| // SPDX-License-Identifier: GPL-2.0 |
| /* Copyright (C) 2006-2019 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, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #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; |
| } |