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/* Shared library add-on to iptables to add customized REJECT support.
*
* (C) 2000 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
*/
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter_ipv4/ipt_REJECT.h>
#include <linux/version.h>
/* If we are compiling against a kernel that does not support
* IPT_ICMP_ADMIN_PROHIBITED, we are emulating it.
* The result will be a plain DROP of the packet instead of
* reject. -- Maciej Soltysiak <solt@dns.toxicfilms.tv>
*/
#ifndef IPT_ICMP_ADMIN_PROHIBITED
#define IPT_ICMP_ADMIN_PROHIBITED IPT_TCP_RESET + 1
#endif
struct reject_names {
const char *name;
const char *alias;
enum ipt_reject_with with;
const char *desc;
};
static const struct reject_names reject_table[] = {
{"icmp-net-unreachable", "net-unreach",
IPT_ICMP_NET_UNREACHABLE, "ICMP network unreachable"},
{"icmp-host-unreachable", "host-unreach",
IPT_ICMP_HOST_UNREACHABLE, "ICMP host unreachable"},
{"icmp-proto-unreachable", "proto-unreach",
IPT_ICMP_PROT_UNREACHABLE, "ICMP protocol unreachable"},
{"icmp-port-unreachable", "port-unreach",
IPT_ICMP_PORT_UNREACHABLE, "ICMP port unreachable (default)"},
#if 0
{"echo-reply", "echoreply",
IPT_ICMP_ECHOREPLY, "for ICMP echo only: faked ICMP echo reply"},
#endif
{"icmp-net-prohibited", "net-prohib",
IPT_ICMP_NET_PROHIBITED, "ICMP network prohibited"},
{"icmp-host-prohibited", "host-prohib",
IPT_ICMP_HOST_PROHIBITED, "ICMP host prohibited"},
{"tcp-reset", "tcp-rst",
IPT_TCP_RESET, "TCP RST packet"},
{"icmp-admin-prohibited", "admin-prohib",
IPT_ICMP_ADMIN_PROHIBITED, "ICMP administratively prohibited (*)"}
};
static void
print_reject_types(void)
{
unsigned int i;
printf("Valid reject types:\n");
for (i = 0; i < ARRAY_SIZE(reject_table); ++i) {
printf(" %-25s\t%s\n", reject_table[i].name, reject_table[i].desc);
printf(" %-25s\talias\n", reject_table[i].alias);
}
printf("\n");
}
static void REJECT_help(void)
{
printf(
"REJECT target options:\n"
"--reject-with type drop input packet and send back\n"
" a reply packet according to type:\n");
print_reject_types();
printf("(*) See man page or read the INCOMPATIBILITES file for compatibility issues.\n");
}
static const struct option REJECT_opts[] = {
{.name = "reject-with", .has_arg = true, .val = '1'},
XT_GETOPT_TABLEEND,
};
static void REJECT_init(struct xt_entry_target *t)
{
struct ipt_reject_info *reject = (struct ipt_reject_info *)t->data;
/* default */
reject->with = IPT_ICMP_PORT_UNREACHABLE;
}
static int REJECT_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_target **target)
{
struct ipt_reject_info *reject = (struct ipt_reject_info *)(*target)->data;
static const unsigned int limit = ARRAY_SIZE(reject_table);
unsigned int i;
switch(c) {
case '1':
if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
xtables_error(PARAMETER_PROBLEM,
"Unexpected `!' after --reject-with");
for (i = 0; i < limit; i++) {
if ((strncasecmp(reject_table[i].name, optarg, strlen(optarg)) == 0)
|| (strncasecmp(reject_table[i].alias, optarg, strlen(optarg)) == 0)) {
reject->with = reject_table[i].with;
return 1;
}
}
/* This due to be dropped late in 2.4 pre-release cycle --RR */
if (strncasecmp("echo-reply", optarg, strlen(optarg)) == 0
|| strncasecmp("echoreply", optarg, strlen(optarg)) == 0)
fprintf(stderr, "--reject-with echo-reply no longer"
" supported\n");
xtables_error(PARAMETER_PROBLEM, "unknown reject type \"%s\"", optarg);
break;
}
return 0;
}
static void REJECT_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct ipt_reject_info *reject
= (const struct ipt_reject_info *)target->data;
unsigned int i;
for (i = 0; i < ARRAY_SIZE(reject_table); ++i)
if (reject_table[i].with == reject->with)
break;
printf(" reject-with %s", reject_table[i].name);
}
static void REJECT_save(const void *ip, const struct xt_entry_target *target)
{
const struct ipt_reject_info *reject
= (const struct ipt_reject_info *)target->data;
unsigned int i;
for (i = 0; i < ARRAY_SIZE(reject_table); ++i)
if (reject_table[i].with == reject->with)
break;
printf(" --reject-with %s", reject_table[i].name);
}
static struct xtables_target reject_tg_reg = {
.name = "REJECT",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct ipt_reject_info)),
.userspacesize = XT_ALIGN(sizeof(struct ipt_reject_info)),
.help = REJECT_help,
.init = REJECT_init,
.parse = REJECT_parse,
.print = REJECT_print,
.save = REJECT_save,
.extra_opts = REJECT_opts,
};
void _init(void)
{
xtables_register_target(&reject_tg_reg);
}
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