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/* Shared library add-on to iptables to add simple non load-balancing SNAT support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter/nf_nat.h>
/* For 64bit kernel / 32bit userspace */
#include "../include/linux/netfilter_ipv4/ipt_SAME.h"
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"SAME v%s 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"
,
IPTABLES_VERSION);
}
static const struct option opts[] = {
{ "to", 1, NULL, '1' },
{ "nodst", 0, NULL, '2'},
{ "random", 0, NULL, '3' },
{ }
};
/* Initialize the target. */
static void
init(struct xt_entry_target *t)
{
struct ipt_same_info *mr = (struct ipt_same_info *)t->data;
/* Set default to 0 */
mr->rangesize = 0;
mr->info = 0;
mr->ipnum = 0;
}
/* Parses range of IPs */
static void
parse_to(char *arg, struct ip_nat_range *range)
{
char *dash;
struct in_addr *ip;
range->flags |= IP_NAT_RANGE_MAP_IPS;
dash = strchr(arg, '-');
if (dash)
*dash = '\0';
ip = dotted_to_addr(arg);
if (!ip)
exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
arg);
range->min_ip = ip->s_addr;
if (dash) {
ip = dotted_to_addr(dash+1);
if (!ip)
exit_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)
exit_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
/* Function which parses command options; returns true if it
ate an option */
static int
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;
int count;
switch (c) {
case '1':
if (mr->rangesize == IPT_SAME_MAX_RANGE)
exit_error(PARAMETER_PROBLEM,
"Too many ranges specified, maximum "
"is %i ranges.\n",
IPT_SAME_MAX_RANGE);
if (check_inverse(optarg, &invert, NULL, 0))
exit_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)
exit_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;
default:
return 0;
}
return 1;
}
/* Final check; need --to. */
static void final_check(unsigned int flags)
{
if (!(flags & IPT_SAME_OPT_TO))
exit_error(PARAMETER_PROBLEM,
"SAME needs --to");
}
/* Prints out the targinfo. */
static void
print(const void *ip,
const struct xt_entry_target *target,
int numeric)
{
int count;
struct ipt_same_info *mr
= (struct ipt_same_info *)target->data;
int random = 0;
printf("same:");
for (count = 0; count < mr->rangesize; count++) {
struct ip_nat_range *r = &mr->range[count];
struct in_addr a;
a.s_addr = r->min_ip;
printf("%s", addr_to_dotted(&a));
a.s_addr = r->max_ip;
if (r->min_ip == r->max_ip)
printf(" ");
else
printf("-%s ", addr_to_dotted(&a));
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
random = 1;
}
if (mr->info & IPT_SAME_NODST)
printf("nodst ");
if (random)
printf("random ");
}
/* Saves the union ipt_targinfo in parsable form to stdout. */
static void
save(const void *ip, const struct xt_entry_target *target)
{
int count;
struct ipt_same_info *mr
= (struct ipt_same_info *)target->data;
int random = 0;
for (count = 0; count < mr->rangesize; count++) {
struct ip_nat_range *r = &mr->range[count];
struct in_addr a;
a.s_addr = r->min_ip;
printf("--to %s", addr_to_dotted(&a));
a.s_addr = r->max_ip;
if (r->min_ip == r->max_ip)
printf(" ");
else
printf("-%s ", addr_to_dotted(&a));
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
random = 1;
}
if (mr->info & IPT_SAME_NODST)
printf("--nodst ");
if (random)
printf("--random ");
}
static struct iptables_target same = {
.name = "SAME",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ipt_same_info)),
.userspacesize = IPT_ALIGN(sizeof(struct ipt_same_info)),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
register_target(&same);
}
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