/*
 * libipt_osf.c
 *
 * Copyright (c) 2003-2006 Evgeniy Polyakov <zbr@ioremap.net>
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 * iptables interface for OS fingerprint matching module.
 */

#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <ctype.h>

#include <xtables.h>

typedef unsigned int __u32;
typedef unsigned short __u16;
typedef unsigned char __u8;

#include "ipt_osf.h"

static void osf_help(void)
{
	printf("OS fingerprint match options:\n"
		"--genre [!] string	Match a OS genre by passive fingerprinting.\n"
		"--ttl			Use some TTL check extensions to determine OS:\n"
		"	0			true ip and fingerprint TTL comparison. Works for LAN.\n"
		"	1			check if ip TTL is less than fingerprint one. Works for global addresses.\n"
		"	2			do not compare TTL at all. Allows to detect NMAP, but can produce false results.\n"
		"--log level		Log determined genres into dmesg even if they do not match desired one:\n"
		"	0			log all matched or unknown signatures.\n"
		"	1			log only first one.\n"
		"	2			log all known matched signatures.\n"
		"--connector		Log through kernel connector [2.6.14+].\n\n"
		);
}


static const struct option osf_opts[] = {
	{ .name = "genre",	.has_arg = 1, .flag = 0, .val = '1' },
	{ .name = "ttl",	.has_arg = 1, .flag = 0, .val = '2' },
	{ .name = "log",	.has_arg = 1, .flag = 0, .val = '3' },
	{ .name = "connector",	.has_arg = 0, .flag = 0, .val = '5' },
	{ .name = NULL }
};


static void osf_init(struct xt_entry_match *m)
{
}

static void osf_parse_string(const unsigned char *s, struct ipt_osf_info *info)
{
	if (strlen(s) < MAXGENRELEN) 
		strcpy(info->genre, s);
	else 
		exit_error(PARAMETER_PROBLEM, "Genre string too long `%s' [%d], max=%d", 
				s, strlen(s), MAXGENRELEN);
}

static int osf_parse(int c, char **argv, int invert, unsigned int *flags,
      			const void *entry,
      			struct xt_entry_match **match)
{
	struct ipt_osf_info *info = (struct ipt_osf_info *)(*match)->data;
	
	switch(c) 
	{
		case '1': /* --genre */
			if (*flags & IPT_OSF_GENRE)
				exit_error(PARAMETER_PROBLEM, "Can't specify multiple genre parameter");
			check_inverse(optarg, &invert, &optind, 0);
			osf_parse_string(argv[optind-1], info);
			if (invert)
				info->flags |= IPT_OSF_INVERT;
			info->len=strlen((char *)info->genre);
			*flags |= IPT_OSF_GENRE;
			break;
		case '2': /* --ttl */
			if (*flags & IPT_OSF_TTL)
				exit_error(PARAMETER_PROBLEM, "Can't specify multiple ttl parameter");
			*flags |= IPT_OSF_TTL;
			info->flags |= IPT_OSF_TTL;
			info->ttl = atoi(argv[optind-1]);
			break;
		case '3': /* --log */
			if (*flags & IPT_OSF_LOG)
				exit_error(PARAMETER_PROBLEM, "Can't specify multiple log parameter");
			*flags |= IPT_OSF_LOG;
			info->loglevel = atoi(argv[optind-1]);
			info->flags |= IPT_OSF_LOG;
			break;
		case '5': /* --connector */
			if (*flags & IPT_OSF_CONNECTOR)
				exit_error(PARAMETER_PROBLEM, "Can't specify multiple connector parameter");
			*flags |= IPT_OSF_CONNECTOR;
			info->flags |= IPT_OSF_CONNECTOR;
			break;
		default:
			return 0;
	}

	return 1;
}

static void osf_final_check(unsigned int flags)
{
	if (!flags)
		exit_error(PARAMETER_PROBLEM, "OS fingerprint match: You must specify `--genre'");
}

static void osf_print(const void *ip, const struct xt_entry_match *match, int numeric)
{
	const struct ipt_osf_info *info = (const struct ipt_osf_info*) match->data;

	printf("OS fingerprint match %s%s ", (info->flags & IPT_OSF_INVERT) ? "!" : "", info->genre);
}

static void osf_save(const void *ip, const struct xt_entry_match *match)
{
	const struct ipt_osf_info *info = (const struct ipt_osf_info*) match->data;

	printf("--genre %s%s ", (info->flags & IPT_OSF_INVERT) ? "! ": "", info->genre);
}


static struct xtables_match osf_match = {
    .name		= "osf",
    .version		= XTABLES_VERSION,
    .size		= XT_ALIGN(sizeof(struct ipt_osf_info)),
    .userspacesize	= XT_ALIGN(sizeof(struct ipt_osf_info)),
    .help		= &osf_help,
    .init		= &osf_init,
    .parse		= &osf_parse,
    .print		= &osf_print,
    .final_check	= &osf_final_check,
    .save		= &osf_save,
    .extra_opts		= osf_opts
};


void _init(void)
{
	xtables_register_match(&osf_match);
}