/***************************************************************************
 *   Copyright (C) 04/2005 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   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.             *
 ***************************************************************************/
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#include "netpkt.h"
#include "plugin.h"
#include "plugin_helper.h"
#include "logging.h"

struct validnet_entry {
	struct list_head list;
	struct in_addr ip;
	struct in_addr netmask;
};

static LIST_HEAD(validnet_list);

static struct scan_ports port_arr[] = {
	{ 27015, 27024,  1 }, /* cs/hl */
	{ 0, 0, 0 }
};

static char scanmsg1[] = "\xff\xff\xff\xff" "details";
static char scanmsg2[] = "\xff\xff\xff\xff\x54";
static char scanmsg3[] = "\xff\xff\xff\xff" "TSource Engine Query";

static int scan(void)
{
	pkt_send_portarr(NULL, port_arr, scanmsg1, strlen(scanmsg1));
	pkt_send_portarr(NULL, port_arr, scanmsg2, strlen(scanmsg2));
	pkt_send_portarr(NULL, port_arr, scanmsg3, strlen(scanmsg3));
	return 1;
}

static int parse(struct net_pkt *pkt)
{
	struct in_addr tmp;
	int port, count, pos;

	if (!pkt_check_portarr(pkt, port_arr))
		return PARSE_REJECT;

	// check 0xFF 0xFF 0xFF 0xFF
	if (pkt_memcmp(pkt, 0, scanmsg1, 4))
		return PARSE_REJECT;

	/* check for short answer without ip/port */
	if (pkt->size >= 5 && pkt->buf[4] == 'm' && pkt->buf[5] == 0x00) {
		server_add_pkt(1, pkt);
		return PARSE_ACCEPT;
	}

	/* second query?! */
	if (pkt->size >= 5 && pkt->buf[4] == 'I' && pkt->buf[5] == 0x07) {
		server_add_pkt(40, pkt);
		return PARSE_ACCEPT;
	}

	/* parse server IP */
	pos = 5;
	if ((count = pkt_parse_ip(pkt, pos, &tmp)) == 0)
		return PARSE_REJECT;

	/* parse server port */
	pos += count +1;
	if ((count = pkt_parse_int(pkt, pos, &port)) == 0)
		return PARSE_REJECT;

	/* check server IP */
	struct validnet_entry *entry;
	list_for_each_entry(entry, &validnet_list, list) {
		if (((entry->ip.s_addr ^ tmp.s_addr) & entry->netmask.s_addr) == 0) {
			server_add(1, tmp.s_addr, port, 0);
			return PARSE_ACCEPT;
		}
	}

	server_add(1, pkt->addr.sin_addr.s_addr, port, 0);
	return PARSE_ACCEPT;
}

// TODO: wrong place
int parse_ipmask(const char *value, struct in_addr *ip, struct in_addr *netmask)
{

	char *buf = strdup(value);
	if (buf == NULL)
		return -1;

	int retval = -1;
	char *p = strchr(buf, '/');

	/* valid_net x.x.x.x */
	if (p == NULL) {
		/* single ip */
		if (inet_pton(AF_INET, buf, ip) > 0) {
			netmask->s_addr = 0xFFFFFFFF;
			retval = 0;
		}

	/* valid_net x.x.x.x/x.x.x.x or x.x.x.x/xx */
	} else {
		*p = 0x00;

		/* ip */
		if (inet_pton(AF_INET, buf, &ip) > 0) {

			/* x.x.x.x/x.x.x.x */
			if (inet_pton(AF_INET, p+1, netmask) > 0) {
				retval = 0;

			/* x.x.x.x/xx */
			} else {
				int mask = atoi(p+1);

				if (mask >= 0 && mask <= 32) {
					netmask->s_addr = htonl(0xFFFFFFFF << (32 - mask));
					retval = 0;
				}
			}
		}
		*p = '/';
	}
	free(buf);
	return retval;
}

static int init_callback(const char *value, void *privdata)
{
	struct validnet_entry *entry = malloc(sizeof(struct validnet_entry));
	if (entry == NULL) {
		log_print(LOG_ERROR, "halflife_init(): out of memory");
		return -1;
	}

	if (parse_ipmask(value, &entry->ip, &entry->netmask) != 0) {
		log_print(LOG_WARN, "  invalid dst: %s", value);
		free(entry);
		return -1;
	}

	list_add(&entry->list, &validnet_list);
	return 0;
}

static int init(void)
{
	config_get_strings("halflife", "valid_net", init_callback, NULL);
	return 0;
}

struct hlswmaster_plugin plugin = {
	.name		= "halflife",
	.scan		= &scan,
	.parse		= &parse,
	.init		= &init,
};