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// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2006-2020 B.A.T.M.A.N. contributors:
*
* Simon Wunderlich, Marek Lindner
*/
#include "bitarray.h"
#include "main.h"
#include <linux/bitmap.h>
#include "log.h"
/* shift the packet array by n places. */
static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n)
{
if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE)
return;
bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE);
}
/**
* batadv_bit_get_packet() - receive and process one packet within the sequence
* number window
* @priv: the bat priv with all the soft interface information
* @seq_bits: pointer to the sequence number receive packet
* @seq_num_diff: difference between the current/received sequence number and
* the last sequence number
* @set_mark: whether this packet should be marked in seq_bits
*
* Return: true if the window was moved (either new or very old),
* false if the window was not moved/shifted.
*/
bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits,
s32 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 false;
}
/* 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 true;
}
/* 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 true;
}
/* 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 true;
}
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