// SPDX-License-Identifier: GPL-2.0/* Copyright (C) B.A.T.M.A.N. contributors: * * Simon Wunderlich, Marek Lindner */ #include "bitarray.h"#include "main.h" #include <linux/bitmap.h> #include "log.h" /** * batadv_bitmap_shift_left() - shift the sequence number bitmap left * @seq_bits: the sequence number bitmap to shift * @n: number of positions to shift left * * Shift @seq_bits by @n positions. No-op if @n is not within the bounds of * the bitmap. */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 mesh interface information * @seq_bits: pointer to the sequence number bitmap of received packets * @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;}