/* Copyright (C) 2006-2013 B.A.T.M.A.N. contributors: * * Simon Wunderlich, Marek Lindner * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. * * 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., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA */ #include "main.h"#include "bitarray.h" #include <linux/bitops.h> /* shift the packet array by n places. */static void batadv_bitmap_shift_left(unsigned long *seq_bits, int32_t n){	if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE)		return; 	bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE);}  /* receive and process one packet within the sequence number window. * * returns: *  1 if the window was moved (either new or very old) *  0 if the window was not moved/shifted. */int batadv_bit_get_packet(void *priv, unsigned long *seq_bits,			  int32_t seq_num_diff, int set_mark){	struct batadv_priv *bat_priv = priv; 	/* sequence number is slightly older. We already got a sequence number	 * higher than this one, so we just mark it.	 */	if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) {		if (set_mark)			batadv_set_bit(seq_bits, -seq_num_diff);		return 0;	} 	/* sequence number is slightly newer, so we shift the window and	 * set the mark if required	 */	if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) {		batadv_bitmap_shift_left(seq_bits, seq_num_diff); 		if (set_mark)			batadv_set_bit(seq_bits, 0);		return 1;	} 	/* sequence number is much newer, probably missed a lot of packets */	if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE &&	    seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) {		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,			   "We missed a lot of packets (%i) !\n",			   seq_num_diff - 1);		bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);		if (set_mark)			batadv_set_bit(seq_bits, 0);		return 1;	} 	/* received a much older packet. The other host either restarted	 * or the old packet got delayed somewhere in the network. The	 * packet should be dropped without calling this function if the	 * seqno window is protected.	 *	 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE	 * or	 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE	 */	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,		   "Other host probably restarted!\n"); 	bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE);	if (set_mark)		batadv_set_bit(seq_bits, 0); 	return 1;}