/* Shared library add-on to iptables to add customized REJECT support.

 *

 * (C) 2000 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

 */

#include <stdio.h>

#include <string.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;

	const char *desc;

	const char *xlate;

};

enum {

	O_REJECT_WITH = 0,

};

static const struct reject_names reject_table[] = {

	[IPT_ICMP_NET_UNREACHABLE] = {

		"icmp-net-unreachable", "net-unreach",

		"ICMP network unreachable",

		"net-unreachable",

	},

	[IPT_ICMP_HOST_UNREACHABLE] = {

		"icmp-host-unreachable", "host-unreach",

		"ICMP host unreachable",

		"host-unreachable",

	},

	[IPT_ICMP_PROT_UNREACHABLE] = {

		"icmp-proto-unreachable", "proto-unreach",

		"ICMP protocol unreachable",

		"prot-unreachable",

	},

	[IPT_ICMP_PORT_UNREACHABLE] = {

		"icmp-port-unreachable", "port-unreach",

		"ICMP port unreachable (default)",

		"port-unreachable",

	},

#if 0

	[IPT_ICMP_ECHOREPLY] = {

		"echo-reply", "echoreply",

		"for ICMP echo only: faked ICMP echo reply",

		"echo-reply",

	},

#endif

	[IPT_ICMP_NET_PROHIBITED] = {

		"icmp-net-prohibited", "net-prohib",

		"ICMP network prohibited",

		"net-prohibited",

	},

	[IPT_ICMP_HOST_PROHIBITED] = {

		"icmp-host-prohibited", "host-prohib",

		"ICMP host prohibited",

		"host-prohibited",

	},

	[IPT_TCP_RESET] = {

		"tcp-reset", "tcp-rst",

		"TCP RST packet",

		"tcp reset",

	},

	[IPT_ICMP_ADMIN_PROHIBITED] = {

		"icmp-admin-prohibited", "admin-prohib",

		"ICMP administratively prohibited (*)",

		"admin-prohibited",

	},

};

static void

print_reject_types(void)

{

	unsigned int i;

	printf("Valid reject types:\n");

	for (i = 0; i < ARRAY_SIZE(reject_table); ++i) {

		if (!reject_table[i].name)

			continue;

		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 xt_option_entry REJECT_opts[] = {

	{.name = "reject-with", .id = O_REJECT_WITH, .type = XTTYPE_STRING},

	XTOPT_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 void REJECT_parse(struct xt_option_call *cb)

{

	struct ipt_reject_info *reject = cb->data;

	unsigned int i;

	xtables_option_parse(cb);

	for (i = 0; i < ARRAY_SIZE(reject_table); ++i) {

		if (!reject_table[i].name)

			continue;

		if (strncasecmp(reject_table[i].name,

		      cb->arg, strlen(cb->arg)) == 0 ||

		    strncasecmp(reject_table[i].alias,

		      cb->arg, strlen(cb->arg)) == 0) {

			reject->with = i;

			return;

		}

	}

	/* This due to be dropped late in 2.4 pre-release cycle --RR */

	if (strncasecmp("echo-reply", cb->arg, strlen(cb->arg)) == 0 ||

	    strncasecmp("echoreply", cb->arg, strlen(cb->arg)) == 0)

		fprintf(stderr, "--reject-with echo-reply no longer"

			" supported\n");

	xtables_error(PARAMETER_PROBLEM,

		"unknown reject type \"%s\"", cb->arg);

}

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;

	printf(" reject-with %s", reject_table[reject->with].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;

	printf(" --reject-with %s", reject_table[reject->with].name);

}

static int REJECT_xlate(struct xt_xlate *xl,

			const struct xt_xlate_tg_params *params)

{

	const struct ipt_reject_info *reject =

		(const struct ipt_reject_info *)params->target->data;

	if (reject->with == IPT_ICMP_PORT_UNREACHABLE)

		xt_xlate_add(xl, "reject");

	else if (reject->with == IPT_TCP_RESET)

		xt_xlate_add(xl, "reject with %s",

			     reject_table[reject->with].xlate);

	else

		xt_xlate_add(xl, "reject with icmp type %s",

			     reject_table[reject->with].xlate);

	return 1;

}

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,

	.print		= REJECT_print,

	.save		= REJECT_save,

	.x6_parse	= REJECT_parse,

	.x6_options	= REJECT_opts,

	.xlate		= REJECT_xlate,

};

void _init(void)

{

	xtables_register_target(&reject_tg_reg);

}