/*
 * (C) 2006 by Pablo Neira Ayuso <pablo@netfilter.org>
 * 
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "conntrackd.h"
#include <libnfnetlink/libnfnetlink.h>
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
#include <errno.h>
#include "us-conntrack.h"
#include <signal.h>
#include <stdlib.h>
#include "network.h"

int ignore_conntrack(struct nf_conntrack *ct)
{
	/* ignore a certain protocol */
	if (CONFIG(ignore_protocol)[nfct_get_attr_u8(ct, ATTR_ORIG_L4PROTO)])
		return 1;

	/* Accept DNAT'ed traffic: not really coming to the local machine */
	if (nfct_getobjopt(ct, NFCT_GOPT_IS_DNAT)) {
		debug_ct(ct, "DNAT");
		return 0;
	}

        /* Accept SNAT'ed traffic: not really coming to the local machine */
	if (nfct_getobjopt(ct, NFCT_GOPT_IS_SNAT)) {
		debug_ct(ct, "SNAT");
		return 0;
	}

	/* Ignore traffic */
	if (ignore_pool_test(STATE(ignore_pool), ct)) {
		debug_ct(ct, "ignore traffic");
		return 1;
	}

	return 0;
}

static int event_handler(enum nf_conntrack_msg_type type,
			 struct nf_conntrack *ct,
			 void *data)
{
	/* 
	 * Ignore this conntrack: it talks about a
	 * connection that is not interesting for us.
	 */
	if (ignore_conntrack(ct))
		return NFCT_CB_STOP;

	switch(type) {
	case NFCT_T_NEW:
		STATE(mode)->event_new(ct);
		break;
	case NFCT_T_UPDATE:
		STATE(mode)->event_upd(ct);
		break;
	case NFCT_T_DESTROY:
		if (STATE(mode)->event_dst(ct))
			update_traffic_stats(ct);
		break;
	default:
		dlog(STATE(log), LOG_WARNING, "unknown msg from ctnetlink\n");
		break;
	}

	return NFCT_CB_CONTINUE;
}

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/fcntl.h>

int nl_init_event_handler(void)
{
	STATE(event) = nfct_open(CONNTRACK, NFCT_ALL_CT_GROUPS);
	if (!STATE(event))
		return -1;

	fcntl(nfct_fd(STATE(event)), F_SETFL, O_NONBLOCK);

	/* set up socket buffer size */
	if (CONFIG(netlink_buffer_size))
		nfnl_rcvbufsiz(nfct_nfnlh(STATE(event)), 
			       CONFIG(netlink_buffer_size));
	else {
		socklen_t socklen = sizeof(unsigned int);
		unsigned int read_size;

		/* get current buffer size */
		getsockopt(nfct_fd(STATE(event)), SOL_SOCKET,
			   SO_RCVBUF, &read_size, &socklen);

		CONFIG(netlink_buffer_size) = read_size;
	}

	/* ensure that maximum grown size is >= than maximum size */
	if (CONFIG(netlink_buffer_size_max_grown) < CONFIG(netlink_buffer_size))
		CONFIG(netlink_buffer_size_max_grown) = 
					CONFIG(netlink_buffer_size);

	/* register callback for events */
	nfct_callback_register(STATE(event), NFCT_T_ALL, event_handler, NULL);

	return 0;
}

static int dump_handler(enum nf_conntrack_msg_type type,
			struct nf_conntrack *ct,
			void *data)
{
	/* 
	 * Ignore this conntrack: it talks about a
	 * connection that is not interesting for us.
	 */
	if (ignore_conntrack(ct))
		return NFCT_CB_CONTINUE;

	switch(type) {
	case NFCT_T_UPDATE:
		STATE(mode)->dump(ct);
		break;
	default:
		dlog(STATE(log), LOG_WARNING, "unknown msg from ctnetlink");
		break;
	}
	return NFCT_CB_CONTINUE;
}

int nl_init_dump_handler(void)
{
	/* open dump netlink socket */
	STATE(dump) = nfct_open(CONNTRACK, 0);
	if (!STATE(dump))
		return -1;

	/* register callback for dumped entries */
	nfct_callback_register(STATE(dump), NFCT_T_ALL, dump_handler, NULL);

	if (nl_dump_conntrack_table() == -1)
		return -1;

	return 0;
}

static int warned = 0;

void nl_resize_socket_buffer(struct nfct_handle *h)
{
	unsigned int s = CONFIG(netlink_buffer_size) * 2;

	/* already warned that we have reached the maximum buffer size */
	if (warned)
		return;

	if (s > CONFIG(netlink_buffer_size_max_grown)) {
		dlog(STATE(log), LOG_WARNING, 
				 "maximum netlink socket buffer "
				 "size has been reached. We are likely to "
				 "be losing events, this may lead to "
				 "unsynchronized replicas. Please, consider "
				 "increasing netlink socket buffer size via "
				 "SocketBufferSize and "
				 "SocketBufferSizeMaxGrown clauses in "
				 "conntrackd.conf");
		s = CONFIG(netlink_buffer_size_max_grown);
		warned = 1;
	}

	CONFIG(netlink_buffer_size) = nfnl_rcvbufsiz(nfct_nfnlh(h), s);

	/* notify the sysadmin */
	dlog(STATE(log), LOG_INFO, "netlink socket buffer size "
				   "has been set to %u bytes",
				   CONFIG(netlink_buffer_size));
}

int nl_dump_conntrack_table(void)
{
	return nfct_query(STATE(dump), NFCT_Q_DUMP, &CONFIG(family));
}