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/* Shared library add-on to iptables to add ROUTE target support.
* Author : Cédric de Launois, <delaunois@info.ucl.ac.be>
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <net/if.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ROUTE.h>
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"ROUTE target v%s options:\n"
" --iface name Send the packet directly through this interface.\n"
" --to ip Route the packet as if its destination address was ip.\n"
"\n",
IPTABLES_VERSION);
}
static struct option opts[] = {
{ "iface", 1, 0, '1' },
{ "to", 1, 0, '2' },
{ 0 }
};
/* Initialize the target. */
static void
init(struct ipt_entry_target *t, unsigned int *nfcache)
{
struct ipt_route_target_info *route_info =
(struct ipt_route_target_info*)t->data;
route_info->ifname[0] = '\0';
route_info->ipto = 0;
}
#define IPT_ROUTE_OPT_IF 0x01
#define IPT_ROUTE_OPT_TO 0x02
/* 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 struct ipt_entry *entry,
struct ipt_entry_target **target)
{
struct ipt_route_target_info *route_info =
(struct ipt_route_target_info*)(*target)->data;
switch (c) {
case '1':
if (*flags & IPT_ROUTE_OPT_IF)
exit_error(PARAMETER_PROBLEM,
"Can't specify --iface twice");
if (check_inverse(optarg, &invert, NULL, 0))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --iface");
if (strlen(optarg) > sizeof(route_info->ifname) - 1)
exit_error(PARAMETER_PROBLEM,
"Maximum interface name length %u",
sizeof(route_info->ifname) - 1);
strcpy(route_info->ifname, optarg);
*flags |= IPT_ROUTE_OPT_IF;
break;
case '2':
if (*flags & IPT_ROUTE_OPT_TO)
exit_error(PARAMETER_PROBLEM,
"Can't specify --to twice");
if (!inet_aton(optarg, (struct in_addr*)&route_info->ipto)) {
exit_error(PARAMETER_PROBLEM,
"Invalid IP address %s",
optarg);
}
*flags |= IPT_ROUTE_OPT_TO;
break;
default:
return 0;
}
return 1;
}
static void
final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"ROUTE target: minimum 1 parameter is required");
}
/* Prints out the targinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_target *target,
int numeric)
{
const struct ipt_route_target_info *route_info
= (const struct ipt_route_target_info *)target->data;
printf("ROUTE ");
if (route_info->ifname[0])
printf("iface %s ", route_info->ifname);
if (route_info->ipto) {
struct in_addr ip = { route_info->ipto };
printf("to %s ", inet_ntoa(ip));
}
}
static
struct iptables_target route
= { NULL,
"ROUTE",
IPTABLES_VERSION,
IPT_ALIGN(sizeof(struct ipt_route_target_info)),
IPT_ALIGN(sizeof(struct ipt_route_target_info)),
&help,
&init,
&parse,
&final_check,
&print,
NULL, /* save */
opts
};
void _init(void)
{
register_target(&route);
}
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