/***************************************************************************
 *   Copyright (C) 07/2007 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; version 2 of the License                *
 *                                                                         *
 *   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 <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <sys/socket.h>
#include <linux/netlink.h>

#include "configfile.h"
#include "event.h"
#include "logging.h"
#include "ulogparse.h"

static struct event_fd *nl_event;

#define BUFLEN 65536
static char buf[BUFLEN];

static int netlink_cb(int fd, void *privdata)
{
	int len = recv(fd, buf, BUFLEN, 0);
	if (len <= 0) {
		log_print(LOG_WARN, "netlink_cb(): recv()");
		return 0;
	}

	struct nlmsghdr *nlh = (struct nlmsghdr *)buf;
	if (nlh->nlmsg_flags & MSG_TRUNC || len > BUFLEN) {
		log_print(LOG_WARN, "netlink_cb(): message truncated");
		return 0;
	}

	if (!NLMSG_OK(nlh, BUFLEN)) {
		log_print(LOG_WARN, "netlink_cb(): parse error");
		return 0;
	}

	while (nlh != NULL) {
		parse_ulog_packet(NLMSG_DATA(nlh));

		if (nlh->nlmsg_flags & NLM_F_MULTI && nlh->nlmsg_type != NLMSG_DONE) {
			int remain_len = (len - ((char *)nlh - buf));
			nlh = NLMSG_NEXT(nlh, remain_len);

		} else {
			nlh = NULL;
		}
	}
	return 0;
}

int netlink_init(void)
{
	int fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_NFLOG);
	if (fd == 0) {
		log_print(LOG_ERROR, "netlink_init(): socket()");
		return -1;
	}

	struct sockaddr_nl local;
	local.nl_family = AF_NETLINK;
	local.nl_pid = 0;
	local.nl_groups = 0;
	if (bind(fd, (struct sockaddr *)&local, sizeof(local)) < 0) {
		log_print(LOG_ERROR, "netlink_init(): bind()");
		close(fd);
		return -1;
	}

	socklen_t addrlen = sizeof(local);
	if (getsockname(fd, (struct sockaddr *)&local, &addrlen) < 0) {
		log_print(LOG_ERROR, "netlink_init(): getsockname()");
		close(fd);
		return -1;
	}

	/* second bind with correct pid (assigned from kernel) */
	local.nl_groups = config_get_int("global", "netlink_group", 1);
	if (bind(fd, (struct sockaddr *)&local, sizeof(local)) < 0) {
		log_print(LOG_ERROR, "netlink_init(): bind()");
		close(fd);
		return -1;
	}

	log_print(LOG_INFO, "netlink: listening on group %d", local.nl_groups);

	nl_event = event_add_readfd(NULL, fd, netlink_cb, NULL);
	return 0;
}

void netlink_close(void)
{
	int fd = event_get_fd(nl_event);
	event_remove_fd(nl_event);
	close(fd);
}