/* Shared library add-on to iptables to add TTL matching support 

 * (C) 2000 by Harald Welte <laforge@gnumonks.org>

 *

 * This program is released under the terms of GNU GPL */

#include <stdio.h>

#include <xtables.h>

#include <linux/netfilter_ipv4/ipt_ttl.h>

enum {

	O_TTL_EQ = 0,

	O_TTL_LT,

	O_TTL_GT,

	F_TTL_EQ = 1 << O_TTL_EQ,

	F_TTL_LT = 1 << O_TTL_LT,

	F_TTL_GT = 1 << O_TTL_GT,

	F_ANY    = F_TTL_EQ | F_TTL_LT | F_TTL_GT,

};

static void ttl_help(void)

{

	printf(

"ttl match options:\n"

"[!] --ttl-eq value	Match time to live value\n"

"  --ttl-lt value	Match TTL < value\n"

"  --ttl-gt value	Match TTL > value\n");

}

static void ttl_parse(struct xt_option_call *cb)

{

	struct ipt_ttl_info *info = cb->data;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_TTL_EQ:

		info->mode = cb->invert ? IPT_TTL_NE : IPT_TTL_EQ;

		break;

	case O_TTL_LT:

		info->mode = IPT_TTL_LT;

		break;

	case O_TTL_GT:

		info->mode = IPT_TTL_GT;

		break;

	}

}

static void ttl_check(struct xt_fcheck_call *cb)

{

	if (!(cb->xflags & F_ANY))

		xtables_error(PARAMETER_PROBLEM,

			"TTL match: You must specify one of "

			"`--ttl-eq', `--ttl-lt', `--ttl-gt");

}

static void ttl_print(const void *ip, const struct xt_entry_match *match,

                      int numeric)

{

	const struct ipt_ttl_info *info = 

		(struct ipt_ttl_info *) match->data;

	printf(" TTL match ");

	switch (info->mode) {

		case IPT_TTL_EQ:

			printf("TTL ==");

			break;

		case IPT_TTL_NE:

			printf("TTL !=");

			break;

		case IPT_TTL_LT:

			printf("TTL <");

			break;

		case IPT_TTL_GT:

			printf("TTL >");

			break;

	}

	printf(" %u", info->ttl);

}

static void ttl_save(const void *ip, const struct xt_entry_match *match)

{

	const struct ipt_ttl_info *info =

		(struct ipt_ttl_info *) match->data;

	switch (info->mode) {

		case IPT_TTL_EQ:

			printf(" --ttl-eq");

			break;

		case IPT_TTL_NE:

			printf(" ! --ttl-eq");

			break;

		case IPT_TTL_LT:

			printf(" --ttl-lt");

			break;

		case IPT_TTL_GT:

			printf(" --ttl-gt");

			break;

		default:

			/* error */

			break;

	}

	printf(" %u", info->ttl);

}

static int ttl_xlate(struct xt_xlate *xl,

		     const struct xt_xlate_mt_params *params)

{

	const struct ipt_ttl_info *info =

		(struct ipt_ttl_info *) params->match->data;

		switch (info->mode) {

		case IPT_TTL_EQ:

			xt_xlate_add(xl, "ip ttl");

			break;

		case IPT_TTL_NE:

			xt_xlate_add(xl, "ip ttl !=");

			break;

		case IPT_TTL_LT:

			xt_xlate_add(xl, "ip ttl lt");

			break;

		case IPT_TTL_GT:

			xt_xlate_add(xl, "ip ttl gt");

			break;

		default:

			/* Should not happen. */

			break;

	}

	xt_xlate_add(xl, " %u", info->ttl);

	return 1;

}

#define s struct ipt_ttl_info

static const struct xt_option_entry ttl_opts[] = {

	{.name = "ttl-lt", .id = O_TTL_LT, .excl = F_ANY, .type = XTTYPE_UINT8,

	 .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)},

	{.name = "ttl-gt", .id = O_TTL_GT, .excl = F_ANY, .type = XTTYPE_UINT8,

	 .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)},

	{.name = "ttl-eq", .id = O_TTL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,

	 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, ttl)},

	{.name = "ttl", .id = O_TTL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,

	 .flags = XTOPT_PUT, XTOPT_POINTER(s, ttl)},

	XTOPT_TABLEEND,

};

#undef s

static struct xtables_match ttl_mt_reg = {

	.name		= "ttl",

	.version	= XTABLES_VERSION,

	.family		= NFPROTO_IPV4,

	.size		= XT_ALIGN(sizeof(struct ipt_ttl_info)),

	.userspacesize	= XT_ALIGN(sizeof(struct ipt_ttl_info)),

	.help		= ttl_help,

	.print		= ttl_print,

	.save		= ttl_save,

	.x6_parse	= ttl_parse,

	.x6_fcheck	= ttl_check,

	.x6_options	= ttl_opts,

	.xlate		= ttl_xlate,

};

void _init(void) 

{

	xtables_register_match(&ttl_mt_reg);

}