/*
 *
 * Copyright (c) 2011-2016 The University of Waikato, Hamilton, New Zealand.
 * All rights reserved.
 *
 * This file is part of libprotoident.
 *
 * This code has been developed by the University of Waikato WAND
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libprotoident is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * libprotoident 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */

#include <string.h>

#include "libprotoident.h"
#include "proto_manager.h"
#include "proto_common.h"

/* Rules adapted from l7-filter */
static inline bool match_telnet_pattern(uint32_t payload, uint32_t len) {

        /* Sadly we cannot use a simple MATCH, because we're looking for
         * two 0xff characters, which happens to be the same value as ANY.
         */

        if (len >= 4) {
                if ((ntohl(payload) & 0xff0000ff) != (0xff0000ff))
                        return false;
        }
        else if (len == 3) {
                if ((ntohl(payload) & 0xff000000) != (0xff000000))
                        return false;
        }
        else
                return false;

        if (MATCH(payload, ANY, 0xfb, ANY, ANY))
                return true;
        if (MATCH(payload, ANY, 0xfc, ANY, ANY))
                return true;
        if (MATCH(payload, ANY, 0xfd, ANY, ANY))
                return true;
        if (MATCH(payload, ANY, 0xfe, ANY, ANY))
                return true;

        return false;
}

static inline bool match_atos_telnet(uint32_t payload) {

	/* ATOS seems to be related to ADSL routers, which really shouldn't
	 * be allowing telnet over the public internet */

	if (MATCH(payload, 0x1b, 0x5b, 0x32, 0x4a))
		return true;
	return false;

}

static inline bool match_telnet(lpi_data_t *data, lpi_module_t *mod UNUSED) {

	if (match_telnet_pattern(data->payload[0], data->payload_len[0]))
                return true;
        if (match_telnet_pattern(data->payload[1], data->payload_len[1]))
                return true;

	if (match_atos_telnet(data->payload[0]) && data->payload_len[1] == 0)
		return true;
	if (match_atos_telnet(data->payload[1]) && data->payload_len[0] == 0)
		return true;

	return false;
}

static lpi_module_t lpi_telnet = {
	LPI_PROTO_TELNET,
	LPI_CATEGORY_REMOTE,
	"Telnet", 
	2,
	match_telnet
};

void register_telnet(LPIModuleMap *mod_map) {
	register_protocol(&lpi_telnet, mod_map);
}