/*
* Copyright (C) 2006-2012 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 bat_bitmap_shift_left(unsigned long *seq_bits, int32_t n)
{
if (n <= 0 || n >= TQ_LOCAL_WINDOW_SIZE)
return;
bitmap_shift_left(seq_bits, seq_bits, n, 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 bit_get_packet(void *priv, unsigned long *seq_bits,
int32_t seq_num_diff, int set_mark)
{
struct bat_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 > -TQ_LOCAL_WINDOW_SIZE)) {
if (set_mark)
bat_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 < TQ_LOCAL_WINDOW_SIZE)) {
bat_bitmap_shift_left(seq_bits, seq_num_diff);
if (set_mark)
bat_set_bit(seq_bits, 0);
return 1;
}
/* sequence number is much newer, probably missed a lot of packets */
if ((seq_num_diff >= TQ_LOCAL_WINDOW_SIZE) &&
(seq_num_diff < EXPECTED_SEQNO_RANGE)) {
bat_dbg(DBG_BATMAN, bat_priv,
"We missed a lot of packets (%i) !\n",
seq_num_diff - 1);
bitmap_zero(seq_bits, TQ_LOCAL_WINDOW_SIZE);
if (set_mark)
bat_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. */
if ((seq_num_diff <= -TQ_LOCAL_WINDOW_SIZE) ||
(seq_num_diff >= EXPECTED_SEQNO_RANGE)) {
bat_dbg(DBG_BATMAN, bat_priv,
"Other host probably restarted!\n");
bitmap_zero(seq_bits, TQ_LOCAL_WINDOW_SIZE);
if (set_mark)
bat_set_bit(seq_bits, 0);
return 1;
}
/* never reached */
return 0;
}
