/*

 * IPv6 Hop Limit matching module

 * Maciej Soltysiak <solt@dns.toxicfilms.tv>

 * Based on HW's ttl match

 * This program is released under the terms of GNU GPL

 * Cleanups by Stephane Ouellette <ouellettes@videotron.ca>

 */

#include <stdio.h>

#include <xtables.h>

#include <linux/netfilter_ipv6/ip6t_hl.h>

enum {

	O_HL_EQ = 0,

	O_HL_LT,

	O_HL_GT,

	F_HL_EQ = 1 << O_HL_EQ,

	F_HL_LT = 1 << O_HL_LT,

	F_HL_GT = 1 << O_HL_GT,

	F_ANY  = F_HL_EQ | F_HL_LT | F_HL_GT,

};

static void hl_help(void)

{

	printf(

"hl match options:\n"

"[!] --hl-eq value	Match hop limit value\n"

"  --hl-lt value	Match HL < value\n"

"  --hl-gt value	Match HL > value\n");

}

static void hl_parse(struct xt_option_call *cb)

{

	struct ip6t_hl_info *info = cb->data;

	xtables_option_parse(cb);

	switch (cb->entry->id) {

	case O_HL_EQ:

		info->mode = cb->invert ? IP6T_HL_NE : IP6T_HL_EQ;

		break;

	case O_HL_LT:

		info->mode = IP6T_HL_LT;

		break;

	case O_HL_GT:

		info->mode = IP6T_HL_GT;

		break;

	}

}

static void hl_check(struct xt_fcheck_call *cb)

{

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

		xtables_error(PARAMETER_PROBLEM,

			"HL match: You must specify one of "

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

}

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

                     int numeric)

{

	static const char *const op[] = {

		[IP6T_HL_EQ] = "==",

		[IP6T_HL_NE] = "!=",

		[IP6T_HL_LT] = "<",

		[IP6T_HL_GT] = ">" };

	const struct ip6t_hl_info *info = 

		(struct ip6t_hl_info *) match->data;

	printf(" HL match HL %s %u", op[info->mode], info->hop_limit);

}

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

{

	static const char *const op[] = {

		[IP6T_HL_EQ] = "--hl-eq",

		[IP6T_HL_NE] = "! --hl-eq",

		[IP6T_HL_LT] = "--hl-lt",

		[IP6T_HL_GT] = "--hl-gt" };

	const struct ip6t_hl_info *info =

		(struct ip6t_hl_info *) match->data;

	printf(" %s %u", op[info->mode], info->hop_limit);

}

static const char *const op[] = {

	[IP6T_HL_EQ] = "",

	[IP6T_HL_NE] = "!= ",

	[IP6T_HL_LT] = "lt ",

	[IP6T_HL_GT] = "gt "

};

static int hl_xlate(struct xt_xlate *xl,

		    const struct xt_xlate_mt_params *params)

{

	const struct ip6t_hl_info *info =

		(struct ip6t_hl_info *) params->match->data;

	xt_xlate_add(xl, "ip6 hoplimit %s%u", op[info->mode], info->hop_limit);

	return 1;

}

#define s struct ip6t_hl_info

static const struct xt_option_entry hl_opts[] = {

	{.name = "hl-lt", .id = O_HL_LT, .excl = F_ANY, .type = XTTYPE_UINT8,

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

	{.name = "hl-gt", .id = O_HL_GT, .excl = F_ANY, .type = XTTYPE_UINT8,

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

	{.name = "hl-eq", .id = O_HL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,

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

	{.name = "hl", .id = O_HL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,

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

	XTOPT_TABLEEND,

};

#undef s

static struct xtables_match hl_mt6_reg = {

	.name          = "hl",

	.version       = XTABLES_VERSION,

	.family        = NFPROTO_IPV6,

	.size          = XT_ALIGN(sizeof(struct ip6t_hl_info)),

	.userspacesize = XT_ALIGN(sizeof(struct ip6t_hl_info)),

	.help          = hl_help,

	.print         = hl_print,

	.save          = hl_save,

	.x6_parse      = hl_parse,

	.x6_fcheck     = hl_check,

	.x6_options    = hl_opts,

	.xlate	       = hl_xlate,

};

void _init(void) 

{

	xtables_register_match(&hl_mt6_reg);

}