flags |= IP_NAT_RANGE_MAP_IPS;
dash = strchr(arg, '-');
if (dash)
*dash = '\0';
ip = xtables_numeric_to_ipaddr(arg);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
arg);
range->min_ip = ip->s_addr;
if (dash) {
ip = xtables_numeric_to_ipaddr(dash+1);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
dash+1);
}
range->max_ip = ip->s_addr;
if (dash)
if (range->min_ip > range->max_ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP range \"%s-%s\"\n",
arg, dash+1);
}
#define IPT_SAME_OPT_TO 0x01
#define IPT_SAME_OPT_NODST 0x02
#define IPT_SAME_OPT_RANDOM 0x04
static int SAME_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_target **target)
{
struct ipt_same_info *mr
= (struct ipt_same_info *)(*target)->data;
unsigned int count;
switch (c) {
case '1':
if (mr->rangesize == IPT_SAME_MAX_RANGE)
xtables_error(PARAMETER_PROBLEM,
"Too many ranges specified, maximum "
"is %i ranges.\n",
IPT_SAME_MAX_RANGE);
if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
xtables_error(PARAMETER_PROBLEM,
"Unexpected `!' after --to");
parse_to(optarg, &mr->range[mr->rangesize]);
/* WTF do we need this for? */
if (*flags & IPT_SAME_OPT_RANDOM)
mr->range[mr->rangesize].flags
|= IP_NAT_RANGE_PROTO_RANDOM;
mr->rangesize++;
*flags |= IPT_SAME_OPT_TO;
break;
case '2':
if (*flags & IPT_SAME_OPT_NODST)
xtables_error(PARAMETER_PROBLEM,
"Can't specify --nodst twice");
mr->info |= IPT_SAME_NODST;
*flags |= IPT_SAME_OPT_NODST;
break;
case '3':
*flags |= IPT_SAME_OPT_RANDOM;
for (count=0; count < mr->rangesize; count++)
mr->range[count].flags |= IP_NAT_RANGE_PROTO_RANDOM;
break;
}
return 1;
}
static void SAME_check(unsigned int flags)
{
if (!(flags & IPT_SAME_OPT_TO))
xtables_error(PARAMETER_PROBLEM,
"SAME needs --to");
}
static void SAME_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
unsigned int count;
const struct ipt_same_info *mr = (const void *)target->data;
int random_selection = 0;
printf(" same:");
for (count = 0; count < mr->rangesize; count++) {
const struct nf_nat_range *r = &mr->range[count];
struct in_addr a;
a.s_addr = r->min_ip;
printf("%s", xtables_ipaddr_to_numeric(&a));
a.s_addr = r->max_ip;
if (r->min_ip != r->max_ip)
printf("-%s", xtables_ipaddr_to_numeric(&a));
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
random_selection = 1;
}
if (mr->info & IPT_SAME_NODST)
printf(" nodst");
if (random_selection)
printf(" random");
}
static void SAME_save(const void *ip, const struct xt_entry_target *target)
{
unsigned int count;
const struct ipt_same_info *mr = (const void *)target->data;
int random_selection = 0;
for (count = 0; count < mr->rangesize; count++) {
const struct nf_nat_range *r = &mr->range[count];
struct in_addr a;
a.s_addr = r->min_ip;
printf(" --to %s", xtables_ipaddr_to_numeric(&a));
a.s_addr = r->max_ip;
if (r->min_ip != r->max_ip)
printf("-%s", xtables_ipaddr_to_numeric(&a));
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
random_selection = 1;
}
if (mr->info & IPT_SAME_NODST)
printf(" --nodst");
if (random_selection)
printf(" --random");
}
static struct xtables_target same_tg_reg = {
.name = "SAME",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct ipt_same_info)),
.userspacesize = XT_ALIGN(sizeof(struct ipt_same_info)),
.help = SAME_help,
.parse = SAME_parse,
.final_check = SAME_check,
.print = SAME_print,
.save = SAME_save,
.extra_opts = SAME_opts,
};
void _init(void)
{
xtables_register_target(&same_tg_reg);
}
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