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/* Shared library add-on to iptables to add simple load-balance 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_ipv4/ip_nat_rule.h>
#define BREAKUP_IP(x) (x)>>24, ((x)>>16) & 0xFF, ((x)>>8) & 0xFF, (x) & 0xFF
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"BALANCE v%s options:\n"
" --to-destination <ipaddr>-<ipaddr>\n"
" Addresses to map destination to.\n",
NETFILTER_VERSION);
}
static struct option opts[] = {
{ "to-destination", 1, 0, '1' },
{ 0 }
};
/* Initialize the target. */
static void
init(struct ipt_entry_target *t, unsigned int *nfcache)
{
struct ip_nat_multi_range *mr = (struct ip_nat_multi_range *)t->data;
/* Actually, it's 0, but it's ignored at the moment. */
mr->rangesize = 1;
/* Can't cache this */
*nfcache |= NFC_UNKNOWN;
}
/* 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';
else
exit_error(PARAMETER_PROBLEM, "Bad IP range `%s'\n", arg);
ip = dotted_to_addr(arg);
if (!ip)
exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
arg);
range->min_ip = ip->s_addr;
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;
}
/* 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 ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)(*target)->data;
switch (c) {
case '1':
if (check_inverse(optarg, &invert))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --to-destination");
parse_to(optarg, &mr->range[0]);
*flags = 1;
return 1;
default:
return 0;
}
}
/* Final check; need --to-dest. */
static void final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM,
"BALANCE needs --to-destination");
}
/* Prints out the targinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_target *target,
int numeric)
{
struct ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)target->data;
struct ip_nat_range *r = &mr->range[0];
struct in_addr a;
a.s_addr = r->min_ip;
printf("balance %s", addr_to_dotted(&a));
a.s_addr = r->max_ip;
printf("-%s ", addr_to_dotted(&a));
}
/* Saves the union ipt_targinfo in parsable form to stdout. */
static void
save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
{
struct ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)target->data;
struct ip_nat_range *r = &mr->range[0];
struct in_addr a;
a.s_addr = r->min_ip;
printf("--to-destination %s", addr_to_dotted(&a));
a.s_addr = r->max_ip;
printf("-%s ", addr_to_dotted(&a));
}
static
struct iptables_target balance
= { NULL,
"BALANCE",
NETFILTER_VERSION,
IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void _init(void)
{
register_target(&balance);
}
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